JP3271119B2 - Signal transmission system and receiving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a MUSE
TECHNICAL FIELD The present invention relates to a signal transmission system and a reception device suitable for use in a system signal transmission system and a reception device.

[0002]

2. Description of the Related Art In the MUSE system, a high-definition (HDTV) signal is converted into a digital signal, sample points are uniformly thinned out, then converted into an analog signal and transmitted. The format is defined as shown in FIG.

In the case of sample value transmission such as the MUSE method, it is necessary for a decoder to accurately resample a sample value that has been D / A converted by an encoder without causing interference with an adjacent sample point. Interference between sample values appears as ringing on the screen, causing image quality degradation.

A transmission condition under which no inter-sample value interference occurs is known as Nyquist's first criterion. That is,
As shown in FIG. 5, the frequency characteristic of the transmission path must be point-symmetrical (-6 dB roll-off characteristic) around a half cycle (= 8.1 MHz) of the sampling frequency fs (= 16.2 MHz). There is. Further, it is necessary that the resampling clock does not deviate in phase from the sampling clock.

In a system output from an encoder and input to a decoder via a transmission path, in the MUSE system, such a system can be satisfied that this criterion can be satisfied.
The VIT signal is transmitted. As shown in FIG. 4, this VIT signal is superimposed on the frame pulse lines of line numbers 1 and 2 as positive and negative impulses.

That is, when an impulse is output from the encoder as shown in FIG. 6A, the output of the transmission line constituting the low-pass filter becomes as shown in FIG. 6B. As shown in FIG. 6C, when the output of this transmission path is resampled by a decoder with a clock having the correct phase,
The output of the decoder is the same as the output of the encoder (FIG. 6A), as shown in FIG. In contrast, FIG.
As shown in (e), when the phase of the resampling pulse in the decoder shifts or the frequency characteristics of the transmission line deviate from the ideal characteristics, the output of the decoder contains noise as shown in FIG. It will be.

In order to prevent such a distortion from occurring, in a conventional apparatus, a VIT signal received at a decoder side is compared with a reference VIT signal, and a matching filter of an encoder side is provided in accordance with the error signal. The characteristics were adjusted ("NHK Technology Research", page 37 and page 38 (Vol. 39, No. 2, 172).
issue)).

Alternatively, in another conventional apparatus, the characteristics of an equalization filter are determined in accordance with an error between a VIT signal received on the decoder side and a reference VIT signal, and data equalized by the equalization filter is determined. The distortion was corrected by adding to the original data (“MUSE decoder built-in waveform equalizer”, 1988, National Convention of the Institute of Television Engineers of Japan).

[0009]

As described above, all of the above-mentioned conventional devices are intended to remove the distortion due to the transmission line by using the VIT signal. For example, there is a problem that the distortion generated in the encoder cannot be removed. there were.

The present invention has been made in view of such a situation, and it is an object of the present invention to eliminate distortion generated in an encoder.

[0011]

A signal transmission method according to the present invention.
Detects the first distortion due to the encoding process on the transmission side
Then, on the receiving side, first correction data corresponding to the first distortion
And second correction data corresponding to the second distortion due to the transmission path.
Is stored in the storage means, and the
Based on the first correction data and the second correction data,
It is characterized in that equalization processing is performed by stages.

[0012] The signal receiving apparatus of the present invention includes an encoder on the transmitting side.
First distortion of the data encoded in the loading processor
And the second distortion due to the transmission path
Storage means for storing second correction data corresponding to
Equalizing means for performing equalization processing of the first distortion and the second distortion;
Setting means for setting characteristics of the converting means,
Are the first correction data stored by the storage means and
Based on the second correction data, the first distortion and the
Setting the characteristic for performing the second distortion equalization processing
Features.

[0013]

According to the signal transmission method of the present invention, on the transmitting side,
The first distortion due to the encoding process is detected, and on the receiving side,
The first correction data corresponding to the first distortion, and
The second correction data corresponding to the second distortion is stored in the storage unit.
First correction data stored and stored in storage means
Equalization processing by the equalization means based on the
Is performed.

In the signal receiving apparatus of the present invention, the transmitting side
Of the data encoded in the encoding unit of
The first correction data corresponding to the first distortion, and
The second correction data corresponding to the second distortion is stored.
The equalization processing of the first distortion and the second distortion is performed, and the characteristics thereof are set.
Is determined. Further, the stored first correction data and the
Equalization of the first distortion and the second distortion based on the second correction data
The characteristics for performing the processing are set.

[0015]

1 and 2 show an encoder on the transmitting side and a decoder on the receiving side, respectively, in an embodiment of the signal transmission system according to the present invention.

In FIG. 1, a digital video signal is inputted to a terminal 1 from a circuit (not shown). The switch circuit 2 selects a video signal input from the terminal 1 or a reference signal output from the reference signal generation circuit 12 and supplies the video signal to the video encoding processing unit 3. Video encoding processing unit 3
Encodes the input data and outputs it to the mixing circuit (switch circuit) 4 and the distortion measuring circuit 13. The reference signal output from the reference signal generation circuit 12 is also supplied to the distortion measurement circuit 13, and the distortion measurement circuit 13 measures distortion in the video encoding processing unit 3 from both input signals. The terminal 5 is supplied with digitized audio data from a circuit (not shown). The audio data is supplied to the mixing circuit 4 after being encoded by the audio encoding unit 6. The mixing circuit 4 mixes the outputs of the video encoding processing unit 3, the audio encoding processing unit 6 and the VIT signal generation unit 7 (selects one of them), and supplies it to the transmission line matching processing unit 8. The output of the transmission line matching processor 8 is
The signal is supplied to the FM modulator 10 via the D / A converter 9.
The output of the FM modulator 10 is supplied to a transmission circuit 11, and is output from the transmission circuit 11 to a transmission line (not shown).

A signal supplied via a transmission line (not shown) is received by a receiving circuit 21 shown in FIG. 2 and supplied to an FM demodulator 22. The output of the FM demodulator 22 is A /
It is supplied to the D converter 23. The waveform equalization processing unit 24
The signal input from the / D converter 23 is equalized and output to the separation circuit 25. The separation circuit 25 separates the audio data and the video data, and converts the audio data into an audio decode processing unit 26.
And video data to the video decoding processor 29. The output of the audio decoding processor 26 is output to a speaker 28 via a D / A converter 27. The output of the video decoding unit 29 is output to the monitor 32 via the D / A converter 31. The video decoding processing unit 29 has a motion part detection circuit 30, and its output is the waveform equalization processing unit 24.
It is supplied to.

FIG. 3 is a block diagram showing a more detailed configuration of the waveform equalization processing section 24. The data input from the A / D converter 23 is supplied to the separation circuit 25 through the addition circuit 41.
Is output to A part of the output of the A / D converter 23 is also supplied to the equalization filter 42. The data processed by the equalization filter 42 is supplied to the addition circuit 41. The characteristic setting unit 43
The characteristics of the equalizing filter 42 are set in accordance with the output of the adder circuit 41 and the outputs of the storage units 44 and 45. The characteristic setting section 43 includes a video decoding processing section 29.
The signal is supplied from the motion part detection circuit 30 of FIG.

Next, the operation will be described. The video data input to the terminal 1 is supplied to the video encoding processing unit 3 via the switch circuit 2. Video encoding processing unit 3
Outputs the input video data to the mixing circuit 4. The audio data input to the terminal 5 is supplied to the mixing circuit 4 after being encoded by the audio encoding unit 6. Further, the VIT signal generation section 7 generates a VIT signal and outputs it to the mixing circuit 4. Mixing circuit (switch) 4
Mixes (selects) the outputs of the video encoding unit 3, the audio encoding unit 6, and the VIT signal generation unit 7 at a predetermined timing. As a result, a signal having a format as shown in FIG. 4 is generated.

The output of the mixing circuit 4 is input to a transmission line matching processing section 8 and processed to have predetermined characteristics. The output of the transmission line matching processing unit 8 is input to the D / A converter 9,
After the A / A conversion, the signal is supplied to the FM modulator 10 and is FM-modulated. The FM modulation signal output from the FM modulator 10 is output to the transmission circuit 11 and transmitted from the transmission circuit 11 to a transmission path such as a broadcast satellite.

The signal transmitted via the transmission path is received by the receiving circuit 21 and supplied to the FM demodulator 22 to be FM-demodulated. The signal subjected to the FM demodulation is input to an A / D converter 23 where the signal is A / D converted, and a waveform equalization processing unit 24
Supplied to The signal equalized to a predetermined characteristic in the waveform equalization processing unit 24 is supplied to a separation circuit 25 and separated into audio data and video data. The audio data is input to the audio decode processing unit 26, and after being decoded,
D / A conversion is performed in the A converter 27, and the D / A converted is further supplied to the speaker 28 for sound emission.

