MM Docket No. 95-42
Digital Data Transmission Within the Video Portion of Television RM-7567 Broadcast Station Transmissions
Adopted: April 10, 1995; Released: May 3, 1995
By the Commission:
Comments due: #/June 12, 1995/#
Reply comments due: #/June 27, 1995/#
1. We are initiating this proceeding to determine how best to permit certain digital technologies to be integrated with the current television broadcast service. Specifically, we seek comment on what procedural and substantive rules, if any, we should establish regarding the transmission of ancillary digital data within the active video portion of broadcast television NTSC signals.(n1)
3. We have taken a different approach to ancillary transmissions
within other portions of the television signal, such as
the video portion. In this regard, we have generally not
allowed the transmission of ancillary telecommunications
services within the video portion of broadcast television
signals without prior Commission consent.(n3) The intent of
this policy is to ensure the public's ability to receive
over-the-air video broadcast transmissions of the highest
quality made possible by the NTSC standard.
4. Recently, two general approaches have been proposed
to the Commission for the transmission of digital data
within the video portion of the television signal, each
intended to be imperceptible to viewers. Both have been
permitted on a limited basis.
5. One of the two methods replaces the transmitted video
signal with digitally encoded information in a part of
the picture not normally seen by viewers. Line 22, the
first line of active video, is used for this purpose.
Depending on the particular encoding method, a video display
of line 22 would look like either stationary and flickering,
or moving black and white or colored dots or dashes. However,
as these visible effects of data encoding are located at
the very top of the TV picture, they are seldom seen because
all TV sets to some extent "overscan" the picture to ensure
that the portion of the picture tube that is visible is
completely filled with the picture. Without the overscan,
the picture would appear with a narrow black border. To
date, the Commission has authorized only line 22 for such
activity, although in theory, digital signals could be
concealed in the left or right edges of the picture, or
at the bottom. In 1985, by letters from the Chief of the
Mass Media Bureau, theCommission authorized the use of
line-22 systems developed by Telescan, Inc. and Ad Audit,
Inc. for electronic verification of television broadcasts.
These systems were designed to convey information about
the date, time of day and length of commercial messages,
as well as the presence of audio and video. Public comment
on these systems, principally from broadcasters, generally
did not oppose their authorization provided that: (1)
broadcasters were advised of the presence of the signals
in the source material provided to the stations and (2)
the ultimate control and authority with respect to the
signal transmission remained with individual television
station licensees. The Commission made these terms a condition
of the subsequent grants.
6. The other method of concealing digital signals distributes
them throughout the visible picture. The amplitudes of
such signals are kept sufficiently low (or they are confined
to such a limited part of the normally emitted video spectrum
bandwidth) that they are invisible to the viewer. Tests
of such systems indicate that, with a proper selection
of system parameters, no degradation to picture brightness,
contrast, color or focus is perceptible to the viewer.
One such system (the Special Data Transmission System
or "SDTS") was proposed by the National Broadcasting Company
(NBC). On March 3, 1992, the staff determined that the
degradation caused to the television picture by NBC's SDTS
was indiscernible, and that no further authorization was
required for its use. (Letter to Jane E. Genster of March
3, 1992.) However, the data rate of the SDTS is only 240
bits per second, which is much less than is being considered
in this proceeding and therefore the performance of the
SDTS may not be indicative of the performance of a system
using a much higher data rate.
8. WavePhore asserts that its system causes no visual
degradation of the television picture as viewed on any
commercial television set, because: (1) all commercial
television tuners filter out that part of the spectrum
that contains the data; (2) the amplitude of the data transmission
is only several IRE units above the video noise floor and
is therefore almost impossible to discern; (3) the data
is injected into a narrow 300 kHz band that adds no significant
component to the video noise floor when integrated and
weighted over a 4.0 MHz video bandwidth; and (4) the data
subcarrier's exact frequency and phase result in a "picket
fence" data spectrum that is interleaved with respect to
the comb structure of the chroma and lumina spectrum.
