Pulse or digital communications – Repeaters – Testing
Patent
1987-09-21
1989-08-22
Griffin, Robert L.
Pulse or digital communications
Repeaters
Testing
375122, 341 61, 358136, H04B 166
Patent
active
048603139
ABSTRACT:
Apparatus and technique for ADPCM transmission of voiceband data at rates up to and including 9600 bits/s via an ADPCM system comprising an ADPCM transmitter receiving PCM encoded signals at an 8 KHz sampling rate and being operative to transmit data at a sampling rate of 6.4 KHz and a transmission rate of 5 bits per sample and an ADPCM receiver having apparatus for receiving the transmitted data from the ADPCM transmitter and being operative for providing PCM encoded signals at an 8 KHz sampling rate. The ADPCM transmitter includes an adaptive quantizer which is operative to provide an output signal I(n), employing a scale factor adapted according to a discrete function difference signal W(I) having a relationship to I(n) which typically is substantially different from that given in recommendation G.721 of the CCITT. The ADPCM transmitter also includes an adaptive predictor having predictor coefficients which are updated using a leak factor lower than that shown in recommendation G.721 of the CCITT.
REFERENCES:
patent: 4319082 (1982-03-01), Gilloire et al.
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patent: 4437087 (1984-03-01), Petr
patent: 4475213 (1984-10-01), Medaugh
patent: 4516241 (1985-05-01), Farah et al.
patent: 4654863 (1987-03-01), Belfield et al.
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Recommendation G.721 of the International Telegraph and Telephone Consultative Committee (CCITT), appearing in vol. III.3 of the Redbook issued at the Malaga-Torremoitnos Plenary Assembly of 19 Oct. 1984, Appendix I.
Report of Study Group VXIII of the CCITT, Apr. 87, Jul. 87.
ECI Telecom Ltd.
Griffin Robert L.
Huseman Marianne
Meller Michael N.
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