FI76661B - FOERFARANDE FOER OEVERFOERING, SAERSKILT FOER REGISTRERING OCH AOTERGIVNING AV TV-SIGNALER. - Google Patents

Description

1 76661

METHOD OF TRANSMISSION, IN PARTICULAR RECORDING AND REPRODUCTION OF TELEVISION SIGNALS

The invention starts from a method for transmitting television signals, in particular for recording and reproducing in analog form, wherein the luminance information is stored during the line drawing of the line period and the color information is time-condensed alternately during the remaining time of the line period during the off time.

This method is described in the title "Timeplex" - Series-10 color coding method for home video recorders in the magazine "Fernseh- und Kinotechnik", 34th volume No. 12/1980 pp. 451-458 and in DE 26 26 706.

This method has proven to be advantageous in the case of color television signals which have to be transmitted via channels of limited quality, such as video recordings. In this case, the luminance signal and the color difference signals are transmitted or stored at the line frequency. This is done in such a way that the luminance signal is recorded during the line-20 drawing time, while both color difference signals are shifted or received, alternately stored by a factor of 5 during time-out during the shutdown time.

A line sync pulse and mounting level must also be connected to the extinguishing opening. However, since the time is very limited to connect these signals due to the presence of color difference signals, it has been proposed to connect the line sync pulse and the attachment pulse alternately line by line. For this reason, a line pulse lasting 1.6 μs sec is connected in line. and during the next line return, an equal pi t-30 hand attachment pulse. However, it has been shown that such a short pulse leads to synchronization difficulties, especially when it occurs only every other line, especially in image recording and playback on home video recorders.

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It is known to store an additional control signal outside the color signal transmission range, which changes the amplitude 5 of the color signal according to the amplitude changes of this control signal (DE publication 18 08 439).

In addition, it is known to record a line-varying amplitude pulse together with a color signal which is stored in the form of a line-varying frequency due to the frequency modulation and which, in addition to line synchronization, also functions to distinguish between two line-difference color difference signals (U.S. Patent No. 3,717).

The object of the invention is to guarantee a secure line synchronization when recording signals transmitted by the timeplex method.

This object is solved by the procedure set out in claim 1.

In the following, an essential part of the invention will be explained by means of a drawing example of recording a timeplex signal.

Figure 1 shows a time diagram of the voltage of the signal 20 produced in the timeplex method.

Figures 2-5 show block diagram views for performing the method shown.

Figure 6 shows the frequency travel of the FM transmission range of the magnetic master signal at the carrier frequencies of the additional pulse signal.

Figure 1 shows an FBAS (combined color video signal) signal produced according to the timeplex method. The luminaire signal Y taken during most of the line period and the time-compressed color difference signals (R-Y), (B-Y) stored in the extinguishing apertures AT 1 and AT E are seen, whereby a fixing pulse K is transmitted during one extinction aperture AT 1 and a pacing pulse S during the next extinction aperture AT 1.

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Figures 2 and 3 illustrate an essential part of the invention in the following block diagram. In this case, the switching groups for the known time-plex method are marked above the dashed lines, while below this line the groups required in the method according to the invention are marked.

First, the timeplex method is briefly explained. Figure 2 shows the recording of a video signal on a magnetic tape. The Y signal arrives through the color carrier separator 1 to the switch 10, which is controlled by a synchronizer 3 so that the Y signal is connected during line drawing to a reception channel 4 consisting of a pre-emphasis FM modulator and an audio head amplifier. During the line return time, the R-Y signal produced by the PAL decoder-15 is switched alternately in line frequency at the fH / 2 rate. The B-Y signal is received in the receiving channel 4 after it is recorded in the memory 6 by means of a recording rate of e.g. 2 MHz produced by the clock generator 3 and output again at a printing rate of 10 MHz, which results in a time compression 20 by a factor 5.

According to the invention, an additional synchronization signal produced by the oscillator 7 is now placed at the recording head of the magnetic tape device 8, which is stored together with the time-compressed color difference signals R-Y, B-Y and Y-signal. The carrier frequency of the synchronization signal is preferably in the upper transmission range of the magnetic access signal. The amplitude of this signal is selected so as not to interfere with the Y and color intensity signals. The ID required for the PAL standard can be generated by the switched carrier frequency of the synchronization signal. To this end, the oscillator 7 is switched by a half-line frequency control rate taken from the synchronous generator 3 via phase 9 symmetrically about the center frequency so that the half-line = · frequency control star via switch 9a - shown here as a mechanical switch for switching simplicity. Thus, the capacitor 23 is connected alternately to the oscillator. The effect of the control clock is switched off by means of the vertical switching of the contact 9a by means of the control clock V taken from the clock generator 3.

