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If you need the complete document, download the WordPerfect version or Adobe Acrobat version, if available. ***************************************************************** Before the Federal Communications Commission Washington, D.C. 20554 Amendment of Parts 2 and 15 of the) Commission's Rules Regarding Spread) ET Docket No. 96-8 Spectrum Transmitters ) RM-8435, RM-8608, RM-8609 REPORT AND ORDER (Proceeding Terminated) Adopted: April 3, 1997 Released: April 10, 1997 By the Commission: TABLE OF CONTENTS Para. I. INTRODUCTION. . . . . . 1 II. BACKGROUND. . . . . . 2-6 III. DISCUSSION. . . . . .7-69 A. HIGH GAIN DIRECTIONAL ANTENNAS . . . . . 7-21 1. Directional antenna gain limits . . . . .7-15 2. Output power reduction in the 2400 MHz band . . . . . .16-17 3. Ratio of horizontal and vertical antenna beamwidths . . . . . .18 4. Limitations on the operation of high gain antenna systems . . . . . . 19-21 B. MINIMUM NUMBER OF HOPPING CHANNELS. . . . . 22-30 C. ADDITIONAL ISSUES. . . . . . . . . . . . . . 31-63 1. Spectral power density. . . . . . .32-35 2. Definition of direct sequence . . . . . 36-37 3. Definition of pseudorandom sequence and frequency hopping systems . . . . . . 38 4. Short duration transmissions. . . .39-43 5. Measurement of processing gain. . . . . 44-45 6. Limits on unwanted emissions. . . .46-47 7. Frequency hopping coordination. . . . . 48-51 8. External radio frequency power amplifiers . . . . . . . . . . . . . . . . .52-55 9. RF exposure hazards . . . . . . . .56-58 10. Cross border operation. . . . . . .59-61 11. Potential interference to LMS services. . . . . . . . . . . . . . . . . . . . 62 12. Reduction in the number of hopping channels at 2450 MHz and 5800 MHz. . . . . . . . . . . . . 63 D. TRANSITION PROVISIONS. . . . . . . 64-65 IV. PROCEDURAL MATTERS. . . . . . 66-75 V. ORDERING CLAUSES. . . . . . . 76-77 Commenting Parties . . . . . . . . . . . . . . . . . . . . . . . APPENDIX A Final Rules. . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX B Laboratory Measurement Procedure . . . . . . . . . . . . . . . . APPENDIX C I. INTRODUCTION 1. By this action, the Commission is amending Parts 2 and 15 of its rules regarding the operation of spread spectrum transmission systems in the 902-928 MHz, 2400-2483.5 MHz and 5725-5850 MHz bands. Specifically, the Commission is eliminating the limit on directional gain antennas for spread spectrum transmitters operating in the 2450 MHz and the 5800 MHz bands. For spread spectrum transmitters operating in the 2450 MHz band, the Commission is implementing its proposal to require that the output power of the transmitter be reduced by 1 dB for every 3 dB that the directional antenna gain exceeds 6 dBi. The Commission is also reducing, from 50 to 25, the minimum number of channels required for frequency hopping spread spectrum systems operating in the 915 MHz band. It is also adopting a number of amendments to the spread spectrum regulations to clarify the existing regulations, to codify existing policies into the rules, and to update the current definitions. These changes to the rules will facilitate the growth of the spread spectrum industry by enabling and encouraging practical applications for these products. The new rules will expand the ability of equipment manufacturers to develop spread spectrum systems for unlicensed use. These systems will provide users with the flexibility to establish radio links without the delays and costs associated with formal frequency coordination and licensing. Such uses may include intelligent transportation system communications links; high speed Internet connections for schools, hospitals, and government offices; energy utility applications; PCS and cellular backbone connections; and T-1 common carrier links in rural areas. The new rules will also permit frequency hopping spread spectrum systems and wideband, multilateration Location Monitoring Service (LMS) systems to operate within the same frequency band with decreased potential for mutual interference problems. II. BACKGROUND 2. Part 15 of the regulations permits the operation of radio frequency (RF) devices without a license from the Commission or the need for frequency coordination. The technical standards for Part 15 transmission systems are designed to ensure that there is a low probability that these devices will cause harmful interference to other users of the spectrum. Indeed, the primary operating conditions under Part 15 are that the operator must accept whatever interference is received and must correct whatever interference is caused. 3. Spread spectrum communications systems use special modulation techniques that spread the energy of the signal being transmitted over a very wide bandwidth. The information to be conveyed is modulated onto a carrier frequency by some conventional technique, such as AM, FM or digital, and the bandwidth of the signal is deliberately widened by means of a spreading function. This spreading reduces the power density of the signal at any frequency within the transmitted bandwidth, thereby reducing the probability of causing interference to other signals occupying the same spectrum. The spreading technique used in the transmitter is reversed in the receiver to enable detection and decoding of the signal. This reversal of the signal spreading process enables the suppression of strong undesired signals in the receiver. Spread spectrum systems are thus able to tolerate strong nonspread signals with a reduced likelihood of receiving harmful interference. 4. Part 15 authorizes the unlicensed operation of spread spectrum transmitters within the 915 MHz, 2450 MHz and 5800 MHz frequency bands at higher power levels than would normally be permitted for other unlicensed devices. The current regulations limit spread spectrum systems to a maximum peak transmitter output power of one watt. When operating at that power level, the maximum directional gain of the associated antenna may not exceed 6 dBi, resulting in a maximum equivalent isotropically radiated power (EIRP) of four watts, i.e., 6 dBW. Direct sequence systems must employ a minimum bandwidth of 500 kHz with a processing gain of at least 10 dB. Frequency hopping systems in the 915 MHz band must use at least 50 hopping channels with a maximum channel bandwidth of 500 kHz, while hopping systems in the 2450 MHz and 5800 MHz bands must use at least 75 hopping channels with a maximum channel bandwidth of 1 MHz. 5. In the Notice of Proposed Rule Making ("Notice") in this proceeding, the Commission proposed to amend Part 15 of its rules to permit the use of higher antenna gains, without a corresponding reduction in transmitter output power, for spread spectrum transmitters operating in the 5800 MHz band. This proposal was in response to a Petition for Rule Making and Request for Immediate Waiver submitted by Western Multiplex Corporation (WMC). In the Notice, the Commission also proposed to reduce the minimum number of channels required for frequency hopping systems operating in the 915 MHz band from 50 to 25 channels, along with a corresponding reduction in the maximum allowable transmitter output power. This latter proposal was in response to a Petition for Rule Making submitted by SpectraLink Corporation (SpectraLink). On its own motion, the Commission also proposed several additional amendments to Part 15 of the rules regarding the maximum permitted spectral power density for direct sequence spread spectrum systems; the definitions of direct sequence, pseudorandom sequence, and frequency hopping systems; the acceptability of transmitters employing short duration transmissions; the measurement of processing gain; clarification of the limits on unwanted emissions; the coordination of frequency hopping transmitters; and the use of external radio frequency power amplifiers. It further proposed that the changes to the regulations adopted in response to the Notice become effective upon the date of publication in the Federal Register in order to make the benefits resulting from the changes available as soon as possible. Finally, the Commission denied a Petition for Rule Making from Symbol Technologies, Inc. (Symbol) which requested that the minimum number of channels required for frequency hopping systems operating in the 2450 MHz or 5800 MHz bands be reduced from 75 to 20. 6. Comments responding to the proposed changes to the rules were submitted by a number of parties. Generally, these comments were supportive of the Commission's proposals. The commenters also submitted numerous suggestions for improving or modifying the proposed rules. A list of the parties submitting comments is contained in Appendix A. III. DISCUSSION A. High gain directional antennas 1. Directional antenna gain limits. 7. In the Notice, the Commission proposed to eliminate the directional antenna gain limit for non-consumer, fixed, point-to-point spread spectrum systems operating in the 5800 MHz band. The Commission indicated that there were few operators, especially mobile users, in the 5800 MHz band and, thus, the potential for harmful interference that could occur from the use of high gain directional antennas in this band was much lower, as compared to the 915 MHz and 2450 MHz bands. While the Commission stated that it was not inclined to provide a similar relaxation for the 2450 MHz band, comments were requested on whether the directional antenna gain limit could also be eliminated for that band. The Commission declined to propose a similar change to the antenna directional limit for spread spectrum systems operating in the 915 MHz band. 8. In general, the commenting parties support the proposal to eliminate the limit on directional antenna gain in the 5800 MHz band. Cellular companies and utilities, including AT&T Wireless Services (AT&T), Columbia Gas Transmission, Oneonta Telephone Company, Inc. (Oneonta Telephone), Rural Cellular Corporation (Rural Cellular) and others, also support the use of high gain directional antennas. Apple Computer, Inc. (Apple) states that longer-reach unlicensed communications are an important step for the expansion of the Internet and the National Information Infrastructure (NII). Apple adds that unlicensed transmitters employing directional, narrow-beam antennas support the goals of the NII band by enabling rapid setup, lower costs, greater frequency reuse and a higher information capacity. The Telecommunications Industry Association, Fixed Point-to-Point Communications Section (TIA Fixed) was the only party strongly to oppose the Commission's proposal to eliminate the limit on directional antenna gain at 5800 MHz. Specifically, it opposes unlicensed, uncoordinated long-range operations in the 5800 MHz band, arguing that longer path lengths, providing cost-effective, high-speed, large capacity capabilities, are already available in the 18, 23 and 38 GHz band to support the NII on a licensed basis. 9. Many of the commenting parties support permitting the use of high gain directional antennas in the 2450 MHz band. Cylink Corp. (Cylink) and WMC state that, under waivers issued by the Commission, they have been operating systems in the 2450 MHz band with directional antenna gains greater than the 6 dBi limit with no reports of interference. Cylink, Mulcay Consulting Associates (MCA) and WMC argue that limiting the EIRP of spread spectrum devices in the 2450 MHz band may adversely impact the ability of Part 15 devices to share the band with Part 18 ISM devices. WMC states that limiting the EIRP to 6 dBW will cause the received signal level from Part 15 communications transmitters to fall below the background radiation from industrial, scientific and medical (ISM) devices operating under Part 18 of the rules, making these applications unusable. Similarly, Metricom, Inc. (Metricom) states that the greatest potential for interference in the 2450 MHz and 5800 MHz bands is from Part 18 ISM transmissions rather than from Part 15 transmitters. 10. Several parties opposed eliminating the limit on directional antenna gain for the 2450 MHz band. The commenters' primary objections are that the 2450 MHz band is more heavily used than the 5800 MHz band and contains both mobile and fixed users. Cushcraft Corporation (Cushcraft) is concerned that high-gain, fixed point-to-point operations may cause too much interference to systems employing lower gain antennas, such as wireless local area network systems (LANs). Cushcraft adds that the increasing proliferation of mobile and portable users in the 2450 MHz is not compatible with high gain, fixed, point-to-point systems. Fusion Systems Corporation (Fusion) points out that compatibility problems may exist between the primary ISM users and the fixed or mobile communications users in the 2450 MHz band. Fusion recommends adopting rules that caution manufacturers and users operating in any of the ISM bands that in-band interference may be intolerable unless susceptibility standards, similar to those currently employed in Europe, are applied to their systems. Fusion Lighting, Inc. (Fusion Lighting) raised identical concerns. 