GB922003A - Improvements in or relating to two-way communication telephone systems - Google Patents

Improvements in or relating to two-way communication telephone systems

Info

Publication number
GB922003A
GB922003A GB3642158A GB3642158A GB922003A GB 922003 A GB922003 A GB 922003A GB 3642158 A GB3642158 A GB 3642158A GB 3642158 A GB3642158 A GB 3642158A GB 922003 A GB922003 A GB 922003A
Authority
GB
United Kingdom
Prior art keywords
transducer
signals
gain
frequencies
transmission
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
GB3642158A
Inventor
William Alexander Cawthra
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.)
Modern Telephones Great Britain Ltd
Original Assignee
Modern Telephones Great Britain Ltd
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 Modern Telephones Great Britain Ltd filed Critical Modern Telephones Great Britain Ltd
Priority to GB3642158A priority Critical patent/GB922003A/en
Publication of GB922003A publication Critical patent/GB922003A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M9/00—Arrangements for interconnection not involving centralised switching
    • H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
    • H04M9/087—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic using different frequency bands for transmitting and receiving paths ; using phase shifting arrangements

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Interconnected Communication Systems, Intercoms, And Interphones (AREA)

Abstract

922,003. Two-way transmission. MODERN TELEPHONES (GREAT BRITAIN) Ltd. Nov. 12, 1959 [Nov. 12, 1958], No. 36421/58. Class 40 (4). In a two-way telephone system or repeater including at least a part having a separate path for each direction of transmission, instability due to feedback is overcome by providing frequency selective switching means, responsive to a narrow band of frequencies in signals applied to the system, for altering the gain in both paths so as to condition the system for transmission in whichever is the direction of the applied signals and filter means for removing frequencies of the switch frequency band from signals transmitted in the other direction. There is thus no possibility of feedback around the loop in the selected band of frequencies. Two transducers 10, 11, functioning both as microphones and loud-speakers, are connected to amplifying means 12 so that microphone signals from transducer 10 are fed through gain-reducing device 15, through filter 16 rejecting narrow-frequency band f, and through amplifier 17 to transducer 11. Microphone signals from transducer 10 are also fed through filter 19 accepting only narrow frequency band f, through amplifier 20 and rectifier 21 to switch control unit 22 for operating gainreducing devices 15, 23 to increase the gain of the former and reduce the gain of the latter. The arrangement is symmetrical, providing similar control for transmission from transducer 11 to transducer 10. An arrangement is also described, Fig. 2, not shown, in which different control frequencies are used for the two directions of communication and in which each station has its own amplifier 12. The stations are similar to one another but the filters are switchable to accept (or reject) either one of the two signals according as the station is a calling or called station.
GB3642158A 1958-11-12 1958-11-12 Improvements in or relating to two-way communication telephone systems Expired GB922003A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB3642158A GB922003A (en) 1958-11-12 1958-11-12 Improvements in or relating to two-way communication telephone systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3642158A GB922003A (en) 1958-11-12 1958-11-12 Improvements in or relating to two-way communication telephone systems

Publications (1)

Publication Number Publication Date
GB922003A true GB922003A (en) 1963-03-27

Family

ID=10387984

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3642158A Expired GB922003A (en) 1958-11-12 1958-11-12 Improvements in or relating to two-way communication telephone systems

Country Status (1)

Country Link
GB (1) GB922003A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4641339A (en) * 1985-03-27 1987-02-03 Itt Corporation Variable bandwidth handsfree telephone using switched capacitor filtering
EP0282334A2 (en) * 1987-03-12 1988-09-14 Nec Corporation Loudspeaking telephone with a frequency shifting circuit

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4641339A (en) * 1985-03-27 1987-02-03 Itt Corporation Variable bandwidth handsfree telephone using switched capacitor filtering
EP0282334A2 (en) * 1987-03-12 1988-09-14 Nec Corporation Loudspeaking telephone with a frequency shifting circuit
EP0282334A3 (en) * 1987-03-12 1989-10-11 Nec Corporation Loudspeaking telephone with a frequency shifting circuit

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