Apparatus having dropout detection and compensation for reproducing a video signal recorded on a record

Claim 3

An apparatus as claimed in claim 1, further comprising a third frequency demodulator means coupled to said first filter for demodulating the modulated carrier, a second comparator means coupled to said first and third demodulator, for comparing the demodulated carrier signal and the demodulated first lower frequency signal, a third comparator means coupled to said second and third demodulators for comparing the demodulated carrier signal and the demodulated second lower frequency signal, a first selection device means coupled to sAid demodulators for selectively applying one of the demodulated signals to a first output terminal as luminance information in accordance with the output signals of the three comparators, the demodulated first lower frequency signal is applied to said first output terminal if the demodulated second lower frequency signal is not equal to said demodulated first lower frequency signal and equal to the demodulated carrier signal, the demodulated second lower frequency signal is applied to said first output terminal if the demodulated first lower frequency signal is not equal to said demodulated second lower frequency signal and equal to the demodulated carrier wave signal, whilst in all other cases the demodulated carrier signal is applied to said first output terminal; whereby dropouts are compensated.

Claim 4

An apparatus as claimed in claim 2, further comprising means for the compensation for comparatively large dropouts, which compensation circuit comprises a first delay means coupled to said first filter with a delay time of one line time of the video signal, a further demodulator coupled to said delay means, and a first switch having inputs coupled to said further and third demodulators respectively and an output means coupled to said selection device, which upon the occurrence of a large dropout applies to the first output terminal a demodulated carrier signal which is delayed by one line time by the delay means.

Claim 5

An apparatus as claimed in claim 3, further comprising a separate dropout detector for controlling said switch and for supplying a control signal to the selection device, whereby during the occurrence of a large dropout said selection device assumes a specific position independently of the output signals of the comparators.

Claim 6

An apparatus as claimed in claim 1, for the reproduction of a colour video signal which is recorded on a record carrier and which contains a colour carrier which is modulated by the chrominance information, which colour carrier is added to the modulated carrier in that the zero crossings of the rising and falling edges of the modulated carrier are shifted in mutually opposite dependence on said modulated colour carrier wave, said apparatus further comprising a second filter having an input means for receiving said recorded signal and an output means for providing for said modulated colour carrier, a third divider having an input means for receiving the signal which is read from the record carrier and an output means for supplying a third lower frequency signal whose zero crossings correspond to the zero crossings of the rising edges of the detected signal, a fourth divider having an input means for receiving the signal which is read from the record carrier and an output means for supplying a fourth lower frequency signal whose zero crossings correspond to the zero crossings of the falling edges of the detected signal, a fourth frequency demodulator means coupled to said third divider output for demodulating the third lower frequency signal, a fifth frequency demodulator means coupled to said fourth divider output for demodulating the fourth lower frequency signal, a first subtractor means for subtracting the demodulated first lower frequency signal from the demodulated third lower frequency signal, a second subtractor means for subtracting the demodulated second lower frequency signal from the demodulated fourth lower frequency signal, a first integrator means for integrating the output signal of the first subtractor to obtain a first chrominance signal, a second integrator means for integrating the output signal of the second subtractor to obtain a second chrominance signal, a fourth comparator means for comparing the integrated or non-integrated output signals of the first and second subtractors, a fifth comparator circuit means for comparing the modulated colour carrier and the first chrominance signal, a sixth comparator means for comparing the modulated colour carrier and the second chrominance signal, and a second selection deVice means for selectively applying either the modulated colour carrier or one of the chrominance signals to a second output terminal, said applying means comprising logic means coupled to the fourth, fifth and sixth comparators for insuring that the first chrominance signal is applied to said second output terminal if the fourth comparator detects an inequality and the sixth comparator an equality of their respective input signals, that the second chrominance signal is applied to said second output terminal if the fourth comparator detects an inequality and the fifth comparator detects an equality of their respective input signals, whilst in all other cases the modulated colour carrier is applied to said second output terminal.

Claim 7

An apparatus as claimed in claim 1 further comprising means for the compensation of comparatively large dropouts, which compensation circuit comprises a third demodulator coupled to said first filter, first output terminal, a first delay means coupled to said first filter with a delay time of one line time of the video signal, a further demodulator coupled to said delay means, and a first switch having inputs coupled to said further and third demodulators respectively and an output means coupled to said selection device, which upon the occurrence of a large dropout applies to the first output terminal a demodulated carrier signal which is delayed by one line time by the delay means.