11. Based on the comments received, the Commission is amending its regulations to eliminate the existing transmitter output power penalty for Part 15 spread spectrum systems operating with high gain directional antennas in the 2450 MHz and 5800 MHz bands. The Commission recognizes the advantages of being able readily to establish radio links capable of transmission distances of 10 km, or greater, without the delays and costs associated with formal frequency coordination and licensing. The ability to establish quickly such transmission links could be critical in emergency situations. Directional antennas can significantly reduce the potential for harmful interference to other radio operations in cases where the location of the directional systems is coordinated and there is a low preponderance of mobile systems. When dealing with fixed radio applications, the use of directional antennas can be particularly important in allowing nearby fixed radio systems to co-exist within the same frequency band. Radio systems located outside the directional beam of the antenna pattern have a low probability of receiving interference. However, radio systems that are located in the main beam of the directional antenna will have a much higher potential for receiving interference, in particular because of the higher signal levels caused by the antenna gain. Thus, mobile systems are particularly susceptible to interference from fixed stations since they can move into the main beam of the fixed station. 12. There are a significant number of mobile operations in the 915 MHz band. It was for this reason that the Commission decided not to eliminate the antenna gain limits for the 915 MHz band. Similarly, the number of mobile applications has continued to increase in the 2450 MHz band. The 2450 MHz band is allocated for ISM devices under Part 18 of the rules, U.S. Government stations, the Private Land Mobile Radio Services under Part 90, the Private Operational-Fixed Microwave Services under Part 94, Television Broadcast Auxiliary Stations under Part 74, and the Amateur Radio Service under Part 97. The primary increase in the number of number of licensed mobile units is from surveillance and other systems operating under the Public Safety Radio Services under Part 90. Further, as in the 915 MHz band, the number of Part 15 systems appearing in the 2450 MHz band is continuing to increase, especially for devices such as wireless local area network systems. Accordingly, the Commission was not inclined in the Notice to eliminate the limit on directional antenna gain for this band. However, as indicated by WMC, the 2450 MHz band has a significant background noise level, primarily from the operation of microwave ovens and other ISM devices. Further, while the background noise level for the 5800 MHz band is not as high as the 2450 MHz band, this noise level is expected to increase as the cost of equipment in the 5800 MHz band continues to decline due to improvements in technology and the number of users in this band increase. The use of directional antennas will help transmission systems to overcome these noise levels in both bands, permitting their use by important communication services. Accordingly, the Commission believes that the limit on directional antenna gain could be relaxed for both the 2450 MHz and 5800 MHz bands without substantially increasing the potential for harmful interference to the licensed radio services. However, as discussed in the next section, the Commission also believes that some corresponding reduction in the transmitter output power is necessary for transmitters operating in the 2450 MHz band. 13. The Commission does not agree with Fusion that additional regulations should be adopted cautioning manufacturers and users that in-band interference may be intolerable unless susceptibility standards are applied to their systems. A note at the end of the spread spectrum rule section already advises that potential interference may occur from other operations in these frequency bands. In addition, the transmitters must already be labelled with a statement that operation under Part 15 is not protected against harmful interference. Further, the Commission has chosen not to establish susceptibility standards under its regulations for other Part 15 products, but has allowed industry to develop these standards as necessary. Further, the Commission's authority to establish susceptibility standards is limited to home electronic equipment and systems. The majority of the spread spectrum systems, especially those systems employing directional antennas, are not classified as home electronic equipment. 14. The manufacturers and operators of spread spectrum transmitters are reminded that the operation of Part 15 devices is subject to the conditions that any received interference, including interference from ISM operations, must be accepted and that harmful interference may not be caused to other radio services. Should the operation of these systems cause harmful interference, the operator of the Part 15 system is required to correct the interference problem, even if such correction requires the cessation of operation of the Part 15 transmitter. The Commission will not exempt Part 15 devices from this latter requirement because of the application for which the Part 15 transmitter is employed. Thus, the Commission strongly recommends that utilities, cellular stations, public safety services, government agencies and others that employ Part 15 transmission systems to provide critical communication services should exercise due caution to determine if there are any nearby radio services that could be affected by their communications. 15. Finally, American Petroleum Institute (API) requests the Commission to clarify that users are permitted to increase the transmitter power or antenna gain to account for transmission line loss. The Commission already permits manufacturers of systems that must use long transmission lines to measure transmitter output at the connection between the transmission line and the antenna. This permission, however, is done on a case-by-case basis and must be justified during the certification procedure. Generally, the manufacturer must be able to demonstrate that the system will be professionally installed and that the design or placement of the equipment requires the use of long transmission lines. In certain cases, external radio frequency power amplifiers, as discussed below, can be incorporated as part of the system design and authorized under the certification procedure in order to offset the effect of long transmission lines. Manufacturers should note that increases to the output power of a transmitter beyond what was authorized under certification normally requires a new application for, and grant of, certification. Further, the antennas employed with a spread spectrum transmitter must be certified as part of the system. 2. Output power reduction in the 2400 MHz band. 16. The Commission proposed that the output power of a transmitter be decreased by 1 dB for every 3 dB that the antenna gain exceeds 6 dBi in order to maintain an "equivalent" area of interference, i.e., the geographic area over which interference could result with a directional antenna as compared to the area obtained with an omnidirectional antenna. Comments regarding this proposal were mixed. Adtran, API, Digital Wireless Corporation (Digital Wireless) and Rockwell International Corporation (Rockwell) support the proposed power reduction. Adtran agrees that the proposed power reduction will provide an equivalent area of potential interference between point-to- point systems using high gain antennas and systems employing an omnidirectional antenna operating at the current maximum EIRP of 6 dBW. API states that it supports this method for limiting the equivalent area of interference for both the 2450 MHz and 5800 MHz bands. Equipment manufacturers in general and many users believe that such a reduction in power is unnecessary and would restrict the use of the systems. Cylink believes that the reduction in power will preclude many uses due to a loss of range and reliability and recommends letting the market forces for frequency reuse determine the technical system design decisions. 17. The Commission recognizes that there is a potential that licensed services could receive harmful interference from ISM devices operating in the 2450 MHz and 5800 MHz bands. However, all radio services operating in these bands are required to accept whatever level of interference is received from ISM devices. On the other hand, Part 15 devices are secondary to all other radio operations. Accordingly, the Commission remains concerned that increases in the proliferation of high powered spread spectrum systems operating in the 2450 MHz band could exacerbate interference problems, especially to the large number of mobile licensees in the Public Safety Radio Services under Part 90 of the regulations. The upper portion of the 2450 MHz band is the only portion of the radio spectrum allocated to the Part 90 Private Land Mobile Radio Services that permits wide bandwidth mobile operation. This wide bandwidth is critical for the operation of police surveillance systems and other functions, such as video links used with bomb disposal systems. In addition, the lower portion of the 2450 MHz band is used for mobile operations by the U.S. Government and by the Amateur Radio Service under Part 97 of the rules. In addition, the Commission has already recognized the extensive applications being developed for Part 15 devices. These Part 15 devices would be used for a variety of consumer and business oriented applications, including wireless LANs, automatic meter reading systems, telephones, broadband access to Internet services, video conferencing, health care monitoring, and traffic light control. In order to lower the probability of harmful interference to these operations, the Commission believes that it is necessary to implement its proposal to decrease the output power of a spread spectrum transmitter operating in the 2450 MHz band by 1 dB for every 3 dB that the antenna gain exceeds 6 dBi. This action will ensure that the area over which harmful interference can occur is equivalent to what would be caused by a spread spectrum system employing an omnidirectional antenna and operating at the current maximum EIRP of 6 dBW. While this minimal reduction in transmitter output power with the use of high gain antennas may cause some decrease in transmission range, the higher gain antenna will still provide amplification of received signals while minimizing interference potential. The Commission is not implementing its proposal to reduce the output power of a transmitter operating in the 5800 MHz band. In addition to the scarcity of mobile units in the 5800 MHz band, the different propagation characteristics at 5800 MHz and the increased attenuation due to terrain and other intervening objects should be sufficient to reduce potential interference to the licensed radio services. 3. Ratio of horizontal and vertical antenna beamwidths. 18. The Commission also proposed that the 3 dB beamwidths of the high gain directional antennas employed with these fixed, point-to-point systems differ by no more than a factor of two between the vertical and the horizontal planes. It indicated that this could reduce potential interference problems due to excessive emissions in the vertical or horizontal plane resulting from the antenna design. Adtran and Digital Wireless were the only parties to support the proposal, believing that it would minimize cross-interference, resulting in a "win-win" situation for point-to- point and mobile users. Cushcraft, Cylink, the Part 15 Coalition and WMC believe that the requirement is an unnecessary regulation. Cushcraft, an antenna manufacturer, believes that the majority of antennas already meet this criterion. Cylink opposes the proposal because it may prevent applications that require a different antenna design, such as communications to off-shore platforms. The Commission agrees with the latter commenters that this portion of its proposal is unnecessary, and it will, therefore not adopt this proposal. 4. Limitations on the operation of high gain antenna systems. 19. The Commission proposed to apply several conditions to the operation of spread spectrum systems employing high gain directional antennas. First, the operation of these systems would be limited to fixed, point-to-point applications. Second, point-to-multipoint systems, omnidirectional applications and multiple co-located transmitters transmitting the same information would be prohibited. Third, the operator of a spread spectrum system would be responsible for ensuring that the system is operated in this manner. Fourth, the manual supplied with the spread spectrum transmitter must contain language in the installation instructions notifying the operator of this responsibility. Fifth, the marketing of spread spectrum systems employing high gain directional antennas would be limited to commercial or industrial operators, and sales to the general public would be prohibited. 