GB873926A - Improvements in or relating to electric pulse code systems of communications - Google Patents

Improvements in or relating to electric pulse code systems of communications

Info

Publication number
GB873926A
GB873926A GB3003659A GB3003659A GB873926A GB 873926 A GB873926 A GB 873926A GB 3003659 A GB3003659 A GB 3003659A GB 3003659 A GB3003659 A GB 3003659A GB 873926 A GB873926 A GB 873926A
Authority
GB
United Kingdom
Prior art keywords
amplitude
noise
signal
frequency
pulse code
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.)
Expired
Application number
GB3003659A
Inventor
Bent Bulow Jacobsen
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to GB3003659A priority Critical patent/GB873926A/en
Priority to FR837642A priority patent/FR78805E/fr
Priority to DEJ18657A priority patent/DE1157652B/en
Publication of GB873926A publication Critical patent/GB873926A/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
    • H04B14/046—Systems or methods for reducing noise or bandwidth

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)
  • Dc Digital Transmission (AREA)
  • Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)

Abstract

873,926. Pulse code modulation systems. STANDARD TELEPHONES & CABLES Ltd. Sept. 3, 1959, No. 30036/59. Class 40(5) In a transmitter for a pulse code modulation system, means are provided for adding a band of "white noise" to the signal before quantising in order to reduce the noise due to quantizing errors. In a multichannel system in which a number of channel frequency bands are arranged on a frequency division basis and transmitted over a pulse code modulation system the quantizing errors arising when only one or two channels are busy are reduced. The added noise removes the discontinuity which exists when the signal amplitude is comparable with but not equal to a quantizing step. As shown, a conventional channelling equipment 1 includes modulators for producing a group frequency band comprising a number of channel frequency bands arranged side-by-side. A filter 3 selects from a noise generator 2 a band of "white noise" which is combined with the group frequency band at 4 and the combined wave is supplied to a conventional pulse coder 6. In Fig. 2 line 7 represents the zero axis of signal amplitude, 5 being the voltage difference between adjacent levels. If the signal amplitude lies anywhere between the values 0 and + 5, then after quantizing it will appear as the amplitude S/2 which is the nearest step. Assuming that the signal has a constant amplitude (1+a) S/2 line 8, in a conventional system, this amplitude would be coded as S/2 for any value of a between +1 and -1, but as 3S/2 for any value of a between +1 and +2. When the noise wave is applied the effective signal waveform 9 will have a relatively large proportion of samples with quantized levels zero and and a few with levels such as 3S/2 and - S/2 When the root mean square value of the amplitude of the added noise wave is at least S/2 the proportion of the various quantized levels will be such that the average quantized level is approximately (1+a) S/2 for all values of a. A similar advantage is obtained with a signal of variable amplitude. If the added noise is confined to a frequency band lying between the maximum signal frequency and a frequency equal to the difference between the sampling frequency and the maximum signal frequency, no noise will be added to the wanted received frequency band.
GB3003659A 1955-06-06 1959-09-03 Improvements in or relating to electric pulse code systems of communications Expired GB873926A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB3003659A GB873926A (en) 1959-09-03 1959-09-03 Improvements in or relating to electric pulse code systems of communications
FR837642A FR78805E (en) 1955-06-06 1960-09-02
DEJ18657A DE1157652B (en) 1959-09-03 1960-09-03 Transmitter for pulse code modulation transmission systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3003659A GB873926A (en) 1959-09-03 1959-09-03 Improvements in or relating to electric pulse code systems of communications

Publications (1)

Publication Number Publication Date
GB873926A true GB873926A (en) 1961-08-02

Family

ID=10301234

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3003659A Expired GB873926A (en) 1955-06-06 1959-09-03 Improvements in or relating to electric pulse code systems of communications

Country Status (2)

Country Link
DE (1) DE1157652B (en)
GB (1) GB873926A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985004995A1 (en) * 1984-04-20 1985-11-07 Motorola, Inc. Extended threshold analog to digital conversion apparatus for an rf receiver
AU572841B2 (en) * 1984-04-20 1988-05-19 Motorola, Inc. Extended threshold analog to digital conversion apparatus foran rf receiver
US4893316A (en) * 1985-04-04 1990-01-09 Motorola, Inc. Digital radio frequency receiver

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3881097A (en) * 1973-05-14 1975-04-29 Weston Instruments Inc Fully digital spectrum analyzer using time compression and discrete fourier transform techniques
JPS5081715A (en) * 1973-11-23 1975-07-02
DE3638006A1 (en) * 1986-11-07 1988-05-19 Ant Nachrichtentech METHOD FOR THE DYNAMIC ENLARGEMENT OF A DIGITALLY PROCESSED PCM SIGNAL

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985004995A1 (en) * 1984-04-20 1985-11-07 Motorola, Inc. Extended threshold analog to digital conversion apparatus for an rf receiver
AU572841B2 (en) * 1984-04-20 1988-05-19 Motorola, Inc. Extended threshold analog to digital conversion apparatus foran rf receiver
US4893316A (en) * 1985-04-04 1990-01-09 Motorola, Inc. Digital radio frequency receiver

Also Published As

Publication number Publication date
DE1157652B (en) 1963-11-21

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