Identifier for a pulse code modulated signal

Claim 2

An identifier for identifying a pulse code modulated signal in a composite signal incuding a video signal and a pulse code modulated audio signal, said video and audio signals being alternately transmitted in a predetermined sequence, said video and audio signals having a pulse coded synchronizing signal inserted in said video and audio signals with a predetermined repetition frequency, said pulse coded synchronizing signal including a predetermined number of pulses synchronized with pulses which form a pulse code of said pulse code modulated audio signal, comprising: a gain control circuit having an input to which is applied the composite signal for controlling gain thereof, said control circuit including an output for the gain controlled composite signal; a means for deriving a pulse series including a signal component having a frequency equal to said repetition frequency of said pulse coded synchronizing signal from said composite signal and for producing a continuous pulse signal synchronized with said pulses which form the pulse code; a means for detecting an amplitude of said pulse coded synchronizing signal and for providing an output signal having a voltage proportional to the detected amplitude; a means for controlling gain of said gain control circuit and for reducing variation of an amplitude of said composite signal by applying the output signal of the amplitude detecting means to said gain control circuit; and a means for identifying the gain controlled composite signal of the output of said gain control circuit, said identifying means including means for responding to the continuous pulse signal synchronized with said pulses which form the pulse code and for shaping a waveform of said gain controlled composite signal so as to obtain a complete pulse train signal.

Claim 3

An identifier as claimed in claim 1, further comprising a clamp circuit connected between said gain control circuit and said identifying means and providing an output signal, said clamp circuit fixing a dc level of the gain controlled composite signal of the output of said gain control circuit, and means for supplying the output signal of said clamp circuit to said identifying means.

Claim 4

An identifier for identifying a pulse code modulated signal in a composite signal including a video signal and a pulse code modulated audio signal, said video and audio signal being alternately transmitted in a predetermined sequence, said video and audio signals having a pulse coded synchronizing signal inserted in said video and audio signals with a predetermined repetition frequency, said pulse coded synchronizing signal including a predetermined number of pulses synchronized with pulses which form a pulse code of said pulse code modulated audio signal, comprising: a gain control circuit having an input to which is applied the composite signal for controlling gain of the composite signal, said control circuit including an output for the gain controlled composite signal; a means for deriving a pulse series includ a signal component having a frequency equal to said repetition frequency of said pulse coded synchronizing signal from said composite signal and for producing a continuous pulse signal synchronized with said pulses which form the pulse code; a means for gating out only said pulse coded synchronizing signal from the composite signal; a means for detecting an amplitude of said pulse coded synchronizing signal which is gated by said gating means, said detecting means providing an output signal having a voltage proportional to the detected amplitude; a means for controlling gain of the gain control circuit and for reducing variation of an amplitude of said composite signal by applying the output signal of the amplitude detecting means to the gain control circuit, and a means for indentifying the gain controlled composite signal of the output of the gain control circuit which has no amplitude variation, said identifying means including means for responding to the continuous pulse signal synchronized with said pulses which form the pulse code and for shaping a waveform of said gain controlled composite signal so as to obtain a complete pulse train signal.

Claim 5

An identifier for identifying a pulse code modulated signal in a composite signal including a video signal and a pulse code modulated audio signal, said video and audio signal being alternately transmitted in a predetermined sequence, said video and audio signals having a pulse coded synchronizing signal inserted in said video and audio signals with a predetermined repetition frequency, said pulse coded synchronizing signal including a predetermined number of pulses synchronized with pulses which form a pulse code of said pulse code modulated audio signal, comprising: a gain control circuit having an input to which is applied the composite signal for controlling gain of the composite signal, said control circuit including an output for the gain controlled composite signal; a means for deriving a pulse series includ a signal component having a frequency equal to said repetition frequency of said pulse coded synchronizing signal from said composite signal and for producing a continuous pulse signal synchronized with said pulses which form the pulse code; a means for gating out only said pulse coded synchronizing signal from the composite signal; a means for detecting an amplitude of said pulse coded synchronizing signal which is gated by said gating means, said detecting means providing an output signal having a voltage proportional to the detected amplitude; a means for controlling gain of the gain control circuit and for reducing variation of an amplitude of said composite signal by applying the output signal of the amplitude detecting means to the gain control circuit, and a means for indentifying the gain controlled composite signal of the output of the gain control circuit which has no amplitude variation, said identifying means including means for responding to the continuous pulse signal synchronized with said pulses which form the pulse code and for shaping a waveform of said gain controlled composite signal so as to obtain a complete pulse train signal.

