GB580167A - Improvements in or relating to secret transmission systems - Google Patents

Improvements in or relating to secret transmission systems

Info

Publication number
GB580167A
GB580167A GB864341A GB864341A GB580167A GB 580167 A GB580167 A GB 580167A GB 864341 A GB864341 A GB 864341A GB 864341 A GB864341 A GB 864341A GB 580167 A GB580167 A GB 580167A
Authority
GB
United Kingdom
Prior art keywords
channel
speech
network
currents
directly
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
GB864341A
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to GB864341A priority Critical patent/GB580167A/en
Publication of GB580167A publication Critical patent/GB580167A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04KSECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K1/00Secret communication
    • H04K1/02Secret communication by adding a second signal to make the desired signal unintelligible

Abstract

580,167. Secret transmission. STANDARD TELEPHONES & CABLES, Ltd., and LEVY, M. M. July 9, 1941, No. 8643. [Class 40 (iv)] [Also in Group XL] In a secrecy system in which separate channels are employed for the transmission of two sets of signals one of which conveys the message in distorted form while the other conveys the " key " to the distortion, one set of signals is applied directly to one channel and through a distorting network to the other, and a similar or an inverse network is used at the receiver. The two channels may be provided by frequency or phase modulation and amplitude modulation of a single carrier. In Fig. 2, speech is masked by mixing it with noise, the noise currents N being applied directly to channel 2 and through a network # to channel 1, to which the speech currents S are also applied. The noise currents N pass through a similar network at the receiver before being combined with the currents from channel 1 to give the original speech. In Fig. 4, the speech is inverted by the use of a wobbling carrier, the inverted speech currents IW being applied directly to channel 2 and through a network # to channel 1, which also transmits the carrier W. At the receiver, the currents from channel 2, after distortion, are combined with those from channel 1 to provide the wobbling carrier for restoring the inverted speech to its original form. In both these arrangements, the noise or inverted speech may be applied directly to channel 1 and through a distorting network to channel 2, the latter then being provided with an inverse or restoring network at the receiver. In a further arrangement in which speech is inverted intermittently under the control of an electronic multi-vibrator, the resulting speech currents are applied directly to one channel and after distortion to the other channel which also carries synchronising signals. The distorting network may take the form of a low-pass filter terminated in a resistance different from its characteristic impedance. When inverse networks are required, one of them may consist of an amplifier with a feed-back path.
GB864341A 1941-07-09 1941-07-09 Improvements in or relating to secret transmission systems Expired GB580167A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB864341A GB580167A (en) 1941-07-09 1941-07-09 Improvements in or relating to secret transmission systems

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
BE477658D BE477658A (en) 1941-07-09
GB864341A GB580167A (en) 1941-07-09 1941-07-09 Improvements in or relating to secret transmission systems
US458061A US2406841A (en) 1941-07-09 1942-09-11 Secret transmission system
FR932703D FR932703A (en) 1941-07-09 1946-08-24 Improvements in secret communication systems
ES0176097A ES176097A1 (en) 1941-07-09 1946-12-14 IMPROVEMENTS OR RELATING TO TRANSMISSION SYSTEMS SECRETA

Publications (1)

Publication Number Publication Date
GB580167A true GB580167A (en) 1946-08-29

Family

ID=9856430

Family Applications (1)

Application Number Title Priority Date Filing Date
GB864341A Expired GB580167A (en) 1941-07-09 1941-07-09 Improvements in or relating to secret transmission systems

Country Status (5)

Country Link
US (1) US2406841A (en)
BE (1) BE477658A (en)
ES (1) ES176097A1 (en)
FR (1) FR932703A (en)
GB (1) GB580167A (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2466959A (en) * 1944-09-30 1949-04-12 Philco Corp Radio receiver noise discriminating circuit
US2953643A (en) * 1945-05-10 1960-09-20 Bell Telephone Labor Inc Inverted speech privacy using irregular inverting wave form
US2521690A (en) * 1945-08-14 1950-09-12 Standard Telephones Cables Ltd Secrecy preserving signaling system
US2556677A (en) * 1946-05-10 1951-06-12 Bell Telephone Labor Inc Secret communication system
US2510046A (en) * 1947-04-18 1950-05-30 Zenith Radio Corp Radio-wire signaling system
US2660666A (en) * 1950-01-05 1953-11-24 Westinghouse Electric Corp Secrecy transmission system
US4176316A (en) * 1953-03-30 1979-11-27 International Telephone & Telegraph Corp. Secure single sideband communication system using modulated noise subcarrier
USRE34004E (en) * 1953-03-30 1992-07-21 Itt Corporation Secure single sideband communication system using modulated noise subcarrier
US3225142A (en) * 1961-12-18 1965-12-21 Bell Telephone Labor Inc Privacy system
US4361729A (en) * 1968-01-24 1982-11-30 American Standard Inc. Narrowband analog message privacy system
US4805216A (en) * 1987-01-08 1989-02-14 Compfax Corporation Method and apparatus for continuously acknowledged link encrypting

Also Published As

Publication number Publication date
US2406841A (en) 1946-09-03
FR932703A (en) 1948-03-31
BE477658A (en)
ES176097A1 (en) 1947-01-16

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