Initial Comments on WavePhore Request
10. Three parties submitted comments in response to the
Public Notice. The Association for Maximum Service Television,
Inc. (MSTV), the Consumer Electronics Group of the Electronic
Industries Association (Electronics Group), and Radio Telecom
& Technology, Inc. (RTT) all support the use of excess
capacity within the video portion of the television broadcast
signal to provide digital data services. However, they
urge the Commission to exercise caution in determining
how best to promote digital data transmission in conjunction
with NTSC television signals. The commenters seek both
to minimize interference with the video and audio portions
of the signal and to encourage further innovation in digital
11. RTT supports WavePhore's specific request. It also
requests the Commission to allow any party to superimpose
signals on an existing television transmission without
prior Commission authorization, as long as the signals
do not degrade television broadcast reception in any discernible
way. This absence of regulatory burden, RTT contends,
would allow broadcasters and those associated with data
transmission to compete most efficiently in the expanding
"information superhighway." Further, RTT notes that WavePhore's
proposal would use an encoder that performs two functions:
(1) a slight low pass filtering and delay equalization
of the video signal; and (2) linear addition of the data
to the video. RTT asks whether, in the data insertion
process, it would be permissible to filter out some of
the video signal in order to insert the desired new data
12. More specifically, citing Section 73.699, Figure
5, of the Commission's Rules, RTT notes that the bandpass
characteristic of the standard transmitted video signal
begins to roll off at frequencies above 4.2 MHz, reaching
a negligible value just below the sound carrier centered
at 4.5 MHz above the visual carrier frequency. Figure
11 of the Rule, RTT adds, indicates that the ideal receiver
detector output rolls off at frequencies above 4.2 MHz.
RTT states that WavePhore proposes to begin to roll off
the video 0.3 MHz lower, at approximately 3.9 MHz, where
its signal begins. According to RTT, this roll off could
not only adversely affect the monochrome fidelity, but
could also make the chroma subcarrier sidebands become
even more asymmetric. Therefore, RTT asks whether a broadcaster
may reshape the output of its transmitted video signal
so as to delete any video that might otherwise interfere
with the proposed new inserted data.
13. The other two commenters urge the Commission to exercise caution in determining the appropriate regulatory framework of the newly emerging digital data transmission industry. MSTV notes that other systems are being developed to transmit digital data, within both the video portion and other portions of the television broadcast signal. However, MSTV asserts that without a specific model as an industry standard for digital transmission within NTSC signals in general, the differing technologies that would be utilized could result in inter-system incompatibility, harming both consumers and the data transmitting industry. Thus, MSTV opines that adoption of a single industry standard would best facilitate the further development of a compatible digital data broadcasting system that would not harm the picture observable by viewers. MSTV adds that such action would be analogous to the Commission's recent determination that the development of another technical innovation, ghost-cancelling in television receivers, would be most efficiently facilitated by the adoption of a single industry technical standard.(n6)
14. In addition, MSTV and the Electronics Group allude
to the National Data Broadcasting Committee (the Committee),
an entity formed in 1993 by the National Association of
Broadcasters (NAB) and the Electronics Group. The Committee
seeks to hasten the development of a voluntary national
technical standard for high-speed data broadcasting using
NTSC television signals as a delivery medium. MSTV and
the Electronics Group assert that the Commission should
rely on the Committee's findings and recommendations in
setting an industry standard. Moreover, MSTV notes that
the Commission has previously relied on the publicsector
to facilitate highly technical improvements in the television
broadcast service. Specifically, it analogizes the work
of this industry Committee to that of the FCC's Advisory
Committee on Advanced Television Service, which has played
an ongoing and critical role in the development of Advanced
Television (ATV) technology.
15. The Electronics Group also requests the Commission
to rely on the findings of the Committee and not enact
any rule that would give one company an unfair competitive
advantage in the introduction of broadcast data services.
Specifically, the Electronics Group asserts that if WavePhore's
request is granted, companies wishing to rapidly commence
data transmission could use only WavePhore's technology,
as it would be the only model not requiring prior Commission
approval. At the same time, the commenter opposes the
expansive rule proposed by RTT, which would allow any digital
data transmission without prior Commission authorization,
so long as there is no discernible effect on NTSC reception
on the same or adjacent channels. Without the need for
prior Commission authorization, the Electronic Group asks,
who would determine whether there was "discernible" interference,
and how would "discernible" be defined? Moreover, the
Electronics Group expresses concern that such a rule would
promote a race to create and utilize what would become
a variety of incompatible systems. Such a reaction, the
commenter warns, could ultimately deter investments by
broadcasters, potential customers of the data services,
equipment manufacturers, and consumers.