5 This operation allows the vertical sync pulse of the playback side11a to be regenerated, as will be explained later.

Figure 3 will now explain the preparation of a pulse for synchronization. The signal transmitted by the recording device 8 10 is amplified in a repeating channel 10 consisting of a repeater amplifier, a dropout compensator, a limiter, an FM demodulator and post-attenuation, and the luminance signal Y arrives from there through the switch 11 controlled by the pacemaker 3. by means of the memory 13a / 13b controlled by the synchronizer 3 and the PAL encoder 14, the color signal is again propagated through the adder stage 12 into a complete FBAS signal which is reproduced by a television receiver. The spreading takes place in such a way that the memory 13 is recorded at a rate of 10 MHz and printed again at a rate of 2 MHz. The synchronization signal required to synchronize the television receiver is regenerated as follows and similarly set in the adder 12. The carrier signal 25 recorded during reception is connected via a signal limiting and amplifying device 15 to a phase discriminator 16. The phase discriminator 16 is tuned to a frequency in the synchronization signal carrier. Phase discriminator 16 or similar coupling produces signals of alternating polarity 30. The produced rectangular signal with half the line frequency serves as the reference frequency of the phase-locked loop (PLL), which consists of a voltage-controlled (VCO) oscillator 19 oscillating with the line frequency, a phase divider 20 of the oscillator frequency 35, a phase divider 20, a phase divider from a low-pass filter 18. The mode of operation of such a connection may be required to be known. The monostable flip-flop 21 connected to the oscillator 19 produces horizontal frequency pulses arriving via a synchronous generator together with similarly regenerated vertical sync pulses 5 to the sum stage 12. The vertical sync pulse is produced by the second monostable flip-flop 22 at the output of phase comparator 10.

Figure 6 shows the FM transmission range of the main signal and the frequency position of the carrier of the generated synchronization pulse, which pulse may be at the upper end of the transmission range.

Another embodiment of the presented method will be explained below with reference to Figs.

The Y signal arrives through the color carrier separator 1 to a switch 2, which is controlled by a pacemaker 3 so that the Y signal is connected during line drawing to a reception channel H consisting of a pre-emphasis FM modulator and 20 audio head amplifiers. During the line return TA, the (R-Y) signal prepared by the PAL decoder 5 is switched alternately line frequency at the fH / 2 rate. The (B-Y) signal to the receiving channel 4, after they are recorded in the memory 6 at the clock rate of e.g. 2 MHz produced by the synchronous generator 3, and output again at a printing rate of 10 MHz, whereby a time seal is formed by a factor of 5.

The carrier pulse produced by the oscillator 7 is set by the pacemaker during the line return via the closed contact 9 to the receiving end-30 of the magnetic tape device 8, so that this pulse is stored together with the time-compressed color difference signals R-Y and 3-Y. The carrier frequency of the generated pulse is also preferably in the upper transmission range of the magnetic main signal. The amplitude of this pulse signal is selected so that the chrominance signal is not disturbed. The symbol required for the PAL standard can be generated by the switched carrier frequency for the pulse.

For this purpose, the oscillator 7 is switched in half-line frequency with a clock produced by a synchronous generator at a frequency FH / 2, e.g. by means of a capacitance diode.

Figure 5 will now explain the preparation of a pulse for synchronization. The signal transmitted by the recording device 8 is amplified in a reproduction channel 10 consisting of a reproduction amplifier, a dropout compensator, a ra-10 receiver, an FM demodulator and post-attenuation, and the luminase signal Y arrives from there via by means of the memory 13 and the PAL encoder 14, the color signal le-15 is again wired through the adder circuit 12 into a complete FBAS signal which is reproduced by a television receiver. The spreading takes place by recording the memory 13 at a rate of 10 MHz and printing again at a rate of 2 MHz. The synchronization signal required for synchronizing the television receiver is regenerated as follows and similarly set to adder 12. The signal received during line return is coupled through a signal limiting and amplifying device 15 to a phase discriminator 16. The phase discriminator 16 is tuned to a frequency between 25 generated pulse carriers. Line-phase discriminator 16 or a similar circuit produces line-frequency pulses. After the connected step 23, the pulses are converted so that half line frequency pulses can be taken at the output A, which act to keep the PAL flip-flop 24 oh-30. The line frequency pulses at the second output B of step 23 operate to synchronize the clock generator 3 during playback, which generator produces horizontal frequency pulses H and vertical frequency pulses V for synchronizing the television receiver, which are added in adder-35 degree 12 to the Y signal and color intensity signal 76. to generate a signal.

The invention can generally be used for transmission via channels of limited quality, such as, for example, recording on video recorders, satellite television or cable channels.

Claims (11)

A method of transmitting, in particular, for recording and reproducing TV signals, wherein the lightness information is recorded during the 1-line period sweep and the color information is sequentially compressed for the remaining 1-injection period during the 1-line quench time, whereby the compression and decompression are decompressed in memory and printed by a clock pulse produced by a transducer, characterized in that in the signal intended for transmission specifically for synchronization, a carrier operating for synchronization is coupled, whose carrier frequency is switched half-line frequency symmetrically to the intermediate frequency and whose frequency and amplitude is chosen so that the light density and color information are not affected. 15 2. A method according to claim 1, characterized in that the pulse acting for synchronization can be switched on during each extinguishing time t1, together with the in-relaying color information and the frequency and amplitude of the pulse is chosen so that the color information is not affected. 20 Method according to claim 1, characterized in that the carrier frequency of the sink carrier is interfered with in the upper transmission range of the magnetic head signal of the recording apparatus. Method according to claim 1, characterized in that the switching of the carrier frequency is interrupted by a vertical frequency control rate V during the iterative range of the image. 5. A method according to claims 1-3, characterized in that during the reproduction the coupled sync signal is coupled after a gain to a discriminator (16), which produces signals of different polarity depending on the carrier frequency. Method according to claim 5, characterized in