JPH0775037A - Synchronization controller and synchronization detection circuit used therefor - Google Patents

Abstract

PURPOSE:To suppress the noise at the time of the special reproduction of a laser disk or the like and at the time of cutting off input signals by adjusting synchronization protective length at the time of cancelling synchronization corresponding to a noise amount included in reception television signals. CONSTITUTION:When the noise amount detected from a noise amount detection circuit 3 is less than a prescribed level, the synchronization protective length value of a synchronization protective length adjusting circuit 4 is switched to a shortened value (a) by changeover control signal and the synchronization protective length at the time of the cancellation of a synchronization pull-in/cancellation circuit 7 is shortened. Thus, noise generation at the time of cancelling the special reproduction of the laser disk or the like and at the time of inputting signals can be prevented. On the other hand, when the detected noise amount is more than the prescribed level, the synchronization protective length of the synchronization protective length circuit 4 is switched to an extended value (b) by the changeover control signal and the synchronization protective length is extended. Thus, synchronization is prevented from being cancelled, sound interruption due to unnecessary mute is prevented, a synchronization pull-in operation length is shortened by the adjusting means of a synchronization pull-in operation period and synchronization pull-in is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal receiving apparatus which is transmitted by adopting a sampled value transmission method using multiple sub-sampling, and a synchronization control apparatus for controlling synchronization of a voice decoding processing circuit and release thereof. Related to the improvement of.

[0002]

2. Description of the Related Art As a method for band-compressing a wide-band television signal by multiple sub-sampling and transmitting it,
USE (Multiple Sub-Nyquist)
There is a sampling encoding method. In this MUSE system, audio / independent data is time-division baseband-multiplexed with a video signal and band-compressed by a quasi-instantaneous companding DPCM coding system for transmission.

Here, the MUSE signal is, in addition to the Y and C video signals, a control signal for each field such as a motion vector, a synchronizing signal, a VIT signal (for equalizing the transmission line), a voice / voice signal.
Independent data is a signal multiplexed in each blanking period. And voice / independent data is MUS
Approximately 100 kbt / s with 4 channels of digitized voice or 2 channels of super high quality voice multiplexed by E method
Refers to the degree of independent data.

At present, there are MUSE decoders and MUSE-NTSC converters as devices for receiving the MUSE type signals. In these decoders and converters, a frame synchronization pattern is used to detect the synchronization pattern for extracting the audio signal, and the conditions for pulling in and releasing the synchronization are determined so as to satisfy the following Table 1.

[0005]

[Table 1]

That is, since the frame synchronization pattern that is supposed to be repeatedly sent together with the voice signal at a constant cycle is composed of 16 bits, each bit of the received signal is monitored and the frame synchronization pattern (16 If a known pattern composed of bits) is detected three times in succession, it is determined that an audio signal has arrived and the audio decoding processing circuit is brought into a synchronous state to start the decoding processing of the audio signal.

[0007] In order to cancel the synchronization after the audio signal is once decoded and the audio signal decoding process is started,
While monitoring each bit of the received signal, the state that only the number of bits of 12 bits or less among the 16 bits that should form the frame synchronization pattern does not match the original bit value as the synchronization pattern continuously. When five frames continue, it is determined that the audio signal has not arrived anymore, the synchronization of the audio decoding processing circuit is released, and the decoding processing of the audio signal is stopped.

Alternatively, in the case where only 16 bits, which are supposed to form a frame synchronization pattern, of 13, 14 or 15 bits, match only the original bit value of the synchronization pattern. However, if that state continues for 32 frames in succession, it is determined that the audio signal has not arrived anymore, the synchronization of the audio decoding processing circuit is released, and the decoding processing of the audio signal is stopped. is there.

As described above, in the prior art, the synchronization pull-in in the audio decoding processing circuit is such that the received 16 bits that should form the frame synchronization pattern and the actual 16 bits that form the frame synchronization pattern match a predetermined number of frames. If this continues (this is called the sync pull-in operation length), it is determined that an audio signal has arrived and the sync pull-in is performed. That is, the number of frames required to determine that an audio signal has arrived (synchronization pull-in operation length)
Was unchanged.

Further, the synchronization cancellation in the audio decoding processing circuit should be a reception 16 which should form a frame synchronization pattern.
The actual 16 bits that make up the frame sync pattern
Depending on the number of bits corresponding to each bit value of the bits, the number of frames in which the state is continuous is appropriately determined, and when the state continues for the number of frames (this is called synchronization protection length), the voice signal no longer arrives. It was decided that it was not done, and the synchronization was canceled.

