U.S. Philips Corporation

Harald E Melwisch

Dietfried Susz

Erich Langer

Helmut Mach

Dietfried Suss

Helfried Kurzmann

Robert Lackner

Hendrikus Looren De Jong

A recording system for recording signals on a magnetic tape uses a recording apparatus and cassettes, each cassette containing a specific length of magnetic tape, and has a timer for setting time-preprogrammed automatic recordings. A detection unit determines the maximum time available for recording on a cassette placed in the apparatus and a comparator compares an output signal of the detection unit with a reference quantity which is a measure of the total time required for the preprogrammed automatic recording(s). When this required time exceeds the maximum time available for recording with this cassette, an alarm signal is produced. The cassette has marks which are sensed by the detection unit and which indicate the length of the magnetic tape in the cassette.

Preprogrammable recording system with automatic warning of time limit

In a reproducing apparatus for a color television signal recorded on a record carrier, of which at least the chrominance signal which contains the color synchronizing signals is recorded with periodically changed polarity in the individual line period sectors in at least one of two adjacent tracks, the polarity of the reproduced signal in the individual line period sectors is switched so by means of a polarity switching device that the polarity change effected during recording is cancelled, which enables cross-talk signals from an adjacent track to be suppressed. In order to ensure that the change in polarity during reproduction is always in synchronism with the change in polarity during recording, there is provided an identification circuit for the phase relationship between two such color synchronizing signals, which should be in phase in conformity with the television standard when the polarity change during reproduction exactly cancels the polarity change effected during recording. Thus, in the case of an incorrect polarity during reproduction this indentification circuit supplies a signal by means of which the switching state of the polarity switching device is each time changed by one switching step, until the polarity change during reproduction is again in synchronism with the polarity change during recording.

Reproducing apparatus with cross-talk suppression for a color television

In a helical scan recorder using multiple heads having gaps positioned at different aximuth angles tracking errors are detected by signal processing the normal synchronization pulses recorded with the television signal. The signal processing is accomplished by using a phase shift detection circuit and a difference circuit for subtracting signals from the phase shift circuit indicating the instantaneous phase shifts produced by the tracking errors.

Playback apparatus for correcting locking errors

A reproducing apparatus for television signals recorded on a magnetizable record carrier in the form of a tape comprises a rotatable transducer arrangement which for reading television signals which are recorded in adjacent oblique tracks which extend parallel to each other carries two magnetic heads of mutually different azimuth angles, whose azimuth angles correspond to the azimuth angles of the magnetic heads used during recording. In such an apparatus steps have been taken to ensure that during a mode of operation with stationary record carrier or with a record carrier speed deviating from the normal speed each of the two magnetic heads reads a track in which the television signals have been recorded with a magnetic head having the same azimuth angle as the magnetic head reading it. Furthermore, the signal path for the television signals being reproduced includes a delay device for said signals, which shifts the television signals corresponding to the consecutive fields in such a time relationship to each other that, without a phase jump between the horizontal synchronizing pulse trains of consecutive fields, the differences in the time intervals between every two consecutive vertical synchronizing pulses of each field are zero or a minimum respectively.

Video reproducing apparatus with variable delay means

For recording and/or reproducing color television signals steps are proposed which enable the crosstalk signal from an adjacent track to be suppressed during reproduction. This is possible both for the chrominance signal and for the luminance signal. For this purpose the polarity of the signals in the line periods in all tracks is switched during recording in periodically recurrent groups with the same pattern of consecutive polarities, the groups comprising at least four line periods and being offset relative to each other in adjacent tracks by at least one line period. During reproduction the signals scanned from the relevant track whose polarities have been switched, at least in respect of the chrominance signal, are restored to signals with the original polarities. The frequency spectra of the useful signal relative to the crosstalk signal from an adjacent track are then interlaced, which is utilized for suppressing the crosstalk signal.

Method of recording color television signals as a repetitive series of

A playback apparatus for a recorded frequency modulated television signal includes a filter between the record carrier pick-up heads and the limiter-demodulator. The filter characteristics increase the ratio of the carrier signal frequency to the lower side band frequencies in response to a drop in carrier amplitude.

Playback apparatus

In a circuit arrangement for a dropout detector for the detection of dropouts in signals which are reproduced from a record carrier, the signal path includes an amplitude discriminator before the threshold device which supplies a switching signal in the event of a dropout, the discriminator characteristic between two threshold levels of the output signals having a steep edge for amplitude discrimination in whose range the signal level which is decisive for the actuation of the threshold device is situated.

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Vienna, Austria

Harald E Melwisch