20. Comments supporting these proposals were received from several parties, including Apple, AT&T, Columbia Gas, OCOM Corporation (OCOM), and Rockwell. Multipoint Networks, in late filed comments, requests that 5800 MHz spread spectrum transmitters be permitted for point- to-multipoint applications as long as directional antennas are employed. It states that the combination of sectored antennas at a central site, along with directional antennas at remote sites, can limit the total interference potential caused by a point-to-multipoint system to levels well below the interference potential caused by the larger number of point-to-point links that would otherwise be required. Rockwell, while opposed to the use of high gain antennas in the 2450 MHz band, recommends that the installation of high gain antennas in the 5800 MHz band could be limited to the equipment authorization grantee or entities contracted by the grantee. Apple asks for clarification that the restriction to commercial and industrial users does not exclude municipalities, health care and educational institutions. 21. The Commission is adopting its proposals from the Notice. It does not agree with Multipoint Networks that point-to-multipoint applications should be permitted for systems employing high gain directional antennas with EIRPs greater than 4 watts. The use of multiple or sectored antennas to provide point-to-multipoint coverage can significantly increase the potential for harmful interference to other radio service by providing what appears, in effect, to be omnidirectional coverage but with a significant increase in EIRP. The potential for harmful interference is reduced by restricting these systems, as proposed in the Notice, to point-to-point applications and prohibiting point-to-multipoint systems, omnidirectional antennas or multiple co- located transmitters transmitting the same information. As proposed by the Commission in the Notice, the operator of the spread spectrum system or, if the equipment is professionally installed, the installer will be responsible for ensuring that the system is operated in this manner; however, the manual supplied with the spread spectrum transmitter must contain language in the installation instructions notifying the operator and the installer of this responsibility. These provisions will lower the potential for high signal level spread spectrum systems to cause harmful interference by limiting the proliferation of these systems and by strongly encouraging professional installations. The Commission no longer agrees that the regulations need to limit the marketing of 2450 MHz or 5800 MHz systems employing high gain directional antennas and high EIRPs to commercial or industrial applications or that sales to the general public need to be specifically prohibited. The use of these systems are already restricted to fixed, point-to-point applications, and the type of antennas employed generally require professional installation. These features should be sufficient to reduce the potential for harmful interference to other radio services without additional restrictions being placed on the marketing of the equipment. B. Minimum number of hopping channels 22. In the Notice, the Commission proposed to reduce the minimum number of non- contiguous channels that must be employed by a frequency hopping spread spectrum system in the 915 MHz band from 50 channels to 25 channels. This reduction in the number of hopping channels would enable frequency hopping spread spectrum systems to avoid operations on frequencies used by wideband, multilateration LMS systems, reducing mutual interference problems. In order to keep the interference potential from increasing due to the reduced number of hopping channels, the Commission also proposed that frequency hopping spread spectrum transmission systems operating with less than 50 channels employ channel bandwidths of at least 250 kHz and operate at a reduced power level. Further, the maximum average time of occupancy on any hopping frequency for transmitters using less than 50 hopping channels would be increased to 0.4 seconds in any 10 second period. 23. The Commission requested comments as to whether the rules should specify a formula for the minimum number of hopping channels based on the amount by which the bandwidth of the hopping channel exceeds 250 kHz. It stated that the use of this formula would result in an even distribution of the hopping channels over that portion of the 915 MHz band that is not employed by wideband multilateration LMS systems. This would prevent frequency hopping systems employing between 250 kHz and 500 kHz bandwidth hopping channels from being concentrated in any single portion of the 915 MHz band. 24. Because the smaller number of hopping channels would increase the potential for interference, the Commission proposed to require that frequency hopping spread spectrum systems in the 915 MHz band that use fewer than 50 hopping channels operate with a maximum peak transmitter output power of 500 mW. However, the Commission indicated that, while the potential for harmful interference can be offset by a reduction in operating power, a linear reduction may not be sufficient to provide this offset. It recognized that the chance of collisions with other transmissions, and resulting interference, would be increased since there are a fewer number of hopping channels resulting in a change to the average time of occupancy on any frequency and the crowding of transmissions into less spectrum. Accordingly, comments were requested as to whether or not a greater reduction in output power should be applied. Comments were also requested on whether a limit on spectral power density, similar to that currently applied to direct sequence systems, should be applied to frequency hopping systems operating with fewer than 50 hopping channels. 25. Most of the commenting parties support the proposal to reduce the minimum number of required channels employed by frequency hopping spread spectrum systems in the 915 MHz band from 50 to 25 channels. The commenters agree that reducing the minimum number of hopping channels will help Part 15 devices to avoid frequencies used by wideband multilateration LMS systems. Ericsson Corporation (Ericsson) and Teletrac License, Inc. (Teletrac) request further restrictions to require frequency hopping systems using less than 50 channels to avoid using LMS spectrum. Teletrac proposes that frequency hopping systems using fewer than 50 channels be restricted from using the LMS sub-bands to occupy more than 50 percent of their needed bandwidth. Teletrac adds that frequency hopping spread spectrum systems that employ at least 50 hopping channels should continue to be presumed not to be a source of harmful interference to multilateration LMS systems, but that this presumption should not apply to systems that employ less than 50 hopping channels and use any channels in the multilateration LMS bands. Digital Wireless strongly opposes Teletrac's proposal, stating that frequency hopping systems should not be restricted from using spectrum in areas where there are no LMS users or only partial use of the spectrum by LMS systems. The International Microwave Power Institute (IMPI) is the only party to oppose a reduction in the number of channels because it is concerned that frequency hopping systems operating in a narrower band may be more susceptible to interference from ISM devices. 26. Apple, Digital Wireless and SpectraLink support the adoption of simple, unambiguous rules rather than limits based on a complex formula. While the commenting parties also support a reduction in power for systems using fewer than 50 channels, the comments vary on the appropriate method and level of reduction. Adtran, Itron, Inc. (Itron), the Part 15 Coalition and SpectraLink support adoption of the proposed 500 mW limit. Ericsson believes that the power limit should be reduced to 100 mW rather than 500 mW. Metricom recommends adopting a 250 mW output limit. Rockwell and Telecommunications Industry Association, Wireless Consumer Communications Section (TIA Wireless) recommend using formulas that relate the power limit to the number of hopping channels. TIA Wireless submitted the only detailed technical analysis relating the interference potential of a frequency hopping system to the number of hopping channels and the transmitter output power. The formula developed by TIA Wireless indicates that a frequency hopping system using 25 hopping channels should have a transmitter output limit of 250 mW in order for the interference potential to be no greater than that of a 50 channel system operating with a transmitter output power of 1 W. RAMAR Technology, Ltd. (RAMAR) believes a power density limit should be applied to frequency hopping transmitters. 27. The Commission agrees with the comments that the minimum number of hopping channels for spread spectrum systems operating in the 915 MHz band should be reduced from 50 to 25 channels for frequency hopping systems employing hopping channels bandwidths of at least 250 kHz. A corresponding change to the average time of occupancy on any hopping frequency, as proposed in the Notice, is also being adopted to accommodate the smaller number of hopping channels. Adoption of these proposals will allow a reduction, from 25 MHz to 12.5 MHz, in the spectral occupancy of frequency hopping spread spectrum systems operating at the maximum channel bandwidth. By decreasing the number of frequency hops, the users of Part 15 spread spectrum systems can avoid operating in the frequency bands employed by wideband multilateration LMS systems and, thereby, reduce mutual interference problems. Part 15 spread spectrum transmitters operating in the 915 MHz band under certain, specified conditions already are presumed not to be a source of harmful interference to wideband multilateration LMS systems; however, it is to the benefit of the spread spectrum operators to avoid using the wideband multilateration LMS channels in order to reduce the potential for received interference. The resulting reduction in the spectral occupancy of the wideband multilateration LMS channels by spread spectrum systems will maximize spectral efficiency by increasing the number of Part 15 devices and LMS users that can coexist in the band. This should facilitate the future deployment of frequency hopping systems in the 915 MHz band. 28. The Commission does not agree with Teletrac that limitations should be placed on spread spectrum signals occupying the LMS sub-bands. As stated by Digital Wireless, there are areas within the U.S. where the wideband multilateration LMS channels are not being used or are only partially used. Further, as indicated above, Part 15 spread spectrum transmitters complying with the conditions in Section 90.361 of the rules are already presumed not to be a source of harmful interference to wideband multilateration LMS systems. Accordingly, there is no basis for prohibiting the operation of spread spectrum systems in the wideband multilateration LMS channels. It is, however, to the benefit of the spread spectrum operator to avoid operating on these LMS channels, as indicated above. 29. The Commission agrees with the comments that simple, unambiguous rules, rather than several different limits based on formulas, are appropriate, and is so amending its regulations. The Commission also agrees with the technical analysis presented by TIA Wireless that the peak output power of a spread spectrum transmitter operating with less than 50 hopping channels should be reduced to 250 mW with a maximum directional antenna gain of 6 dBi. As shown by TIA Wireless, this change is necessary to avoid increasing the interference potential of frequency hopping spread spectrum systems operating with a reduced number of hopping channels. Accordingly, the regulations are being amended to adopt a peak transmitter output limit of 250 mW for frequency hopping spread spectrum systems operating with less than 50 hopping channels. 30. Finally, the Commission noted that a number of petitions for reconsideration had been received in response to the recent Report and Order implementing the LMS systems. It indicated that any changes to the LMS rules in response to those petitions could result in modifications to the amendments that were proposed in the Notice for Part 15 spread spectrum operation in the 915 MHz band. Adtran, Lucent Technologies Inc. (Lucent), Metricom, the Part 15 Coalition and TIA Wireless oppose any changes to Part 15 rules in this proceeding based on changes made to the LMS regulations. Lucent states that there is no need to link Part 15 rules with LMS rules. Metricom and the Part 15 Coalition state that parties must be given an opportunity to make comments under the Administrative Procedure Act and that no changes to the spread spectrum rules based on changes to the LMS regulations should be made without a new rule making. The Commission concurs with the comments that these changes to the regulations should not be linked to future possible changes to the LMS regulations under Part 90 of the rules. C. Additional issues 31. The Notice contained several additional proposals to clarify, codify or amend the regulations concerning Part 15 spread spectrum transmission systems. These are discussed below. 