That is, if the number of transmission errors (the number of mismatched bits) of the voice signal is large, the number of frames (synchronization protection length) required to judge that the voice signal has not arrived anymore is shortened. If the number of transmission errors is small, the synchronization protection length is extended. If the synchronization is released and the processing operation of the audio decoding processing circuit is stopped, the audio is muted (silent) and no audio is output. For detection of the frame synchronization pattern, for example,
An example is described in JP-A-1-228337.

[0012]

The problems in the prior art will be described below with reference to Table 1 above. For example, when the audio decoding processing circuit receives and processes the playback MUSE signal from the laser disk (LD), if the input signal is disconnected or the special playback operation (fast, forward, still, etc.) is performed, synchronization will start from that point. During the period from the release to the mute (the process up to the synchronization release), the number of matching bits between the received bit that should form the frame synchronization pattern and the frame synchronization pattern (original pattern bit value) is 15 After the state of 13 bits is reached, the number of matching bits may shift to a state of 12 bits or less.

In this case, the desynchronization condition is 32 consecutive frames corresponding to a state where the number of matching bits is 15 to 13 bits, and then 5 consecutive frames corresponding to a state where the number of matching bits is 12 bits or less. Move to. Therefore,
During the period when the number of matching bits is 15 to 13 bits, the synchronization protection length is extended, so that it takes time until the synchronization is released, and the mute is generated when the input signal is disconnected or the special reproduction operation is started. It wasn't in time.

When a high-definition satellite broadcast transmitted by the MUSE transmission system is received, the required reception C / N may not always be obtained. In such a decoder that receives a MUSE signal with a low received C / N, the received C / N is low and there is a lot of noise, so that the number of coincident bits suddenly becomes 12 bits or less, which is 5 frames. There may be cases where the above continues, and in this case, although it is originally desired to continue synchronization (in the case of interference due to noise, there is no alternative but to wait for the noise to stop while maintaining the synchronization state). Is canceled and unnecessary mute is applied, resulting in voice interruption.

Further, for example, in a voice decoding processing circuit,
When the reproduction MUSE signal is input from the laser disk or the special reproduction operation is canceled, the synchronization pull-in condition is short for three consecutive frames, so that the synchronization is pulled before the audio signal is established. Therefore, an abnormal audio signal is output, which causes noise.

Further, the reproduction M from the above laser disk
If the synchronization pull-in condition is long for noise suppression when inputting the USE signal or canceling the special playback operation,
In a decoder receiving a MUSE signal having a low received C / N, since there is a lot of noise, the number of coincident bits is unlikely to be 16 bits, so that synchronization may not be pulled in.

An object of the present invention is to solve the above-mentioned problems of the prior art and to cut off an input signal or perform a special reproduction operation (such as fast or fast feed,
When you want to mute and quickly cancel the sync, such as when you are still), on the other hand, there is a lot of noise mixed in the received signal, so the sync is unintentionally canceled. If you want to wait for the sync pull-in until the audio signal is established, such as when unnecessary mute is applied, it is prevented, and when the signal input or the special playback operation of the laser disk is canceled, etc. Further, it is possible to provide a synchronization control device and a synchronization detection circuit used therefor which can prevent such a situation when synchronization is not pulled in due to a large amount of noise mixed in the received signal. It is in.

[0018]

In order to achieve the above object, the present invention provides a receiving apparatus for a television signal transmitted by adopting a sample value transmission method using multiple subsampling,

A / D conversion means for the received television signal, audio signal separation means for separating, extracting and outputting the digital audio signal, an audio demodulation circuit for demodulating the digital audio signal, and decoding of the demodulated audio output. An audio decoding processing circuit that performs processing, an output processing circuit that performs output processing of the decoded audio signal,

When the demodulated voice output from the voice demodulation circuit is fetched and the synchronization pattern, which should have been repeatedly inserted into the voice output at a constant cycle, is detected a predetermined number of times in an incomplete form, the predetermined number of times is detected. After the lapse of the sync protection period, the sync release signal is output to the audio decoding processing circuit, and thereafter,
Stop the audio output decoding process by using the audio decoding processing circuit,

Further, in the demodulated voice output taken in from the voice demodulation circuit, when a synchronization pattern which should be repeatedly inserted into the voice output at a constant cycle is detected a predetermined number of times in a complete form, the predetermined number of times is detected. Is set as the synchronous pull-in operation period, and after the synchronous pull-in operation period elapses, a signal with synchronization is output to the audio decoding processing circuit, and thereafter, the audio decoding processing circuit is pulled in to the synchronous state. Synchronous pull-in / release means for starting the decoding process of audio output with

Noise amount detecting means for detecting the amount of noise contained in the television signal after being converted to a digital format by the A / D converter, and the synchronization pull-in / detection means according to the detected amount of noise. A synchronization control device is provided, which comprises an adjusting means for variably adjusting the synchronization protection period and the synchronization pull-in operation period in the releasing means.

