Method and apparatus for monitoring the reproduction of recorded information

Claim 3

The method of claim 1, wherein said auxiliary information signal is recorded on the first recording medium with an amplitude whose level is lower by at least 20 db than that of the maximum level of the recorded audio information signal.

Claim 4

The method of claim 1, wherein the auxiliary information signal comprises a first period formed by a signal of fixed frequency located in the range of inaudible frequencies, a second period of primary synchronization defining a digital bit synchronization rhythm, a third period of secondary synchronization containing a coded format synchronization word and a fourth period containing a coded message specifying the auxiliary information.

Claim 5

The method of claim 1, wherein the auxiliary signal is repeated throughout along said track of the first recording medium.

Claim 8

A reproduction device for monitoring the reproduction of a principal audio information recorded on at least one track of a recording medium, said device comprising a head for reading the information recorded on said track and a reproduction circuit connected at the output of the reading head to reproduce said principal audio information from the read-out signal furnished by the reading head, the improvement comprising detecting means for detecting the presence in the recorded signal of a superimposed digital auxiliary information signal coded by derivation from a pilot frequency in a predetermined limited frequency range outside the spectrum of audible frequencies towards the ultra sounds, said detecting means being connected to said reading head through a pass band filter centered on said pilot frequency and comprising a demodulation circuit to produce a demodulated digital output signal; a primary synchronization signal generator activated by said demodulated digital output signal; a format recognition circuit piloted by the primary synchronization signal outputted by said primary synchronization signal generator, and memory means for storing said demodulated digital output signal.

Claim 9

A reproduction device for monitoring the reproduction of a principal audio information recorded on at least one track of a recording medium, said device comprising a head for reading the information recorded on said track and a reproduction circuit connected at the output of the reading head to reproduce said principal audio information from the read-out signal furnished by the reading head, the improvement comprising detecting means for detecting the presence in the recorded signal of a superimposed digital auxiliary information signal coded by derivation from a pilot frequency in a predetermined limited frequency range outside the spectrum of audible frequencies towards the ultra sounds, said detecting means being connected to said reading head through a pass band filter centered on said pilot frequency and comprising a demodulation circuit to produce a demodulated digital output signal; a primary synchronization signal generator activated by said demodulated digital output signal; a format recognition circuit piloted by the primary synchronization signal outputted by said primary synchronization signal generator, and memory means for storing said demodulated digital output signal.

Claim 10

The device of claim 6, wherein said detecting means comprises a voltage controlled oscillator, and a phase locked loop centered on said pilot frequency.

Claim 11

The device of claim 6, wherein said memory means comprises at least a buffer register loaded with the demodulated digital output signal and a peripheral storage means receiving the content of said buffer register.

Claim 12

The device of claim 8, wherein said memory means comprises a first and a second buffer register, a comparator connected between said first and second buffer register, first transfer means connected between said first and second buffer registers and second transfer means connected between said second buffer register and said peripheral storage means, said comparator activating said peripheral storage means, said comparator activating said first transfer means responsive to an inequality in the contents of said first and second buffer registers and said comparator activating said second transfer means responsive to an equality in the contents of said first and second buffer registers.

Claim 13

The device of claim 9, wherein a digital counter is connected between said comparator and said second transfer means, and said comparator enabling said second transfer means responsive to a sequence of a predetermined number of equalities of contents of said first and second buffer registers.