Robert Boschgmbh

Bts Broadcast Television Systems Gmbh

Josef Sochor

Hubert Foerster

Winfried Horstmann

Axel Schulz

Richard Heinz

Reinhard Kutzner

Werner Staude

Process for directly copying frequency modulated video signals from

A first counter operating at the PCM sampling frequency counts out the normal minimum period between successive synchronization words in the data stream. In a following 'window' the detection of another synchronization word produces a check signal and in all other cases a provisional check signal. In such other case the data for the next period are marked as dubious. A second counter counts out twice the minimum normal interval between synchronization words and in a following 'window', the appearance of a synchronization word produces a verification signal. The occurrence of a verification signal one normal interval after a provisional check signal removes the marking of intervening data as 'dubious'. If no verification signal is then produced, the intervening data are marked and treated as erroneous.

Detection and verification of lapses or shifts of synch words in PCM data

By varying the supply voltage, the output current is adjusted. The push-pull amplifier comprises two branches I, II, each having at least one transistor of the identical conductivity type, the emitters of which are connected with one another and, via a resistor (38, 118), with one pole of the supply voltage source, and the collectors of which are connected with the end terminals (34, 35; 107, 108) of a transformer coil, and one biasing circuit comprising two resistors in a series circuit, the junction points (J1, J2) of which are connected to the bases of the transistors. The common emitter current is varied virtually exclusively by means of varying the supply voltage, and upon a variation of the supply voltage, the sum of the currents in the two resistor networks are substantially independent of the supply voltage established.

Push-pull amplifier and method for operation, particularly recording

The magnitude of time-compression of audio signals recorded following the recording of video signals in the end portion of the same oblique track on magnetic tape is so related to the bit rate of recording of the video signals, in the recording of digital signals encoded in binary transmission codes, that the minimum interval between successive level changes in the audio signals is greater than the minimum interval between successive level changes in the video signal. This has the advantage of reducing the error rate in the audio signals in order to facilitate processing of digital signals of the audio information and of the video information in common processing channels, the minimum interval between successive level changes in the digital audio signals is made an integral multiple, preferably the double, of the minimum interval between successive level changes in the video signals. It is also advantageous to use different binary transmission codes for audio and video signals, particularly with respect to whether or not a level transition is permitted in the middle of a bit cell. Preferably the digital audio signals are recorded in a transmission code in which level changes are permitted in the middle of a bit cell, and the digital video signals are recorded in a transmission code in which level changes are not permitted in the middle of a bit cell.

Method of recording digital audio and video signals in the same track

For every playback head (6) on the head wheel (1) a sector (5) of the head wheel disk carries a preamplifier consisting of two amplifier branches operating in phase opposition, each having an input transistor stage of the grounded emitter configuration and an output transistor stage of the grounded collector configuration (sometimes referred to as an emitter follower). Both stages have voltage negative feedback. The outputs of the amplifying branches are respectively connected to opposite ends of a rotary primary coil of a multiple transformer serving to couple the rotating preamplifier circuits to stationary outputs. Blocking capacitors prevent the flow of equalizing currents in the event of any deviations from electrical symmetry. The circuit is usable for playback of recordings in the form of digital signals picked up at a rate of 2 megabits per second.

Playback preamplifier for magnetic tape recordings

In order that each of two recording channels utilized for a single color television signal may be used if necessary to provide a complete picture with only a loss of quality, digitally coded signal samples of the luminance signal and of the two chrominance signal components are equally distributed between the two channels, successive luminance component samples going alternately to the two channels, each pair made up of related samples of the two chrominance components going entirely to one channel or the other, with successive pairs going to different channels. With the usual input sequence, a simple transposition of the sample sequence in one channel can make the sequences of the various components in the two channels identical.

Two-channel transmission or storage method for digital color television

Picture points represented by a digital signal that is found to be in error are set to zero (black) value. Incoming 8-bit signals are twice delayed by one line delays, and 8-bit shift registers are provided for the undelayed, once delayed and twice delayed signals, each shift register providing three places for successive picture points. Averages are continuously formed horizontally, vertically and on both diagonals about every picture point, and when one value which is averaged is faulty, the divider at the output of the addition stage has its divisor changed from 2 to 1. The averages themselves are averaged to eliminate averages that are unusable because both inputs are faulty. The color television signal must be separately coded for the color and luminance information, and essentially the same scheme may be used for covering over errors in the color information as in the luminance information.

Method and apparatus approximately correcting errors in a digital video

Digitalized audio signals of a plurality of channels are stored blockwise in each channel and then recorded blockwise in repeating channel sequence in similarly situated portions of successive oblique tracks in which are also recorded concurrent video signals, but the recording of a channel block is skipped once per picture field, so that an integral number of channel sequences will record all the audio channel information for a period equal to a picture field. In the video track where audio recording is skipped, other information may be recorded. The read-out rate of the channel blocks is slightly accelerated so that the track skipping loses no information. Consequently, the recorded signals can be cut in, or cut off, or edited at any frame end without loss of registry of the audio channels.

Method and apparatus for recording digitally coded television signals

To obtain a timing signal in the regeneration of digital pulses from recordings or after transmission, two start-stop oscillators are triggered, respectively, by signals to be regenerated and by the same signals after inversion. The output signals from these oscillators are combined into a single signal which has the frequency of the desired timing signal, and a flywheel circuit is used to produce a continuously alternating voltage. Each of the start-stop oscillators is conveniently implemented by a pair of transistors whose emitters are interconnected by an inductor and individually connected to an operating voltage via a capacitor and a resistor, respectively.

Circuit for deriving a timing signal from digital imput signals

To obtain timing signals which continue essentially in phase even in the case of signal drop-out, a timing signal is supplied to a phase comparator which is also connected to a variable oscillator. Low-frequency output of the comparator is supplied to circuitry which, in the case of signal drop-out, initially retains a most recently encountered frequency and which then gradually shifts to a frequency which is the average of recent frequencies.

Circuit for producing timing pulses in the regeneration of square signals

The invention relates to a method of recording a television signal of the kind in which the signal is recorded on a relatively slowly moving tape in a plurality of inclined tracks by a plurality of recording heads carried at the periphery of a head wheel rotating at a relatively high speed in a plane non-parallel to the direction of tape motion. The head wheel executes m complete revolutions for each n complete television pictures, where the ratio m/n is non-integral, and control signals having a frequency of 1/n of the picture frequency are recorded along a longitudinal control track by a fixed head. For recording signals according to the 625 line European standard, m is chosen to be 25 and n is chosen to be 2. For the U.S. 525 line standard, m is 21 and n is 2. In both cases 25 lines per track are recorded.

Method of recording television 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

To simplify coupling of a video recording transducer to a recording network, and to improve the fidelity of the signals as actually recorded with respect to the signals applied to the recording network, an amplifier, preferably a current amplifier including emitter-coupled transistors, is connected between a current-supplied compensating network and the transducer, the connection being through a short cable, preferably a coaxial cable which has a length substantially less than the wave length of the signals to be recorded, so that the overall response of the compensating network-amplifier-cable-transducer will be essentially linear with respect to the signals to be recorded.

Inductive signal transducer supply circuit particularly for video

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.

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Dieburg, Germany

Josef Sochor