[0023]

In the above structure, when the required reception C / N is obtained, the noise amount detected by the noise amount detecting means becomes small. In this case, by shortening the synchronization protection length by the synchronization protection period adjusting means, noise is generated at the time of input signal disconnection or special reproduction of a laser disk, or by the synchronization pull-in operation period adjusting means.
By extending the sync pull-in operation length, it is possible to prevent noise generation at the time of signal input or special playback cancellation of a laser disk or the like.

When a large amount of noise is generated in the transmission line, the amount of noise detected by the noise amount detecting means becomes large. In this case, the synchronization protection period is adjusted by the synchronization protection period to prevent the synchronization from being released, the audio is prevented from being cut off by an unnecessary mute, and the synchronization pull-in operation period is adjusted by the synchronization pull-in operation period. By shortening, it is possible to facilitate synchronization pull-in.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a synchronous control device (an example applied to a MUSE decoding circuit of a television audio receiving / reproducing device) as one embodiment of the present invention. In the figure, 1 is an input terminal for the MUSE signal, 2 is an A / D converter,
3 is a noise amount detection circuit, 4 is a synchronization protection length adjusting circuit, 5 is an audio signal separation circuit, 6 is an audio demodulation circuit, 7 is a synchronization pull-in / cancel circuit, 8 is an audio decoding processing circuit, 9 is an output processing circuit, 10 Is a synchronization detection circuit.

In FIG. 1, the MUSE signal is input from the input terminal 1 and supplied to the A / D converter 2. The A / D converter 2 converts the analog MUSE signal into a digital signal and supplies the digital signal to the noise amount detection circuit 3 and the audio signal separation circuit 5. The noise amount detection circuit 3 detects the noise amount from the digital signal, and then supplies a signal corresponding to this noise amount to the synchronization protection length adjustment circuit 4 in the synchronization detection circuit 10 as a switching control signal.

The synchronization protection length adjusting circuit 4 supplies a synchronization protection length value corresponding to the switching control signal to the synchronization pull-in / release circuit 7. On the other hand, the audio signal separation circuit 5 extracts the digital audio data signal which is time-division baseband-multiplexed with the received television signal (video signal) and supplies it to the audio demodulation circuit 6. The audio demodulation circuit 6 performs level conversion, frequency conversion, three-value / two-value conversion, time axis expansion, inter-frame deinterleaving, etc., and outputs the demodulated audio data signal as the sync pull-in / cancel circuit 7 and audio. It is supplied to the decoding processing circuit 8.

When the sync pull-in / release circuit 7 detects that the sync pull-in condition described above with reference to Table 1 is satisfied during the sync pull-in, it sends an output signal to that effect to the audio decoding processing circuit 8. Then, the audio decoding processing circuit 8 is pulled into a synchronous state and audio decoding processing is performed.

Next, there is a case of shifting from the sync pull-in state to the sync release state. At this time, the sync pull-in / release circuit has a sync-protection length according to the sync-protection length value from the sync-protection length adjusting circuit 4. Reference numeral 7 indicates that the synchronization state is to be released, and an output signal to that effect is sent to the audio decoding processing circuit 8 to shift the audio decoding processing circuit 8 to the synchronization released state, and audio decoding processing (from the audio data signal Control code detection, bit / word deinterleaving, error correction / interpolation, PCM demodulation, etc.) are stopped and muted.

Although the circuits 5, 6, 8 and 9 are well-known and well-known circuits, detailed description thereof will be omitted. However, the output processing circuit 9 will be described briefly. Digital filtering of signals, D
A / A conversion, low-pass filter processing, selective output, mute on / off, amplification, and other processing.

FIG. 2 shows a noise amount detection circuit 3 in FIG.
It is a block diagram showing a concrete example of. In FIG. 2, 11
Is a digital signal input terminal, 12 is a DC level period detection circuit for the MUSE signal, 13 is a high pass filter (HPF), 15 is an ABS (absolute value) circuit, 16 is a level detection circuit, and 17 is a noise amount signal output terminal. is there.

In FIG. 2, the input signal from the input terminal 11, that is, the MUSE signal after A / D conversion is inserted by the DC level period detection circuit 12 into, for example, the latter half 4/5 of the clamp line 128. The / 256 level DC signal period or the flat portion in the first half of the frame pulse line is extracted and supplied to the high-pass filter 13. The high-pass filter 13 extracts the noise component of the signal extracted by the circuit 11 and supplies it to the ABS circuit 15. In the ABS circuit 15, the absolute value of the noise signal is detected by the level detection circuit 1
Supply to 6. The level detection circuit 16 detects a noise amount signal corresponding to the noise level from the absolute value of the noise signal and outputs it to the output terminal 17.