1. Spectral power density. 32. When the rules for direct sequence systems were modified in 1990, a specification was added for maximum spectral power density. As stated in the 1990 Report and Order, the standard on spectral power density was intended to ensure that the transmitted energy is uniformly spread over the minimum channel bandwidth of 500 kHz in order to limit interference to other systems in this band. At the maximum output power level of one watt, this equates to a limit of 8 dBm in any 3 kHz band. However, the one watt output power on which the limit on spectral power density is based is a peak limit, whereas the spectral power density standard was incorrectly stated in the rules as an average limit. Accordingly, the Commission proposed to change the reference in the rules to the maximum spectral power density from an average limit to a peak limit. The measurement procedure was further described in Appendix C of the Notice. 33. In their comments, Adtran and Digital Wireless indicated that changing the rule to specify a peak spectral power density limit might be in conflict with the reference in Appendix C of the Notice to the noise density function as an acceptable means of measuring systems with no resolvable spectral lines. They support using the noise density function but recommend further clarification to avoid confusion. Rockwell agrees with the Commission's reasons for imposing a power spectral density limit but believes there are problems with using a peak limit. It proposes using an 8 dBm RMS limit and proposes a measurement procedure using the spectrum analyzer noise density function. Rockwell also notes that there is in error in the correction factor applied for the measurement of noise density function. 34. The Commission is adopting its proposal to specify the limit on spectral power density as a peak limit. It does not agree with the comments that there is a conflict with the noise density measurement nor does it agree with Rockwell that the rules should specify a limit on spectral power density of 8 dBm RMS. On the first issue, the spectral power density is normally measured with the analyzer bandwidth setting adjusted to permit resolution of the individual spectral components. With such a measurement, the peak levels being measured are the same as average measurements. The noise density is measured only during the infrequent occurrence when the individual spectral components can not be resolved. Under this specific test condition, the Commission recognizes that no instrumentation is available that is capable of measuring peak noise. Thus, an average measurement must be accepted, but only under this extenuating circumstance. With regard to Rockwell's concern, measurements obtained from a spectrum analyzer operating in the peak detection mode are in reality the RMS measurements sought by Rockwell. The specification in the rules of a peak limit, combined with the measurement procedure in Appendix C, merely ensures that parties making these measurements do not further average the obtained measurements. 35. The Commission notes that all spread spectrum transmitters previously authorized comply with the peak spectral power density limit being adopted and that this change to the rules should not impact any systems. The Commission is also correcting the error in the measurement procedure for direct sequence systems, as shown in Appendix C. The current procedure states that, when measuring spectral power density where the spectrum line spacing can not be resolved, the noise density function on most modern conventional spectrum analyzers will directly measure the noise power density normalized to a 1 Hz noise power bandwidth. If further states that 30 dB should be added for correction to a 3 kHz bandwidth. The proper correction factor is 10 * log (3 kHz/1 Hz) dB which equals 34.8 dB. 2. Definition of direct sequence. 36. The definition of direct sequence spread spectrum systems contained in the rules has become outdated. For example, the incoming information is always digitized but is not necessarily modulo 2 added to the higher speed code (spreading) sequence. The Commission proposed to amend the existing definition to simplify it and to make it more compatible with existing product designs. The definition proposed in the Notice was: "a spread spectrum system in which the carrier has been modulated by a high speed spread code and an information data stream. The high speed code sequence dominates the 'modulating function' and is the direct cause of the wide spreading of the transmitted signal." Comments in support of this new definition were received from Adtran, Apple, and Rockwell. Rockwell requests that language be added to ensure the independence of the high speed spreading code from the modulation technique, such as TDMA or FDMA. Rockwell believes that such language would ensure that systems do not partially rely on the modulation of the data stream to meet the processing gain requirement. 37. The Commission does not agree with Rockwell that the definition needs to be modified to ensure that the ability to meet the processing gain requirement does not encompass a modulation technique applied to the data stream. The definition already states that the spreading code, and not the modulation applied to the data stream, is directly responsible for the wide spreading of the transmitted signal. Further, the processing gain is determined based on the ratio of the signal-to- noise of the received signal both with and without the spreading code applied. Thus, the modulation technique applied to the data stream should not affect the measured processing gain. Accordingly, the Commission is adopting the definition proposed in the Notice. 3. Definition of pseudorandom sequence and frequency hopping systems. 38. The current definition of a pseudorandom sequence is used to establish standards for frequency hopping systems. However, the wording of this definition has caused considerable confusion in industry as to exactly how a frequency hopping system must be designed to ensure that the system meets the pseudorandom sequence definition. In the Notice, the Commission proposed to simplify the standards by eliminating the definition of pseudorandom sequence and by amending the definition of frequency hopping systems to include a simple description of the required hopping sequence. The definition of a frequency hopping system proposed in the Notice was: "a spread spectrum system in which the carrier is modulated with the coded information in a conventional manner causing a conventional spreading of the RF energy about the frequency carrier. The frequency of the carrier is not fixed but changes at fixed intervals under the direction of a coded sequence. The wide RF bandwidth needed by such a system is not required by spreading the RF energy about the carrier but rather to accommodate the range of frequencies to which the carrier frequency can hop. The test of a frequency hopping system is that the near term distribution of hops appears random, the long term distribution appears evenly distributed over the hop set, and sequential hops are randomly distributed in both direction and magnitude of change in the hop set." General supporting comments for this new definition were received from Adtran and Apple. The Commission agrees with the comments and is adopting this change to the rules, as proposed in the Notice. 4. Short duration transmissions. 39. As indicated in the Notice, the Commission has received a number of applications for frequency hopping systems that transmit only for short periods of time. Most of these systems can transmit all necessary information using a single transmission, i.e., without the need to hop to a second frequency. These applicants request inclusion under the spread spectrum rules in order to be allowed to use transmitters with an output power of one watt. 40. The current rules and definitions require that a spread spectrum system, consisting of both the transmitter and the receiver, must be designed to act as a frequency hopping system, should the transmitter be presented with a data stream longer than that which could be completed in a single hop. The Commission proposed to leave these criteria intact, requiring that products being authorized as frequency hopping systems be capable of acting as frequency hopping systems. However, it requested comments on these issues and indicated that it would consider proposals for alternative approaches to the existing regulations that would facilitate or prohibit the operation of short duration transmission systems under the spread spectrum frequency hopping regulations. 41. Many of the commenting parties, including API, Cylink, Master Lock Company (Master Lock) and Metricom, recommend that the Commission retain the requirement that frequency hopping systems must be capable of hopping. API states that maintaining the requirement that systems authorized as frequency hoppers actually be capable of hopping will prevent the proliferation of technically-inferior, single frequency radios. Metricom states that short hop systems must comply with Section 15.247 rules or else they could cause problems with spread spectrum systems. However, it also believes that systems employing short duration transmissions that are capable of hopping should not be precluded. 42. Itron supports permitting short duration systems and recommends eliminating the requirement for transmitter/receiver hopping channel synchronization for systems with channel occupancy of less than 400 ms. The Itron meter-reading system uses a bank of parallel receivers that detect messages transmitted from the meters being read. Further, Itron recommends that there be no minimum requirement on the number of frequency hops during any one transmission, provided that there is a minimum of 25 or 50 total hopping frequencies in the system, the minimum channel spacing requirements are maintained, and the transmitter utilizes all frequencies in a pseudorandom sequence uniformly over time. CellNet Data Systems (CellNet) recommends retaining a requirement for transmitter and receiver synchronization. Alternatively, CellNet and the Part 15 Coalition support the use of a parallel receiver architecture, as proposed by Itron, but maintain that the transmitter and receiver should have the same number of channels and the same bandwidth. Lucent believes that it is unnecessary to change the rules at this time to permit short duration systems. It states that there are only a limited number of proposed systems at this time and that they should be addressed individually under the waiver process. 43. As stated in the Notice, a frequency hopping system only exhibits the characteristics of a spread spectrum system, i.e., a low propensity to cause interference and a relatively high tolerance of interference from other sources, when it hops to multiple channels. Consequently, a transmission that does not hop also does not exhibit any of the characteristics of a spread spectrum system, e.g., processing gain exhibited by the receiver. Thus, absent processing gain, a system employing short transmission bursts must transmit at higher power levels than would be required by a spread spectrum system, increasing the potential for harmful interference to other users. Because of this risk of increased interference, the Commission sees no justification at this time for permitting the higher power levels currently available for spread spectrum systems to be employed by systems that do not employ spread spectrum modulation techniques. The Commission is, however, amending the regulations to clarify that short duration transmission systems are permitted provided the systems are capable of complying with all of the standards should the system be presented with a continuous data or information stream. This equipment, when operating with the short transmission bursts, must also comply with the definition of a frequency hopping system and must distribute its transmissions over the minimum number of hopping channels specified in the regulations. 