GB579677A - Electric signal communication system - Google Patents
Electric signal communication systemInfo
- Publication number
- GB579677A GB579677A GB20746/43A GB2074643A GB579677A GB 579677 A GB579677 A GB 579677A GB 20746/43 A GB20746/43 A GB 20746/43A GB 2074643 A GB2074643 A GB 2074643A GB 579677 A GB579677 A GB 579677A
- Authority
- GB
- United Kingdom
- Prior art keywords
- harmonic
- carrier
- phase
- sub
- signal
- 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
Links
Classifications
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Transmitters (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
579,677. Phase modulation. STANDARD TELEPHONES & CABLES, Ltd. Dec. 10, 1943, No. 20746. Convention date, Sept. 19, 1942. [Class 40 (v)] For obtaining secrecy in communication, a carrier wave is modulated by a sub-carrier and one of its harmonics, and a signal is sent by varying the phase of the harmonic. The generator 12 of the sub-carrier is connected to a frequency-multiplier 16 producing a harmonic, preferably the third. This harmonic is phasemodulated at 22 by a signal from the source 18, and is added to the sub-carrier in the element 26. The resultant is impressed on an amplitude or frequency modulator 28 interposed between the carrier generator 32 and the radio transmitter 30. At the receiver, the carrier is demodulated and the sub-carrier is separated from its harmonic by filters 40, 44. The subcarrier passes to a frequency multiplier 42 comparable with that at the transmitter, and the harmonic thus produced is fed, together with the phase-modulated harmonic from the filter 44, to a phase-comparing device 46, the signal resulting therefrom being fed to an amplifier 41 and reproducer 50. When the third harmonic is used, its amplitude should not be more than 30 per cent of the fundamental, and the phasing should be such that the peak of unmodulated harmonic B coincides with that of the fundamental A, Fig. 2. The effect of phase-shifting the harmonic B to B<1> is to shift the combination C to C<1>.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US458934A US2406881A (en) | 1942-09-19 | 1942-09-19 | Method and system for communicating intelligence |
Publications (1)
Publication Number | Publication Date |
---|---|
GB579677A true GB579677A (en) | 1946-08-12 |
Family
ID=23822685
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB20746/43A Expired GB579677A (en) | 1942-09-19 | 1943-12-10 | Electric signal communication system |
Country Status (2)
Country | Link |
---|---|
US (1) | US2406881A (en) |
GB (1) | GB579677A (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2709218A (en) * | 1945-03-06 | 1955-05-24 | Leonide E Gabrilovitch | Method and means for anti-jamming in radio |
US3953677A (en) * | 1945-05-10 | 1976-04-27 | Bell Telephone Laboratories, Incorporated | Key signaling system with multiple pulse generators |
US2707749A (en) * | 1949-06-21 | 1955-05-03 | Rines Robert Harvey | System of light beam communication |
USRE34004E (en) * | 1953-03-30 | 1992-07-21 | Itt Corporation | Secure single sideband communication system using modulated noise subcarrier |
US6313782B1 (en) * | 1960-11-16 | 2001-11-06 | The United States Of America As Represented By The Secretary Of The Army | Coded phase modulation communications system |
-
1942
- 1942-09-19 US US458934A patent/US2406881A/en not_active Expired - Lifetime
-
1943
- 1943-12-10 GB GB20746/43A patent/GB579677A/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
US2406881A (en) | 1946-09-03 |
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