Claim 6

An identifier for identifying a pulse code modulated signal in a composite signal including a video signal and a pulse code modulated audio signal, said video and audio signals being alternately transmitted in a predetermined sequence, said video and audio signals having a pulse coded synchronizing signal inserted in said video and audio signals with a predetermined repetition frequency, said pulse coded synchronizing signal including a predetermined number of pulses synchronized with pulses which form a pulse code of said pulse code modulated audio signal, comprising: a gain control circuit having an input to which is applied the composite signal for controlling gain of the composite signal, said control circuit including an output for the gain controlled composite signal; a band-pass-filter for passing a signal component of the gain controlled composite signal, said signal component having frequencies equal to that of the pulses which form said pulse coded synchronizing signal; an amplitude separating means for passing signals having an amplitude exceeding a certain predetermined value; a means for deriving a pulse series including a signal component having a frequency equal to said repetition frequency of said pulse coded synchronizing signal from said signal having an amplitude exceeding a certain predetermined value and for producing a continuous pulse signal synchronized with said pulses which form the pulse code; a synchronization detector; a means for supplying a signal passed from the band-pass-filter to said amplutide separating means; a means for supplying the signals passed by said amplitude separating means and the pulse signal produced by said deriving and producing means to said synchronization detector, said synchronization detector providing an output signal; a means for controlling gain of the gain control circuit and for reducing variation of an amplitude of said composite signal by supplyIng the output signal of the synchronization detector to said gain control circuit; and a means for identifying the gain controlled composite signal of the output of said gain control circuit.

Claim 7

An identifier for identifying a pulse code modulated signal in a composite signal including a video signal and a pulse code modulated audio signal, said video and audio signals being alternately transmitted in a predetermined sequence, said video and audio signals having a pulse coded synchronizing signal inserted in said video and audio signals with a predetermined repetition frequency, said pulse coded synchronizing signal including a predetermined number of pulses synchronized with pulses which form a pulse code of said pulse code modulated audio signal, comprising: a gain control circuit having an input to which is applied the composite signal for controlling gain of the composite signal, said control circuit including an output for the gain controlled composite signal; a band-pass-filter for passing a signal component of the gain controlled composite signal, said signal component having frequencies equal to that of the pulses which form said pulse coded synchronizing signal; an amplitude separating means for passing signals having an amplitude exceeding a certain predetermined value; a means for deriving a pulse series including a signal component having a frequency equal to said repetition frequency of said pulse coded synchronizing signal from said signal having an amplitude exceeding a certain predetermined value and for producing a continuous pulse signal synchronized with said pulses which form the pulse code; a synchronization detector; a means for supplying a signal passed from the band-pass-filter to said amplutide separating means; a means for supplying the signals passed by said amplitude separating means and the pulse signal produced by said deriving and producing means to said synchronization detector, said synchronization detector providing an output signal; a means for controlling gain of the gain control circuit and for reducing variation of an amplitude of said composite signal by supplyIng the output signal of the synchronization detector to said gain control circuit; and a means for identifying the gain controlled composite signal of the output of said gain control circuit.

