GB579972A - Secrecy communication system - Google Patents

Secrecy communication system


Publication number
GB579972A GB1010942A GB1010942A GB579972A GB 579972 A GB579972 A GB 579972A GB 1010942 A GB1010942 A GB 1010942A GB 1010942 A GB1010942 A GB 1010942A GB 579972 A GB579972 A GB 579972A
United Kingdom
Prior art keywords
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.)
Application number
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.)
Hazeltine Corp
Original Assignee
Hazeltine Corp
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
Priority to US399637A priority Critical patent/US2402058A/en
Application filed by Hazeltine Corp filed Critical Hazeltine Corp
Publication of GB579972A publication Critical patent/GB579972A/en
Expired legal-status Critical Current



    • H04K1/00Secret communication


579,972. Secret transmission. HAZELTINE CORPORATION. July 20, 1942, No. 10109. Convention date, June 25, 1941. [Class 40 (iv)] In a secret transmission system, speech or telegraph signals are passed to a balanced modulator 15 which is fed by a phase-inverter 34 with one or other of two potentials which vary in an irregular manner in accordance with the arrangement of transparent and opaque portions on a card 28 interposed between the fluorescent end of a cathode-ray tube 27 and a photo-electric cell 30. The cathode beam is controlled by apparatus 33 which also sends synchronizing impulses to the distant station. The signal in the output of apparatus 15 is thus repeatedly reversed in phase in an irregular way as shown at C, Fig. 2. Alternatively, the system may be regarded as one in which the signal is modulated by a current with an irregular frequency-variation. Secrecy may be improved by limiting the output of the modulator 15 to the useful portion of the lower sideband resulting from this operation by means of a filter 22. Further secrecy may be given by superimposing a masking tone at 13. This is arranged to be disconnected during the intervals in speech. Converse operations are performed at the receiving end.
GB1010942A 1941-06-25 1942-07-20 Secrecy communication system Expired GB579972A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US399637A US2402058A (en) 1941-06-25 1941-06-25 Secrecy communication system

Publications (1)

Publication Number Publication Date
GB579972A true GB579972A (en) 1946-08-22



Family Applications (1)

Application Number Title Priority Date Filing Date
GB1010942A Expired GB579972A (en) 1941-06-25 1942-07-20 Secrecy communication system

Country Status (2)

Country Link
US (1) US2402058A (en)
GB (1) GB579972A (en)

Families Citing this family (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2734100A (en) * 1956-02-07 Kendall
US2733358A (en) * 1956-01-31 Signal
US3470323A (en) * 1944-06-30 1969-09-30 Bell Telephone Labor Inc Signaling system
US2705901A (en) * 1946-01-15 1955-04-12 Chalmers W Sherwin Oscillographic integrator
US2543116A (en) * 1946-07-08 1951-02-27 Bell Telephone Labor Inc Means and method for the secret transmission of message intelligence
US2636936A (en) * 1946-09-10 1953-04-28 Rca Corp Television secrecy system
US2489883A (en) * 1946-12-28 1949-11-29 Bell Telephone Labor Inc Pulse code modulation receiver employing cathode-ray tube demodulators
FR960660A (en) * 1947-02-07 1950-04-22
US2547598A (en) * 1947-09-13 1951-04-03 Zenith Radio Corp Subscription image transmission system and apparatus
IT454079A (en) * 1948-07-02
NL147061B (en) * 1948-07-21 Soederhamns Verkstaeder A B A method for making right side of wooden boards.
US2596741A (en) * 1948-08-28 1952-05-13 Eastman Kodak Co External memory device for electronic digital computers
US2525156A (en) * 1949-01-31 1950-10-10 Robert M Tink Method of and means for electrically generating tones
US2557691A (en) * 1949-03-19 1951-06-19 Geovision Inc Electronic function generator
FR986834A (en) * 1949-03-22 1951-08-06 S E D A C Soc A method of acting on the cathode ray tube of a television to ensure its secrecy
US2703150A (en) * 1949-09-29 1955-03-01 Lu Garda Rieber Geophysical display system
US2705740A (en) * 1949-12-14 1955-04-05 Zenith Radio Corp Subscription type signalling system
CA888373A (en) * 1949-12-21 1971-12-14 Her Majesty The Queen In Right Of Canada As Represented By The Minister Of National Defence Of Her Majesty's Canadian Government Secret signalling system
BE507023A (en) * 1950-04-05
GB705510A (en) * 1951-02-09 1954-03-17 Nat Res Dev Improvements in and relating to the electrostatic storage of digital information
US2769025A (en) * 1951-05-04 1956-10-30 Internat Telemeter Corp Prepaid entertainment distribution system
US2770803A (en) * 1951-10-31 1956-11-13 Zenith Radio Corp Subscription television system
US2809231A (en) * 1951-11-09 1957-10-08 Zenith Radio Corp Subscriber television system
US2727157A (en) * 1951-12-22 1955-12-13 Westinghouse Electric Corp Fluorescent tube
US2847501A (en) * 1952-02-06 1958-08-12 Zenith Radio Corp Subscription television system
US2795705A (en) * 1952-08-26 1957-06-11 Rabinow Jacob Optical coincidence devices
US3274333A (en) * 1952-10-23 1966-09-20 Skiatron Elect & Tele Scrambled television system
USRE34004E (en) * 1953-03-30 1992-07-21 Itt Corporation Secure single sideband communication system using modulated noise subcarrier
US2909592A (en) * 1953-04-15 1959-10-20 Zenith Radio Corp Subscription television system
NL187162B (en) * 1953-05-26 Texaco Development Corp Quaternary acrylamides and methacrylamides and preparation therefor.
US2896071A (en) * 1954-03-01 1959-07-21 Zenith Radio Corp Secrecy communication system
US2994739A (en) * 1955-04-13 1961-08-01 Zenith Radio Corp Subscription television receiver and method of operating the same
US2982952A (en) * 1955-06-28 1961-05-02 Zenith Radio Corp Subscription television
DE1010997B (en) * 1955-07-23 1957-06-27 Boelkow Entwicklungen Kg Method and device for encryption for messages wired or wireless transmission
GB825052A (en) * 1956-01-11 1959-12-09 Rank Cintel Ltd Improvements in or relating to control circuits for cathode ray tubes
NL127168C (en) * 1956-04-27 1900-01-01
US2924645A (en) * 1956-09-04 1960-02-09 Skiatron Elect & Tele Scrambled television transmission
US3071762A (en) * 1956-11-09 1963-01-01 North American Aviation Inc Analog-to-digital converter
US3180927A (en) * 1961-09-07 1965-04-27 Itt Cryptosecure transmission system
CA1054407A (en) * 1975-10-22 1979-05-15 Hiroshi Ichigaya Signal generating system utilizing a cathode ray tube
US4389671A (en) * 1980-09-29 1983-06-21 Harris Corporation Digitally-controlled analog encrypton
US4888799A (en) * 1986-01-03 1989-12-19 Scientific Atlanta, Inc. Scrambling of signals by inversion

Also Published As

Publication number Publication date
US2402058A (en) 1946-06-11

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