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Our most commonly asked questions for grades 4-8 are:
 What is the difference between AM radio and FM radio?
 What is Cable Television?
 Why is the 555 exchange used on television shows?
 What is a Satellite?
 What is Broadband?
 How does someone with a hearing disability use a telephone?
 What is Telecommunications Relay Service?
 Can People with Hearing Aids use Standard Telephones?
 What is Video Relay Services?
 What do the end of the Web addressess stand for?
 What is a Satellite dish?
 How do Descramblers work?
AM and FM radio waves What is the difference between AM radio and FM radio?
AM stands for “amplitude modulation” – a type of signal. With AM, the amplitude of the combined audio frequency and radio frequency waves varies to match the audio signal. AM radio can develop problems with interference. This makes it hard to hear the radio show. Interference can be caused by many sources. For example, sparks discharge when a car is started, in electric motors in all sorts of electrical appliances, and even lightning. All of these things can produce interference to AM radio. As you can see, there is a lot of background noise that changes the amplitude of the radio wave signal. This creates the random crackling noises call static.
FM stands for “frequency modulation”- a type of radio transmission, the frequency of the combined waves change to reproduce the audio signal. For example, higher frequency is associated with the peak amplitude in the audio wave. FM waves do not have a problem with interference because the noise background does not modify the radio wave frequency. In addition FM waves give better sound reproduction.

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cable tv What Is Cable Television?
Cable television is a type of delivery system for video programming. It is provided by a cable operator to people that pay for it - called “subscribers”. The video program is sent to the subscriber’s television using coaxial cable or fiber optics. Cable companies often use coaxial cable to transmit or send television shows to your television. Coaxial cable is a wire with a stiff copper as the core, surrounded by an insulating material to prevent the wire from transmitting the cable signal through the air. This insulation is covered by a conductor, which often consists of a closely woven braided mesh. The conductor allows the video signal to move through the coaxial cable and into your television set. The conductor is protected by a plastic covering.
Fiber Optic lines or optical fibers can also be used as a delivery system for cable video programming. They are made of glass, which is made from sand or silicon and other, inexpensive raw material. The glass used for modern fibers is so transparent that if the oceans were full of it instead of water, the seabed would be as visible from the surface as the ground is visible from an airplane on a clear day. Video programming can also be delivered without a wire via satellite "cable television" under the Commission's definitions.