Claim 8

An identifier for identifying a pulse code modulated signal in a composite signal including a video signal and a pulse code modulated audio signal, said video and audio signals being alternately transmitted in a predetermined sequence, said video and audio signals having a pulse coded synchronizing signal which is transmitted in a given period, said pulse coded synchronizing signal having a predetermined repetition frequency and including a number of pulses synchronized with pulses which form a pulse code of said pulse code modulated audio signal, comprising: a gain control circuit having an input to which is applied the composite signal for controlling gain thereof, said control circuit including an output for the gain controlled composite signal; a switcher for switching either to pass said composite signal from an input to an output of the switcher or to pass the gain controlled composite signal from an input to an output of the switcher; a means for deriving a pulse series including a signal component having a frequency equal to said repetition frequency of said pulse coded synchronizing signal from said composite signal and for producing a continuous pulse signal synchronized with said pulses which form the pulse code; a means for reproducing a synchronizing signal having a period equal to the period in which the pulse coded synchronizing signal is transmitted; a synchronization confirming means for producing an output signal having a voltage of a predetermined value when the period of the synchronizing signal reproduced by the synchronizing signal reproducing means is equal to a predetermined period; a gate circuit operated by said synchronizing signal reproduced by said means for reproducing, said gate circuit providing a gated output signal; a means for supplying an output of the switcher to said gate circuit and a means for detecting an amplitude of the gated output signal, said detecting means providing an output signal having a voltage proportional to the detected amplitude; a means for controlling gain of the gain control circuit and for reducing variation of an amplitude of said composite signal by applying the output signal of the amplitude detecting means to said gain control circuit; a means for identifying an output signal of the switcher, said identifying means including means for responding to the continuous pulse signal synchronized with said pulses which form the pulse code of said pulse code modulated audio signal and for converting the composite signal into a pulse train signal; and a means for applying the output signal of the synchronization confirming means to said switcher and for causing said switcher to pass the gain controlled composite signal from the gain control circuit when the output signal of the synchronization confirming means has a value exceeding a predetermined value.

Claim 9

An identifier for identifying a pulse code modulated signal in a composite signal including a video signal and a pulse code modulated audio signal, said video and audio signals being alternately transmitted in a predetermined sequence, said video and audio signals having a pulse coded synchronizing signal which is transmitted in a given period, said pulse coded synchronizing signal having a predetermined repetition frequency and including a number of pulses synchronized with pulses which form a pulse code of said pulse code modulated audio signal, comprising: a gain control circuit having an input to which is applied the composite signal for controlling gain thereof, said control circuit including an output for the gain controlled composite signal; a switcher for switching either to pass said composite signal from an input to an output of the switcher or to pass the gain controlled composite signal from an input to an output of the switcher; a means for deriving a pulse series including a signal component having a frequency equal to said repetition frequency of said pulse coded synchronizing signal from said composite signal and for producing a continuous pulse signal synchronized with said pulses which form the pulse code; a means for reproducing a synchronizing signal having a period equal to the period in which the pulse coded synchronizing signal is transmitted; a synchronization confirming means for producing an output signal having a voltage of a predetermined value when the period of the synchronizing signal reproduced by the synchronizing signal reproducing means is equal to a predetermined period; a gate circuit operated by said synchronizing signal reproduced by said means for reproducing, said gate circuit providing a gated output signal; a means for supplying an output of the switcher to said gate circuit and a means for detecting an amplitude of the gated output signal, said detecting means providing an output signal having a voltage proportional to the detected amplitude; a means for controlling gain of the gain control circuit and for reducing variation of an amplitude of said composite signal by applying the output signal of the amplitude detecting means to said gain control circuit; a means for identifying an output signal of the switcher, said identifying means including means for responding to the continuous pulse signal synchronized with said pulses which form the pulse code of said pulse code modulated audio signal and for converting the composite signal into a pulse train signal; and a means for applying the output signal of the synchronization confirming means to said switcher and for causing said switcher to pass the gain controlled composite signal from the gain control circuit when the output signal of the synchronization confirming means has a value exceeding a predetermined value.

Claim 10

An identifier as claimed in claim 3, further comprising a clamp circuit having an output connected to an input of the means for identifying for fixing a dc level of the composite signal.

Claim 11

An identifier as claimed in claim 4, further comprising a clamp circuit having an output connected to an input of the means for identifying for fixing a dc level of the composite signal.

Claim 12

An identifier as claimed in claim 5, further comprising a clamp circuit having an output connected to an input of the means for identifying for fixing a dc level of the composite signal.