FIG. 3 is a block diagram of the sync detection circuit 10 shown in FIG.
FIG. 6 is a block diagram showing details of (in particular, a synchronization pull-in / release circuit 7). In FIG. 3, reference numeral 21 is a voice data signal input terminal, 22 is a shift register, 23 is a pattern comparator, 24 is a sync pattern memory, 25 is a match counter, 26 is a sync pull-in operation length comparator, and 27 is a mismatch. A number counter, 28 is a sync protection length comparator, 29 is a sync signal generation circuit, 30 is an input terminal for a switching control signal from the noise amount detection circuit 3, and 31 is an output terminal for a sync pull-in / cancel signal.

The input signal from the input terminal 21 is once stored in the shift register 22 having the same bit length as the frame synchronization pattern, and is stored in the synchronization pattern memory 24 in advance.
3, the comparison result is output as a comparison output.

The comparison output is input to the match number counter 25 if the comparison results match, and to the mismatch number counter 27 if the comparison results do not match. Matching number counter 25
Then, the number of coincidences is counted from the comparison output, and the count value is supplied to the synchronous pull-in operation length comparator 26. The sync pull-in operation length comparator 26 compares the count value as the predetermined sync pull-in operation length with the count value from the match counter 25, and supplies the comparison result to the sync signal generating circuit 29 as a match signal.

On the other hand, the mismatch count counter 27 counts the mismatch count from the comparison output, and the count value is supplied to the synchronization protection length comparator 28. In the sync protection length comparator 28, the count value as the sync protection length (sync protection length value according to the switching control signal from the noise amount detection circuit 3) given from the sync protection length adjustment circuit 4 and the mismatch count counter 27 are supplied. And the comparison result is supplied to the synchronization signal generating circuit 29 as a coincidence signal. When the sync signal generation circuit 29 detects the match signal from the sync pull-in operation length comparator 26, it outputs the sync pull-in signal to the output terminal 31, while detecting the match signal from the sync protection length comparator 28. In this case, output the sync release signal to terminal 3
Output to 1.

Next, the function and operation of the synchronous control device according to the present invention will be described again with reference to FIGS. 1, 4 and 5. FIG. 4 shows an example of the timing of the frame synchronization signal (frame synchronization pattern) when the audio data signal is disconnected and the synchronization is released accordingly. FIG. 5 shows the audio data with a lot of noise and many errors. An example of the timing of the frame synchronization signal when desynchronization occurs when the signal is received is shown. 4 and 5, a, b
Indicates the shortened value and the extended value of the synchronization protection length value, respectively. A,
B indicates the timing (frame synchronization signal) at which synchronization is released when the synchronization protection length value is set to the shortened value a and the extended value b.

For example, assume that the sync protection length value of the sync protection length adjusting circuit 4 is set to be switchable between the shortened value a and the expanded value b in response to the switching control signal from the noise amount detection circuit 3 in FIG. . When the noise amount detected by the noise amount detection circuit 3 is below a predetermined level, the synchronization protection length value of the synchronization protection length adjustment circuit 4 is switched to the shortened value a by the switching control signal, and the synchronization pull-in / cancel circuit. 7, the synchronization protection length at the time of cancellation is shortened.

As a result, as shown in A of FIG. 4, the frame synchronization signal is released from synchronization at the timing of the a-th frame synchronization pattern counted from the signal disconnection point (timing of signal disconnection) of the audio data. Mute is applied. That is, it is possible to suppress noise that occurs after the timing of the a-th frame synchronization pattern after starting the signal reproduction or the special reproduction operation of the laser disk or the like. Since a is a shortened value, it can be seen that the synchronization can be released quickly, which is convenient.

On the other hand, when the noise amount detected by the noise amount detection circuit 3 is equal to or higher than the predetermined level, the synchronization protection length value of the synchronization protection length adjustment circuit 4 is switched to the extension value b by the switching control signal, and the synchronization is adjusted. Extend the protection length. As a result, as shown in B of FIG. 5, when the number of disagreement periods (frames) between the frame synchronization pattern and the synchronization pattern is less than b at the time of receiving the voice data signal with noise,
Even if a or more of them continue, the synchronization is not released, and unnecessary muting can be prevented. Since b is an expanded value, even if there is much noise,
This proves that desynchronization is unlikely to occur and is convenient.

FIG. 6 is a block diagram showing a synchronization control device as another embodiment of the present invention. In the figure, 18
Is a synchronous pull-in operation length adjusting circuit, and the same blocks as those in FIG. What is Figure 1?
The synchronization protection length adjusting circuit 4 is used as the synchronization pull-in operation length adjusting circuit 1.
The difference is that it is replaced with 8. In FIG. 6, 1-3,
The operations of 5, 6, 8 and 9 are the same as those in FIG.
Will be described.

