JPH0614308A - Method and device for multiplexing data - Google Patents

Abstract

PURPOSE:To provide data multiplexing method and device capable of effectively attaining multiplex transmission without generating disturbance on a screen. CONSTITUTION:A level detecting means 6 outputs a gate signal for distinguishing the flyback time of an input video signal from a video period and a level signal corresponding to a luminance signal amplitude in the video period of the input video signal. An amplitude/speed converting means 7 converts the amplitude and speed of input data based upon the gate signal and the level signal outputted from the means 6. A digital modulation means 4 executes the digital modulation of an orthogonal carrier orthogonally intersecting with the phase of a video carrier based upon the data modulated by the means 7. A VSB modulation means 2 executes the vestigial side-band modulation of the video carrier by the input video signal. A synthesizing means 5 synthesizes the video carrier modulated by the means 2 and the orthogonal carrier modulated by the means 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data multiplexing method and a data multiplexing apparatus for multiplexing data on a television signal without disturbing an existing television receiver.

[0002]

2. Description of the Related Art PCM can be used without disturbing existing television receivers, that is, with compatibility.
As an example of a conventional data multiplexing apparatus for multiplexing a relatively large amount of data such as voice, there is one as shown in FIG. 7 (Noda et al .: Digital voice multiplexing system for terrestrial television broadcasting, television. Technical Report of the Society, 11
-22, see October 1987).

This conventional data multiplexer comprises a video carrier oscillation means 31 and a vestigial sideband modulation means (hereinafter referred to as "VSB").
(Vestigial Side Band) modulation means ") 32,
The phase shift means 33, the digital modulation means 34, and the synthesizing means 35 were provided. The image carrier wave generation means 31 generates an image carrier wave. The VSB modulating means 32 performs vestigial sideband modulation on the video carrier from the video carrier oscillating means 31 according to the input video signal. The phase shifter 33 phase shifts the video carrier from the video carrier oscillator 31 by 90 degrees to generate an orthogonal carrier. The digital modulation means 34 modulates the quadrature carrier wave from the phase shift means 33 with the input data (multi-level ASK of carrier wave suppression, etc.). The synthesizing means 35 uses V
Signal from SB modulator 32 and digital modulator 34
And the signal from.

In such a conventional data multiplexer, the input video signal is supplied to the VSB modulating means 32.
As a result, the VSB modulating means 32 VSB-modulates the video carrier from the video carrier oscillating means 31 by the input video signal. On the other hand, the input data is supplied to the digital modulation means 34. As a result, the digital modulator 34 digitally modulates the quadrature carrier (PSK: Phase) from the phase shifter 33 whose phase is orthogonal to that of the video carrier according to the input data.
Shift Keying etc.) Then, the synthesizing means 35 displays V
Signal from SB modulator 32 and digital modulator 34
The signal from is combined and output.

That is, if the modulation speed by the input data is set to a certain value or less, the digital modulation wave is orthogonally multiplexed as a double sideband signal near the video carrier. As a result, the frequency spectrum falls within the band of the television signal, and the quadrature signal component is not detected by the synchronous detection type receiver, so compatibility can be maintained.

[0006]

However, in the above-mentioned conventional configuration, ideally, it does not interfere with the existing receiver, but there is a problem in reality. That is, due to factors such as a slight error in the phase of the carrier wave in the synchronous detection of the receiver, the quadrature component in which the data is multiplexed is detected as crosstalk, which causes interference on the screen. To alleviate this crosstalk, it is sufficient to lower the modulation degree on the quadrature side, but if this is done, the SN ratio of the demodulated data deteriorates, and there is the problem that normal multiplex transmission cannot be realized. It was

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a data multiplexing method and a data multiplexing apparatus that can realize excellent multiplex transmission without causing interference on the screen. .

[0008]

According to a first aspect of the present invention, when data is multiplexed on a video signal, the video signal has a smaller amplitude and a lower speed than the blanking period of the video signal in the video period of the video signal, and The feature is that the data of the amplitude corresponding to the brightness signal amplitude of the video signal is multiplexed.

According to a second aspect of the present invention, a gate signal for distinguishing the blanking period and the video period of the input video signal and a level signal corresponding to the luminance signal amplitude in the video period of the input video signal are output. The level detection means, the amplitude / speed conversion means for converting the amplitude and speed of the input data based on the gate signal and the level signal from the level detection means, and the image converted by the amplitude / speed conversion means Digital modulating means for digitally modulating a quadrature carrier orthogonal to the phase of the carrier wave, video modulating means for vestigial sideband modulation of the video carrier by the input video signal, video carrier modulated by the video modulating means, and the digital signal. A synthesizing means for synthesizing the orthogonal carrier wave modulated by the modulating means, and a video period of the input video signal Oite is characterized in that small amplitude and at a low speed, yet where the structure is multiplexed amplitude data corresponding to the luminance signal amplitude of the input video signal than the blanking period of the input video signal.

According to a third aspect of the present invention, when the data is multiplexed with the video signal, in the video period of the video signal,
It is characterized in that data having a smaller amplitude and a lower speed than the blanking period of the video signal and having an amplitude corresponding to a value obtained by averaging the luminance signal amplitude of the video signal at regular intervals is multiplexed. According to a fourth aspect of the invention, a gate signal for distinguishing a blanking period and a video period of the input video signal, and a level corresponding to a value obtained by averaging luminance signal amplitudes of the input video signal in the video period at regular intervals. A level detecting means for outputting a signal, an amplitude / speed converting means for converting the amplitude and speed of the input data based on the gate signal and the level signal from the level detecting means, and the amplitude / speed converting means. Digital modulating means for digitally modulating a quadrature carrier orthogonal to the phase of the video carrier by the received data, delay means for delaying the input video signal by a time corresponding to the certain period, and video signal delayed by the delay means. An image modulating means for vestigial sideband modulation of the image carrier by the image modulating means, and an image carrier modulated by the image modulating means. A synthesizing means for synthesizing the quadrature carrier wave modulated by the digital modulating means, and having a smaller amplitude and a lower speed than the blanking period of the input video signal in the video period of the input video signal, and The feature is that the data of the amplitude corresponding to the value obtained by averaging the brightness signal amplitude for every fixed period is multiplexed.

[0011]

According to the first aspect of the invention, when the data is multiplexed with the video signal, during the video period of the video signal,
Data having a smaller amplitude and a lower speed than the blanking period of the video signal and having an amplitude corresponding to the brightness signal amplitude of the video signal is multiplexed. In the invention of claim 2, the level detecting means outputs a gate signal for distinguishing a blanking period and a video period of the input video signal, and a level signal according to a luminance signal amplitude in the video period of the input video signal. To do. The amplitude / speed conversion means converts the amplitude and speed of the input data based on the gate signal and the level signal from the level detection means.
The digital modulation means digitally modulates the quadrature carrier orthogonal to the phase of the video carrier by the data converted by the amplitude / speed converting means. The video modulation means performs vestigial sideband modulation on the video carrier according to the input video signal. The synthesizing means synthesizes the video carrier modulated by the video modulating means and the quadrature carrier modulated by the digital modulating means. Then, in the video period of the input video signal, the data having a smaller amplitude and a lower speed than the blanking period of the input video signal and having the amplitude corresponding to the brightness signal amplitude of the input video signal are multiplexed.

According to the third aspect of the present invention, when the data is multiplexed with the video signal, the amplitude of the video signal is constant and has a smaller amplitude and a lower speed than the blanking period of the video signal during the video period of the video signal. Amplitude data corresponding to the averaged value for each period is multiplexed. In the invention of claim 4, the level detection means averages the gate signal for distinguishing the blanking period and the video period of the input video signal, and the luminance signal amplitude in the video period of the input video signal at regular intervals. And a level signal corresponding to the. The amplitude / speed conversion means converts the amplitude and speed of the input data based on the gate signal and the level signal from the level detection means. The digital modulation means digitally modulates the quadrature carrier orthogonal to the phase of the video carrier by the data converted by the amplitude / speed converting means. The delay means delays the input video signal by a time corresponding to a certain period. The video modulation means performs vestigial sideband modulation of the video carrier with the video signal delayed by the delay means. The synthesizing means synthesizes the video carrier modulated by the video modulating means and the quadrature carrier modulated by the digital modulating means. Then, in the video period of the input video signal, the data having a smaller amplitude and a lower speed than the blanking period of the input video signal, and the amplitude data corresponding to a value obtained by averaging the luminance signal amplitude of the input video signal at regular intervals are multiplexed. .

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing an overall configuration of a data multiplexing apparatus in Embodiment 1 of the present invention, in which an FM modulator for multiplexing analog voice is omitted. This data multiplexer includes a video carrier oscillation means 1, a VSB modulation means 2, a phase shift means 3, a digital modulation means 4, a synthesizing means 5, a level detecting means 6, and an amplitude / speed converting means 7. I have it. The image carrier wave oscillating means 1 generates an image carrier wave. The VSB modulator 2 modulates the video carrier from the video carrier oscillator 1 with the vestigial sideband by the input video signal. The phase shift means 3 phase-shifts the video carrier wave from the video carrier wave oscillating means 90 by 90 degrees to generate a quadrature carrier wave. The digital modulation means 4 modulates the quadrature carrier wave from the phase shift means 3 by the multiplexed signal from the amplitude / speed conversion means 7 (multi-level ASK for carrier wave suppression, etc.). Synthesis means 5
Combines the signal from the VSB modulator 2 and the signal from the digital modulator 4. The level detection means 6 produces a gate signal having different levels in the blanking period and the video period of the input video signal, and a level signal having information corresponding to the luminance signal amplitude of the video signal in the video period. The amplitude / speed conversion means 7 performs speed conversion of the input data according to the gate signal from the level detection means 6, and then changes the amplitude of the data according to the level signal from the level detection means 6,
Create multiple signals.

FIG. 2 is a block diagram showing the detailed structure of the level detecting means 6 and the amplitude / speed converting means 7. The level detecting means 6 includes a gate signal generating circuit 9 and a gain setting circuit 1.
The amplitude / speed conversion means 7 has an address control circuit 12, a buffer memory 13, a gain variable circuit 14, and a low-pass filter 15. The gate signal generation circuit 9 produces a gate signal based on the input video signal. The gain setting circuit 10 produces a level signal based on the input video signal and the gate signal from the gate signal generation circuit 9. The address control circuit 12 creates a read address based on the high speed clock a, the low speed clock b, and the gate signal from the gate signal generation circuit 9. The buffer memory 13 stores the input data, and the input data is read by the read address from the address control circuit 12. The gain varying circuit 14 varies the amplitude of the read data from the buffer memory 13 based on the level signal from the gain setting circuit 10. The low-pass filter 15 has its bandwidth switched by the gate signal from the gate signal generation circuit 9, and limits the bandwidth of the multiplexed data from the variable gain circuit 14.

Next, the operation will be described. Input video signal is V
It is supplied to the SB modulating means 2, the gate signal generating circuit 9 and the gain setting circuit 10 of the level detecting means 6. As a result, the gate signal generation circuit 9 generates gate signals having different levels in the blanking period and the video period of the video signal as shown in FIG.
It is supplied to the gain setting circuit 10, the address control circuit 12 of the amplitude / speed conversion means 7, and the low-pass filter 15. Further, the gain setting circuit 10 fixes the level signal as the gain information data, which is fixed to a predetermined constant value during the blanking period and corresponds to the luminance signal level of the video signal during the video period.
It is supplied to the gain variable circuit 14 of the amplitude / speed conversion means 7. The gain setting circuit 10 switches between two inputs of a luminance signal and a fixed voltage in the input video signal by a gate signal from the gate signal generation circuit 9, and A / D-converts the data into an amplitude / speed converting means. It is configured to convert into data corresponding to the amplifier gain of the gain variable circuit 14 in FIG.

On the other hand, the input data is a buffer memory 13 of the amplitude / speed converting means 7 by a write clock (not shown).
Written in. Then, the address control circuit 12 reads the input data from the buffer memory 13 while changing the speed between the blanking period and the video period. That is, the address control circuit 1
2 is a counter for generating a read address (not shown)
At the clock input terminal of the high-speed clock a during the blanking period,
In the video period, the low-speed clock b is input so that it is switched by the gate signal from the gate signal generating circuit 9, and the read address is supplied to the buffer memory 13. The read data read from the buffer memory 13 in this way is input to the gain variable circuit 14. As a result, the variable gain circuit 1
4 changes the amplitude of the read data by changing the gain of the amplifier according to the level signal from the gain setting circuit 10 to generate the multiplexed data as shown in FIG. 3, and supplies it to the low pass filter 15. As a result, the low-pass filter 15 in which the two limiting bands have been set limits the band of the multiplexed data while switching the filters by the gate signal to generate a multiplexed signal, which is supplied to the digital modulator 4.

