Method and circuit for the transmitting, recording, and/or reproducing of wide-band signals

State of the art

The invention is based on a method according to the preamble of claim 1. From DE-PS 9 69 818 is already a method for transmitting and recording signals comprising a wide frequency band known. In the known method, the signal is decomposed into a plurality of smaller frequency range signals and these are transmitted or recorded independently. To obtain the plurality of signals corresponding to the intended number of transmission channels, instantaneous values ​​of the output signal are blanked out with the aid of phase-shifted pulse trains. For the time-correct composition of the transmitted or recorded in the individual channels intermediate signals to the original signal, the transfer of the sampling frequency is required.

For the transmission or recording frequenzmoduliertcr output signals, the known method is not useful because the instantaneous values ​​of the output signal only in the frequency, but not in the

3 »differ in amplitude. Although the carrier-frequency transmission of the intermediate signals is conceivable in principle and also leads to a reduction in the bandwidth requirement of the individual transmission channels for the intermediate signals with respect to the required

j5 before bandwidth for the frequency-modulated transmission of the output signal, but make the adjustment of the then necessary plurality of modulators and the phase errors occurring in assembling the intermediate signals to the original signal extraordinary difficulties. In particular, in the magnetic storage of the intermediate signals in multiple tracks of a magnetic tape inaccuracies of the tape run lead to intolerable phase errors between the individual channels, which the perfect

Vi demodulation of the intermediate signals and their complete composition complicate.

From DE-AS 22 37 255 another system is known with which the bandwidth of a video signal recording and playback device is reduced. For this

5 ", the video signal containing any information is decomposed into a number of signals. These signals are recorded in multiple channels in memory circuits. The video signal is modulated into a lower frequency range by adjusting the output

5^r> or read the signals in a longer period than the registered. During playback, the recorded signals are again written in memory circuits, in order to then be canceled again in a shorter period of time than during writing.

wi give to be. This restores the original time and thus the original video signal.

It is an object of the invention to specify a method and a circuit arrangement with which it is possible

ιΓ) is to reduce the number of required modulators and demodulators and thus the Ableiieharbeiien to be performed.

The solution to this problem is in terms of

Method with the measures specified in the characterizing part of claim 1, with regard to the circuit arrangement with the measures indicated in the characterizing part of claim 7.

Advantageous embodiments of the method are specified in the dependent claims 2 to 6, the circuit arrangement in the dependent claims 8 to 10.

Advantages of the invention

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The inventive method with the characterizing features of claim 1 has the advantage that for the carrier-frequency transmission of the sub-signals, the number of required modulators and demodulators does not depend on the number of transmission channels. A further advantage is to be considered that the adjustment of the individual transmission channels is easier to carry out as a result of the omission of numerous modulators and demodulators.

Advantageously, in a television signal, the signal portions subjected to the time transformation correspond to a length of time. The switching operations are preferably placed in the blanking intervals.

It is particularly advantageous that transmission errors, in particular amplitude errors of the transmission chain, remain without influence on the level of the demodulated video signal, regardless of which transmission channel the signal is instantaneously removed. The problem of the time and phase accurate composition of the sub-signals to the original signal is thus easier to deal with.

It is also advantageous, according to another embodiment of the invention, to convert the color information into one of FM sidebands substantially free frequency band and add in supported form before the division and time transformation to the FM-modulated BAS signal and analogous to the Rücktransformior. to reverse and add to the demodulated BAS signal. The elements for time transformation can thus be used jointly and simultaneously for both signal components (luminance, chrominance).

Advantageously, the separation takes place only after the time error compensation carried out for both signal components.

drawing

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows

Fig. 1 shows schematically the block diagram of a device for carrier-frequency recording and reproducing a video signal in a plurality of adjacent tracks;

FIG. 2 shows a schematic block diagram of the device according to the invention for carrier-frequency recording and reproduction of a video signal in several adjacent tracks;

Fig. 3 is a schematic block diagram of another embodiment of the device according to the invention.

Description of the invention

As from the F i g. 1, which shows the prior art known to the Applicant, it is customary to subject fractions of the television signal to a time transformation (time stretching) and to assign the time-transformed signal sections simultaneously to individual tracks, airfropduliert a carrier frequency and recorded. Due to the modulation after the division and time transformation, as many modulators are required as there are channels (tracks). Accordingly, as many demodulators as channels (tracks) are required. However, ensuring equal transmission characteristics for all channels and channel-wise time-transformation of video signals is difficult and time-consuming, and success is not always given.

In the method according to the invention, for which FIG. 2 illustrates a circuit arrangement as an exemplary embodiment, the video signal arriving at 10 is fed back to the input of a modulator 11 and modulated in the modulator 11 of a carrier frequency in a known manner. The appearing at the output of the modulator 11 frequency-modulated signal is distributed according to the position of the switches 12.1, 12.2 ... 12./7 sequentially to the intended η channels. The sequence may be a time-clock signal or fraction or a multiple thereof used in the original signal.

In the time stretchers 13.1, 13.2 ... 13.n, the signal sections of the individual channels (tracks) are stretched n times, thereby simultaneously carrying out a frequency transformation by the factor '/ ". These stretched, frequency-transformed signal sections can be recorded by means of the converter devices 14.1, 14.2... 14.n in η adjacent tracks on a (not shown) magnetic tape.

For the reproduction of the time-stretched signal sections stored on the magnetic tape, these are read out by the transducers 14.1, 14.2... 14.n and supplied to the digit transformer elements 15.1, 15.2... 15n for time-lightening. The signal sections which are present at the output of the time-delay elements 15.1, 15.2 ... 15./7 correspond again to the signal portions present at the output of the switches 12.1, 12.2 ... 12.n before the time extension and can thus be replaced by a same set of switches 16.1, 16.2. .. 16.n be assembled to the continuous frequency modulated signal. This composite signal passes through the demodulator 17 and appears at its output as a demodulated original video signal.

The embodiment of the invention according to F i g. 3 partly contains the same circuit elements as those of FIG. 2. which perform the same functions and are therefore also provided with the same reference numerals. In addition, the circuit arrangement according to F i g. 3, a converter 18 for converting the carried chrominance signal from, for example, 4.43 MHz to 0.562 MHz. This converted chrominance signal is added in the adder 19 to the frequency-modulated BAS signal.

Similarly, after being transferred from the FM-modulated signal, the color component at 0.562 MHz is filtered out, converted back to 4.43 MHz in the converter 20, and combined by means of the adder 21 into the complete CVBS signal.

With the described circuit arrangement, it is possible to store frequency-modulated signals in a plurality of tracks or to transmit in a plurality of channels, whereby the transmission characteristics of the individual channels can be kept more easily the same.

For this 1 sheet drawings