5. Measurement of processing gain. 44. Under the rules, direct sequence systems are required to exhibit a processing gain of at least 10 dB. This processing gain is determined from the ratio in dB of the signal-to-noise ratio with the system spreading code turned off and the signal to noise ratio with the system spreading code turned on, as measured at the demodulated output of the receiver. The standard for a minimum processing gain was established to ensure that a system is, in fact, spread spectrum in nature. Absent this standard, there is a strong potential for abuse of the Part 15 spread spectrum provisions. However, in the Notice the Commission noted that this method of measurement does not always work since many equipment designs do not provide an ability to turn off the system spreading code. In these cases, an indirect measurement of processing gain, based on the receiver jamming margin, is permitted. Some manufacturers have indicated that processing gain could be based on the ratio of the chipping (spreading) rate to data rate; however, this method would calculate the maximum possible gain assuming a perfect receiver, whereas the actual gain achieved may be significantly less. The actual processing gain is dependent on the design of the complete spread spectrum system, including the receiver. For this reason, the Commission believes it is necessary to require a demonstration of the improvement in received signal-to-noise ratio produced by the spreading/despreading process. Thus, in the Notice the Commission proposed to incorporate the measurement procedure shown in Appendix C into the regulations to provide an alternative method of measuring processing gain. Interested parties were invited to comment on this proposal and to submit suggestions for alternative methods of measuring the processing gain of the complete spread spectrum system. 45. General comments supporting the proposal to incorporate into the rules an alternative method of measuring processing gain were received from Adtran, Apple, Digital Wireless, Microwave Data Systems (MDS), and the Part 15 Coalition. Adtran and Digital Wireless believe the two alternative procedures contained in the Notice are nearly equivalent and will preclude the approval of non-compliant systems. The Commission agrees with these comments and is amending the rules, as proposed. 6. Limits on unwanted emissions. 46. The current regulations require that all spurious emissions outside of the frequency band employed by the spread spectrum transmitter be attenuated as follows: 20 dB for emissions produced by the modulation products of the spreading sequence, the information sequence, and the carrier; and, the general limits in 47 CFR Section 15.209 for all other emissions. This regulation has caused some confusion to equipment manufacturers regarding the proper attenuation limits for specific spurious signals and whether these limits are based on radiated emissions or emissions conducted to the antenna. In addition, many applicants appear to be unaware that the attenuation requirements for emissions appearing in the restricted bands also apply to spread spectrum transmitters. Thus, in the Notice the Commission proposed to simplify the existing standards by stating that all emissions outside of the frequency band employed by the spread spectrum transmitter, except for emissions within the restricted bands, must be attenuated by at least 20 dB. It further proposed to clarify these requirements by stating that demonstration of compliance with this 20 dB emission standard can be based on RF antenna conducted or radiated measurements. Finally, it proposed to reference in the spread spectrum rules the requirements for the attenuation of radiated emissions in the restricted bands. Since the limits for emissions appearing in the restricted bands are expressed in terms of the field strength of the signals, emission levels in these bands must always be determined based on radiated emission measurements. 47. The comments from Adtran, Apple, Digital Wireless, MDS, and the Part 15 Coalition supported the proposal in the Notice. The Commission received no opposition to this proposal. It agrees with the comments and believes that this change to the regulations will provide needed simplification and clarification to the rules. Accordingly, the Commission is adopting the changes to the regulations, as proposed. 7. Frequency hopping coordination. 48. Prior to issuance of the Notice, several manufacturers requested authorization of frequency hopping systems that contain intelligence to recognize other users within the spectrum band and avoid hopping on occupied channels. Under the current rules, coordination between hopping transmitters is not normally permitted since this would easily allow an operator of multiple transmitters to monopolize the spectrum in a given location. Further, the resulting greater average occupancy of spectrum from a coordinated system could increase the interference potential to other services, undermining the Commission's intent to establish spread spectrum standards to facilitate spectrum sharing. In the Notice, the Commission proposed to permit the operation of frequency hopping spread spectrum systems that individually and independently choose and adapt their hopsets to react to the environment in which the system is operating, moving themselves out of the way should another user come on the air in the same band. 49. Adtran, Apple, Digital Wireless, Part 15 Coalition, and Rockwell supported the proposal in the Notice. Apple believes that the coordination provision should be permitted in the 915 MHz, 2450 MHz and 5800 MHz bands. Adtran and Digital Wireless state that the Commission should address the situation of collocated transmitters to prevent virtual synchronization and may wish to limit the number of collocated adaptive systems. Digital Wireless requests that adaptive hopsets be permitted, where the number of hops may drop below the minimum number in order to avoid collisions with another system. Master Lock states that if a system is designed to drop a channel from the hopset because it is in use, then the rules should require that dropped channel be reassessed within 20 seconds and either be reinstated or replaced by another channel in order to maintain the minimum number of required channels. 50. Tadiran Telecommunications, Inc. (Tadiran) states that coordinated transmitters should be permitted provided the transmitters are isolated from one another by means of physical separation or antenna directivity, or if the number of coordinated transmitters is small. Lucent opposes Tadiran's request to permit coordination among collocated transmitters and asks that the Commission clarify that centralized coordination of systems is not allowed. Lucent supports the Commission's coordination proposal but asks for clarification that the coordination is between a single transmitter- receiver pair engaged in communication. Further, Lucent believes it is unnecessary to limit the number of collocated transmitters provided each transmitter independently adapts its hopping sequence. Metricom asks that the Commission clarify that the prohibition against the coordination of frequency hopping systems applies only to intrasystem coordination and does not restrict a transmitter's ability to avoid occupied channels. 51. The proposal in the Notice that would permit coordination between intelligent frequency hopping transmitters would not result in an increase in interference potential to other users of the spectrum. Such systems are able to detect interfering sources, both from other spread spectrum transmitters and from other radio services, and avoid operating on occupied portions of the spectrum. By avoiding operation on frequencies used by other radio services, the principle Part 15 operational requirement that the equipment not cause harmful interference to other users of the spectrum is fulfilled. However, permitting frequency hopping systems to directly coordinate their hopping sequences, as requested by Tadiran, would not necessarily enable these systems to avoid operation on portions of the spectrum used by any other radio operators. The suggestion by Tadiran to require coordinated transmitters to be isolated from one another by distance or antenna directivity would not ensure that interference is not caused to other radio services, but would serve only to reduce the interference that the co-located spread spectrum system causes to itself. Further, absent station licensing, the Commission can not readily control the number of Part 15 spread spectrum transmitters in any given location nor can it ensure that coordinated transmitters are properly isolated from other users of the spectrum. Thus, permitting a frequency hopping system to coordinate its hop sequences in a direct fashion could result in the system monopolizing the spectrum and could cause interference to other operators trying to use the same spectrum. Accordingly, the Commission is amending its regulations to permit the operation of frequency hopping systems that incorporate intelligence that permits the system to recognize other users within the spectrum band so that it individually and independently chooses and adapts its hopping sequence to avoid hopping on occupied channels. It is not permitting the coordination of frequency hopping systems using other methods for the express purpose of avoiding the simultaneous occupancy of individual hopping frequencies by multiple systems. Manufacturers are reminded that such systems must continue to comply with the other standards applicable to spread spectrum systems, including the minimum number of hopping channels and the channel maximum dwell times. 8. External radio frequency power amplifiers. 52. As stated in the Notice, several companies appear to be marketing external radio frequency power amplifiers to increase the transmission range of Part 15 spread spectrum transmission systems. It also appears that several manufacturers are marketing replacement antenna systems with higher directional gains to increase transmission range. The marketing and use of these amplifiers or antennas violates Federal law and the Commission's regulations. The rules specifically limit the output power of the transmitter, the EIRP from the combination of the transmitter and the antenna, and the levels of the radiated emissions in certain restricted frequency bands. The addition of an external radio frequency power amplifier or of an antenna other than the one with which the spread spectrum transmission system was originally certified can cause the system to exceed these limits and the use of this system to violate the rules. However, the Part 15 rules do not specifically discuss external amplifiers or replacement antennas as such. Thus, the Commission acknowledges that some equipment manufacturers may not be aware of these requirements. Accordingly, in the Notice the Commission proposed to clarify its regulations by adding a new section prohibiting the manufacture, importation, marketing and use of external radio frequency power amplifiers intended for use with Part 15 transmitters unless those amplifiers are certified as part of a Part 15 system. Similarly, the Commission proposed to amend the regulations to state that the use of an antenna, other than the type with which the product was originally certified, is in violation of the rules. Since the prohibition against the use of external amplifiers or after- market antennas is equally applicable to all Part 15 transmission systems, it further proposed that this amendment apply to all Part 15 transmission systems. 53. Several parties, including Adtran, Apple, Cushcraft, Cylink and the Part 15 Coalition, support the intent of this proposal. Adtran supports a prohibition of external amplifiers and higher gain antenna replacements but wants an exclusion for professional installation of equivalent antennas from different manufacturers. Similarly, Digital Wireless requests an exclusion for high-gain antennas since these systems cannot practically be sold with attached antennas. Adtran and Cushcraft request that the use of alternate antennas be allowed as either Class I or Class II permissive changes. MDS and WMC specifically oppose the language proposed in the Notice for in the proposed Section 15.204(d). MDS is concerned because it produces a software controlled radio that would have to be approved with each antenna. WMC requests that the proposed Section 15.204(d) be deleted so that high gain antennas may be used with professional installation. 54. The Commission is adopting its proposal as detailed in the Notice. In accordance with 47 USC 302, radio frequency devices must comply with the Commission's standards as a condition of manufacture, marketing and use. These requirements include obtaining a grant of certification for the transmitter and meeting the emission limits specified in the rules. The Commission will not certify an external radio frequency power amplifier under Part 15 of its rules as a stand-alone device. However, it will certify such an amplifier as part of a system since it is the specific combination of transmitter, amplifier and antenna that determines whether or not the resulting system will comply with the standards. If an external amplifier has not been certified as part of the system but is employed with a Part 15 transmitter, the certification on the transmitter is no longer valid. 