Robert Boschgmbh

Winfried Horstmann

Hubert Foerster

Josef Sochor

Four magnetic heads are provided on a rotary mount equally spaced around the circumference, so when they are rotated to scan a tape wound around the headwheel in half a turn of a helix, each oblique track on the tape corresponds to half a revolution of the headwheel. In recording, the incoming signals are subdivided in time demultiplex into segments alternately distributed first to one diametryl pair of heads on the headwheel and then to the other diametryl pair, in each case through a digital time expander that doubles the time required to transmit the signal segment, thus reducing the bit rate by half. The reverse operations are done in playback, with time-expansion before the signal segments are put together into a continuous signal channel stream at the original bit rate. If the time-expansion is by just a little less than the factor of two, and the time-compression likewise, the places on the tape where two heads of the same channel would instantaneously both be in contact with the tape are left clear of signals, and disturbances are avoided, without interfering with the continuity of the playback signal.

System of recording and playback of digitally recorded signals,

Color television signals are split up to provide a luminance signal and a chrominance signal. These are recombined in a manner designed to reduce the frequency bandwidth and, furthermore, time-subdivision is used to distribute signals for recording between two channels, with time expansion being provided in each channel before recording each channel on a separate track on the recording medium. In playback, the signals of the separate channels are time-compressed and then sequentially switched back into the original signal sequence. The time-expansion and distribution among channels can be performed after the color television signal has been rearranged to occupy smaller bandwidth or the components of the television signal can be separately time divided, distributed and time expanded in the recording technique, with the converse signal processing being performed in playback.

Method and apparatus for magnetic tape recording of color television

Time-expansion is provided to one-line segments of the luminance component of a color television signal, and time-compression is applied to one-line segments of the chrominance component, so that both components can be recorded on magnetic tape with optimum utilization of the bandwidth of recording channels utilized for both components. Time-compression and -expansion is provided by control of the independent write-in and read-out rates of charge coupled device stores. A commutation system is provided for applying the required clock rates in proper sequence to the various stores, and another commutation system is provided for stringing signal segments of television line lengths of the respective luminance and chrominance components, so that recording can be done in reel time in two channels on a magnetic tape. In one embodiment, the basic delay involved is reduced by reading in a component of one kind, while another component is being read out, and setting the clock rates, so that this operation can proceed at a single one of the clock rates.

Method and means for recording and playback of color television signals

A method and a circuit for transmitting or storing a wide-band signal in several, narrow-band channels, wherein frequency modulation and demodulation occur in the wideband channel. The uniformity of the transmission characteristics of the entire system is improved by obviating the necessity for multiple modulators and demodulators in the individual transmission channels.

Method and circuit for the transmitting, recording, and/or reproducing

There is shown a method for correction of rapid periodic frequency characteristic errors in the reproduction of signals with periodic synchronizing signals from magnetic tape as well a circuit arrangement for carrying out the method. For repeated correction of the error within the period between two successive synchronizing signals, there are brought into account the stored error magnitudes of similarly positioned synchronizing signals on adjacent tracks, since the synchronizing signals of successive oblique tracks are offset by a fraction of a line. The circuit arrangement comprises a storage device with a number of storage places corresponding to the number of lines and/or to the number of color television signals of a television picture. In each storage place the average value of the frequency response error of previous lines of the same kind is stored and is superimposed on the actual error value.

Method and apparatus for frequency characteristic compensation of

Time base errors arising during the playback of a broadband signal previously stored in segments in a plurality of narrow-band channels with a first time transformation are corrected. Specifically, these signals are read out in turn from the narrow channels on the tape and applied at a slow rate to a plurality of buffer storages. They are read out from the buffer storages at a relatively fast rate, in sequence, so that the broadband signal is reconstituted. The broadband signal is then demodulated. For time base correction, the horizontal synchronization signals are separated from the reconstituted demodulated signal and their timing is compared to the timing of horizontal reference signals. A pulse is formed whose pulse width is equal to the time interval between occurrence of a horizontal synchronization pulse separated from the demodulated signal and the occurrence of the corresponding reference synchronization signal. The output of the clock generator controlling the readout from the buffer storages is delayed by a time interval equal to the pulse width. Further measures for decreasing residual errors are also specified. The measurement is carried on at the start of each line and after the signal has been reconstituted and demodulated and is thus present in a single channel.

Method and system for correcting time base errors in broadband signals

Since frequency modulated signals such as color television signals are subject to amplitude changes as well as timing changes if the playback speed is not the same as the recording speed, a variable gain amplifier is provided. The gain of the variable gain amplifier is controlled by an error signal which corresponds to a measured difference between the recording and playback speed. The measured difference is derived from a phase comparison of separated color bursts and of the same bursts delayed by one line period. The amplitude corrected signals at the output of the variable gain amplifier are also applied to an amplitude measuring stage 16 whose output in turn controls the frequency characteristic of a filter filtering the color television signals prior to demodulation.

Playback system with amplitude correction for frequency modulated signals

Furnishing a signal having an amplitude corresponding to the difference between the recording and playback speed of a tape recorded color television signal, the phase of the color burst of two successive lines is compared. When the speed difference includes a known difference such as, for example, for slow motion reproduction, a compensating delay is added to the single line delay of the known apparatus and simultaneously a DC voltage corresponding to the so-added delay is added to the error signal derived from the phase comparator. The additional delay and the additional voltage for the error signal are automatically inserted into the circuit by ganging a switch or potentiometer for the additional delay and for the additional voltage to the speed control for the tape drive.

System for generating an error signal indicative of differences between

Timing errors are detected by phase comparison of the color carrier at the line scanning frequency repetition rate and the errors so successively determined for one oblique track on the tape are loaded into an intermediate register. While a second magnetic head of the reproducer performs the same operation on the next track, the errors stored in the intermediate register are subtracted from their average value produced by an integrator and loaded into a final storage register, of which there is one for each track of a line packet, but only after being combined, in a noise-scrubbing process, with an error value previously stored in a corresponding location in that register so as to provide a suitable moving average. During the next period in which the intermediate storage register is loaded with the errors relating to another track, all of the main storage registers are read, providing as many pulses as there are tracks in a packet for recurrent correction of timing errors within the period of one television line.

Correction of rapid periodic timing errors in the production of

A system for suppressing signal disturbances, which are due to switching from a first television signal to a second television signal, for use during a playback of the television signals on a magnetic tape recorder and in connection with an electronic switch for disconnecting the first television signal and connecting the second television signal to output terminals of the switch includes a delay line coupled between a demodulator and a timing error corrector for receiving and delaying the demodulated signals for a time substantially equal to a line period. Additionally, a switching sub-system is coupled to the demodulator for receiving and demodulated signals and the delayed demodulated signals, and for switching for a period of time substantially equal to the line period to generate another output signal from the demodulated signals; furthermore an amplitude filter is coupled to the switching subsystem, and the timing error corrector for receiving the output signals, and selectively passing synchronous signals, forming a portion of the output signals, to the timing error corrector.

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Griesheim, Germany

Winfried Horstmann