Posted by Franz [209.86.226.56] on Sunday, March 23, 2014 at 02:20:15 :
In Reply to: Interesting posted by gmharris [72.219.148.98] on Saturday, March 22, 2014 at 17:57:31 :
Full Duplex was damn expensive to build when you factor in the cost of a tuned cavity in the mobil unit that will accommodate the frequency spread of MTS and IMTS. Add in the efficiency of a tube radio with a dynamotor for the transmit side, and you need a huge cable on 6 volts. Transmit had to be a similar power draw to the starter turning over the engine. Receiver definitely would kill a battery fast too.
In the early days of MTS there wasn't a viable decoder to ring the vehicle end, so the operator voice paged the unit. There was no privacy.
On a side note, Rochester, NY had both MTS & IMTS service until about 1987. IMTS was limited to 200 phones in vehicles because there were only 2 channels. The ringing system of those phones is quite similar to a party line, and the phone itself only identified by area code and 3 digits.
If the phone was on a foreign tower, you could still dial it by punching in 17 digits, but you needed to know the towers number.
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