Voice compression method and apparatus in a communication system

A method for compressing a plurality of voice signals within a voice communication resource within a voice communication system, comprising the steps of:

• (a) subchanneling the voice communication resource into a plurality of subchannels and simultaneously placing a pair of the plurality of voice signals on a subchannel;
• (b) modulating the pair of the plurality of voice signals about a pilot signal within the subchannel within the voice communication resource using single sideband modulation;
• and
• (c) compressing the time of each of the voice signals within the plurality of subchannels, wherein the result of steps (a), (b), and (c) provides a compressed voice signal for transmission via a transmitter.

A communication system using voice compression having at least one transmitter base station and a plurality of selective call receivers, comprising:

• at the transmitter base station:
• an input device for receiving an audio signal;
• a processing device for compressing the audio signal using time-scale compression and a single side band modulation technique to provide a processed signal;
• and
• a pilot carrier signal generator that generates a pilot carrier for a pair of single side band signals which includes the processed signal, wherein the pilot carrier serves as an amplitude and phase reference for distortion that occurs as a result of channel aberrations;
• and
• a transmitter for transmitting the processed signal;
• at each of the plurality of selective call receivers:
• a selective call receiver for receiving the transmitted processed signal;
• a receiver circuit for detecting, filtering and responding to the amplitude and phase reference generated by the pilot carrier signal generator;
• a processing device for demodulating the received processed signal using single side band demodulation and time-scale expansion to provide a reconstructed signal;
• and
• an amplifier for amplifying the reconstructed signal into an reconstructed audio signal.

A selective call receiver for receiving compressed voice signals, comprising:

• a selective call receiver for receiving a transmitted processed signal that includes compressed voice signals that have been compressed using time-scale compression;
• a processing device for demodulating the received processed signal, wherein said processing device demodulates both and upper and a lower sideband of a subchannel, the upper and lower sidebands having independent information therein, and wherein said processing device uses time-scale expansion to provide a reconstructed signal;
• a receiver circuit for detecting, filtering and responding to the amplitude and phase reference generated by a pilot carrier signal generator in a transmitter at a base station;
• and
• an amplifier for amplifying the reconstructed signal into an reconstructed audio signal.

A selective call paging base station for transmitting selective call signals on a communication resource having a predetermined bandwidth, comprising:

• an input device for receiving a plurality of audio signals;
• a means for subchannelizing the communication resource into a predetermined number of subchannels;
• an amplitude compression and filtering module for each subchannel for compressing the amplitude of the respective audio signal and filtering the respective audio signal;
• a time compression module for compressing the time of the respective audio signal for each subchannel;
• and
• a quadrature amplitude modulation transmitter for transmitting the processed signal.

A selective call receiver unit for receiving compressed voice selective call signals, comprising:

• a receiver having a analog to digital converter for providing a digitized received signal;
• a digital signal processor for performing single sideband demodulation of a subchannel having a pilot carrier and independent information on an upper and a lower sideband of a subchannel, wherein the digital signal processor also performs the functions of filtering the pilot carrier, performing automatic gain control using a feedforward loop, and decompanding the digitized received signal to provide a processed signal;
• and
• a digital to analog converter and reconstruction filter for converting the processed signal into a digitized audio signal;
• and
• an amplifier for amplifying the digitized audio signal.

A communication base station, comprising:

• a terminal for receiving an audio speech signal;
• an analog to digital converter for converting the audio speech signal into a digitized speech signal;
• a digital signal processor for processing the digitized speech signal by performing the function of splitting the digitized speech signal and at least one of the functions of bandpass filtering, automatic gain control, time scaling, companding, or buffering;
• and
• a transmitter having at least a Hilbert transform filter coupled to a digital to analog converter coupled to a reconstruction filter coupled to a quadrature, amplitude modulator which is coupled to a radio frequency power amplifier.