As a result, the digital modulating means 4 supplies the signal obtained by modulating the orthogonal video carrier with the multiplex signal to the synthesizing means 5. On the other hand, the VSB modulating means 2 supplies the synthesizing means 5 with a signal obtained by vestigial sideband-modulating the video carrier with the input video signal. As a result, the synthesizing means 5 synthesizes the signal from the VSB modulating means 2 and the signal from the digital modulating means 4 and outputs the synthesized output.

When the video signal thus obtained is demodulated in the existing television receiver, when the data is multiplexed on the orthogonal carrier wave, the multiplex amplitude and the multiple speed of the data are set as the blanking period of the video signal. Even if crosstalk occurs, the screen is switched even if crosstalk occurs compared to the conventional device, because the signal is modulated at an amplitude that corresponds to the amplitude level of the luminance signal of the video signal during the video period. There is little interference with the data, and there is little interference with multiple data from the video.

That is, since the crosstalk is a region that does not appear on the screen during the blanking period, and the reproduction of the synchronization signal in the receiver is extremely resistant to noise, high-speed large-amplitude data is multiplexed. There is. On the other hand, since the crosstalk component appears on the screen as it is in the effective video period, it is desirable to reduce the amplitude of the multiplexed data as much as possible. However, if the data amplitude is simply reduced, the SN ratio of the demodulated data will be reduced by that amount. Therefore, the data transmission rate is reduced and the SN of the demodulated data in the blanking period is reduced.
It is desirable to make the value equivalent to the ratio. Assuming that only white noise in the transmission system is a noise factor, if the data amplitude ratio between the blanking period and the effective video period is 1: a (a <1), the ratio of multiple speeds is 1: a ² . At the same time, the SN ratio of the demodulated data in both periods can be made equal. It is possible to reduce the interference to the screen by setting the amplitude value of the multiplexed data to the amplitude value that satisfies the above conditions, but the effect of crosstalk from the video signal to the multiplexed data is to reduce the amplitude. Since it becomes remarkable, the amplitude level of the luminance signal of the video signal is detected in the video period of the input video signal, and the data is multiplexed with the amplitude corresponding to the level. By thus multiplexing the input data, it is possible to reduce the interference from the video signal to the multiple data and the interference from the multiple data to the video signal due to the crosstalk. (Embodiment 2) FIG. 4 is a block diagram showing the overall configuration of a data multiplexing apparatus according to Embodiment 2 of the present invention. The difference from the configuration of the data multiplexing apparatus according to Embodiment 1 shown in FIG. And the configuration of the level detecting means 18. The delay unit 17 delays the input video signal for a certain period.

FIG. 5 is a block diagram showing a detailed structure of the level detecting means 18, which has a gate signal generating circuit 20, a gain setting circuit 21, and an integrating circuit 22. The gate signal generation circuit 20 produces a gate signal based on the input video signal. Gain setting circuit 2
1 produces a level signal based on the integrated signal from the integrating circuit 22. The integrating circuit 22 receives the input video signal and the signal c
And an integrated signal is generated based on the gate signal from the gate signal generation circuit 20.

Next, the operation will be described. In order to vary the amplitude of the data multiplexed in the video period of the input video signal, the integrator circuit 22 uses the gate signal from the gate signal generating circuit 20 having different levels in the blanking period and the video period to set 1 at the low rate. The luminance signal waveform is integrated over the symbol period to generate an integrated signal. The integration operation is reset in the leading period of the symbol by the signal c indicating the period of the symbol. Then, the gain setting circuit 21 outputs a level signal corresponding to the integration signal from the integration circuit 22 during the video period. Therefore, the amplitude of the multiplexed data becomes constant over one symbol as shown in FIG. The delay means 17 is arranged to combine the VSB modulation means 2 in order to match the time difference between the input video signal and the multiplexed signal (in this embodiment, one symbol period of low-speed multiplexed data) when the orthogonal multiplexed signals are combined.
Is inserted in the previous stage. The other operations are similar to those of the data multiplexing apparatus of the first embodiment.

When such multiplexed data is demodulated by the existing receiver, when identifying the demodulated data, the amplitude of the demodulated data in the video period is constant over the period of one symbol, so that noise or phase shift of the identification clock is generated. It is possible to reduce erroneous determination of data identification due to.

[0023]

As described above, according to the present invention, when data is multiplexed on a video signal, the amplitude of the video signal is smaller than that of the blanking period of the video signal in the video period of the video signal, and the speed is low. Since the data having the amplitude corresponding to the amplitude of the luminance signal is multiplexed, it is possible to more reliably multiplex and transmit the relatively large capacity data while maintaining compatibility without interfering with the existing television receiver.
Therefore, for example, apart from the existing analog FM audio,
It can be used for high quality PCM voice data and various other data services.

When data is multiplexed on the video signal, the amplitude of the video signal is smaller and slower than the blanking period of the video signal during the video period of the video signal, and the luminance signal amplitude of the video signal is averaged at regular intervals. If the data of the amplitude corresponding to the above is multiplexed, the amplitude of the demodulated data in the video period is constant over a certain period, so that the erroneous determination of the data identification due to the noise or the phase shift of the identification clock can be further reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a data multiplexing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of level detection means and amplitude / speed conversion means.

FIG. 3 is a waveform diagram showing a temporal relationship between a video signal, multiplexed data and a gate signal.

FIG. 4 is a block diagram showing an overall configuration of a data multiplexing apparatus according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a detailed configuration of a level detecting means.

FIG. 6 is a waveform diagram showing a temporal relationship between a video signal, multiplexed data, and a gate signal.

FIG. 7 is a block diagram showing an overall configuration of a conventional data multiplexing device.

[Explanation of symbols]

 2 VSB modulating means 4 Digital modulating means 5 Combining means 6 Level detecting means 7 Amplitude / speed converting means 17 Delaying means 18 Level detecting means

Claims (4)

[Claims] 1. When multiplexing data on a video signal, the amplitude of the video signal is smaller and slower than the blanking period of the video signal during the video period of the video signal, and the amplitude corresponding to the amplitude of the luminance signal of the video signal. A data multiplexing method characterized by multiplexing data. 2. A level detecting means for outputting a gate signal for distinguishing a blanking period and a video period of an input video signal, and a level signal according to a luminance signal amplitude in the video period of the input video signal, Amplitude / speed conversion means for converting the amplitude and speed of the input data based on the gate signal and the level signal from the level detection means, and the data converted by the amplitude / speed conversion means are orthogonal to the phase of the video carrier. Digital modulating means for digitally modulating the quadrature carrier, video modulating means for vestigial sideband modulation of the video carrier by the input video signal, video carrier modulated by the video modulating means and modulated by the digital modulating means. And a synthesizing means for synthesizing the orthogonal carrier wave, and in the video period of the input video signal, Small amplitude and at a lower speed than the blanking period of the force video signal, yet the data multiplexer being characterized in that the arrangement for multiplexing the amplitude of the data corresponding to the luminance signal amplitude of the input video signal. 3. When multiplexing data on a video signal, in the video period of the video signal, the amplitude of the video signal is smaller and slower than the blanking period of the video signal, and the amplitude of the luminance signal of the video signal is fixed at regular intervals. A data multiplexing method characterized by multiplexing data of amplitude according to an averaged value. 4. A gate signal for distinguishing a blanking period and a video period of an input video signal, and a level signal according to a value obtained by averaging luminance signal amplitudes in the video period of the input video signal at regular intervals. A level detecting means for outputting, an amplitude / speed converting means for converting the amplitude and speed of the input data based on the gate signal and the level signal from the level detecting means, and the amplitude / speed converting means. Digital modulating means for digitally modulating a quadrature carrier orthogonal to the phase of the video carrier according to data, delay means for delaying the input video signal by a time corresponding to the certain period, and the video signal delayed by the delay means An image modulating means for modulating the image carrier by vestigial sideband; an image carrier modulated by the image modulating means; A synthesizing means for synthesizing the orthogonal carrier wave modulated by the digital modulating means, and having a smaller amplitude and a lower speed than the blanking period of the input video signal in the video period of the input video signal, and A data multiplexing device characterized in that data of an amplitude corresponding to a value obtained by averaging luminance signal amplitudes at regular intervals is multiplexed.