55. With regard to the antenna employed with the system, changes to the antenna certified with the system often will change the amplitude levels of both the fundamental and the unwanted emissions. The Commission is particularly concerned about possible increases to emissions appearing in frequency bands allocated to sensitive radio services or services used for safety-of-life applications. Thus, changes to the antenna can be made only if the equipment continues to comply with the standards. Further, changes to the antenna may be made only by the holder of grant of certification following the procedures for Class II permissive changes specified in Part 2 of the regulations. In order to simplify the measurement requirements when a manufacturer wishes to produce a transmitter that can be used with several different antennas, the Commission has permitted tests of representative antennas instead of requiring the transmitter to be tested with each possible antenna; however, this testing criteria is established on a case-by-case basis and is dependent on the specific type of transmitter and antennas being employed. Additional information on how to simplify the test requirements when multiple antenna choices are being made available should be obtained from the Commission's Laboratory staff just prior to the equipment being tested in preparation for submission for a grant of certification. 9. RF exposure hazards. 56. In the Notice, the Commission noted that, absent controls regarding the locations and manner in which spread spectrum transmitters may be used, systems employing high gain directional antennas could expose the public to potentially harmful signal levels that exceed the radio frequency exposure limits set forth in the rules and recommended by various standards-setting organizations. In order to meet its obligation under the National Environmental Policy Act, the Commission proposed to consider the holder of the grant of certification for the transmitter, the grantee, responsible for ensuring that the equipment is designed to minimize exposure of the public to excessive radio frequency (RF) signal levels. Comments were requested on possible methods of incorporating a warning of some type into the equipment design. Comments were also requested concerning possible biological hazards from the high effective radiated power levels that could be emitted from these systems, additional methods that can be employed to prevent unnecessary exposure of the public, and whether the Commission should prescribe the use of specific means for preventing such exposure. 57. The commenters agree that cautionary information regarding any potential RF hazard is sufficient, either as warning signs near the antenna or as information in a user/installation manual. They oppose the use of proximity sensors or any other preventive methods that would interrupt transmissions. Apple, Cylink, the Part 15 Coalition and Metricom support using the ANSI/IEEE standard for RF exposure to ensure protection from high gain antennas. Additionally, the Part 15 Coalition recommends that the equipment certification grantee be responsible for ensuring compliance with the RF hazard standard. Finally, WMC requests that the proposed amendment to Section 15.247(b)(4)(v) be deleted or that the rule be applied to all RF emissions, whether the emissions come from Part 15 devices or from equipment operating under some other rule part. 58. The Commission agrees with the comments that cautionary information regarding potential RF hazards, either as warning signs near the antenna or as information in a user/installation manual is a step that could be taken by the responsible party to ensure that the system is operated in accordance with the RF guidelines for human exposure adopted by the Commission. However, it is the responsibility of the installer and the user of the equipment to ensure that the public is not exposed to excessive RF levels. Further, these RF hazard requirements apply to all radio frequency devices, not just to Part 15 spread spectrum transmitters. The Commission is amending its rules to clarify this issue. 10. Cross border operation. 59. In the Notice, the Commission noted that informal comments raising concerns with the WMC petition, particularly regarding operation in the 2450 MHz band, have already been received from the staff at Industry Canada, an agency of the Canadian Government. Similarly, the Mexican Government has expressed its concern regarding unlicensed spread spectrum operations between stations in the U.S. and stations in Mexico. Because of this, comments were requested on actions that could be taken to limit operation near the Canadian and Mexican borders to avoid unauthorized crossborder operations and interference to licensed systems in Canada and Mexico. 60. Many commenters, including AT&T, Columbia Gas, the Part 15 Coalition, Rural Cellular, and WMC, opposed any restrictions that would limit transmissions or the use of high gain antennas near the Canadian or Mexican borders. These parties believe that existing rules contain adequate protection to prevent interference. The Part 15 Coalition states that it opposes any restriction on equipment use within the U.S. near the borders but would support a prohibition on cross-border transmissions. WMC believes that directional antennas will help minimize any signals into Canada or Mexico because transmissions will be directed towards receivers within the United States. 61. As previously indicated, the operation of Part 15 devices is subject to the condition that no harmful interference be caused to other radio operations. This requirement also applies to harmful interference caused to Canadian or Mexican radio operations. The Commission believes that this requirement, in combination with the standards applicable to these systems, is sufficient to protect radio systems operating in Canada or Mexico. Further, the Commission emphasizes that agreements between the U.S. and Canada or Mexico to permit cross-border operation do not exist. Accordingly, the Commission can not authorize cross-border operation. 11. Interference to LMS services. 62. Apple requests that Part 15 of the rules be amended to reflect the presumption of non- interference for Part 15 devices operating in the frequency bands allocated to wideband multilateration LMS services. This statement currently is contained in Section 90.361 of the rules, and addresses the operating conditions under which a Part 15 spread spectrum transmitter in the 915 MHz band is presumed not to cause interference to wideband multilateration LMS services. The Commission does not agree that these provisions should be placed in Part 15 of its rules. These provisions were developed in conjunction with the LMS rule making and any changes to the regulations would be associated with that radio service. Further, and most important, placing these provisions in Part 90 of the rules serve to alert LMS operators that they can not claim harmful interference has occurred from most spread spectrum operations. There are no similar provisions that permit operators of Part 15 devices to ameliorate harmful interference from wideband multilateration LMS operations. 12. Reduction in the number of hopping channels at 2450 MHz and 5800 MHz. 63. In the Notice, the Commission denied the petition from Symbol Technologies, Inc. to reduce the number of hopping channels in the 2450 MHz and 5800 MHz bands. Several of the comments indicated agreement with this decision. However, GEC Plessey Semiconductors (GPS) requests that the Commission reconsider its decision to permit wider bandwidth channels to support wireless LAN systems. Tadiran also requests that the Commission reduce the minimum number of frequency hopping channels to permit wider bandwidths to be employed. Neither of these parties offer new or novel arguments that were not previously considered by the Commission in its denial of the Symbol petition. Tadiran indicates that it would be desirable to avoid operating in the frequency range of 2450-2483.5 MHz due to the allocation to broadcasters and private microwave licensees. However, Tadiran fails to account for similar problems that would occur in the 2400-2450 MHz band due to operations in the Amateur Radio Service or to other radio frequency noise produced throughout the 2450 MHz band by ISM equipment. Accordingly, the Commission is reaffirming its previous decision denying a reduction of the minimum number of frequency hopping channels for spread spectrum systems operating in the 2450 MHz and 5800 MHz bands. D. Transition provisions 64. The amendments being adopted in this proceeding clarify permissible methods of operation. With the exception of limits on directional antenna gain versus transmitter output power for systems in the 2450 MHz band, these amendments should not impact any existing equipment designs. As mentioned above, waivers were issued previously to WMC, Cylink Corporation, Atlantic Communications Sciences, MDS, Larus Corporation and Wi-LAN to manufacture fixed, point-to-point spread spectrum systems in the 2450 MHz and 5800 MHz bands without a limit on directional antenna gain. These manufacturers would be impacted by a decision to reduce the output power of a 2450 MHz transmitter by 1 dB for every 3 dB the directional antenna gain exceeds 6 dBi. Under the terms of the waivers, this equipment can only be manufactured until final action in this proceeding. 65. Cylink requests that any restrictive regulations to limit antenna gain in the 2450 MHz band be phased in over a twelve month period to permit the completion of any existing contractual obligations. However, Cylink, along with the other manufacturers that were issued waivers, was aware of the possibility that its waiver may not continue subsequent to finalization of this rule making proceeding. Any contractual obligations based on a temporary, and possibly non-continuing, waiver must be considered to have been taken at the manufacturer's own risk. Accordingly, the Commission sees no reason to delay the effective date of these amendments to the regulations. While the Commission originally proposed to make these amendments effective upon the date of publication of the final rules in the Federal Register, the Contract With America Advancement Act of 1996 requires that these amendments not become effective prior to 30 days from publication in the Federal Register. IV. PROCEDURAL MATTERS Final Regulatory Flexibility Analysis 66. As required by Section 603 of the Regulatory Flexibility Act, 5 U.S.C.  603 (RFA), Initial Regulatory Flexibility Analysis (IRFA) was incorporated in the Notice of Proposed Rule Making ("Notice") in ET Docket No. 96-8. The Commission sought written public comments on the proposals in the Notice including the IRFA. The Commission's Regulatory Flexibility Analysis (FRFA) in this Report and Order conforms to the RFA, as amended by the Contract with America Advancement Act of 1996 (CWAAA), Public Law No. 104-121, 110 Stat. 847 (1996). 1. Need for and Objective of the Rule. 67. The objective is to amend Parts 2 and 15 of the rules regarding the operation of spread spectrum transmission systems in the 902-928 MHz, 2400-2483.5 MHz and 5725-5850 MHz bands. The Commission is also adopting a number of amendments to the spread spectrum regulations to clarify the existing regulations, to codify existing policies into the rules, and to update the current definitions. These changes to the rules will facilitate the growth of the spread spectrum industry by enabling and encouraging practical applications for these products. The new rules will expand the ability of equipment manufacturers to develop spread spectrum systems for unlicensed use that provide users with the flexibility to establish radio links without the delays and costs associated with formal frequency coordination and licensing. Such uses may include intelligent transportation system communications links; high speed Internet connections for schools, hospitals, and government offices; energy utility applications; PCS and cellular backbone connections; and T-1 common carrier links in rural areas. The new rules will also permit frequency hopping spread spectrum systems and wideband, multilateration Location Monitoring Service (LMS) systems to operate within the same frequency band with decreased potential for mutual interference problems. 2. Summary of Significant Issues Raised by the Public Comments in Response to the Initial Regulatory Flexibility Analysis. 