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An SSTV repeater is an amateur radio repeater station that relays slow-scan television signals. A typical SSTV repeater is equipped with a HF or VHF transceiver and a computer with a sound card, which serves as a demodulator/modulator of SSTV signals. SSTV repeaters are used by amateur radio operators for exchanging pictures.
Because the transmitter and receiver are on at the same time, isolation must exist to keep the repeater's own transmitter from degrading the repeater receiver. If the repeater transmitter and receiver are not isolated well, the repeater's own transmitter desensitizes the repeater receiver. The problem is similar to being at a rock concert and ...
Channels 58 and 59 are often offset in frequency to limit interference to the weak-signal and amateur radio satellite sub-bands (431–433 & 435–438 MHz respectively). Many modern CATV receivers can still lock-on to frequencies offset as much as 1 MHz. Rarely used today due to heavy FM repeater use in this range.
This was a windfall for amateur radio enthusiasts, allowing access to fairly inexpensive radios which could easily be modified for use in the 10 meter band. American Novice and Technician class licensees were granted CW and SSB segments on the 10 meter band as of 21 March 1987.
Morse code is called the original digital mode. Radio telegraphy, designed for machine-to-machine communication is the direct on / off keying of a continuous wave carrier by Morse code symbols, often called amplitude-shift keying or ASK, may be considered to be an amplitude modulated mode of communications, and is rightfully considered the first digital data mode.
There are several different types of repeaters; a telephone repeater is an amplifier in a telephone line, an optical repeater is an optoelectronic circuit that amplifies the light beam in an optical fiber cable; and a radio repeater is a radio receiver and transmitter that retransmits a radio signal.
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RFinder's main service is the World Wide Repeater Directory (WWRD), which is a directory of amateur radio repeaters. RFinder is the official repeater directory of several amateur radio associations. RFinder has listings for several amateur radio modes , including FM , D-STAR , DMR , and ATV .