JPH06113173A - Ghost removal reference signal detection device - Google Patents

Abstract

PURPOSE:To provide a ghost removal reference signal detection device where the storage capacity of a storage element storing a signal becoming the detection object of a ghost removal reference signal. CONSTITUTION:A processing for the setting of the initial state of tap coefficients C-7-C8 in TF15 is executed (step 102) accompanied by power supply (step 101). Then, GCR waveforms (S1-S8) are fetched (step 103). The fetch range of the waveforms consists of a period Te which is required for waveform equalization and a period Ts which is immediately before a part where the rise of a GCR signal is to be existed by 2mus. The waveforms are checked and the presence or absence of the GCR signal is judged (step 104). When the signal is judged to be the GCR signal, an eight field sequence operation is executed for fetched waveform data in the period Te (step 105).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ghost elimination reference signal detecting device for detecting a ghost elimination reference signal in a television broadcasting system.

[0002]

2. Description of the Related Art At present, in an NTSC television broadcasting system, a GCR is used as a ghost eliminating reference signal.
(Ghosto Cancel Reference) signal is used. This GCR signal is, as shown in FIG. 5, the 18th horizontal scanning period (18H) and the 281st horizontal scanning period of the vertical blanking period.
It is inserted in a sequence called an 8-field sequence in the second horizontal scanning period (281H).

A GCR signal (S _GCR ) having only a step shape in which the horizontal synchronizing signal, the burst signal and the like are canceled can be obtained by performing an operation on the eight field sequence represented by the following equation (1).

[0004]

[Equation 1] Incidentally, "GCR", "0" , "X A", "X B" is attached to the shoulder "+" and "-" symbols represent the polarity of the burst of that line. 4 f _sc (f for S _GCR
sc : color subcarrier frequency = 3.579545 MHz) is used as a clock signal, and ghost removal and transmission system f-correction are performed based on an impulse waveform obtained by applying a 1-clock difference.

Next, an 8-field sequence type GC
Using the R signal, the figure shows a proximity ghost having a delay time in the range of -0.5 to +0.6 μs, a waveform equalizer that corrects f-specific disturbance from the tuner section to the detection section, and an operation sequence, respectively. It will be explained with reference to FIG. FIG. 7 is a block diagram showing the configuration of a conventional waveform equalizer, and FIG. 8 is a flow chart for explaining the operation of the waveform equalizer of FIG.

As shown in FIG. 7, a waveform equalizer using a ghost elimination reference signal detecting device has an input terminal 11
From the analog / digital conversion circuit 12 for inputting the video signal including the GCR signal, the 18H detection circuit 31, and the clock generation circuit 14.

The digital video signal output from the A / D conversion circuit 12 is input to the TF 15. The input video signal has a cycle T (= 1 / 4f) by the delay line 151 with a tap.
_sc ) and the coefficient multiplier 152 corresponding to each output
After being multiplied by the tap coefficient in, the sum is added in the adder 153. The output from the adder 153 is held at the output terminal 16 and supplied to the output waveform memory 20.

The 18H detection circuit 31 detects the 18th horizontal scanning period (18H) from the input video signal,
A detection signal indicating the detection of H is output.

The detection signal from the 18H detection circuit 31 is given to the capture control circuit 21. Acquisition control circuit 21 is 18H
An instruction signal for the microprocessor 32 and a control signal for the output waveform memory 20 are generated based on the detection signal from the detection circuit 31.

The microprocessor 32 is a work RAM
A predetermined calculation is performed using the data stored in 19 and the ROM 18 to obtain the final GCR signal.

The clock generation circuit 14 has a predetermined frequency 4f.
Generate a clock signal with _sc .

Next, the operation of the conventional waveform equalizer will be described. Referring to FIG. 8, first, when the power is turned on and the channel is switched (step 301), the tap coefficient C held in the tap gain memory 154 of the 16-tap transversal filter (hereinafter referred to as TF) 15 is used.
Processing is performed in _-7 -C ₈ with respect to the initial state set (step 302). In the processing for this initial state setting, for example, the main tap coefficient C _{0 is set} to “1”, and the other coefficients C ₋₇ , ..., C ₈ other than C ₀ are set to “0”.

Next, the waveform of the GCR signal (S1 to S8)
Output waveform memory 20 according to an instruction from the acquisition control circuit 21.
(Step 303).

After capturing the GCR signal waveform, these GCR
An 8-field sequence operation (shown by equation (1)) is performed on the signal to obtain the final GCR signal (step 304).

