. Bell telephone magazine . being used commercially for trans-mitting 24 telephone calls, or comparableamounts of data, over distances of up to 50miles on a pair of wires. The new high-speedPCM system, when fully developed, will beable to transmit voice, television and datasignals of the highest quality from coast tocoast over coaxial cable. In PCM, the varying electrical signals thatrepresent sound or picture information arenot sent in their entirety but, instead, aresampled many times a second and encodedinto groups of nine electrical pulses. Thesepulses are sent over the cable at a rate of2
. Bell telephone magazine . being used commercially for trans-mitting 24 telephone calls, or comparableamounts of data, over distances of up to 50miles on a pair of wires. The new high-speedPCM system, when fully developed, will beable to transmit voice, television and datasignals of the highest quality from coast tocoast over coaxial cable. In PCM, the varying electrical signals thatrepresent sound or picture information arenot sent in their entirety but, instead, aresampled many times a second and encodedinto groups of nine electrical pulses. Thesepulses are sent over the cable at a rate of224 million pulses per second. Becausepulses are sent, the codes of many differentsignals—voices, data and pictures—can beeasily interleaved on the same transmissionpath. At the far end of the line the pulsesare sorted out and converted back into voiceand television signals, and then into soundand pictures with no loss in quality. LETS network was developed by the Bell System working with local, state police NATIONWIDE LETS N6TW0P uExdQiAnnns in phoenix. ^ Along the route signals can be added ortaken off the main stream of pulses as de-sired. The performance of this experimentalhigh-speed PCM system indicates that evenhigher speed systems—with greater informa-tion capacity—are possible. New Coin Phone M A new model of the Bell Systems pub-lic phone, going into production at West-ern Electrics Oklahoma City plant, will con-tain a handful of pleasant surprises for cus-tomers—and some unpleasant ones for van-dals who attempt to burglarize phone booths. The new set contains the largest numberof changes ever made at one time in thefamiliar coin phone. The sound of gongsand chimes as nickels, dimes and quartersare deposited is giving way to electronicbeeps of tone that will indicate to operatorsthe number and type of coins. The three coin slots, standard on cointelephones for more than 50 years, have beenreplaced by a single slot in the upper lefthand corner of
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Keywords: ., bookauthoramerican, bookcentury1900, bookdecade1920, bookyear1922
