GB2004149A - PCM codec using common d/a converter for encoding and decoding - Google Patents

PCM codec using common d/a converter for encoding and decoding

Info

Publication number
GB2004149A
GB2004149A GB7834133A GB7834133A GB2004149A GB 2004149 A GB2004149 A GB 2004149A GB 7834133 A GB7834133 A GB 7834133A GB 7834133 A GB7834133 A GB 7834133A GB 2004149 A GB2004149 A GB 2004149A
Authority
GB
United Kingdom
Prior art keywords
pcm
encoding
decoding
decoded
level
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB7834133A
Other versions
GB2004149B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Publication of GB2004149A publication Critical patent/GB2004149A/en
Application granted granted Critical
Publication of GB2004149B publication Critical patent/GB2004149B/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B14/00—Transmission systems not characterised by the medium used for transmission
    • H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
    • H04B14/04—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse code modulation
    • H04B14/042—Special circuits, e.g. comparators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H03M1/66—Digital/analogue converters

Abstract

A coder/decoder in a PCM communications system, employs a common digital-to-analog converter. In a basic sampling interval the incoming PCM signal is decoded at a decision level on one side of the desired reconstruction level; then modified and again decoded at a different decision level on the other side of the desired level. The average of the two decoded signals then lies on the desired level giving a decoding characteristic having decision levels between those of the encoding characteristics. As used in a conventional PCM system, the two PCM samples differ by only one least significant bit. In a preferred embodiment, separate storage registers R1 R2 are used for encoding and decoding, plus a selector 262 for switching between the two registers during the decoding intervals. Thus, encoding may be effected during a substantial portion of the basic sampling cycle, being interrupted only to generate decoded samples. The invention is applicable to PCM systems generally, including compressed pulse code modulation systems. <IMAGE>
GB7834133A 1977-09-06 1978-08-22 Pcm codec using common d/a converter for encoding and decoding Expired GB2004149B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US83077977A 1977-09-06 1977-09-06

Publications (2)

Publication Number Publication Date
GB2004149A true GB2004149A (en) 1979-03-21
GB2004149B GB2004149B (en) 1982-02-03

Family

ID=25257676

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7834133A Expired GB2004149B (en) 1977-09-06 1978-08-22 Pcm codec using common d/a converter for encoding and decoding

Country Status (5)

Country Link
JP (1) JPS6017256B2 (en)
BR (1) BR7805867A (en)
CA (1) CA1132711A (en)
ES (1) ES473132A1 (en)
GB (1) GB2004149B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4392123A (en) * 1980-06-02 1983-07-05 The Dindima Group Pty. Ltd. Signal-to-noise improving system
US4535474A (en) * 1983-08-15 1985-08-13 Signal Research Laboratory Audio ambience simulator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4392123A (en) * 1980-06-02 1983-07-05 The Dindima Group Pty. Ltd. Signal-to-noise improving system
US4535474A (en) * 1983-08-15 1985-08-13 Signal Research Laboratory Audio ambience simulator

Also Published As

Publication number Publication date
GB2004149B (en) 1982-02-03
JPS6017256B2 (en) 1985-05-01
ES473132A1 (en) 1979-10-16
CA1132711A (en) 1982-09-28
JPS5496312A (en) 1979-07-30
BR7805867A (en) 1979-05-02

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee