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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.
Simplex's time-division began to lose market share, but their newly founded fire alarm division significantly prospered. In 1970, Simplex introduced conventional control panels . In 1979, Simplex introduced the industry's first networked multiplex building control system that was capable of handling fire alarm, security, HVAC, synchronized time ...
Coded panels were the earliest type of central fire alarm control, and were made during the 1800s to the 1970s. A coded panel is similar in many ways to a modern conventional panel (described below), except each zone was connected to its own code wheel, which, depending on the way the panel was set up, would either do sets of four rounds of code until the initiating pull station was reset ...
Repeater use sparked a huge interest in the 2-meter and 70-centimeter (420–450 MHz) bands; however, this interest never fully found its way into the 1.25-meter band. Many amateurs attribute this to the abundance of commercial radio equipment designed for 136–174 MHz and 450–512 MHz that amateurs could easily modify for use on the 2-meter ...
British hams commonly use the 29.400 to 29.500 MHz band for FM as well with 29.400, 29.450, and 29.500 MHz being common. USA hams can be found on FM anywhere above 29.000 MHz, commonly on the above frequencies talking to overseas hams. 29.200 to 29.300 MHz is set aside in some area band plans for FM simplex use.
To avoid interference within the equipment at the station, the two frequencies used need to be separated, and ideally on different 'bands'. An unattended station working in this way is a radio repeater. It re-transmits the same information that it receives. This principle is used by telecommunications satellites and terrestrial mobile radio ...
A typical microwave repeater link setup, this one located near Salt Lake City, Utah, USA(removed in 2013) Operation principle. A passive repeater or passive radio link deflection, is a reflective or sometimes refractive panel or other object that assists in closing a radio or microwave link, in places where an obstacle in the signal path blocks any direct, line of sight communication.
A 20/28 hp plate-frame Simplex built in 1941, running at the Moseley Railway Trust Simplex 40 hp armoured 600 mm (1 ft 11 + 5 ⁄ 8 in) gauge, built for the British Army for World War I Two models of Simplex locomotive at Alan Keef's works, 1999 Red Rum at Leighton Buzzard Narrow Gauge Railway