DE69415555D1 - METHOD AND DEVICE FOR ENCRYPTING AND DECRYLING AUDIO SIGNALS - Google Patents
METHOD AND DEVICE FOR ENCRYPTING AND DECRYLING AUDIO SIGNALSInfo
- Publication number
- DE69415555D1 DE69415555D1 DE69415555T DE69415555T DE69415555D1 DE 69415555 D1 DE69415555 D1 DE 69415555D1 DE 69415555 T DE69415555 T DE 69415555T DE 69415555 T DE69415555 T DE 69415555T DE 69415555 D1 DE69415555 D1 DE 69415555D1
- Authority
- DE
- Germany
- Prior art keywords
- signal
- carrier
- modulators
- scrambled
- audio
- 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 - Fee Related
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)
- Amplitude Modulation (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
- Reverberation, Karaoke And Other Acoustics (AREA)
- Noise Elimination (AREA)
- Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
- Transmitters (AREA)
- Stereo-Broadcasting Methods (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
Audio signals are descrambled by double sideband modulating the scrambled audio signal with a modulation carrier having a carrier frequency slightly above the highest audio signal present in the scrambled audio. This produces a double sideband signal that is passed through a low pass filter which in turn is modulated by a second carrier frequency lower than the first carrier signal by equal to the offset spectrum of the original scrambled signal. The first low pass filter nulls out any residual carrier from the first modulator that results form the intermodulation of the two modulation frequencies that would be audible at its descrambler output. The modulators used are low noise switch type modulators that improve the signal to noise ratio in the descrambled signal over the previously used linear modulators. The use of switch type modulators provides a lower cost device with improved performance. A companion scrambling device uses similar techniques to provide improved performance at a lower cost.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14506693A | 1993-10-26 | 1993-10-26 | |
| PCT/US1994/011891 WO1995012922A2 (en) | 1993-10-26 | 1994-10-18 | Method and apparatus for low cost audio scrambling and descrambling |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| DE69415555D1 true DE69415555D1 (en) | 1999-02-04 |
| DE69415555T2 DE69415555T2 (en) | 1999-05-12 |
Family
ID=22511456
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DE69415555T Expired - Fee Related DE69415555T2 (en) | 1993-10-26 | 1994-10-18 | METHOD AND DEVICE FOR ENCRYPTING AND DECRYLING AUDIO SIGNALS |
Country Status (14)
| Country | Link |
|---|---|
| EP (1) | EP0744105B1 (en) |
| JP (1) | JP3150700B2 (en) |
| KR (1) | KR100249656B1 (en) |
| AT (1) | ATE175063T1 (en) |
| AU (1) | AU695981B2 (en) |
| CA (1) | CA2181691C (en) |
| DE (1) | DE69415555T2 (en) |
| DK (1) | DK0744105T3 (en) |
| ES (1) | ES2125494T3 (en) |
| HK (1) | HK1013747A1 (en) |
| MY (1) | MY111488A (en) |
| NZ (1) | NZ275269A (en) |
| TW (1) | TW311307B (en) |
| WO (1) | WO1995012922A2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4636853A (en) * | 1983-12-21 | 1987-01-13 | Zenith Electronics Corporation | Dynamic audio scrambling system |
| US5058159A (en) * | 1989-06-15 | 1991-10-15 | Macrovision Corporation | Method and system for scrambling and descrambling audio information signals |
| US5159631A (en) * | 1990-04-26 | 1992-10-27 | Macrovision Corporation | Audio scrambling system using in-band carrier |
-
1994
- 1994-10-18 CA CA002181691A patent/CA2181691C/en not_active Expired - Fee Related
- 1994-10-18 DK DK94931915T patent/DK0744105T3/en active
- 1994-10-18 ES ES94931915T patent/ES2125494T3/en not_active Expired - Lifetime
- 1994-10-18 EP EP94931915A patent/EP0744105B1/en not_active Expired - Lifetime
- 1994-10-18 KR KR1019960703240A patent/KR100249656B1/en not_active IP Right Cessation
- 1994-10-18 DE DE69415555T patent/DE69415555T2/en not_active Expired - Fee Related
- 1994-10-18 AT AT94931915T patent/ATE175063T1/en not_active IP Right Cessation
- 1994-10-18 WO PCT/US1994/011891 patent/WO1995012922A2/en active IP Right Grant
- 1994-10-18 AU AU80828/94A patent/AU695981B2/en not_active Ceased
- 1994-10-18 JP JP51324395A patent/JP3150700B2/en not_active Expired - Lifetime
- 1994-10-18 NZ NZ275269A patent/NZ275269A/en unknown
- 1994-10-25 MY MYPI94002827A patent/MY111488A/en unknown
- 1994-12-02 TW TW083111250A patent/TW311307B/zh not_active IP Right Cessation
-
1998
- 1998-12-23 HK HK98114981A patent/HK1013747A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ES2125494T3 (en) | 1999-03-01 |
| DE69415555T2 (en) | 1999-05-12 |
| ATE175063T1 (en) | 1999-01-15 |
| TW311307B (en) | 1997-07-21 |
| CA2181691A1 (en) | 1995-05-11 |
| AU8082894A (en) | 1995-05-23 |
| DK0744105T3 (en) | 1999-08-23 |
| MY111488A (en) | 2000-06-30 |
| EP0744105B1 (en) | 1998-12-23 |
| WO1995012922A3 (en) | 1995-07-13 |
| WO1995012922A2 (en) | 1995-05-11 |
| JPH10500259A (en) | 1998-01-06 |
| KR100249656B1 (en) | 2000-03-15 |
| AU695981B2 (en) | 1998-08-27 |
| JP3150700B2 (en) | 2001-03-26 |
| HK1013747A1 (en) | 1999-09-03 |
| NZ275269A (en) | 1998-08-26 |
| EP0744105A1 (en) | 1996-11-27 |
| CA2181691C (en) | 2000-10-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 8364 | No opposition during term of opposition | ||
| 8339 | Ceased/non-payment of the annual fee |