68. Only one commenter, Adtran submitted comments that were specifically in response to the IRFA. It agrees with the Commission's assessment that the changes made in the R&O will have no negative impact on small entities. In general, commenters were supportive of the Commission's proposed changes to the rule. The Commission also received numerous suggestions for improving or modifying the rules. In response to a Petition for Rule Making filed by WMC, the Commission is eliminating the limit on directional gain antennas for spread spectrum transmitters operating in the 2450 MHz and 5800 MHz bands. For spread spectrum systems operating in the 2450 MHz band, the Commission is implementing its proposal to require that the output power for the transmitter be reduced by 1 dB for every 3 dB that the directional gain exceeds 6 dBi. In addition, in response to a Petition for Rule Making filed by SpectraLink, the Commission is reducing, from 50 to 25, the minimum number of channels required for frequency hopping spread spectrum systems operating in the 915 MHz band. 3. Description and Estimate of the Number of Small Entities Subject to Which the Rules Apply. 69. The RFA generally defines the term "small business" as having the same meaning as the term "small business concern" under the Small Business Act, 15 U.S.C. 632. Based on that statutory provision, we will consider a small business concern one which: (1) is independently owned and operated; (2) is not dominant in its field of operation; and (3) satisfies any additional criteria established by the Small Business Administration (SBA). The RFA SBREFA provisions also apply to nonprofit organizations and to governmental organizations. Since the Regulatory Flexibility Act amendments were not in effect until the record in this proceeding was closed, the Commission was unable to request information regarding the number of small businesses that manufacture spread spectrum transmitters and is unable at this time to determine the number of small businesses that would be affected by this action. However, the Commission believes that the amendments being adopted in this proceeding clarify permissible methods of operation. With the exception of limits on directional antenna gain versus transmitter output power for systems in the 2450 MHz band, these amendments should not impact any existing equipment designs. The only parties that would be impacted by the requirement to reduce transmitter output power when high antenna gains are employed are WMC, Cylink, ACS, MDS, Larus, and Wi-LAN Inc. These companies are currently producing this equipment under the conditions of a temporary waiver that permits them to manufacture fixed, point-to-point spread spectrum systems in the 2450 MHz band without a limit on directional antenna gain. All of these companies were notified at the time the waivers were granted that the waivers would expire upon the date of final action in this proceeding. 70. The rules adopted in this R&O will apply to any entities manufacturing equipment for unlicensed Part 15 spread spectrum transmitters. The Commission has not developed a definition of small entities applicable to manufacturers of spread spectrum transmitters. Therefore, the applicable definition of small entity is the definition under the Small Business Administration ("SBA") rules applicable to manufacturers of "Radio and Television Broadcasting and Communications Equipment". According to the SBA's regulations, radio frequency manufacturers must have 750 or fewer employees in order to qualify as a small business. Census Bureau data indicates that there are 858 companies in the United States that manufacture radio and television broadcasting and communications equipment, and that 778 of these firms have fewer than 750 employees and would be classified as small entities. 4. Description of Projected Reporting, Recordkeeping and Other Compliance Requirements. 71. Part 15 spread spectrum transmitters are already required to be authorized under the Commission's certification procedure as a prerequisite to marketing and importation. The changes proposed in this proceeding would not change any of the current reporting or recordkeeping requirements. Further, the proposed regulations add permissible methods of operation and would not require the modification of any existing products, except for those currently operating under limited waivers that expire upon adoption of this R&O. These requirements include obtaining a grant of certification for the transmitter and meeting the emission limits specified in the rules. 72. Skills of an application examiner, radio technician or engineer will be needed to meet the requirements. In many cases the studies can be done by a radio technician or engineer. Certification applications are usually done by applications examiners. It is the responsibility of the manufacturer of the device to determine whether the device will comply with the RF radiation limits. This study can be done by calculation or measurement, depending upon the situation. 5. Significant Alternatives and Steps Taken by Agency to Minimize Significant Economic Impact on a Substantial Number of Small Entities Consistent with Stated Objectives. 73. In response to concerns raised in comments filed in response to the Notice, the Commission made several minor clarifying amendments to its proposals. However, there was only one issue raised in the comments that could have had a significant economic impact on the manufacturers of spread spectrum systems. In the Notice, the Commission proposed to require that the 3 dB beamwidths of the high gain directional antennas employed with spread spectrum transmitters differ by no more than a factor of two between the vertical and horizontal planes. Supporting comments were received from Adtran and Digital Wireless; however, Cushcraft, Cylink, the Part 15 Coalition and WMC believe that the requirement is an unnecessary regulation. Cushcraft believes that the majority of antennas already meet this criterion. Cylink states that this proposal may prevent applications that require a different antenna design, such as communications to off- shore platforms. The Commission agrees with the latter commenters that this portion of its proposal is unnecessary. 6. Commission's Outreach Efforts to Learn of and Respond to the Views of Small Entities pursuant to SBREFA 5 U.S.C.  609. 74. During the course of this proceeding Office of Engineering and Technology staff members have had numerous ex parte meetings with representatives from Metricom, Inc., Cylink Corporation, Mulcay Consulting Association, and Digital Wireless Corporation. 7. Report to Congress. 75. The Commission shall send a copy of this Final Regulatory Flexibility Analysis, along with this Report and Order, in a report to Congress pursuant to the Small Business Regulatory Enforcement Fairness Act of 1996, 5 U.S.C.  801(a)(1)(A). A copy of this FRFA will also be published in the Federal Register. V. ORDERING CLAUSES 76. Accordingly, IT IS ORDERED that Parts 2 and 15 of the Commission's Rules and Regulations ARE AMENDED as specified in Appendix B, effective 30 days after publication in the Federal Register. This action is taken pursuant to Sections 4(i), 301, 302, 303(e), 303(f), 303(r), 304 and 307 of the Communications Act of 1934, as amended, 47 U.S.C. Sections 154(i), 301, 302, 303(e), 303(f), 303(r), 304 and 307. 77. For further information regarding this Report and Order, contact the Office of Engineering and Technology, John Reed at (202) 418-2455 or Anthony Serafini at (202) 418-2456. FEDERAL COMMUNICATIONS COMMISSION William F. Caton Acting Secretary APPENDIX A LIST OF COMMENTING PARTIES Comments Adtran Alliant Techsystems, Inc. American Petroleum Institute Apple Computer, Inc. AT&T Wireless Services Columbia Gas Transmission Cushcraft Corporation Cylink Corporation Digital Wireless Corporation The Ericsson Corporation Fusion Systems Corporation Fusion Lighting, Inc. Gabriel Electronics, Inc. GEC Plessey Semiconductors International Microwave Power Institute Itron, Inc. Lucent Technologies Inc. Mario Proietti Master Lock Company Metricom, Inc. Microwave Communications Technology Inc. Microwave Data Systems OCOM Corporation Oneonta Telephone Company, Inc. Part 15 Coalition Questar InfoComm, Inc. RadioShack Division of Tandy Corporation RAMAR Technology, Ltd. Rural Cellular Corporation Scott Townley Sola Communications, Inc. SpectraLink Corporation Tadiran Telecommunications, Inc. Telecommunications Industry Association , Wireless Consumer Communications Section Teletrac License, Inc. United States Cellular Corporation Western Multiplex Corporation Late Filed Comments Multipoint Networks, Inc. Rockwell International Corporation Tadiran Telecommunications, Inc. Reply Comments Adtran CellNet Data Systems Cylink Corp. Digital Wireless Corporation Itron, Inc. Lucent Technologies Inc. Master Lock Company Metricom, Inc. Mulcay Consulting Associates Part 15 Coalition SpectraLink Corporation Telecommunications Industry Association, Fixed Point-to-Point Communications Section Telecommunications Industry Association, Wireless Consumer Communications Section Teletrac License, Inc. US West, Inc. (US West) Western Multiplex Corporation APPENDIX B CHANGES TO THE REGULATIONS I. Title 47 of the Code of Federal Regulations, Part 2, is amended to read as follows: 1. The authority citation for Part 2 continues to read as follows: AUTHORITY: Sec. 4, 302, 303, and 307 of the Communications Act of 1934, as amended, 47 U.S.C. Sections 154, 302, 303 and 307, unless otherwise noted. 2. Section 2.1, paragraph (c), is amended by deleting the definition for "pseudorandom sequence" and by revising the following definitions to read as follows: Section 2.1 Terms and definitions. * * * * * (c) * * * * * * * * Direct Sequence Systems. A spread spectrum system in which the carrier has been modulated by a high speed spreading code and an information data stream. The high speed code sequence dominates the "modulating function" and is the direct cause of the wide spreading of the transmitted signal. * * * * * Frequency Hopping Systems. A spread spectrum system in which the carrier is modulated with the coded information in a conventional manner causing a conventional spreading of the RF energy about the frequency carrier. The frequency of the carrier is not fixed but changes at fixed intervals under the direction of a coded sequence. The wide RF bandwidth needed by such a system is not required by spreading of the RF energy about the carrier but rather to accommodate the range of frequencies to which the carrier frequency can hop. The test of a frequency hopping system is that the near term distribution of hops appears random, the long term distribution appears evenly distributed over the hop set, and sequential hops are randomly distributed in both direction and magnitude of change in the hop set. * * * * * II. Title 47 of the Code of Federal Regulations, Part 15, is amended to read as follows: 1. The authority citation for Part 15 continues to read as follows: AUTHORITY: Secs. 4, 302, 303, 304, 307 and 624A of the Communications Act of 1934, as amended, 47 U.S.C. 154, 302, 303, 304, 307 and 544A. 2. Section 15.3 is amended by adding a new paragraph (bb), to read as follows: Section 15.3 Definitions. * * * * * (bb) External radio frequency power amplifier. A device which is not an integral part of an intentional radiator as manufactured and which, when used in conjunction with an intentional radiator as a signal source, is capable of amplifying that signal. 3. Part 15 is amended by adding a new Section 15.204, to read as follows: Section 15.204 External radio frequency power amplifiers and antenna modifications. (a) Except as otherwise described in paragraph (b) of this section, no person shall use, manufacture, sell or lease, offer for sale or lease (including advertising for sale or lease), or import, ship, or distribute for the purpose of selling or leasing, any external radio frequency power amplifier or amplifier kit intended for use with a Part 15 intentional radiator. (b) A transmission system consisting of an intentional radiator, an external radio frequency power amplifier, and an antenna, may be authorized, marketed and used under this part. However, when a transmission system is authorized as a system, it must always be marketed as a complete system and must always be used in the configuration in which it was authorized. An external radio frequency power amplifier shall be marketed only in the system configuration with which the amplifier is authorized and shall not be marketed as a separate product. (c) Only the antenna with which an intentional radiator is authorized may be used with the intentional radiator. 