Nielsen Temporary Authority
Initial Comments on Airtrax Petition
19. MSTV opposed ancillary use of active video lines
and particularly opposed administrative rules to permit
more widespread use of line 22. As an alternative, it
favored more efficient use of the vertical blanking interval
by broadcasters, advertisers and other ancillary-service
providers. It disagreed with Airtrax that line 22 issues
should be addressed in a rulemaking proceeding, although
it agreed that the Commission's current ad hoc process
for line 22 authorization was not an effective means of
providing due process to all interested parties. In lieu
of acting favorably upon the Airtrax petition, MSTV encouraged
the Commission to consider the merits of adopting new rules
to protect the active video lines from ancillary uses.
20. Nielsen filed an opposition to petition for rule
making and motion to dismiss in response to the Airtrax
petition. Nielsen argued that the actions Airtrax advocated
were unnecessary and that if standards for compatibility
among line 22 signals and coordination among line 22 users
became necessary, the industry could develop them without
the Commission's regulatory involvement. Nielsen suggested
that the Airtrax objectives of maintaining licensee discretion
to broadcast special signals and to ensure that the broadcast
signal is not degraded are basic conditions of authority
granted under the Commission's existing ad hoc approval
approach and do not require a rule making. Nielsen further
suggested that normal business practices will prevent the
"overwriting" of line 22 signals that Airtrax feared.
Nielsen also claimed that the lack of a technical standard
would foster innovation and development.
Yes! Entertainment Corporation Proposal
22. Lastly (with respect to newer digital data transmission
technologies), on January 19, 1995, the staff authorized
Station WWOR-TV in Secaucus, New Jersey, to conduct tests
of a data transmission technology developed by Digideck,
Inc. (Digideck) called "D-Channel."(n11) This system, like
that of WavePhore, operates in the active video part of
the TV spectrum and is represented as being imperceptible
to viewers. Specifically, it adds a constant carrier level,
quadrature phase-shifted (QPSK) data signal to the vestigial
sideband (VSB) region of the video signal. The data carrier
is placed 1 MHz below the picture carrier at a level between
-30 and -36 dB relative to the video carrier at peak of
sync. Data throughput is said to be 525,000 bps. A potential
drawback of this system is that it operates near the edge
of the television channel spectrum and it is possible that
at higher injection levels, a slight increase in interference
(on the order of 1 dB) to the lower adjacent channel may
24. In light of the above two goals, we believe that
we do not yet have sufficient information upon which to
act on the requests from Yes! and WavePhore. Both requests
raise significant questions pertaining to potential use
for other purposes and technical compatibility. We solicit
additional information in order to ascertain the long-term
impact our authorization of these or other potential systems
(such as Digideck's) may have on broadcasters, the data
transmitting industry, consumers, and others. We also
solicit the informationwe need to reach a conclusion on
the Airtrax proposal for regulation of the use of line
26. Generally, we propose that licensees be allowed to transmit acceptable data signals without prior Commission authority or notification but not be allowed to relinquish to the data or program supplier the right to delete the data. We expect a licensee to be notified of any upstream data insertion in programming supplied to it unless the presence of the data is readily detectable. We further propose that a licensee be required to maintain a copy at the station of any contract regarding ancillary data transmissions within the video, as we currently require for data transmissions in the VBI.(n13)
27. With the possibility that other manufacturers will
want to employ different schemes for their own products
or services, a substantial demand for such "hidden video
spectrum" could develop, potentially posing difficult system
compatibility problems. Our "licensee is responsible"
approach gives the broadcaster the flexibility to choose
among clearly mutually-exclusive uses. However, we are
concerned that newly-developed systems might be incompatible
with systems already in use without that fact being obvious
to the broadcaster. It is also possible that while a single
system's digital data insertions on a particular video
signal would cause no discernible degradation to reception
of the TV signal by itself, a combination of transmissions
could have destructive cumulative effects. We seek comment
on how to be certain that broadcasters and users are aware
of such cumulative effects and also on how, if at all,
such incompatibilities could harm consumers, broadcasters,
or the datadelivery industry. We also solicit comment
on whether we should leave the resolution of questions
concerning system compatibility and the impact of cumulative
effects on the video signal to presumably informed broadcasters
or prescribe compatibility standards and insertion limits
Overscan vs. sub-video
30. We note, however, that over the last twenty-five
years (as solid state technology replaced vacuum tube technology),
the amount of "overscan" used in television receivers has
decreased from about five percent to a significantly smaller
value, perhaps to less than two percent. We ask for comment
on whether further reductions in overscan might result
in signals in "overscan" areas becoming discernible to
viewers in the future. The visibility of "overscan" data
also may increase as multi-function video display devices
increase their penetration in homes.(n14) We seek comment on
whether "overscan" technologies are visible on standard
TVs and VCR recordings when "picture-in-picture" modes
of viewing are invoked or will be more visible in the future
when a TV signal is displayed as a "window" on a computer
terminal graphics display. If development of these methods
of television video display suggests that continuing use
of "overscan" data transmission technology could create
problems as the previously hidden information becomes visible
on the screen, we requestcomment on whether "overscan"
technologies should be phased out in favor of more subtle,
less intrusive methods of data transmission. We seek comment
on this issue and on a timetable for phasing out use of
such systems, should we conclude to do so.