In FIG. 6, the synchronization pull-in / release circuit 7
Then, upon desynchronization, when it is detected that the desynchronization condition described above with reference to Table 1 is satisfied, an output signal to that effect is sent to the audio decoding processing circuit 8 to synchronize the audio decoding processing circuit 8. It shifts to the release state, stops the audio decoding process, and mutes it.

Next, there is a case of shifting from the sync release state to the sync pull-in state. At this time, the sync pull-in operation length according to the sync pull-in operation length value from the sync pull-in operation length adjusting circuit 18 is used.・ The release circuit 7
In order to pull in the synchronized state, an output signal to that effect is sent to the audio decoding processing circuit 8 to bring the audio decoding processing circuit 8 into the synchronized state and perform audio decoding processing.

FIG. 7 is a block diagram showing details of the synchronization detection circuit 10 in FIG. In FIG. 7, the same blocks as those in FIG. 3 have the same reference numerals. Figure 3
Is different from the above in that the sync protection length adjusting circuit 4 is replaced with a sync pull-in operation length adjusting circuit 18. In FIG. 7, 21
The operations of .about.25, 27, and 29 are the same as those in FIG. 3, and therefore the description thereof will be omitted. Here, the synchronous pull-in operation length comparator 26 and the synchronous protection length comparator 28 will be described.

In the sync pull-in operation length comparator 26, the count value as the sync pull-in operation length given from the sync pull-in operation length adjusting circuit 18 (the sync pull-in operation length value according to the switching control signal from the noise amount detection circuit 3)
And the count value from the match counter 25,
The comparison result is supplied to the synchronization signal generation circuit 29 as a coincidence signal. On the other hand, in the synchronization protection length comparator 28, the count value as the predetermined synchronization protection length and the mismatch number counter 27
The count value from is compared and the comparison result is supplied to the synchronization signal generation circuit 29 as a coincidence signal.

Next, the function and operation of the synchronous control device according to the present invention will be explained again with reference to FIGS. 6, 8 and 9. FIG. 8 shows an example of the timing of the frame synchronization signal when the synchronization pull-in is performed in response to the input of the audio data signal, and FIG. 9 shows the timing of the reception of the audio data signal with a lot of noise and many errors. An example of the timing of the frame synchronization signal when the synchronization pull-in is not performed by is shown.

In FIGS. 8 and 9, c and d represent the shortened value and the extended value of the synchronous pull-in operation length value, respectively. C, D
Indicates the timing at which the synchronous pull-in occurs when the synchronous pull-in operation length value is set to the shortened value c and the extended value d.

For example, according to the switching control signal from the noise amount detection circuit 3 of FIG. 6, the sync pull-in operation length value of the sync pull-in operation length adjustment circuit 18 is shortened value a / extended value b.
Suppose you have set to switch to. Noise amount detection circuit 3
When the detected noise amount is less than a predetermined level, the switching control signal switches the synchronous pull-in operation length value of the synchronous pull-in operation length adjusting circuit 18 to the extension value d, and the pull-in of the synchronous pull-in / release circuit is performed. The length of the synchronous pull-in operation is extended.

As a result, as shown in D of FIG. 8, the frame sync signal is synchronized with the audio data at the timing of the d-th frame sync pattern counted from the signal input point (timing of signal input) of the audio data. Is output. That is, it is possible to suppress the noise that occurs before the timing of the d-th frame synchronization pattern after the start of the special reproduction cancellation operation of the signal input or the laser disk. Since d is an extension value, it is convenient that the synchronization pull-in can be performed after the audio data is established.

On the other hand, when the noise amount detected by the noise amount detecting circuit 3 is equal to or higher than the predetermined level, the synchronization pull-in operation length value of the sync pull-in operation length adjusting circuit 18 is set to the shortened value c by the switching control signal. The length of the synchronous pull-in operation of the switching and synchronous pull-in / release circuits at the time of pull-in is shortened. As a result, as shown in FIG. 9C, the frame sync signal is received when a mismatch between the frame sync pattern and the sync pattern appears at the c-th time and after from the desynchronization at the time of receiving the voice data signal with noise. Even if it appears before the d-th time, the synchronization can be pulled in and the voice can be output. Since c is a shortened value, it can be seen that even if there is a lot of noise, synchronization pull-in is easy and convenient.

FIG. 10 is a block diagram showing a synchronization control device as still another embodiment of the present invention. In the figure, the same blocks as those in FIGS. 1 and 6 are designated by the same reference numerals. 10 includes both the sync protection length adjusting circuit 4 of FIG. 1 and the sync pull-in operation length adjusting circuit 18 of FIG. In FIG. 10, the operations of 1 to 3, 5, 6, 6, 8 and 9 are the same as those in FIGS. 1 and 6, and therefore description thereof will be omitted. Here, the synchronization detection circuit 10 will be described.

