GB582709A - Improvements in or relating to secrecy communication systems - Google Patents

Improvements in or relating to secrecy communication systems

Info

Publication number
GB582709A
GB582709A GB1493842A GB1493842A GB582709A GB 582709 A GB582709 A GB 582709A GB 1493842 A GB1493842 A GB 1493842A GB 1493842 A GB1493842 A GB 1493842A GB 582709 A GB582709 A GB 582709A
Authority
GB
United Kingdom
Prior art keywords
impulses
output
signal
modulated
masking
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
GB1493842A
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
Priority to BE471102D priority Critical patent/BE471102A/xx
Priority to BE473048D priority patent/BE473048A/xx
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to US500416A priority patent/US2412964A/en
Priority to FR939295D priority patent/FR939295A/en
Publication of GB582709A publication Critical patent/GB582709A/en
Priority to FR939428D priority patent/FR939428A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K7/00—Modulating pulses with a continuously-variable modulating signal
    • H03K7/02—Amplitude modulation, i.e. PAM
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K1/00—Secret communication
    • H04K1/02—Secret communication by adding a second signal to make the desired signal unintelligible

Abstract

582.709. Secret transmission. STANDARD TELEPHONES & CABLES, Ltd., CHATTERJEA, P. K., and HOUGHTON, L. W. Oct. 23, 1942, No. 14938. Addition to 580,843. [Class 40 (iv)] [Also in Group XL] In a system for secret transmission in which, as in the arrangement described in the parent Specification, the signal in the line consists of an interrupted masking signal, the periods of interruption being occupied by impulses modulated by the secret message, the sending system comprises means 6 in which the masking and message signals are mixed and a modulator 4 in which impulses are modulated by the mixed signals. The output of this modulator is then added in apparatus 7 to the masking signal and this has the effect of removing that part of the modulation of the impulses that is due to the masking signal. The output from this apparatus thus consists of interrupted masking signal combined with impulses modulated by the message and may be used to modulate the carrier of a radio transmitter 8. Fig. 4 shows a circuit for modulating the pulses which are fed to the grids of a pair of identical valves in parallel. The anode resistance R1 of one valve is coupled to the grid of a further valve V4 and the cathode resistance R4 of the other to the grid of an identical valve V3, the valves having a common anode resistance R5. Normally no signal appears at the output terminals 15, 16 since the impulses from R1 and R4 are equal and of opposite sign. Modulating currents fed to the anode circuit of V2, however, vary the impulse from R4 and cause an output of the form shown in Fig. 2 to appear at terminals 15; 16.
GB1493842A 1941-12-18 1942-10-23 Improvements in or relating to secrecy communication systems Expired GB582709A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE471102D BE471102A (en) 1941-12-18
BE473048D BE473048A (en) 1941-12-18
US500416A US2412964A (en) 1941-12-18 1943-08-28 Secrecy communication system
FR939295D FR939295A (en) 1941-12-18 1946-08-29 Improvements to electrical systems for transmitting a secret message
FR939428D FR939428A (en) 1941-12-18 1946-11-27 Secret communications transmission systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1637841A GB580843A (en) 1941-12-18 1941-12-18 Improvements in or relating to secrecy communication systems

Publications (1)

Publication Number Publication Date
GB582709A true GB582709A (en) 1946-11-26

Family

ID=10076234

Family Applications (2)

Application Number Title Priority Date Filing Date
GB1637841A Expired GB580843A (en) 1941-12-18 1941-12-18 Improvements in or relating to secrecy communication systems
GB1493842A Expired GB582709A (en) 1941-12-18 1942-10-23 Improvements in or relating to secrecy communication systems

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB1637841A Expired GB580843A (en) 1941-12-18 1941-12-18 Improvements in or relating to secrecy communication systems

Country Status (2)

Country Link
ES (1) ES177437A1 (en)
GB (2) GB580843A (en)

Also Published As

Publication number Publication date
GB580843A (en) 1946-09-23
ES177437A1 (en) 1947-05-01

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