The length of the captured GCR signal and the length of the final GCR signal obtained based on them are in the interval T3 [-
173, 17] (shown in FIG. 10B), 191 words, and one word has 8 bits. The GCR signal and the final GCR signal are represented by the following equation (2) as sample values.

[0016]

[Equation 2] However, i is the field number and k is the sample number of the captured waveform. Note that k = 0 is the rising point of the GCR signal.

Next, a waveform check is performed to determine whether the acquired waveform is a GCR signal that can be used for waveform equalization (step 305). When the GCR signal is not detected by the waveform check, such as when the GCR signal is not transmitted, when the GCR signal is disturbed due to signal switching on the broadcasting station side, etc., the operation of the waveform equalizer is temporarily stopped, and the malfunction does not occur. It is prevented.

When the GCR signal is detected in the waveform check, the microprocessor 32 calculates the difference signal {y _k } from S _{GCR, K} obtained in step 304, and the working R
It is stored in the AM 19 (step 306). This difference signal {y _k } is calculated from the following equation.

[0019]

[Equation 3] Then, the maximum peak value p of the differential signal {y _k } is detected (step 307). The maximum peak value p is originally near sample number 0, that is, y _p is the peak of the impulse of the main signal.

Next, the reference waveform {r _k } stored in the ROM 18 is subtracted from the difference signal {y _k } in accordance with the peak position (p) to obtain the error waveform signal {e _k } and the error waveform signal {e _k }. e _k } is stored in the work RAM 19 (step 308).

The following equation is used to calculate the error waveform signal {e _k }.

[0022]

[Equation 4] Next, the tap gain is corrected by calculation using the following equation (5) (step 309).

[0023]

[Equation 5] However, k = i + p, i = −7 to 8 Here, the subscript i indicates a tap coefficient number for correcting the waveform distortion of the delay time iT seconds. “New” and “old” indicate after correction and before correction, respectively, and δ indicates a positive minute correction amount.

Waveform equalization is performed by repeating the equalization loop composed of the above sequence.

Next, a method of checking a waveform in the operation sequence of the waveform equalizer will be described with reference to the drawings. FIG. 9 is a flowchart showing the operation of the waveform check in the waveform equalizer of FIG. 7, and FIG. 10 is a waveform diagram used for explaining the operation of the waveform equalizer of FIG. In FIGS. 10B and 10C, T1 is a section of the burst portion which is canceled after the 8-field sequence operation, and T2 is a part of the high level section of the bar waveform. Further, as the amplitude unit of the waveform in FIG. 10, the IRE unit and the straight binary level when standard conversion is performed by the 8-bit analog / digital converter are used.

When jitter occurs near the insertion position of the GCR signal due to abnormal signal switching on the broadcast station side, the waveform shown in FIG. 10B should be obtained after the 8-field sequence calculation. As shown in (c), the horizontal synchronizing signal, the burst signal, etc. may not be canceled, and these signals may remain. Further, as another example, when another signal different from the GCR signal is transmitted due to an accident or the like, the bar waveform of the GCR signal may not exist in its original form.

To detect the presence or absence of the GCR signal in these cases, a waveform check is performed as shown in FIG. This waveform checking method is disclosed in Japanese Patent Laid-Open No. 3-19858.
No. 6 publication.

Firstly, 8 field sequence after obtained S _GCR data {S _{GCR, k}} square of {S _{GCR, k} 2}
Is required (step 401).

Next, the integrated value S _a of the section T1 is obtained from the following equation (step 402).

[0030]

[Equation 6] However, k indicates the sample number in the section T1.

Then, the minimum value M _b of {S _{GCR, k} 2} in the section T2 is obtained (step 403).

After the calculation of the minimum value M _b , the square integrated value S _a of the section T1 is compared with the constant value L _a and the minimum value M _b of the amplitude square of the section T2 is compared with the predetermined value L _b ( Step 404). Satisfy both a first condition that the square integration value S _a of the interval T1 is not more than a predetermined value L _a, the minimum value M _b of the amplitude square of the interval T2 is a second condition that is greater than or equal to a predetermined value L _b When it does, the equalization loop is executed.
On the other hand, when at least one of the first condition and the second condition is not satisfied, the operation of the waveform equalizer is stopped and the malfunction of the waveform equalizer is prevented.