31. The picture degradation that results from sub-video
methods of data transmission appears to be much more difficult
to define and to detect. We seek comment on whether there
is some method by which such picture degradation or "distortion"
can be objectively measured and on whether there is some
limit which should not be exceeded. We are also concerned
about the filtering issue raised by RTT and seek comments
on the extent, if at all, we should permit alteration of
the video signal or the video bandpass characteristics
to permit the insertion of data. Any further information
on the potential for Digideck's D-Channel system to cause
adjacent channel interference also is requested. Finally,
we ask whether some types of receivers (such as the computer
monitors mentioned in the preceding paragraph) might be
more prone to showing degradation caused by any method
of sub-video data transmission.
Broadcasters' ability to delete the data
33. "Overscan" data signals are limited to specific places
in the picture and are easily deleted by the licensee.
While the actual original picture content is lost when
the data is inserted, it can be replaced either by a solid
line (which would reduce the size of the picture slightly
by adding to the border) or by duplicating the adjacent
picture elements (for example, sending line 23 content
on line 22, as well), making any picture degradation very
difficult to detect or observe. We seek comment on what
would happen to the picture if the licensee deletes sub-video
data, if the licensee replaces sub-video data, and if multiple
occurrences of such deletions or replacements take place.
We are concerned that individually insignificant degradations
to the picture could become cumulative, noticeable, and
35. While we are seeking comments now to expedite resolution
of this proceeding and to gain information that can assist
any interim decisions we may make, we intend also to consider
the work of the National Data Broadcasting Committee when
we adopt a final decision.(n15) If the Committee submits a
recommendation to the Commission after comments are due,
we intend to provide notice of that recommendation and
to solicit public comment on it. We have successfully
relied on similar industry groups in the past. Specifically,
we note the success of the National Television Systems
Committee, an industry group established in 1940 to develop
technical standards for television broadcasts. The standard
proposed by the industry and adopted by the Commission
has served the nation's needs for half a century. As it
continues its work, we encourage the Committee to take
into consideration the many issues raised in this Notice,
so as to formulate the most flexible and potentially useful
method or methods of data transmission possible.
36. We also seek comments on whether there are limitations
that we should impose on a technical standard developed
by industry. For example, should a portion of a sub-video
data transmission system's capacity be reserved for current
line 22-type uses (which have not been intended for use
by the general public)? Should any additional portions
of its capacity be reserved for communications that would
be targeted toward specific users (such as the Yes! proposal
for its "TV Teddy" toy)? We request comment on whether
that kind of application requires a specifically dedicated
portion of the data signal instead of extracting needed
information from a more general digital data signal. In
sum, we ask whether any system that may be recommended
as a standard must be "partitioned by use" at the time
of its possible adoption or whether its design permits
its adaptation to potential future uses on a flexible or
dynamic basis. This question should also be considered
in relation to digital signal decoders that might be used
by the general public, either as an optional accessory
provided on certain models of televisions or as some kind
of external converter.