4. Section 15.247 is amended by revising paragraphs (a)(1)(i), (b), (c), (d), and (e), and by adding new paragraphs (g) and (h) before the note at the end of the section, to read as follows: Section 15.247 Operation within the bands 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz. (a) * * * (1) * * * (i) For frequency hopping systems operating in the 902-928 MHz band: if the 20 dB bandwidth of the hopping channel is less than 250 kHz, the system shall use at least 50 hopping frequencies and the average time of occupancy on any frequency shall not be greater than 0.4 seconds within a 20 second period; if the 20 dB bandwidth of the hopping channel is 250 kHz or greater, the system shall use at least 25 hopping frequencies and the average time of occupancy on any frequency shall not be greater than 0.4 seconds within a 10 second period. The maximum allowed 20 dB bandwidth of the hopping channel is 500 kHz. (ii) * * * (2) * * * (b) The maximum peak output power of the intentional radiator shall not exceed the following: (1) For frequency hopping systems operating in the 2400-2483.5 MHz or 5725-5850 MHz band and for all direct sequence systems: 1 watt. (2) For frequency hopping systems operating in the 902-928 MHz band: 1 watt for systems employing at least 50 hopping channels; and, 0.25 watts for systems employing less than 50 hopping channels, but at least 25 hopping channels, as permitted under paragraph (a)(1)(i) of this section. (3) Except as shown below, if transmitting antennas of directional gain greater than 6 dBi are used the peak output power from the intentional radiator shall be reduced below the above stated values by the amount in dB that the directional gain of the antenna exceeds 6 dBi. (i) Systems operating in the 2400-2483.5 MHz band that are used exclusively for fixed, point-to- point operations may employ transmitting antennas with directional gain greater than 6 dBi provided the maximum peak output power of the intentional radiator is reduced by 1 dB for every 3 dB that the directional gain of the antenna exceeds 6 dBi. (ii) Systems operating in the 5725-5850 MHz band that are used exclusively for fixed, point-to-point operations may employ transmitting antennas with directional gain greater than 6 dBi without any corresponding reduction in transmitter peak output power. (iii) Fixed, point-to-point operation, as used in paragraphs (b)(3)(i) and (b)(3)(ii) of this section, excludes the use of point-to-multipoint systems, omnidirectional applications, and multiple co- located intentional radiators transmitting the same information. The operator of the spread spectrum intentional radiator or, if the equipment is professionally installed, the installer is responsible for ensuring that the system is used exclusively for fixed, point-to-point operations. The instruction manual furnished with the intentional radiator shall contain language in the installation instructions informing the operator and the installer of this responsibility. (4) Systems operating under the provisions of this section shall be operated in a manner that ensures that the public is not exposed to radio frequency energy levels in excess of the Commission's guidelines. See  1.1307(b)(1) of this Chapter. (c) In any 100 kHz bandwidth outside the frequency band in which the spread spectrum intentional radiator is operating, the radio frequency power that is produced by the intentional radiator shall be at least 20 dB below that in the 100 kHz bandwidth within the band that contains the highest level of the desired power, based on either an RF conducted or a radiated measurement. Attenuation below the general limits specified in Section 15.209(a) is not required. In addition, radiated emissions which fall in the restricted bands, as defined in Section 15.205(a), must also comply with the radiated emission limits specified in Section 15.209(a) (see Section 15.205(c)). (d) For direct sequence systems, the peak power spectral density conducted from the intentional radiator to the antenna shall not be greater than 8 dBm in any 3 kHz band during any time interval of continuous transmission. (e) The processing gain of a direct sequence system shall be at least 10 dB. The processing gain represents the improvement to the received signal-to-noise ratio, after filtering to the information bandwidth, from the spreading/despreading function. The processing gain may be determined using one of the following methods: (1) As measured at the demodulated output of the receiver: the ratio in dB of the signal-to-noise ratio with the system spreading code turned off to the signal-to-noise ratio with the system spreading code turned on. (2) As measured using the CW jamming margin method: a signal generator is stepped in 50 kHz increments across the passband of the system, recording at each point the generator level required to produce the recommended Bit Error Rate (BER). This level is the jammer level. The output power of the intentional radiator is measured at the same point. The jammer to signal ratio (J/S) is then calculated, discarding the worst 20% of the J/S data points. The lowest remaining J/S ratio is used to calculate the processing gain, as follows: Gp = (S/N)o + Mj + Lsys, where Gp = processing gain of the system, (S/N)o = signal to noise ratio required for the chosen BER, Mj = J/S ratio, and Lsys = system losses. Note that total losses in a system, including intentional radiator and receiver, should be assumed to be no more than 2 dB. * * * * * (g) Frequency hopping spread spectrum systems are not required to employ all available hopping channels during each transmission. However, the system, consisting of both the transmitter and the receiver, must be designed to comply with all of the regulations in this section should the transmitter be presented with a continuous data (or information) stream. In addition, a system employing short transmission bursts must comply with the definition of a frequency hopping system and must distribute its transmissions over the minimum number of hopping channels specified in this section. (h) The incorporation of intelligence within a frequency hopping spread spectrum system that permits the system to recognize other users within the spectrum band so that it individually and independently chooses and adapts its hopsets to avoid hopping on occupied channels is permitted. The coordination of frequency hopping systems in any other manner for the express purpose of avoiding the simultaneous occupancy of individual hopping frequencies by multiple transmitters is not permitted. * * * * * APPENDIX C FEDERAL COMMUNICATIONS COMMISSION Equipment Authorization Division 7435 Oakland Mills Road Columbia, MD 21046 Telephone: (301) 725-1585 Facsimile: (301) 344-2050 Guidance on Measurements for Direct Sequence Spread Spectrum Systems Part 15 of the FCC Rules provides for operation of direct sequence spread spectrum transmitters. Examples of devices that operate under these rules include radio local area networks, cordless telephones, wireless cash registers, and wireless inventory tracking systems. The Commission frequently receives requests for guidance as to how to perform measurements to demonstrate compliance with the technical standards for such systems. No formal measurement procedure has been established for determining compliance with the technical standards. Such tests are to be performed following the general guidance in Section 15.31 of the FCC Rules and using good engineering practice. The following provides information on the measurement techniques the Commission has accepted in the past for equipment authorization purposes. Alternative techniques may be acceptable upon consultation and approval by the Commission staff. The information is organized according to the pertinent FCC rule sections. Section 15.31(m): This rule specifies the number of operating frequencies to be examined for tunable equipment. Section 15.207: Power line conducted emissions. If the unit is AC powered, an AC power line conducted test is also required per this rule. Section 15.247(a)(2): Bandwidth. Make the measurement with the spectrum analyzer's resolution bandwidth (RBW) = 100 kHz. In order to make an accurate measurement, set the span >> RBW. Section 15.247(b): Power output. This is an RF conducted test. Use a direct connection between the antenna port of the transmitter and the spectrum analyzer, through suitable attenuation. Set the RBW > 6 dB bandwidth of the emission or use a peak power meter. Section 15.247(c): Spurious emissions. The following tests are required : (1) RF antenna conducted test: Set RBW = 100 kHz, Video bandwidth (VBW) > RBW, scan up through 10th harmonic. All harmonics/spurs must be at least 20 dB down from the highest emission level within the authorized band as measured with a 100 kHz RBW. (2) Radiated emission test: Applies to harmonics/spurs that fall in the restricted bands listed in Section 15.205. The maximum permitted average field strength is listed in Section 15.209. A pre-amp (and possibly a high-pass filter) is necessary for this measurement. For measurements above 1 GHz, set RBW = 1 MHz, VBW = 10 Hz, Sweep: Auto. If the emission is pulsed, modify the unit for continuous operation, use the settings shown above, then correct the reading by subtracting the peak-average correction factor, derived from the appropriate duty cycle calculation. See Section 15.35(b) and (c). Section 15.247(d): Power spectral density. Locate and zoom in on emission peak(s) within the passband. Set RBW = 3 kHz, VBW > RBW, sweep = (SPAN/3 kHz) e.g., for a span of 1.5 MHz, the sweep should be 1.5 x 106 ö 3 x 103 = 500 seconds. The peak level measured must be no greater than +8 dBm. If external attenuation is used, don't forget to add this value to the reading. Use the following guidelines for modifying the power spectral density measurement procedure when necessary.  For devices with spectrum line spacing greater than 3 kHz no change is required.  For devices with spectrum line spacing equal to or less than 3 kHz, the resolution bandwidth must be reduced below 3 kHz until the individual lines in the spectrum are resolved. The measurement data must then be normalized to 3 kHz by summing the power of all the individual spectral lines within a 3 kHz band (in linear power units) to determine compliance.  If the spectrum line spacing cannot be resolved on the available spectrum analyzer, the noise density function on most modern conventional spectrum analyzers will directly measure the noise power density normalized to a 1 Hz noise power bandwidth. Add 34.8 dB for correction to 3 kHz.  Should all the above fail or any controversy develop regarding accuracy of measurement, the Laboratory will use the HP 89440A Vector Signal Analyzer for final measurement unless a clear showing can be made for a further alternate. Section 15.247(e): Processing Gain. The Processing Gain may be measured using the CW jamming margin method. Figure 1 shows the test configuration. The test consists of stepping a signal generator in 50 kHz increments across the passband of the system. At each point, the generator level required to produce the recommended Bit Error Rate (BER) is recorded. This level is the jammer level. The output power of the transmitting unit is measured at the same point. The Jammer to Signal (J/S) ratio is then calculated. Discard the worst 20% of the J/S data points. The lowest remaining J/S ratio is used when calculating the Processing Gain. In a practical system, there are always implementation losses which degrade the performance below that of an optimal theoretical system of the same type. Losses occur due to non-optimal filtering, lack of equalization, LO phase noise, "corner cutting in digital processing", etc. Total losses in a system, including transmitter and receiver, should be assumed to be no more than 2 dB. The signal to noise ratio for an ideal non-coherent receiver is calculated from: (1) Pe = «e(-«(S/N)o) where : Pe = probability of error (BER) (S/N)o = the required signal to noise ratio at the receiver output for a given received signal quality This is an example. You should use the equation (or curve) dictated by your demodulation scheme. Ref.: Viterbi, A. J. Principles of Coherent Communications, (New York: McGraw-Hill 1966), Pg. 207 Using equation (1) shown above, calculate the signal to noise ratio required for your chosen BER. This value and the measured J/S ratio are used in the following equation to calculate the Processing Gain (Gp) of the system. Gp=(S/N)o+Mj+Lsys where: (S/N)o = Signal to noise ratio Mj = J/S ratio Lsys = System losses. Ref.: Dixon, R., Spread Spectrum Systems (New York: Wiley, 1984), Chapter 1. ALTERNATIVE TEST PROCEDURES If antenna conducted tests cannot be performed on this device, radiated tests to show compliance with the various conducted requirements of Section 15.247 are acceptable. As stated previously, a pre-amp must be used in making the following measurements. 1) Calculate the transmitter's peak power using the following equation: Where: E is the measured maximum field strength in V/m utilizing the widest available RBW. G is the numeric gain of the transmitting antenna over an isotropic radiator. d is the distance in meters from which the field strength was measured. P is the power in watts for which you are solving: 2) Measure the power spectral density as follows: A. Tune the analyzer to the highest point of the maximized fundamental emission. Reset the analyzer to a RBW = 3 kHz, VBW > RBW, span = 300 kHz, sweep = 100 sec. B. From the peak level obtained in (A), derive the field strength, E, by applying the appropriate antenna factor, cable loss, pre-amp gain, etc. Using the equation listed in (1), calculate a power level for comparison to the +8 dBm limit.