ATE175063T1 - METHOD AND DEVICE FOR ENCRYPTING AND DECRYPTING AUDIO SIGNALS - Google Patents

METHOD AND DEVICE FOR ENCRYPTING AND DECRYPTING AUDIO SIGNALS

Info

Publication number
ATE175063T1
ATE175063T1 AT94931915T AT94931915T ATE175063T1 AT E175063 T1 ATE175063 T1 AT E175063T1 AT 94931915 T AT94931915 T AT 94931915T AT 94931915 T AT94931915 T AT 94931915T AT E175063 T1 ATE175063 T1 AT E175063T1
Authority
AT
Austria
Prior art keywords
signal
carrier
modulators
scrambled
audio
Prior art date
Application number
AT94931915T
Other languages
German (de)
Inventor
Ronald Quan
Original Assignee
Macrovision Corp
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
Application filed by Macrovision Corp filed Critical Macrovision Corp
Application granted granted Critical
Publication of ATE175063T1 publication Critical patent/ATE175063T1/en

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04KSECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K1/00Secret communication
    • H04K1/04Secret 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)
  • Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Stereo-Broadcasting Methods (AREA)
  • Transmitters (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.
AT94931915T 1993-10-26 1994-10-18 METHOD AND DEVICE FOR ENCRYPTING AND DECRYPTING AUDIO SIGNALS ATE175063T1 (en)

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 (1)

Publication Number Publication Date
ATE175063T1 true ATE175063T1 (en) 1999-01-15

Family

ID=22511456

Family Applications (1)

Application Number Title Priority Date Filing Date
AT94931915T ATE175063T1 (en) 1993-10-26 1994-10-18 METHOD AND DEVICE FOR ENCRYPTING AND DECRYPTING 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)

* Cited by examiner, † Cited by third party
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

Also Published As

Publication number Publication date
ES2125494T3 (en) 1999-03-01
CA2181691C (en) 2000-10-17
JPH10500259A (en) 1998-01-06
NZ275269A (en) 1998-08-26
TW311307B (en) 1997-07-21
DE69415555D1 (en) 1999-02-04
JP3150700B2 (en) 2001-03-26
MY111488A (en) 2000-06-30
DE69415555T2 (en) 1999-05-12
DK0744105T3 (en) 1999-08-23
AU695981B2 (en) 1998-08-27
KR100249656B1 (en) 2000-03-15
AU8082894A (en) 1995-05-23
HK1013747A1 (en) 1999-09-03
CA2181691A1 (en) 1995-05-11
WO1995012922A2 (en) 1995-05-11
EP0744105B1 (en) 1998-12-23
EP0744105A1 (en) 1996-11-27
WO1995012922A3 (en) 1995-07-13

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Legal Events

Date Code Title Description
UEP Publication of translation of european patent specification
REN Ceased due to non-payment of the annual fee