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TDM carrier transmission system for order telegrams - operates over single HF channel between different transmitting and receiving stations and uses timer actuating transmitter
TDM carrier transmission system for order telegrams - operates over single HF channel between different transmitting and receiving stations and uses timer actuating transmitter
Each transmitter is controlled by a transmission time generator and HF detector (pref. squelch filter). Fixed-frequency pulses trigger the transmission of an order telegram via an AND gate and OR gate only when no HF is detected. A monitor circuit inhibits the HF detector after a delay of about 100 to 200 ms. The transmitter is triggered only if the detector has emitted no signal for a min. duration of at least two chain lengths (50 to 75 ms). A counter counts the number of inhibitions of transmission by the HF detector, and is reset to zero by an end-of-transmission switch. The ratio of the fixed duration to the fixed interval of each transmitting station is predetermined in a different manner.
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