GB727656A - Improvements in or relating to loud-speaking telephone systems - Google Patents

Improvements in or relating to loud-speaking telephone systems

Info

Publication number
GB727656A
GB727656A GB2231051A GB2231051A GB727656A GB 727656 A GB727656 A GB 727656A GB 2231051 A GB2231051 A GB 2231051A GB 2231051 A GB2231051 A GB 2231051A GB 727656 A GB727656 A GB 727656A
Authority
GB
United Kingdom
Prior art keywords
loud
microphone
output
relay
transformer
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
GB2231051A
Inventor
Roger Frederic Laurence
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.)
Winston Electronics Ltd
Original Assignee
Winston Electronics 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 Winston Electronics Ltd filed Critical Winston Electronics Ltd
Priority to GB2231051A priority Critical patent/GB727656A/en
Publication of GB727656A publication Critical patent/GB727656A/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
    • H04M9/10—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic with switching of direction of transmission by voice frequency

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Interconnected Communication Systems, Intercoms, And Interphones (AREA)

Abstract

727,656. Two-way transmission. WINSTON ELECTRONICS, Ltd. Aug. 5, 1952 [Sept. 24, 1951; Nov. 6, 1951; Nov. 6, 1951], Nos. 22310/51, 25972/51 and 25973/51. Class 40 (4). In a loud-speaking telephone system wherein a proportion of the signal in each channel is rectified and compared by a circuit which mutes the channel producing the smaller, and one of the channels is muted at any time, the rectifier has a condenser input filter having a pick-up time of three milliseconds or less and a much longer discharge time, also the ratio of signal current to resulting control voltage is greater in the case of the muted channel than in the unmuted one. In the system, Fig. 2, speech voltages from each direction of transmission are sampled at Y and Z and applied after amplification in valves V7, V9 and rectification in MR1-4 to a commoncathode triggered pair V11, V12 to mute the unwanted direction of transmission. The muting is effected by the connection by relay A of resistors R17, R18 across points TU and VW in the microphone and loudspeaker amplifiers respectively. The sampled microphone output from point Y comprising the voltage induced in the secondary of transformer T3 reinforced by the output from the centre tap of resistors R6, R7 is applied to rectifiers MR1, MR2 via a high isolating resistance R30 and cathode follower V8. The sample of the incoming signal is similarly applied to rectifiers MR3, MR4, but to provide a bias on valve V10 opposite to that from MR1, MR2. Relay B connects a low resistance shunt across the rectifier pair proper to the unwanted direction. The microphone output to line is applied in parallel to two windings P, Q of line transformer T1 and the loud-speaker input windings r, s are connected in phase opposition to eliminate the transfer of microphone currents to the loud-speaker. Modification of the amplifier arrangement for three or four-wire working by dispensing with the line unit valves V3, V4 and transformer T1 is also described, and in a further embodiment, Fig. 3 (not shown), three relays are included in the bathode-coupled triggered pair. Muting in this embodiment is achieved by disconnecting the loud-speaker circuit, and the output of the control rectifier proper to the unwanted direction is also reduced by a relay.
GB2231051A 1951-09-24 1951-09-24 Improvements in or relating to loud-speaking telephone systems Expired GB727656A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2231051A GB727656A (en) 1951-09-24 1951-09-24 Improvements in or relating to loud-speaking telephone systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2231051A GB727656A (en) 1951-09-24 1951-09-24 Improvements in or relating to loud-speaking telephone systems

Publications (1)

Publication Number Publication Date
GB727656A true GB727656A (en) 1955-04-06

Family

ID=10177310

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2231051A Expired GB727656A (en) 1951-09-24 1951-09-24 Improvements in or relating to loud-speaking telephone systems

Country Status (1)

Country Link
GB (1) GB727656A (en)

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