37. We seek comment on how our rules should reflect theindustry
standards. The options range from our continuing to authorize
such transmissions on an ad hoc basis to our adopting a
comprehensive set of rules defining and regulating permissible
transmissions. We request comment on adopting rules analogous
to those that govern multichannel television sound.(n16) There,
an industry committee evaluated the technology and recommended
a standard. Our rules refer to the standard, which is
also published in a Bulletin issued by our Office of Engineering
and Technology, but are only designed to protect receivers
designed to the standard from signals to which they would
38. Pending the Committee's completion of its work,
we seek comments on whether we should consider the near-term
authorization of individual methods of such transmission
on an ad hoc basis. We would expect technical conflicts
between users to be resolved by the individual licensees,
but request comments on whether Commission involvement
or guidance is necessary to focus licensee decisions on
the public interest. Commenters are invited to address
how we could resolve questions of picture or sound degradation.
40. However, lines in the VBI are also used for broadcast
and broadcast-related services. Line 21(n17) is used for closed-captioning
(text depiction of picture content) and for text mode data
and extended data service information (the content of the
latter is not regulated and may include any kind of information
the broadcaster believes would serve the public interest).
Line 17,(n18) reserved for the use of the broadcast-related
ghost-cancelling reference signal, is being used by many
newer NTSC television receivers to improve picture quality.
Accordingly,consistent with the inference made in paragraphs
34-36, supra, concerning transmissions directed to the
general public, we propose to permit broadcast and broadcast-related
use of sub-video data transmission technology and ask for
comment on this proposal.
41. This Notice was formulated in response to the referenced pending petitions and is consistent with the Commission's general policy to foster more efficient use of spectrum and improve the diversity and quality of the telecommunications services available to the public. As a final matter, given the pendency of proposals to replace the current NTSC transmission standard,(n19) we ask whether by further enhancing NTSC television in the manner described herein the Commission would provide a disincentive for the public to readily accept and upgrade to the digital service that we expect will be introduced in the near future. Similarly, we request comment on the extent to which enhancing NTSC service in the manner described herein could slow or create a disincentive to the recovery of the spectrum currently used by NTSC stations, as discussed in the advanced television proceeding.(n20)
44. This is a non-restricted notice and comment rulemaking
proceeding. Ex parte presentations are permitted, except
during the Sunshine Agenda period, provided they are disclosed
as provided in the Commission Rules. See generally 47
C.F.R. Sections 1.1202, 1.1203, and 1.1206(a).
45. As required by Section 603 of the Regulatory Flexibility
Act, the Commission has prepared an Initial Regulatory
Flexibility Analysis (IRFA) of the expected impact on small
entities of the proposals suggested in this document.
The IRFA is set forth in the attached Appendix. Written
public comments are requested on the IRFA. These comments
must be filed in accordance with the same filing deadlines
as comments on the rest of the Notice, but they must have
a separate and distinct heading designating them as responses
to the Initial Regulatory Flexibility Analysis. The Secretary
shall send a copy of this Notice of Proposed Rule Making,
including the Initial Regulatory Flexibility Analysis,
to the Chief Counsel for Advocacy of the Small Business
Administration in accordance with paragraph 603(a) of the
Regulatory Flexibility Act. Pub. L. No. 96-354, 94 Stat.
1164, 5 U.S.C. Section 601 et seq (1981).
46. Authority for the proposed amendments is contained
in Sections 4(i) and 303 of the Communications Act of 1934,
47. For further information, please contact Paul Gordon
at (202) 776-1653 or James E. McNally, Jr. at (202) 418-2190.
FEDERAL COMMUNICATIONS COMMISSION
William F. Caton
In recent years, a number of requests have been submitted
to the Commission concerning systems for embedding digital
data within television video signals. These proposals
raise important questions about how embedded data systems
could be accommodated, concerns over the extent to which
broadcasters' control over their signals may be impaired
or lost, and to what degree embedding multiple digital
signals in the television picture may result in discernable
II. Objectives of the Action
The purpose of this proceeding is to develop policies
and rules defining the respective rights and responsibilities
of broadcast licensees and persons wishing to provide different
types of digital information service, to explore the potential
uses of such digital technology, to determine to what extent
different systems may be compatible, to determine whether
a national technical standard is necessary for the provision
of such service, and to determine the probable impact of
such service on the quality of primary television service.