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Why is the 555 exchange used on television shows?
You may have noticed that, when characters in television shows use a telephone number the prefix is always 555. 555 is used only on television shows and is not a prefix to a real telephone number. This “fake” prefix ensures that a viewer can not dial the number and bother the subscriber to whom that telephone number is assigned. Fictitious numbers for movies and television use 555-0100 to 555-0199. Before the 555 exchange was established, prefixes such as GRAMERCY, PLAZA or KLONDIKE were used.
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image of earth and satelliteWhat is a Satellite?
A satellite is basically any object that revolves around a planet in a circular or elliptical path or orbit. The moon is Earth's original, natural satellite, and there are many manmade (artificial) satellites, their orbits are usually closer to Earth. Satellite service is the only broadband technology that is able to reach virtually any part of the United States. Television viewers are familiar with the concept of satellite dishes that receive TV channels. It can be used to carry phone calls, and radio signals, as well as video programs and internet service, which require more bandwidth and are within the category of communications services called “broadband” services. Other broadband data is delivered in exactly the same way. For many rural areas of the United States, and especially Alaska, satellite service is the only way that residents and businesses will ever have access to the Internet and to other broadband services. Satellite is currently the most expensive way to deliver telecommunications and broad band services like Internet access.
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What is Broadband?
The term “broadband” refers to telecommunication in which a wide band of frequencies is available to transmit information. It is frequently used as another term for high-speed Internet access which allows users to access the Internet and Internet-related services at significantly higher speeds than traditional modems like a regular telephone line. High-speed Internet allows users access to advance data processing and high-speed transmission technologies such as: cable modem; wireless access, satellite access, and power line access. There are many advantages to broadband, some of these are: your connection is always on, there is no need to dial-up your Internet provider; information can be downloaded into our computer at significantly higher speeds than with traditional modems; users can go on line without tying up their telephone lines.
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image of a TTY telephone How does someone with a hearing disability use a telephone?
A text telephone (TTY) allows a deaf, hard-of-hearing or speech-disabled person to make a telephone call. The TTY is a telephone that looks like a typewriter with a text screen – the TTY is connected to the telephone line in the users home or business. Once the telephone connection is made the TTY user types his message to the called party and the words appear on the TTY screen. The called party responds to the caller by typing on his TTY- all conversation is printed on the screen. Instead of listening to what the other person on the phone call says deaf, hard-of-hearing or speech disabled people reads what the person said. The TTY allows a person with a hearing disability to directly call another person who has a TTY. Persons using a TTY may also call any standard phone user by placing the call through a Telecommunications Relay Service.
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What is Telecommunications Relay Service?
Telecommunications Relay Service (TRS) is provided over the telephone line and allows persons with hearing and speech disabilities to communicate by telephone with persons who may or may not have such disabilities. TRS facilities have special equipment and are staffed by communications assistants (CAs) who relay conversations between people who use text telecommunications devices and people who communicate by voice. The caller can use a text telephone (TTY) to dial the telephone number of the local TRS center. For the TTY user, the first step – the inbound call to the TRS center – is functionally equivalent to receiving a dial tone. The CA in turn places an outbound voice call from the TRS center to the called party. The CA serves as the link in the conversation, converting all typed TTY messages from the TTY caller into voice messages, and all voice messages from the called party into typed messages for the TTY user. The process is performed in reverse when a voice telephone user initiates the call to a TTY user.
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Can People with Hearing Aids Use Standard Telephones?
The Hearing Aid Compatibility Act of 1988 (HAC Act) requires that the Federal Communications Commission ( FCC ) ensure that all telephones manufactured or imported for use in the United States after August 1989, and all "essential" telephones are hearing aid compatible. "Essential" phones are defined as "coin-operated telephones, telephones provided for emergency use, and other telephones frequently needed for use by persons using such hearing aids." These might include workplace telephones, telephones in confined settings (like hospitals and nursing homes), and telephones in hotel and motel rooms. Secure telephones, as well as telephones used with public mobile and private radio services, are exempt from the HAC Act.
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sign language What is Video Relay Service
This type of Telecommunications Relay Service enables individuals who use sign language to make relay calls through Communications Assistant (CA) who can interpret their calls. To use video relay service the telephone call is made over the internet and uses video equipment so the CA and the caller can see each other. The caller uses sign language to tell the CA who to call and what to say. The CA voices what is signed to the called party and signs back to the caller. This type of relay service is not required by the FCC, but is offered on a voluntary basis by certain TRS programs. This option is helpful for people who use American Sign Language (ASL), and for people who cannot type on a TTY easily, such as children who are ASL users. Video Relay Service is another type of Telecommunications Relay Service that allows persons with hearing and speech disabilities to use the telephone.
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dot com balloon What do the end of Web addresses stand for?
In the United States, there are five main web page endings. These are intended to tell you where the information you are looking at: comes from: ".edu" for educational institutions, ".gov" for government agencies, ".org" for non-profit organizations, ".com" for commercial or business sites, and ".net" for network providers.
In countries outside the United States, the Web addresses end with the country’s abbreviation, such as ".uk", which means that the web site comes from the United Kingdom.

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satellite dish What is a satellite dish?
The dish is the part of satellite TV that you see the most. It is a reflector which is usually made out of aluminum. Dish sizes vary from small (3-4 feet) all the way to 16-20 Ft with the average falling between 7-12 ft, 10 ft being most common. This device focuses the microwave signals coming from the satellites much as the mirror in a reflecting telescope concentrates the light from distant galaxies.
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How Do Descramblers Work?
Each device has a unique ID number, which you give to programming services to subscribe to a channel or package. The programming service broadcasts your ID number, and a special code that instructs your descrambler to work when tuned to a subscribed channel.
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On April 3, 1973, Martin Cooper made the first cellular phone call.



last reviewed/updated on 01/10/06 

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