brian@sdccsu3.UUCP (Brian Kantor) (07/25/84)
A simplex autopatch (called a 'simplex phone machine' out here in California) is a telephone intertie that works in the following manner: A receiver listens to a simplex channel (preferably a lesser used one, but some people aren't that courteous), and waits for a specific tone sequence to appear - usually a combination of a touchtone sequence and a subaudible (PL) tone. When that is detected, the control equipment takes the phone line off-hook, and transmits on the same frequency as the receiver was listening. Every so often (typically, once a second) the transmitter is dropped to allow the receiver to sample the channel. If a carrier is detected during this receiver sampling slot, the transmitter is inhibited and the receiver feeds the phone line. As soon as the receiver detects the carrier has dropped, the transmitter is enabled again and the sampling begins. Because of the simplex operation, it is a trivial matter to adapt your home transceiver to operate in this manner, and because of the tone access, the device is assumed to operate under the 'automatic control' provisions of the Rules. Except for the annoying bursts of noise (the 'squelch tails') caused by the transmitter cycling during receiver polling, they seem to work pretty well. All you have to do is remember to wait about a second after you key your transmitter to talk, to allow the receiver sampler time to notice that you are transmitting. ihnp4 \ Brian Kantor WB6CYT, UC San Diego decvax \ akgua >---- sdcsvax ----- brian dcdwest/ ucbvax/ Kantor@Nosc