III. Legal Basis
Authority for the actions proposed in this Notice may
be found in Sections 4(i) and 303 of the Communications
act of 1934, as amended, 47 U.S.C. 154 and 303.
IV. Reporting, recordkeeping and other compliance requirements
Policies adopted in this proceeding could lead to increased
record-keeping requirements being imposed on broadcast
licensees and/or providers of digital information service.
If such requirements are imposed, they would probably
take the form of such entities being required to maintain
copies of contracts relating to the provision of such service
and making them available to the Commission upon request.
V. Federal rules which overlap, duplicate or conflict with
VI. Description, potential impact and number of small entities
Approximately 10,000 licensees of television broadcast
facilities of all types (Commercial and educational VHF
and UHF stations, translators, boosters and Low Power TV
stations) could be affected. The number of digital service
providers affected would probably be much less.
VII. Any significant alternatives minimizing the impact
on small entities consistent with stated objectives.
A decision to implement a national standard applicable to all digital information to be contained within the television picture, in conjunction with a decision as to the general types of information that could be provided, could greatly reduce or eliminate the compatibility problems related to the provision of digital data services and decrease the need for additional record-keeping requirements.
NTSC is the acronym for the National Television Systems
Committee, which developed the standards for the television
broadcast system currently employed in the United States.
An NTSC television picture consists of 525 lines, half
transmitted during each of two interlaced fields. Each
field contains 21
lines of vertical blanking interval, with the remainder of the lines containing picture information. See 47 C.F.R. §§ 73.681, 73.682.
Footnote 2 The VBI is the portion of the television broadcast signal that occurs at the beginning of each field. In the VBI, synchronizing pulses are transmitted and the electronic beam is turned off while it retraces from the bottom to the top of the screen, where the beam then begins the vertical scan of the next television picture. No picture information is transmitted during the VBI.
Footnote 3 Public Notice, FCC 70-387 (April 20, 1970), 22 FCC 2d 779 (1970).
Footnote 4 WavePhore's petition is hereby incorporated into this proceeding. A copy of it and the associated comments have been placed in the docket file.
Footnote 5 Public Notice, DA 94-67 (January 25, 1994).
Footnote 6 Report and Order in MM Docket No. 92-305 (Permissible Uses of the Vertical Blanking Interval of Broadcast Television Signals) 8 FCC Rcd 3613 (1993).
Footnote 7 Letter to Grier C. Raclin dated November 22, 1989. Nielsen's initial request for temporary authorization and subsequent request for permanent authorization of its AMOL system are hereby incorporated into this proceeding. Copies have been placed in the docket file.
Footnote 8 Letter to Grier C. Raclin dated May 1, 1990.
Footnote 9 Public Notice, Report No. 1833, released January 14, 1991. Airtrax's petition is hereby incorporated into this proceeding. A copy of it and the associated comments have been placed in the docket file.
Footnote 10 Yes! Entertainment Corporation's letter of request is hereby incorporated into this proceeding. A copy of it has been placed in the docket file.
Footnote 11 Letter to WWOR-TV, Inc. from Barbara A. Kreisman dated January 19, 1995.
Footnote 12 47 C.F.R. § 73.646(d).
Footnote 13 47 C.F.R. § 73.3613(e).
Footnote 14 See NAB comments on the Airtrax petition at para. 18, supra.
Footnote 15 See para. 14, supra.
Footnote 16 See 47 C.F.R. § 73.682(c)(3), the definition of BTSC in 47 C.F.R. § 73.681, and the Second Report and Order in Docket No. 21323, FCC 84-116, released April 23, 1984, 55 RR 2d 1642, 1984, 49 Fed. Reg. 18100, April 27, 1984.
Footnote 17 See 47 C.F.R. § 73.682(a)(22)(i).
Footnote 18 See 47 C.F.R. § 73.682(a)(21)(iv).
Footnote 19 See Memorandum Opinion and Order/Third Report and Order/Third Further Notice of Proposed Rule Making in MM Docket No. 87-268, 7 FCC Rcd 6924 (1992).
Footnote 20 See Second Report and Order/Further Notice of Proposed Rule Making in MM Docket No. 87-268, 7 FCC Rcd 3340 (1992) and Second Further Notice of Proposed Rule Making in MM Docket No. 87-268, 7 FCC Rcd 5376 (1992).