GB912250A - Improvements in and relating to electrical apparatus - Google Patents

Improvements in and relating to electrical apparatus

Info

Publication number
GB912250A
GB912250A GB1274261A GB1274261A GB912250A GB 912250 A GB912250 A GB 912250A GB 1274261 A GB1274261 A GB 1274261A GB 1274261 A GB1274261 A GB 1274261A GB 912250 A GB912250 A GB 912250A
Authority
GB
United Kingdom
Prior art keywords
secrecy
conventional handset
microphone
receiver
relating
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
GB1274261A
Inventor
Kenneth Cedric Arthur King
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.)
Telephone Manufacturing Co Ltd
Original Assignee
Telephone Manufacturing Co 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 Telephone Manufacturing Co Ltd filed Critical Telephone Manufacturing Co Ltd
Priority to GB1274261A priority Critical patent/GB912250A/en
Publication of GB912250A publication Critical patent/GB912250A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/68—Circuit arrangements for preventing eavesdropping
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K1/00—Secret communication
    • H04K1/04—Secret communication by frequency scrambling, i.e. by transposing or inverting parts of the frequency band or by inverting the whole band

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Telephone Set Structure (AREA)

Abstract

912,250. Secrecy equipment. TELEPHONE MANUFACTURING CO. Ltd. April 8, 1961, No. 12742/61. Drawings to Specification. Class 40 (4). Secrecy equipment is housed in a support base for a conventional handset and has coupling means for passing secret signals to and from it, a further microtelephone being provided for conveying the non-secret signals to and from the secrecy device. The coupling may be purely inductive via the earpiece of the conventional handset, or may consist of a microphone and receiver for co-operation with the receiver and microphone, respectively, of the conventional handset. The secrecy device may be enabled by the placing of the conventional handset on the base. Secrecy is effected by frequency inversion.
GB1274261A 1961-04-08 1961-04-08 Improvements in and relating to electrical apparatus Expired GB912250A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1274261A GB912250A (en) 1961-04-08 1961-04-08 Improvements in and relating to electrical apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1274261A GB912250A (en) 1961-04-08 1961-04-08 Improvements in and relating to electrical apparatus

Publications (1)

Publication Number Publication Date
GB912250A true GB912250A (en) 1962-12-05

Family

ID=10010272

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1274261A Expired GB912250A (en) 1961-04-08 1961-04-08 Improvements in and relating to electrical apparatus

Country Status (1)

Country Link
GB (1) GB912250A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2633125A1 (en) * 1988-06-17 1989-12-22 Sgs Thomson Microelectronics Acoustic apparatus with voice filtering card

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2633125A1 (en) * 1988-06-17 1989-12-22 Sgs Thomson Microelectronics Acoustic apparatus with voice filtering card

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