Therefore, the sample length required for the original waveform equalization is 1 in the section Te [-7, 9] (shown in FIG. 10B).
Although there are 7 samples, in the above-mentioned waveform check method,
A section T1 close to the −173rd sample (FIG. 10B)
And the interval T near at least the 17th sample
2 waveforms (shown in Figure 10 (b)) are required, a total of 1
It is necessary to capture the waveform of 91 samples.

Next, a laser disk (hereinafter referred to as LD) by an apparatus using the above-mentioned waveform check method.
The reproduction operation of the recorded video signal will be described with reference to the drawings. FIG. 11 shows 18H and 2 of the recorded video signal of the LD.
81H is a diagram showing the configuration of bits inserted in 81H, and Table 1 is a table showing bit codes inserted in the recording video signal of the LD.

As shown in FIG. 11 and Table 1, a 24-bit code consisting of a picture number and a time number is inserted in 18H and 281H of the video signal recorded in the LD, but no GCR signal is inserted. .

[0036]

[Table 1] In the device where this waveform check method is used,
When the video signal recorded in the LD is input to the waveform equalizer through an external input terminal or an empty channel such as RF 2 channel, the bit code inserted in 18H and the bit inserted in 281H Although the code may be replaced at random, the second word (X1) of the bit code is the highest word such as picture number, time number, chapter number, etc.
There is almost no change during the 8-field period, and it becomes 0 after the 8-field sequence operation. Therefore, the second condition is not satisfied in the section T2 (shown in FIG. 10 (b)) spanning the first word of F or 8 and the next word indicated by X1, and it is determined that the signal is not the GCR signal.
As an example, in the case of the bit codes shown in Table 2 below, the waveform after the 8-field sequence operation is shown in FIG.
It becomes the form shown in (e).

[0037]

[Table 2]

[0038]

As described above, the conventional ghost elimination reference signal detecting device requires a memory capacity which is about 10 times the memory capacity required for the original waveform equalization.

It is an object of the present invention to provide a ghost elimination reference signal detecting device capable of reducing the storage capacity of a storage element or the like for storing a signal to be detected as a ghost elimination reference signal.

[0040]

SUMMARY OF THE INVENTION The present invention is a ghost elimination reference signal detecting apparatus for detecting a ghost elimination reference signal inserted by an 8-field case in a vertical blanking period of a television signal, wherein an input signal From the reference signal line detecting means for detecting the line into which the ghost removal reference signal is to be inserted, the capturing means for capturing the signal of the line detected by the reference signal line detecting means, and the capturing means. Preliminarily calculated by performing substantially the same operation as the operation of the operation means on the operation means for performing operation on the signal and the result of the operation by the operation means and the pedestal portion in the period immediately before the rise of the ghost elimination reference signal. Comparing the result of the comparison with the result obtained by the comparison means, and based on the comparison result of the comparison means, the captured signal is a ghost elimination criterion. And a determination means for determining whether or not a degree.

[0041]

[Operation] In the ghost elimination reference signal detection device of the present invention, an operation is performed on the signal captured by the capturing means, and the result of this operation and the pedestal portion in the period immediately before the rise of the ghost removal reference signal are calculated. On the other hand, a result calculated in advance by performing substantially the same operation as the above is compared, and based on the result of this comparison, it is determined whether or not the captured signal is the ghost elimination reference signal.

Therefore, in addition to the waveform required for waveform equalization,
To determine whether or not the captured signal is the ghost elimination reference signal, the waveform of the signal captured during a short period immediately before the portion where the rise of the ghost elimination reference signal is present, for example, a period of approximately 2 μs is used. Therefore, it is not necessary to use a storage element having a large capacity for this calculation, and the capacity of the storage element can be reduced.

[0043]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a waveform equalizer in which an embodiment of the ghost elimination reference signal detecting apparatus of the present invention is used, and FIG. 2 is a flow chart showing the operation of the waveform equalizer of FIG.
FIG. 3 is a flow chart showing a waveform check operation by the ghost elimination reference signal detection device used in the waveform equalizer of FIG.

As shown in FIG. 1, the waveform equalizer in which the ghost elimination reference signal detecting device is used has an input terminal 11
From the analog / digital conversion circuit 12 for inputting the video signal including the GCR signal, the 18H detection circuit 31, and the clock generation circuit 14.

The digital video signal output from the A / D conversion circuit 12 is input to the TF 15. The input video signal has a cycle T (= 1 / 4f) by the delay line 151 with a tap.
_sc ) and the coefficient multiplier 152 corresponding to each output
After being multiplied by the tap coefficient in, the sum is added in the adder 153. The output from the adder 153 is held at the output terminal 16 and supplied to the output waveform memory 20.

