GB853770A - Improvements in or relating to loudspeaking telephone systems - Google Patents

Improvements in or relating to loudspeaking telephone systems

Info

Publication number
GB853770A
GB853770A GB2804257A GB2804257A GB853770A GB 853770 A GB853770 A GB 853770A GB 2804257 A GB2804257 A GB 2804257A GB 2804257 A GB2804257 A GB 2804257A GB 853770 A GB853770 A GB 853770A
Authority
GB
United Kingdom
Prior art keywords
amplifier
speech
bridge
loud
class
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
GB2804257A
Inventor
Arthur Ian Forbes Simpson
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 GB2804257A priority Critical patent/GB853770A/en
Publication of GB853770A publication Critical patent/GB853770A/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

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Devices For Supply Of Signal Current (AREA)

Abstract

853,770. Two-way transmission. MODERN TELEPHONES (GREAT BRITAIN) Ltd. Sept. 1, 1958 [Sept. 5, 1957], No. 28042/57. Class 40 (4). Speech incoming to a loud-speaking telephone station increases the load current taken by a class B amplifier and this increase is used to control a variable impedance to block speech in the outgoing direction. As shown, the station 13 is connectible to another station such as 10 over a switching selector 18. Incoming speech goes to a loud-speaker over a multistage transistor amplifier 16 one stage at least of which works in class B and consequently increases the current taken from D.C. power supply terminals 20, 21. One diagonal of a bridge of four filament lamps 22-25 is connected in the power supply so that the impedance of the other diagonal increases as the signal to the loud-speaker increases. The other diagonal shunts the secondary of a transformer 26 in a bridge circuit, with resistors 29, 30, 31, such that with maximum load current taken by amplifier 16 the bridge is balanced and outgoing signals from microphone 15 over transistor amplifier 17 are blocked. With no incoming signals the bridge is out of balance and outgoing signals may be transmitted. Amplifier 17 may be class B and its load current used to control an impedance in a bridge between the amplifier 16 and loud-speaker to block incoming speech during periods of outgoing speech. The use of filament lamps provides a time constant. The amplifier outputs may directly control saturable transformers to block speech. Specification 853,671 is referred to.
GB2804257A 1957-09-05 1957-09-05 Improvements in or relating to loudspeaking telephone systems Expired GB853770A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2804257A GB853770A (en) 1957-09-05 1957-09-05 Improvements in or relating to loudspeaking telephone systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2804257A GB853770A (en) 1957-09-05 1957-09-05 Improvements in or relating to loudspeaking telephone systems

Publications (1)

Publication Number Publication Date
GB853770A true GB853770A (en) 1960-11-09

Family

ID=10269327

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2804257A Expired GB853770A (en) 1957-09-05 1957-09-05 Improvements in or relating to loudspeaking telephone systems

Country Status (1)

Country Link
GB (1) GB853770A (en)

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