Circuit for identifying when a reproduced color video signal has been recorded in a high-band or low-band mode

Claim 1

A recording mode identifying circuit for determining whether a reproduced FM signal is of a first mode in which recording is effected with frequency modulation of a first carrier having a first center frequency by a level of an information signal or of a second mode in which recording is effected with frequency modulation of a second carrier having a second center frequency by the level of the information signal, said mode identifying circuit comprising: phase inverting means for inverting a predetermined frequency component of a reproduced FM signal which corresponds to the frequency of one of said first and second carriers when modulated by a predetermined value of said level of the information signal; limiter means for eliminating an amplitude component of an output of said phase inverting means; and level detecting means for detecting a level of said predetermined frequency component in the reproduced FM signal which has had said predetermined frequency component inverted and said amplitude component eliminated, whereby the mode with which said reproduced FM signal was recorded is determined from said level detected by said level detecting means.

Claim 7

An apparatus for reproducing a color video signal composed of a luminance signal and a chroma signal and which is recorded on a magnetic tape either according to a first mode in which recording is effected with frequency modulation of a first carrier having a first center frequency by said luminance signal or according to a second mode in which recording is effected with frequency modulation of a second carrier having a second center frequency by said luminance signal, said apparatus comprising: magnetic head means for reproducing said color video signal recorded on the magnetic tape; separation circuit means for separating the reproduced color video signal from said magnetic head means into an FM luminance signal and a chroma signal; processing circuit means for processing the separated chroma signal; FM demodulation means which is selectively operative in a first mode or a second mode for demodulating the separated FM luminance signal when the color video signal is recorded in said first mode or said second mode, respectively; de-emphasis means for de-emphasizing the demodulated luminance signal from said FM demodulation means; a recording mode identifying circuit for determining whether said reproduced color video signal is of said first mode or said second mode and which include phase inverting means for inverting a predetermined frequency component of a separated FM luminance signal which corresponds to the frequency of one of said first and second carriers when modulated by a predetermined level of the luminance signal, limiter means for eliminating an amplitude component of an output of said phase inverting means, and level detecting means for detecting a level of said predetermined frequency component in the separated FM luminance signal which has had said predetermined frequency component inverted and said amplitude component eliminated, whereby the one of said first and second modes with which said reproduced color video signal was recorded is identified from said level detected by said level detecting means; and system control means responsive to an identification of said one of the first and second modes with which the reproduced color video signal was recorded for selectively operating said FM demodulating means in said one of said first and second modes.

Claim 8

An apparatus for reproducing a color video signal composed of a luminance signal and a chroma signal and which is recorded on a magnetic tape either according to a first mode in which recording is effected with frequency modulation of a first carrier having a first center frequency by said luminance signal or according to a second mode in which recording is effected with frequency modulation of a second carrier having a second center frequency by said luminance signal, said apparatus comprising: magnetic head means for reproducing said color video signal recorded on the magnetic tape; separation circuit means for separating the reproduced color video signal from said magnetic head means into an FM luminance signal and a chroma signal; processing circuit means for processing the separated chroma signal; FM demodulation means which is selectively operative in a first mode or a second mode for demodulating the separated FM luminance signal when the color video signal is recorded in said first mode or said second mode, respectively; de-emphasis means for de-emphasizing the demodulated luminance signal from said FM demodulation means; a recording mode identifying circuit for determining whether said reproduced color video signal is of said first mode or said second mode and which include phase inverting means for inverting a predetermined frequency component of a separated FM luminance signal which corresponds to the frequency of one of said first and second carriers when modulated by a predetermined level of the luminance signal, limiter means for eliminating an amplitude component of an output of said phase inverting means, and level detecting means for detecting a level of said predetermined frequency component in the separated FM luminance signal which has had said predetermined frequency component inverted and said amplitude component eliminated, whereby the one of said first and second modes with which said reproduced color video signal was recorded is identified from said level detected by said level detecting means; and system control means responsive to an identification of said one of the first and second modes with which the reproduced color video signal was recorded for selectively operating said FM demodulating means in said one of said first and second modes.