On the other hand, the video data is transmitted to the video decoding
9 and decoded. The decoded video data is input to a D / A converter 31 and D / A converted, and then supplied to a monitor 32 for display.

Next, the operation of the waveform equalization processing section 24 will be described. The motion part detection circuit 30 in the video decoding processing unit 29 uses the video data and the motion vector input from the separation circuit 25 to
Is determined. That is, the video decoding processing unit 29 performs still image processing and moving image processing on the input video data, and mixes the still image processed data and the moving image processed data at a predetermined ratio and outputs them. The motion part detection circuit 30 controls the ratio of the mixture.

The characteristic setting unit 43 monitors the output of the moving part detection circuit 30, and refers to the data in the storage unit 45 when the video decoding processing unit 29 is performing the still image processing, and performs the moving image processing. If there is (when processing other than the still image processing is performed), the characteristics are calculated and set based on the data stored in the storage unit 44.

Now, assuming that the video decoding processing unit 29 is performing moving image processing, the characteristic setting unit 43
Is compared with the data stored in the storage unit 44. The storage unit 44 stores ideal data of the VIT signal (data not subjected to distortion in the transmission path). Therefore, the characteristic setting unit 43 includes the video data that is distorted in the transmission path input from the addition circuit 41,
The data is compared with ideal data that has not been subjected to distortion and stored in the storage unit 44, and the error signal is output to the equalization filter 42. The equalizing filter 42 is set to have a characteristic corresponding to the error signal. The equalizing filter 42 is used for the A / D converter 2
3 is equalized according to the set characteristics, and is output to the addition circuit 41. The addition circuit 41
The data input from the / D converter 23 and the data input from the equalization filter 42 are added and output to the separation circuit 25 and the characteristic setting unit 43. As a result, servo is applied so that distortion in the transmission path is removed.

As described above, the distortion in the transmission line is removed by the VIT signal.
In the present embodiment, distortion in the video encoding unit 3 is also removed as follows.

That is, on the encoder side shown in FIG. 1, before transmitting the mixed data of the video data and the audio data to the decoder side as described above, the distortion in the video encoding processing section 3 is reduced as follows. Measure. Therefore, a predetermined reference signal output from the reference signal generation circuit 12 is supplied to the switch circuit 2. This reference signal can be, for example, a sine wave of a predetermined frequency. This frequency is lower than 8.1 MHz in the MUSE system so that aliasing noise does not occur. The video encode processing unit 3 encodes the reference signal input via the switch circuit 2 and outputs the encoded reference signal to the distortion measurement circuit 13. The reference signal output from the video encoding unit 3 has undergone distortion corresponding to the processing in the video encoding unit 3.
On the other hand, from the reference signal generation circuit 12 to the distortion measurement circuit 1
The reference signal supplied to 3 is not subjected to distortion since it does not pass through the video encoding processing unit 3. Distortion measurement circuit 1
Reference numeral 3 compares the output of the video encoding unit 3 with the output of the reference signal generation circuit 12, and measures the distortion in the video encoding unit 3.

The waveform equalizer 24 of the decoder shown in FIG.
1 stores data corresponding to the distortion measured by the distortion measuring circuit 13 in the encoder shown in FIG. That is, reference data for canceling the distortion in the video encoding processing unit 3 is stored in the storage unit 45. When the moving part detection circuit 30 detects that the video decoding processing unit 29 is executing the still image processing, the characteristic setting unit 43 performs processing based on the data stored in the storage unit 44 and the storage unit 45. The characteristics of the equalization filter 42 are set. That is, in this case, as described above, the storage unit 4
4 corresponding to the data stored in
Are set so as to remove the distortion due to the transmission path, and the characteristics of the equalization filter 42 are set in consideration of the data stored in the storage unit 45. That is, the characteristics of the equalizing filter 42 are set to characteristics obtained by combining the characteristics for correcting distortion in the transmission path and the characteristics for correcting distortion in the video encoding unit 3 (characteristics represented by the product of the transfer functions of the two). Is set to.) Thus, in the still image processing period in which noise is conspicuous, not only the distortion due to the transmission path but also the distortion in the video encoding unit 3 is removed, and a good image can be viewed on the monitor 32.

In the above description, the distortion component by the video encoding unit 3 is corrected only during the still image processing period. However, the distortion by the video encoding unit 3 may be corrected also during the moving image processing period. Of course. In addition, it is possible to remove distortion not only during processing of a still image or a moving image of a luminance signal but also during processing of a still image or a moving image of a chroma signal. Furthermore, the output of the reference signal generation circuit 12 is input to the previous stage of the audio encoding processing unit 6 so as to remove the distortion in the audio encoding processing unit 6, and the distortion in the audio encoding processing unit 6 is measured. The data may be stored in the storage unit in the waveform equalization processing unit 24.

In the above description, the distortion in the video encoding unit 3 is measured using the reference signal, and the data corresponding to the distortion is stored in the storage unit. The distortion in the video encoding processing unit 3 can be removed by using the portion. That is, in this case, the rising portion in the video signal is compared with the ideal rising portion, and the characteristics of the equalization filter are set corresponding to the error signal. In this case, the rising portion becomes the pseudo reference signal.

Although the present invention has been described above by way of an example in which the present invention is applied to a MUSE signal transmission system, the present invention can be applied to other signal transmission systems that transmit sample values .

[0032]

According to the signal transmission method of the present invention, the transmitting side
Then, the first distortion due to the encoding process is detected, and
Then, the first correction data corresponding to the first distortion and the transmission path
And second correction data corresponding to the second distortion caused by the
First correction data stored in the stage and stored in the storage means
Equalization processing by the equalization means based on the
And distortion along the transmission path,
It is possible to remove distortion in the encoding processing unit.

According to the signal receiving apparatus of the present invention,
Of the data encoded in the encoding unit
The first correction data corresponding to the distortion of No. 1 and the
And the second correction data corresponding to the second distortion.
Performs equalization processing of the distortion and the second distortion, and sets the characteristics.
You. The stored first correction data and second correction data
Based on the data, the first distortion and the second distortion are equalized.
Characteristics for the transmission path.
Together with the distortion caused by the encoding unit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an encoder in a signal transmission system of the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of a decoder in the signal transmission system of the present invention.

FIG. 3 is a block diagram illustrating a configuration of an embodiment of a waveform equalization processing unit in the embodiment of FIG. 2;

FIG. 4 is a diagram illustrating a format of the MUSE system.

FIG. 5 is a diagram illustrating frequency characteristics of a transmission path.

FIG. 6 is a diagram illustrating a function of a VIT signal in the MUSE system.

[Description of Signs] 3 Video encoding processing unit 6 Audio encoding processing unit 7 VIT signal generation unit 8 Transmission line matching processing unit 12 Reference signal generation circuit 13 Distortion measurement circuit 24 Waveform equalization processing unit 26 Audio decoding processing unit 29 Video decoding processing Unit 30 motion detection circuit 41 addition circuit 42 equalization filter 43 characteristic setting unit 44, 45 storage unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/14 H04N 5/44 H04N 7/015

Claims (2)

(57) [Claims] 1. A signal transmission method in which a transmission side encodes by a predetermined encoding process, transmits a sample value to a transmission path, and decodes a sample value supplied via the transmission path by a decoding processing unit on a reception side. The transmitting side detects a first distortion due to the encoding process.
Output the first correction data corresponding to the first distortion on the receiving side.
And a second complement corresponding to a second distortion caused by the transmission path.
Positive data is stored in storage means, and the first correction data and
Equalizing by the equalizing means based on the second correction data
A signal transmission method comprising performing processing . 2. A signal receiving apparatus for receiving and decoding sample data which has been encoded by a transmission side encoding processing unit and transmitted by a sample value via a transmission path , wherein the encoding processing unit on the transmission side encodes the data.
Correction data corresponding to a first distortion of the extracted data
And a second correction data corresponding to a second distortion caused by the transmission path.
Storage means for storing data and an equalizing means for performing equalization processing of the first distortion and the second distortion.
Stage, and setting means for setting characteristics of the equalizing means , wherein the setting means is configured to store the characteristics before storing by the storage means.
Based on the first correction data and the second correction data.
The equalization means is configured to determine whether the first distortion and the second distortion
A signal receiving device for setting characteristics for performing a conversion process .