The 18H detection circuit 31 detects the 18th horizontal scanning period (18H) from the input video signal,
A detection signal indicating the detection of H is output.

The detection signal from the 18H detection circuit 31 is given to the capture control circuit 21. Acquisition control circuit 21 is 18H
A control signal for the microprocessor 17 and a control signal for the output waveform memory 20 are generated based on the detection signal from the detection circuit 31.

The microprocessor 17 is a work RAM
A predetermined calculation is performed using the data stored in 19 and the ROM 18, and the calculation result is output.

The clock generation circuit 14 has a predetermined frequency 4f.
Generate a clock signal with _sc .

Next, the operation of the above waveform equalizer will be described with reference to the drawings.

Referring to FIG. 2, first, when the power is turned on and the channel is switched (step 101), the tap coefficients C _{-7 to} C ₈ held in the tap gain memory 154 of the 16-tap TF 15 are initialized. The processing for the status setting is performed (step 102).

Next, the GCR waveform (S1 to S8) is fetched (step 103). The acquisition range of this waveform is
Unlike the conventional waveform capture range, it consists of a Te section (shown in FIG. 10B) required for waveform equalization and a 2 μs section Ts immediately before the portion where the GCR signal should originally rise. The total number of samples for the waveform acquired in this acquisition range is 3
The sample number is 9, and the sample number is from -29 to 9.

Next, a waveform check is performed to determine the presence / absence of a GCR signal (step 104).

When it is determined that the signal is a GCR signal,
An 8-field sequence calculation is performed on the waveform data within the fetched period Te (step 105).

After the 8-field sequence calculation, the waveform equalization sequence (steps 106 to 109) is executed.

Next, taking the recorded video signal of the LD as an example, a method of checking the waveform in the operation sequence of the waveform equalizer will be described with reference to the drawings. FIG. 3 is a flow chart for explaining the waveform check by the ghost elimination reference signal detection device used in the waveform equalizer of FIG.

First, the 8-field total sum Sa is obtained from the waveform data {S _{i, k} } after waveform acquisition by the following equation (step 201).

[0059]

[Equation 7] After the calculation, the maximum value S _max within the period Ts of {S _k } is obtained (step 202). Referring to FIG.
In the waveform shown in (a), the LD bit code MSB is F8.
F8F8F8 are waveforms obtained when they appear in this order, and the waveforms shown in FIGS. 6B and 6C have LD bit codes MSB of 888888888 and F8, respectively.
It is a waveform obtained when they appear in the order of F8F888.

When the captured signal is an LD video signal, each bit is a bi-phase code, so that the amplitude is within the pedestal level (50 μm) within 1 bit width (2 μs).
There is always a portion larger than 4 LSB). Figure (a),
The maximum values within the period Ts shown in (b) and (c) are 1 respectively.
004 (188 x 4 + 63 x 4), 1504 (188 x
8), 1129 (188 × 5 + 63 × 3) LSB.

On the other hand, the maximum value of the sum of the eight fields immediately before the rising edge in the GCR signal is 504 (63 × 8) LSB, which is smaller than the maximum value in the case of LD, as shown in FIG. 6 (d). Become.

The high level of the GCR signal is 8
56 (151 × 4 + 63 × 4). Further, when there is a positive front ghost, the total sum of the GCR signal immediately before the rising edge becomes larger than the above value. As shown in FIG. 6E, for example, when there is a positive front ghost of 6 dB, the total sum is 6
21 (504+ (856−504) × 1/3) LSB. Therefore, the maximum value of the total sum of bit codes in the LD in the 2 μs period immediately before the rise of the GCR signal is smaller than the maximum value.

Next, the maximum value S _max is a predetermined value L (eg 800 LS) in which a margin margin such as noise is expected.
B and below), and the result of this comparison indicates that GCR
It is determined whether the signal is a signal (step 20).
3). When the maximum value S _max is less than or equal to the predetermined value L, GCR
It is determined that the signal is a signal.

As described above, the determination of whether or not the signals inserted in 18H and 281H of the LD recording video signal taken in via the 2nd channel is the ghost elimination reference signal originally involves the rise of the GCR signal. The result of the operation performed for the 2 μs period immediately before the power part is used. Since the signal portion to be calculated is a signal in a short period of 2 μs, it is not necessary to increase the storage capacity of the work RAM 19 used for this calculation, and the capacity of the work RAM 19 can be reduced.

Next, another ghost elimination reference signal detecting device will be described with reference to the drawings. FIG. 4 is a diagram for explaining the operation of another embodiment of the ghost elimination reference signal detecting device of the present invention.

In the ghost elimination reference signal detection device, the waveform data {S _{i, k} } of the taken-in signal is integrated by the following equation, and the total sum S _c of 8 fields is obtained by the following equation (step 211). .

[0067]

[Equation 8] Taking the capture signals shown in FIGS. 6A, 6B, and 6C as an example, since each bit is a biphase code, the sum total for each signal is 29000 (1004 × 29).
The LSB is equal to or higher than the LSB, and the sum of the GCR signals is larger than about 14000. Therefore, the sum S _c is the predetermined value L _c (for example, 2
If it is 2000 LSB or less, it is determined that the signal is a GCR signal (step 212).

When the captured signal is a GCR signal, as shown in FIG. 6 (e), the sum S _c is a positive -2 μs ghost of 6 dB in the range where waveform equalization is practically possible. Maximum when present. The maximum value of this sum S _c is about 18000 (621 (LSB) × 29 (the number of samples in Ts)) LSB. Even in such a case, it can be determined that the GCR signal has the predetermined value L _c .

In the present embodiment, the above-mentioned calculation is executed by the microprocessor, but instead of this, it may be realized by hardware such as a latch or adder.

[0070]

As described above, according to the ghost elimination reference signal detecting apparatus of the present invention, it is possible to reduce the storage capacity of the storage element or the like for storing the signal to be detected as the ghost elimination reference signal. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a waveform equalizer in which an embodiment of a ghost elimination reference signal detection device of the present invention is used.

FIG. 2 is a flowchart showing the operation of the waveform equalizer of FIG.

FIG. 3 is a flowchart showing a waveform check operation by the ghost elimination reference signal detection device used in the waveform equalizer of FIG.

FIG. 4 is a flow chart for explaining the operation of another embodiment of the ghost elimination reference signal detection device of the present invention.

FIG. 5 is a waveform diagram showing a GCR signal.

FIG. 6 is a diagram showing a signal waveform of an LD and a waveform of a GCR signal after addition calculation for 8 fields.

FIG. 7 is a block diagram showing a waveform equalizer in which a conventional ghost elimination reference signal detection device is used.

FIG. 8 is a flowchart showing the operation of the waveform equalizer of FIG.

9 is a flowchart showing a waveform check operation by the ghost elimination reference signal detection device used in the waveform equalizer of FIG.

10 is a waveform diagram used for explaining the operation of the waveform equalizer of FIG.

FIG. 11: 18H and 281H of recorded video signal of LD
It is a figure which shows the structure of the bit inserted in.

[Explanation of symbols]

15 ... Transversal filter, 17 ... Microprocessor, 18 ... ROM, 19 ... Work RAM, 20 ... Output waveform memory, 21 ... Acquisition control circuit, 31 ... 18H detection circuit.

Claims (3)

[Claims] 1. A ghost elimination reference signal detecting device for detecting a ghost elimination reference signal inserted by an 8-field case in a vertical blanking period of a television signal, wherein the ghost elimination reference signal is obtained from an input television signal. A reference signal line detecting means for detecting a line to be inserted, a capturing means for capturing the signal of the line detected by the reference signal line detecting means, and storing the signal in a storage element; Operation means for performing an operation on the signal stored in the storage element, and an operation substantially the same as the operation of the operation means for the result of the operation by the operation means and the pedestal portion in the period immediately before the rise of the ghost elimination reference signal. Comparing means for comparing the result calculated in advance by performing the above, and the above-mentioned acquisition based on the comparison result of the comparing means. Ghost canceling reference signal detection apparatus signals captured in means, characterized in that it comprises a determining means for determining whether a ghost cancellation reference signal. 2. The calculating means adds a value obtained by adding for 8 fields to a signal captured by the capturing means in a period corresponding to approximately 2 μs period immediately before the rise of the ghost elimination signal. The ghost elimination reference signal detection device according to claim 1, wherein a maximum value is obtained from the inside. 3. The calculation means obtains the total sum of 8 fields with respect to the signals captured by the capturing means during the capturing period corresponding to approximately 2 μs period immediately before the rise of the ghost elimination signal. The ghost elimination reference signal detection device described.