In FIG. 10, the sync pull-in / cancel circuit 7 cancels the sync state with the sync protection length according to the sync protection length value from the sync protection length adjusting circuit 4 when canceling the sync. Is sent to the audio decoding processing circuit 8 to shift the audio decoding processing circuit 8 to the desynchronized state, and the audio decoding processing is stopped and muted.

Next is the case of shifting from the sync release state to the sync pull-in state. At this time, the sync pull-in operation length according to the sync pull-in operation length value from the sync pull-in operation length adjusting circuit 18 is used. The canceling circuit 7 pulls in the synchronized state, sends an output signal to that effect to the audio decoding processing circuit 8, and pulls the audio decoding processing circuit 8 into the synchronized state to perform the audio decoding processing.

FIG. 11 shows the synchronization detection circuit 1 in FIG.
It is a block diagram which shows the detail of 0. 11, the same blocks as those in FIGS. 3 and 7 are denoted by the same reference numerals. 11 includes both the sync protection length adjusting circuit 4 of FIG. 3 and the sync pull-in operation length adjusting circuit 18 of FIG.

As a result, noise can be suppressed at the time of turning on / off the signal and at the time of starting and canceling the special reproduction operation of the laser disk or the like, and the voice due to the unintentional desynchronization when the signal with the low received C / N is received. It is also possible to prevent disconnection and synchronization not being pulled in.

[0056]

According to the present invention, in the synchronization control device including the audio decoding processing circuit, the input signal is adjusted by adjusting the synchronization protection length at the time of releasing synchronization in accordance with the amount of noise included in the received television signal. There is an advantage that unwanted noise can be suppressed at the time of disconnection or during special reproduction of a laser disk, and undesired desynchronization that is likely to occur when the received C / N in the received television signal is low. There is an advantage that can prevent.

Furthermore, by adjusting the sync pull-in operation length at the time of sync pull-in, unwanted noise can be suppressed at the time of signal input or cancellation of special reproduction operation of a laser disk or the like, and reception C / in the received television signal can be suppressed. It is also possible to prevent the undesired state of not pulling the synchronization, which often occurs when N is low.

[Brief description of drawings]

FIG. 1 is a block diagram showing a synchronization control device as an embodiment of the present invention.

FIG. 2 is a block diagram showing a specific example of a noise amount detection circuit 3 in FIG.

3 is a block diagram showing details of a synchronization detection circuit 10 (in particular, a synchronization pull-in / release circuit 7) in FIG.

FIG. 4 is a timing chart showing an example of the timing of a frame synchronization signal when the audio data signal is disconnected and the synchronization is released accordingly.

FIG. 5 is a timing diagram showing an example of the timing of a frame synchronization signal when desynchronization occurs when a voice data signal with a large amount of noise and many errors is received.

FIG. 6 is a block diagram showing a synchronization control device as another embodiment of the present invention.

7 is a block diagram showing details of a synchronization detection circuit 10 (particularly, a synchronization pull-in / release circuit 7) in FIG.

FIG. 8 is a timing chart showing an example of the timing of the frame synchronization signal when the synchronization pull-in is performed in response to the input of the audio data signal.

FIG. 9 is a timing chart showing an example of the timing of a frame synchronization signal when it becomes difficult to pull in synchronization due to reception of a voice data signal with a large amount of noise and many errors.

FIG. 10 is a block diagram showing a synchronization control device as still another embodiment of the present invention.

11 is a block diagram showing details of the synchronization detection circuit 10 (particularly, the synchronization pull-in / release circuit 7) in FIG.

[Explanation of symbols]

1 ... MUSE signal input terminal, 2 ... A / D converter, 3 ...
Noise amount detection circuit, 4 ... Sync protection length adjustment circuit, 5 ... Audio signal separation circuit, 6 ... Audio demodulation circuit, 7 ... Sync pull-in circuit
Release circuit, 8 ... Audio decoding processing circuit, 9 ... Output processing circuit, 10 ... Synchronization detection circuit, 11 ... Digital signal input terminal, 12 ... DC level period detection circuit, 13 ... High pass filter, 15 ... ABS (absolute value) Circuits, 16 ... Level detection circuit, 17 ... Noise amount signal output terminal, 18 ... Sync pull-in operation length adjusting circuit, 21 ... Voice data signal input terminal, 22 ... Shift register, 23 ... Pattern comparator, 2
4 ... Synchronous pattern memory, 25 ... Matching counter, 26
... Synchronous pull-in operation length comparator, 27 ... Mismatch counter,
28 ... Sync protection length comparator, 29 ... Sync signal generation circuit, 3
0 ... Switching control signal input terminal, 31 ... Frame synchronization signal output terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takaaki Matono, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Information & Video Media Division, Hitachi, Ltd. (72) In-house Taihei Yoshida, Totsuka-ku, Yokohama, Kanagawa 292, Machi, Hitachi, Ltd. Visual Media Research Institute (72) Inventor Noboru Kojima Yoshida, Totsuka-ku, Yokohama, Kanagawa 292, Hitachi, Ltd. Visual Media Research Laboratory (72) Inventor, Yuichi Ninomiya Kinuta, Setagaya-ku, Tokyo 1-10-11, Japan Broadcasting Corporation Broadcasting Technology Laboratory

