EP 0424201 B1 19920812 - DECODER FOR DECODING AN ENCRYPTED TELEVISION AUDIO SIGNAL
Title (en)
DECODER FOR DECODING AN ENCRYPTED TELEVISION AUDIO SIGNAL
Publication
Application
Priority
FR 8912844 A 19891002
Abstract (en)
[origin: EP0424201A1] An encrypted sound decoder is obtained by feeding back the output from a demodulator (1) (used in the decryption) to an input (9) of a phase comparator (7) whose output controls a voltage-controlled oscillator (6) which drives the demodulator. The phase comparator moreover receives on another input (8) the signal to be decrypted (to be demodulated). The signal to be decrypted is a signal modulated by a carrier whose frequency is unknown. It is shown that this system makes it possible to avoid employing a microprocessor tasked with calculating the unknown frequency and with producing a signal at a demodulation frequency equal to this unknown frequency. <IMAGE>
IPC 1-7
IPC 8 full level
H04K 1/00 (2006.01); H04N 7/167 (2006.01)
CPC (source: EP US)
H04K 1/003 (2013.01 - EP US)
Designated contracting state (EPC)
CH DE FR GB IT LI
DOCDB simple family (publication)
EP 0424201 A1 19910424; EP 0424201 B1 19920812; DE 69000257 D1 19920917; DE 69000257 T2 19930408; FR 2652698 A1 19910405; JP H03158033 A 19910708; US 5144666 A 19920901
DOCDB simple family (application)
EP 90402682 A 19900928; DE 69000257 T 19900928; FR 8912844 A 19891002; JP 26489690 A 19901002; US 59168090 A 19901001