GB666868A - Loudspeaking telephone system - Google Patents

Loudspeaking telephone system

Info

Publication number
GB666868A
GB666868A GB2322348A GB2322348A GB666868A GB 666868 A GB666868 A GB 666868A GB 2322348 A GB2322348 A GB 2322348A GB 2322348 A GB2322348 A GB 2322348A GB 666868 A GB666868 A GB 666868A
Authority
GB
United Kingdom
Prior art keywords
loud
speakers
currents
produce
phase
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
GB2322348A
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.)
Nokia Bell NV
Original Assignee
Bell Telephone Manufacturing Co NV
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 Bell Telephone Manufacturing Co NV filed Critical Bell Telephone Manufacturing Co NV
Priority to GB2322348A priority Critical patent/GB666868A/en
Publication of GB666868A publication Critical patent/GB666868A/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)
  • Interconnected Communication Systems, Intercoms, And Interphones (AREA)

Abstract

666,868. Substation circuits. STANDARD TELEPHONES & CABLES, Ltd. (Bell Telephone Manufacturing Co.). Sept. 3, 1948, No. 23223/48. Class 40 (iv). In a loud-speaking telephone interconnection system employing at least one amplifier a substation is provided with two transducers each acting as a microphone and as a loud-speaker (or with two loud-speakers and two microphones) arranged so that sounds applied to and reaching them substantially in phase produce assisting currents for transmission to line and currents received from line produce vibrations of the diaphragms in phase opposition or vice versa. In the embodiment the two loud-speakers A, B which function also as microphones and have the same acoustic and electrical characteristics are connected in series opposing to the output terminals 1, 2 of the receiving amplifier AR of the substation, and in parallel assisting to the input terminals of the transmitting amplifier AT by means of their junction-point 4 and the centre tap 3 of the output transformer of AR. Vibration of the loudspeaker diaphragms out-ofphase in response to incoming currents produce no voltage across 3-4, and no output to line. Acoustic coupling, however large, produces no ill effects. As the loud-speakers are not point sources and are not superimposed interference phenomena occur when they vibrate out-ofphase but without complete cancellation and reception is possible without serious influence upon the intelligibility of the speech. To reduce the loss of efficiency the loud-speakers are separated by a baffle C. Sounds originated in front of the loud-speakers vibrate the diaphragms in phase and produce mutually assisting currents, the distances being chosen so that the frequencies lost by interference are high enough not to influence intelligibility. Alternatively it may be arranged that sounds reaching the loud-speakers in phase opposition produce assisting currents and incoming currents vibrate the loud-speakers in phase. Each double-purpose loud-speaker may be replaced by a loud-speaker and a microphone.
GB2322348A 1948-09-03 1948-09-03 Loudspeaking telephone system Expired GB666868A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2322348A GB666868A (en) 1948-09-03 1948-09-03 Loudspeaking telephone system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2322348A GB666868A (en) 1948-09-03 1948-09-03 Loudspeaking telephone system

Publications (1)

Publication Number Publication Date
GB666868A true GB666868A (en) 1952-02-20

Family

ID=10192143

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2322348A Expired GB666868A (en) 1948-09-03 1948-09-03 Loudspeaking telephone system

Country Status (1)

Country Link
GB (1) GB666868A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2047711A1 (en) * 2006-08-04 2009-04-15 Bose Corporation Electroacoustical transducing
US8639300B2 (en) 2009-12-09 2014-01-28 Motorola Solutions, Inc. Method and apparatus for maintaining transmit audio in a half duplex system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2047711A1 (en) * 2006-08-04 2009-04-15 Bose Corporation Electroacoustical transducing
US8639300B2 (en) 2009-12-09 2014-01-28 Motorola Solutions, Inc. Method and apparatus for maintaining transmit audio in a half duplex system

Similar Documents

Publication Publication Date Title
JPH01319360A (en) Voice conference equipment
US2177769A (en) Loud-speaking intercommunicating system
JPH01260967A (en) Voice conference equipment for multi-channel signal
US4837829A (en) Acoustic sound system for a room
US4002860A (en) Transmitting and receiving apparatus
GB666868A (en) Loudspeaking telephone system
CN213990749U (en) Intercommunication audio circuit and device based on mobile phone
US3787621A (en) Telephone set with transmission by microphone and amplifier and reception by loudspeaker
CN205283527U (en) Words system that receives that send of quick -witted bluetooth of arranging that half -duplex is wireless
US2535681A (en) Electroacoustic system and means
US2166775A (en) Electronic amplifying coupler and system therefor
Clemency et al. The Bell system speakerphone
JP2727599B2 (en) Speaker system
US2461945A (en) Receiver connection in electroacoustic duplex system
US2336880A (en) Stereophonic conference system
US2332551A (en) Telephone set circuit
US2913524A (en) Loudspeaking interoffice telephone
KR940007686B1 (en) Multiple sound input treating appartus
US3766319A (en) Transducer circuit for simultaneous two way operation
JPS5966294A (en) Telephone set for one-ear transmission and receiving
JPH02250556A (en) Handset device for bidirectional simultaneous calling
SU56970A1 (en) Termination Telephone, for two-way speakerphone
US3172959A (en) Telephone amplifier
US2240509A (en) Balanced telephone circuit
GB801469A (en) Improvements in devices for improving the intelligibility of electrically transmitted sound signals