GB346422A - Improvements in or relating to carrier signalling systems - Google Patents
Improvements in or relating to carrier signalling systemsInfo
- Publication number
- GB346422A GB346422A GB15630A GB15630A GB346422A GB 346422 A GB346422 A GB 346422A GB 15630 A GB15630 A GB 15630A GB 15630 A GB15630 A GB 15630A GB 346422 A GB346422 A GB 346422A
- Authority
- GB
- United Kingdom
- Prior art keywords
- carrier
- sideband
- filter
- carrier frequency
- frequency
- 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
- H04K1/04—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)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
346,422. Secret telephony. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London.- (Chereau, L.; 46, Avenue de Breteuil, Paris.) Jan. 2, 1930, No. 156. [Class 40 (iv).] In a wireless transmitting system a sideband is spaced from the carrier so that the upper limit of the sideband is substantially twice the original limiting frequency from the carrier so that during selective fading demodulation between the sidebands does not produce an audible signal. The invention is particularly applicable to systems employing signal frequency band inversion as in this system the fading causes the sidebands to produce noise instead of a harmonic of the signal as is the case with normal transmission. Fig. 5 shows a system in which voice frequencies are applied to a low pass filter LP with a cut-off at 3 kc. and modulated by a carrier frequency of 20 kc. and applied to filter F with a range of 20-23 kc. After further modulation by a carrier frequency of 26 kc. filter LP<1> applies to the transmitter T an inverted speech band of range 3-6 kc. At the receiver R a similar process is employed to re-invert and transpose the signals to voice frequencies. In a multiplex system with a carrier frequency c, Fig. 3, the sideband frequencies are alternately useful and useless a, b representing two signals and 2a, 2b the spacing. Specification 229,732, [Class 40 (v), Wireless signalling &c.], is referred to.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB15630A GB346422A (en) | 1930-01-02 | 1930-01-02 | Improvements in or relating to carrier signalling systems |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB15630A GB346422A (en) | 1930-01-02 | 1930-01-02 | Improvements in or relating to carrier signalling systems |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB346422A true GB346422A (en) | 1931-04-02 |
Family
ID=9699380
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB15630A Expired GB346422A (en) | 1930-01-02 | 1930-01-02 | Improvements in or relating to carrier signalling systems |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB346422A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2447121A1 (en) * | 1979-01-22 | 1980-08-14 | United Kingdom Government | RADIO COMMUNICATION SYSTEM, PARTICULARLY FOR AIRCRAFT |
-
1930
- 1930-01-02 GB GB15630A patent/GB346422A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2447121A1 (en) * | 1979-01-22 | 1980-08-14 | United Kingdom Government | RADIO COMMUNICATION SYSTEM, PARTICULARLY FOR AIRCRAFT |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| GB536383A (en) | Improvements in frequency modulation systems for radio signalling | |
| GB527666A (en) | Improvements in or relating to modulated carrier wave signalling systems | |
| US2798902A (en) | System and method for underwater communication | |
| GB529984A (en) | Improvements in or relating to radio transmission systems employing pulse modulation | |
| GB582044A (en) | Improvements in multiplex radio systems | |
| GB541665A (en) | Improvements relating to high frequency wave transmission systems | |
| GB540185A (en) | System of transmission of electrical waves | |
| GB590506A (en) | Radio relay station | |
| GB270001A (en) | Carrier wave signalling systems | |
| US2276863A (en) | Signaling by modulated waves | |
| GB346422A (en) | Improvements in or relating to carrier signalling systems | |
| GB579677A (en) | Electric signal communication system | |
| FR2266985A1 (en) | Radio communication method for service conversations - has message and distance monitoring signal transmission in digital form | |
| GB492006A (en) | Improvements in high frequency signalling systems | |
| US1954185A (en) | Method of transmitting signals on short radiowaves | |
| GB668000A (en) | Duplex signalling system for sound and facsimile | |
| GB268055A (en) | Improvements in secret signalling | |
| JPS5936052Y2 (en) | Confidential device | |
| GB336096A (en) | Improvements in multiplex high frequency signalling systems | |
| GB295957A (en) | Improvements in wireless transmission and reception | |
| GB352590A (en) | Improvements in or relating to radio signalling systems | |
| GB601644A (en) | Pulse communication system | |
| GB1007432A (en) | Improvements in or relating to the transmission of two audio channels over a singlemodulated carrier or a single pair of wires | |
| GB338617A (en) | Improvements relating to signalling systems and in particular to radio communication | |
| GB353490A (en) | Improvements in or relating to wave signalling systems |