Apparatus for marking a recorded signal

• US 4,963,998 A
• Filed: 04/20/1989
• Issued: 10/16/1990
• Est. Priority Date: 04/20/1988
• Status: Expired due to Fees

• Current Assignee: Thorn EMI Plc (Universal Music Group NV)
• Original Assignee: Thorn EMI Plc (Universal Music Group NV)
• Inventors: Maufe, Barry G.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Hoff, Marc S.
• Application Number:
  US07/341,943
• Time in Patent Office: 544 Days
• Field of Search: 360/60, 380/4, 332/170, 369/84, 369/85, 369/90, 455/109, 455/47, 341/143
• US Class Current: 360/60
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm

Abstract

This invention relates to apparatus for marking a recorded signal. The apparatus includes means for generating and storing a marking signal comprising at least two codes which are mutually in phase quadrature. The codes are converted to analogue signal and are used to phase-shift modulate the signal to be recorded, the modulating means performing the function of a single side band modulator on the signal to be recorded.

Claims

1. Apparatus for marking a recorded signal, said apparatus including:

means for generating and storing a marking signal comprising at least two codes which are mutually in phase quadrature;

means for converting said codes from a digital to an analogue signal; and

modulating means including phase shift means such that the two marking codes can be used to phase-shift modulate the signal to be recorded, said modulating means performing the function of a single side band modulator on the said signal to be recorded.

2. Apparatus as claimed in claim 1, said apparatus for marking the recorded signal including:

means for generating a marking signal, said signal comprising a sequence of binary elements;

and means for translating each like binary element of said sequence into a randomised sequence of binary elements prior to modulation.

3. Apparatus as claimed in claim 1, said apparatus including:

means for demodulating said modulated signal;

means for digitising said demodulated signal into a sequence; and

means for correlating said demodulated, digitised sequence with reference sequences stored in the means for generating and storing the marking signal.