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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 .
Repeater frequency sets are known as "repeater pairs", and in the ham radio community most follow ad hoc standards for the difference between the two frequencies, commonly called the offset. In the USA two-meter band, the standard offset is 600 kHz (0.6 MHz), but sometimes unusual offsets, referred to as oddball splits, are used. The actual ...
Repeater systems use two different radio frequencies; the mobiles transmit on one frequency, and the repeater station receives those transmission and transmits on a second frequency. Since the repeater must transmit at the same time as the signal is being received, and may even use the same antenna for both transmitting and receiving, frequency ...
M17 uses Frequency-Division Multiple Access (FDMA) technology in which different communication streams are separated by frequency and run concurrently. It utilizes 4,800 symbols per second, 4-level frequency-shift keying (4FSK) with a root Nyquist filter applied to the bitstream. Radio channels are 9 kHz wide, with channel spacing of 12.5 kHz.
eQSO is a client–server software program designed by amateur radio enthusiasts for linking amateur radio frequency gateways and repeaters via the internet by using a Voice over IP protocol. It is developed for licence free radios like Citizens Band, PMR446 and Family Radio Service.
Some repeaters have automatic call sign transmission at regular intervals and use the secondary suffix /R at the call sign's end. Some jurisdictions discourage this practice on the grounds that it could be confused with an amateur from the repeater's location working portable in Russia.
Monitor mode, or RFMON (Radio Frequency MONitor) mode, allows a computer with a wireless network interface controller (WNIC) to monitor all traffic received on a wireless channel. Unlike promiscuous mode , which is also used for packet sniffing , monitor mode allows packets to be captured without having to associate with an access point or ad ...
The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, nature of the modulating signal, and type of information transmitted on the carrier signal.