GB1227215A - - Google Patents
Info
- Publication number
- GB1227215A GB1227215A GB1227215DA GB1227215A GB 1227215 A GB1227215 A GB 1227215A GB 1227215D A GB1227215D A GB 1227215DA GB 1227215 A GB1227215 A GB 1227215A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- speech
- synchronizing
- transmitter
- synchronizing 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
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
- Telephonic Communication Services (AREA)
- Telephone Function (AREA)
Abstract
1,227,215. Speech secrecy systems. TELEFONAKTIEBOLAGET L. M. ERICSSON. 20 June, 1968 [21 June, 1967], No. 29551/68. Heading H4R. In a speech scrambling device the incoming speech is converted to digital form, e.g. by p.c.m. or delta modulation, the resulting digits are ciphered and the ciphered digits converted back to an analogue signal for transmission. At the receiver the analogue signal is converted to digital form, the digital signal deciphered, and the original speech recovered from the deciphered digital signal by decoding. A synchronizing signal is transmitted with the scrambled speech to allow synchronization of the digita coding and decoding at the receiver with that at the transmitter, the synchronizing signal also being used for a.v.c. The synchronizing signal may be added before or after the conversion of the digital signal to analogue form at the transmitter and removed from the incoming signal at the receiver. A band of frequencies about the synchronizing frequency may be removed from the incoming signal at the transmitter. Two frequencies may be transmitted, the difference being used to provide the synchronizing signal in order to avoid the synchronizing signal being lost by frequency shift in a carrier transmission system.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8919/67A SE305470B (en) | 1967-06-21 | 1967-06-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1227215A true GB1227215A (en) | 1971-04-07 |
Family
ID=20275361
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1227215D Expired GB1227215A (en) | 1967-06-21 | 1968-06-20 |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US3504286A (en) |
| DE (1) | DE1762441A1 (en) |
| GB (1) | GB1227215A (en) |
| NL (1) | NL6808682A (en) |
| SE (1) | SE305470B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2134756A (en) * | 1983-01-10 | 1984-08-15 | Nec Corp | Signal transmission system having encoder/decoder without frame synchronization signal |
| GB2156190A (en) * | 1984-01-26 | 1985-10-02 | Univ British Columbia | Modem |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH572650A5 (en) * | 1972-12-21 | 1976-02-13 | Gretag Ag | |
| US4086435A (en) * | 1976-09-17 | 1978-04-25 | Biosystems Research Group Ii | Method of and means for scrambling and descrambling speech at audio frequencies |
| US4126761A (en) * | 1977-02-11 | 1978-11-21 | Daniel Graupe | Method of and means for processing an audio frequency signal to conceal intelligility |
| US4156107A (en) * | 1978-02-03 | 1979-05-22 | Bell Telephone Laboratories, Incorporated | Speech signal scrambler |
| US4367456A (en) * | 1979-03-09 | 1983-01-04 | Northern Telecom Limited | PCM and PAM Conversion circuit including signal level variation on the PCM portion of the circuit |
| FR2606237B1 (en) * | 1986-10-31 | 1988-12-09 | Trt Telecom Radio Electr | ANALOG CRYPTOPHONY DEVICE WITH DYNAMIC BAND PERMUTATIONS |
| US5581614A (en) * | 1991-08-19 | 1996-12-03 | Index Systems, Inc. | Method for encrypting and embedding information in a video program |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH311424A (en) * | 1950-04-22 | 1955-11-30 | Gretener Edgar Ing Dr | Method for the secrecy of speech in communication channels. |
-
1967
- 1967-06-21 SE SE8919/67A patent/SE305470B/xx unknown
-
1968
- 1968-05-29 US US732994A patent/US3504286A/en not_active Expired - Lifetime
- 1968-06-19 DE DE19681762441 patent/DE1762441A1/en active Pending
- 1968-06-20 NL NL6808682A patent/NL6808682A/xx unknown
- 1968-06-20 GB GB1227215D patent/GB1227215A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2134756A (en) * | 1983-01-10 | 1984-08-15 | Nec Corp | Signal transmission system having encoder/decoder without frame synchronization signal |
| GB2156190A (en) * | 1984-01-26 | 1985-10-02 | Univ British Columbia | Modem |
Also Published As
| Publication number | Publication date |
|---|---|
| NL6808682A (en) | 1968-12-23 |
| SE305470B (en) | 1968-10-28 |
| DE1762441A1 (en) | 1970-04-30 |
| US3504286A (en) | 1970-03-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| PCNP | Patent ceased through non-payment of renewal fee |