T1 radio having coding gain adjustable for number of channels
View Patent ↗A communication system for transmitting (T 1 ) digital communication signals between a transmit site and a receiver site includes an M:1 multiplexer, coupled to a rate 1/N convolutional encoder, which is operative to output an encoded output signal modulated in quaternary phase shift keyed (QPSK) space having a prescribed symbol rate. The receive site has a rate 1/N Viterbi decoder which is operative to decode the encoded output signal output by the rate 1/N convolutional encoder, and a 1:M demultiplexer having an input coupled to the Viterbi decoder and M plurality of outputs, and being operative to demultiplex the decoded signal from the Viterbi decoder into a plurality of M time division multiplexed digital communication signals. For any selected values for of M and N, the product of M and N is constant.
1. A communication system for transmitting digital communication signals between a transmit site and a receiver site comprising:
at said transmit site,
an M:1 multiplexer, wherein M is variable, having an M plurality of inputs coupled to receive up to M time division multiplexed digital communication signals;
a rate 1/N convolutional encoder, where N is variable, coupled to the output of said multiplexer and being operative to output an encoded output signal modulated in quaternary phase shift keyed (QPSK) space having a prescribed symbol rate;
at said receiver site,
a rate 1/N Viterbi decoder which is operative to decode the encoded output signal output by said rate 1/N convolutional encoder;
a 1:M demultiplexer having an input coupled to said Viterbi decoder and M plurality of outputs, and being operative to demultiplex the decoded signal from said Viterbi decoder into a plurality of M time division multiplexed digital communication signals, and wherein
for any selected values for of M and N, the product of M and N is constant.
2. A transmitter subsystem for transmitting digital communication signals from a transmit site to a receiver site comprising:
an M:1 multiplexer, wherein M is variable, having an M plurality of inputs coupled to receive up to M time division multiplexed digital communication signals;
a rate 1/N convolutional encoder, where N is variable, coupled to the output of said multiplexer and being operative to output an encoded output signal modulated in quaternary phase shift keyed (QPSK) space having a prescribed symbol rate;
an interleaver coupled to interleave I and Q outputs of said rate 1/N convolutional encoder;
an RF transmitter coupled to transmit interleaved I and Q outputs supplied thereto by said interleaver, and wherein
for any selected values for of M and N, the product of M and N is constant.
3. A receiver subsystem for receiving digital communication signals that have been transmitted from a transmit site to a receiver site comprising:
an RF front end which is operative to receive an RF signal encoded modulated in quaternary phase shift keyed (QPSK) space having a prescribed symbol rate;
a rate 1/N Viterbi decoder which is operative to decode the received encoded output signal output by said RF front end;
a 1:M demultiplexer having an input coupled to said Viterbi decoder and M plurality of outputs, and being operative to demultiplex the decoded signal from said Viterbi decoder into a plurality of M time division multiplexed digital communication signals, and wherein
for any selected values for of M and N, the product of M and N is constant.
4. A method of increasing the wireless transport distance of digital communication signals transmitted from a transmit site comprising the steps of:
(a) coupling said digital communication signals to one input of an M:1 multiplexer, wherein M is a variable greater than one, having an M plurality of inputs capable of receiving up to M time division multiplexed digital communication signals;
(b) coupling the output of said M:1 multiplexer to a rate 1/N convolutional encoder, where N is variable, said encoder being operative to output an encoded output signal modulated in quaternary phase shift keyed (QPSK) space having a prescribed symbol rate;
(c) transmitting the output of said rate 1/N convolutional encoder to a receive site, and wherein
for any selected values for of M and N, the product of M and N is constant.