Claims (6)

[Claims] 1. A receiving apparatus for a television signal transmitted by adopting a sample value transmission method using multiple sub-sampling, comprising A / D conversion means for converting the received television signal from an analog format to a digital format. Audio signal separating means for inputting the television signal converted into a digital format, separating, extracting and outputting a digital audio signal from the television signal, and inputting and demodulating the separated and extracted digital audio signal An audio demodulation circuit for outputting, an audio decoding process circuit for taking in the demodulated audio output and subjecting it to decoding processing, and outputting, an output processing circuit for taking in the decoded audio signal for output processing and outputting, The demodulated audio output from the demodulation circuit should be taken in and repeatedly inserted into the audio output at regular intervals. When the synchronization pattern is completely detected a predetermined number of times, a signal with synchronization is output to the audio decoding processing circuit, and thereafter, the audio decoding processing circuit causes the audio decoding processing circuit to bring the signal into a synchronous state and decode the audio output. Then, in the demodulated voice output fetched from the voice demodulation circuit, when the synchronization pattern that should have been repeatedly inserted at a constant cycle is detected a predetermined number of times in an incomplete form,
A period determined by the predetermined number of times is set as a synchronization protection period, and after the synchronization protection period elapses, a synchronization release signal is output to the audio decoding processing circuit, and thereafter, the audio decoding processing circuit is operated to output the audio. Sync pull-in / release means for stopping the decoding process, noise amount detecting means for taking in the television signal after being converted into a digital format by the A / D converter, and detecting the noise amount contained therein, and detecting A synchronization control device comprising: an adjustment unit that variably adjusts the synchronization protection period in the synchronization pull-in / cancellation unit according to the amount of generated noise. 2. A receiving device for a television signal transmitted by adopting a sample value transmission method using multiple sub-sampling, and A / D conversion means for converting the received television signal from an analog format to a digital format. Audio signal separating means for inputting the television signal converted into a digital format, separating, extracting and outputting a digital audio signal from the television signal, and inputting and demodulating the separated and extracted digital audio signal An audio demodulation circuit for outputting, an audio decoding process circuit for taking in the demodulated audio output and subjecting it to decoding processing, and outputting, an output processing circuit for taking in the decoded audio signal for output processing and outputting, The demodulated audio output from the demodulation circuit should be taken in and repeatedly inserted into the audio output at regular intervals. A synchronization pattern, when a predetermined number of times detected in incomplete form,
A signal for desynchronization is output to the audio decoding processing circuit, and thereafter, the audio decoding processing circuit is caused to stop the decoding processing of the audio output, and then in the demodulated audio output taken from the audio demodulating circuit. , When a synchronization pattern that should be repeatedly inserted in the audio output at a constant cycle is detected a predetermined number of times in a complete form, the period determined by the predetermined number of times is set as the synchronization pull-in operation period, and the synchronization pull-in operation period elapses. And a synchronization pull-in / release means for outputting a signal with synchronization to the audio decoding processing circuit and thereafter causing the audio decoding processing circuit to bring the audio decoding processing circuit into a synchronous state and start decoding processing of audio output. A television signal that has been converted to a digital format by the / D converter is taken in and the amount of noise contained in it is detected. A's amount detecting means, in accordance with the detected noise amount, the adjustment means for the synchronization pull-in operation period in the pull-releasing means for variably adjusting, characterized in that it comprises comprises a synchronous control device. 3. A receiving device for a television signal transmitted by adopting a sampled value transmission method using multiple sub-sampling, and A / D conversion means for converting the received television signal from an analog format to a digital format. Audio signal separating means for inputting the television signal converted into a digital format, separating, extracting and outputting a digital audio signal from the television signal, and inputting and demodulating the separated and extracted digital audio signal An audio demodulation circuit for outputting, an audio decoding process circuit for taking in the demodulated audio output and subjecting it to decoding processing, and outputting, an output processing circuit for taking in the decoded audio signal for output processing and outputting, The demodulated audio output from the demodulation circuit should be taken in and repeatedly inserted into the audio output at regular intervals. The synchronization pattern, when the predetermined number of times detected in an incomplete form, as a synchronization guard period duration determined by the predetermined number of times,
After the lapse of the synchronization protection period, a synchronization release signal is output to the audio decoding processing circuit, and thereafter, the audio decoding processing circuit is caused to stop the decoding processing of the audio output, and is taken in from the audio demodulating circuit. In the demodulated audio output, when a synchronization pattern that should have been repeatedly inserted at a constant cycle is detected a predetermined number of times in a complete form, the period determined by the predetermined number of times is set as the synchronization pull-in operation period, and the synchronization pull-in operation period And a synchronization pull-in / release means for outputting a signal with synchronization to the audio decoding processing circuit after that, and for starting the decoding processing of the audio output by causing the audio decoding processing circuit to enter the synchronized state thereafter. , Captures the television signal after being converted to a digital format by the A / D converter, and detects the amount of noise contained therein Noise amount detection means for adjusting the synchronization protection period and the synchronization pull-in operation period of the synchronization pull-in / cancellation means according to the detected noise amount. Synchronous control device. 4. A circuit for detecting the synchronization of an audio signal of a television signal transmitted by adopting a sample value transmission method using multiple sub-sampling, which is repeatedly inserted into a received audio signal at a constant cycle. The synchronization pattern that should be present is compared with a predetermined synchronization pattern and the result is output as a comparison result, and the number of coincidences of the comparison results from the synchronization pattern comparison means is counted and the count value is output. A match counter,
A count value from the coincidence counter is compared with a predetermined count value, and a synchronization pull-in operation period comparing means for outputting the result as a comparison result and the number of disagreements in the comparison result from the synchronization pattern comparing means are counted, A discrepancy number counter that outputs the count value, a synchronization protection period comparison unit that compares the count value from the discrepancy number counter with a predetermined count value, and outputs the result as a comparison result, and the synchronization pull-in operation period comparison Synchronization signal generating means for outputting a signal with synchronization according to the comparison result from the means, and a signal for releasing synchronization according to the comparison result from the synchronization protection period comparison means, and a predetermined count of the synchronization protection period comparison means A synchronization detection circuit comprising: a synchronization protection period adjustment means for variably adjusting a value. 5. A circuit for detecting the synchronization of an audio signal of a television signal transmitted by adopting a sample value transmission method using multiple sub-sampling, which is repeatedly inserted into a received audio signal at a constant cycle. The synchronization pattern that should be present is compared with a predetermined synchronization pattern, and the result is output as a comparison result. The synchronization pattern comparison means counts the number of coincidences of the comparison results from the synchronization pattern comparison means, and outputs the count value. Mismatch between the coincidence counter, the synchronization pull-in operation period comparing means for comparing the count value from the coincidence counter with a predetermined count value and outputting the result as a comparison result, and the comparison result from the synchronization pattern comparing means. A discrepancy counter that counts the number and outputs the count value, and a count value from the discrepancy counter. It compares the count value of,
The synchronization protection period comparison means for outputting the result as a comparison result, and the signal with synchronization according to the comparison result from the synchronization pull-in operation period comparison means, the synchronization release according to the comparison result from the synchronization protection period comparison means. And a sync pull-in operation period adjusting unit that variably adjusts a predetermined count value of the sync pull-in operation period comparing unit. 6. A circuit for detecting the synchronization of an audio signal of a television signal transmitted by adopting a sample value transmission method using multiple sub-sampling, which is repeatedly inserted into a received audio signal at a constant cycle. The synchronization pattern that should be present is compared with a predetermined synchronization pattern, and the result is output as a comparison result. The synchronization pattern comparison means counts the number of coincidences of the comparison results from the synchronization pattern comparison means, and outputs the count value. Mismatch between the coincidence counter, the synchronization pull-in operation period comparing means for comparing the count value from the coincidence counter with a predetermined count value and outputting the result as a comparison result, and the comparison result from the synchronization pattern comparing means. A discrepancy counter that counts the number and outputs the count value, and a count value from the discrepancy counter. It compares the count value of,
The synchronization protection period comparison means for outputting the result as a comparison result, and the signal with synchronization according to the comparison result from the synchronization pull-in operation period comparison means, the synchronization release according to the comparison result from the synchronization protection period comparison means. A sync signal generating means for outputting the signal, a sync protection period adjusting means for variably adjusting a predetermined count value of the sync protection period comparing means, and a sync for variably adjusting a predetermined count value of the sync pull-in operation period comparing means. A synchronization detecting circuit comprising: a pull-in operation period adjusting means.