JPS6019387A - Comb line filter device - Google Patents

Abstract

PURPOSE:To reduce the circuit scale and the number of stages of delay circuits and also a YC separating circuit and an averaging circuit for chrominance signal incorporated together with high performance by constituting the circuit that the separation of a luminance signal and the separation of a chrominance signal and the averaging are conducted at the same time. CONSTITUTION:A delay circuit inputting a PAL system color television signal 90 sampled by a clock signal having four times the chrominance subcarrier frequency and having each clock period delay output of the 1,135th stage, 2,269th stage, 2,270th stage and 2,271th stage, an adder circuit 58 adding the input and the delayed output of the 2,270th stage and outputting a luminance signal 91, a signal switching circuit 60 selecting the 2,271th stage delayed output when the input sampled phase is 0 deg. and 180 deg. and selecting the 2,269th stage delayed output when the phase is 90 deg.20 and 270 deg. while taking the sampling phase of the chrominance subcarrier burst as 180+ or -45 deg., and a chroma band pass filter 61 inputting an output of a subtraction circuit 59 subtracting the selected output of the said signal switching circuit from the 1,135th stage delayed output and outputting a chrominance signal 92, are provided so as to conduct the separation of the luminance signal and the chrominance signal and the averaging at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a YC separation circuit that separates a luminance signal (to) and a color signal (C) in a PAL color television receiver, and particularly relates to a YC separation circuit that separates a luminance signal (from) and a color signal (C) in a PAL color television receiver. YC division of PAL color television signal using D
This invention relates to a comb-shaped digital filter that performs matrix averaging.

Conventional configurations and their problems In recent years, with the speeding up of digital ICs, advances in semiconductor LSI technology, and reductions in the cost of electronic devices, analog 0 and zero signals are increasingly being processed digitally. Ma1ko,
Things that were previously difficult to do with analog processing are now being realized through the use of mechari.

Recently, digital signal processing is being applied to audio signal processing inside power-unit televisions, and the trend is toward higher quality and multifunctionality.

As for the comb filter related to the present invention, those using an analogous Crow delay line or CCD have recently been adopted in N'rSC system receivers. In the NTSC system, the luminance signal @
(Yl and color signal (C1 are interleaved, 1
The separation can be performed by a comb filter using a delay line of H (H is a horizontal period, hereinafter abbreviated as such). On the other hand, P
In the AL system, in order to improve the effects of phase distortion on the transmission line, the polarity of one (V signal) of two orthogonal color signals (U, V signals) is inverted for each IH and transmitted. And b l! ``I Ria-) f Can the influence of phase distortion of the transmission life be improved by reproducing the color signal by taking the average value of these two lives? ■Since the signal is inverted every IH, the frequency spectrum is 1 If you try to shift /2H and perform frequency interleaving similar to the NTSC system, the V signal and R degree signal will overlap.For this reason, the carrier color signal in the PAL system has a horizontal frequency and 1/4 line off.・The spectral arrangement is as shown in Figure 2 (a).In order to perform the YC separation of the PAL system, A comb-shaped filter using a 2-II delay line is required, and an IH delay line is required at the t end of the average value of the color signal, and even when digitalized, a large amount of metric is required, so it is rarely implemented. Ta.

A conventional PAL comb filter will be described below with reference to the drawings. FIG. 1 is a block diagram of a configuration example of a conventional PAL comb filter. The input signal can be an analog signal or an digital signal, as long as it is a sampled signal. The 2H delay line (1), addition circuit (2), and subtraction circuit (3) constitute a 2H comb filter.
The frequency characteristics of the luminance signal (9) are as shown in 03 in Fig. 2 (a) when Y=1+Z-2H, and the color signal (nj and C
=1-Z-2Hte as shown in Fig. 2(b) (7) <14). Since the luminance signal (to) and the chrominance signal (U, V) have a distribution as shown in FIG. 2(a), the luminance signal and chrominance signal can be separated by such a filter. Since the PAL system requires further averaging of color signals, signals outside the band are removed using a bandpass filter (4), and then averaged using an IH delay line (5), an addition circuit (6), and a subtraction circuit (7). is being carried out. This circuit configuration is also an IH comb filter circuit, and its frequency characteristics are as follows: U signal output Uη is equal to α of Fig. 2 + C), and ■ signal output C12 is as shown in Fig. 2 (C) t + CS. PAL 4:l
-') sent to the circuit.

However, in the above configuration, since the 2H comb filter for YC separation and the 17 averaging circuit are separate, a total of 3H delay lines are required, and the circuit size increases when digitalized. and 2.

OBJECT OF THE INVENTION An object of the present invention is to provide a PAL color television signal Y
It is an object of the present invention to provide a comb filter device for PAL which integrates a comb filter of a C separation circuit and a color signal averaging circuit.

Structure of the Invention The PAL comb filter device of the present invention manually processes a PAL color television signal sampled with a black riff signal of four times the color subcarrier frequency synchronized with the color subcarrier, and processes it in 1135 stages. Eye, 2269th row, 2270th row, 22
a delay circuit having 71 stages of each clock cycle delay output;
An addition circuit that adds the input and the 2270th stage delayed output to output a luminance signal, and a sampling phase of the color subcarrier burst of 1
Assuming 80 ± 45 degrees, the manual sampling phase is 0 degrees and 180 degrees.
a signal switching circuit that selects the 2271st stage delayed output when the input sampling phase is 90 degrees and 2269th stage delayed output when the input sampling phase is 90 degrees and 270 degrees; It has a subtraction circuit that subtracts the selected output, and a zero-mover pass filter that inputs the output of the subtraction circuit and outputs a color signal. This method simultaneously separates the luminance signal and chrominance signal from the PAL color television signal and averages the chrominance signal, thereby achieving the effect of reducing the number of delay circuit stages.

Furthermore, the present invention divides the 1135-stage delay section in the first half of the delay circuit into 1 stage, 1 stage, and 1134 stages like the latter half,
A similar signal switching circuit is provided and the color signals between three lines are averaged.

Furthermore, in the present invention, although the total number of delay circuits used is approximately the same and corresponds to <2H, it is divided into 1184 stages, 2 stages, and 1134 stages, and 1 line around the sample point and 1 D
・It is configured to separate the luminance signal and separate and average the color signal from sample points before and after the riff.
The number of delay circuit stages and circuit scale can be further reduced, and an integrated high-performance YC separation circuit and color signal averaging circuit can be obtained.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Before that, the properties of a PAL color television signal sampled at four times the color subcarrier will be explained using FIG. FIG. 3 is an explanatory diagram showing the positional relationship between sampled PAL color television signal values and sample points on the screen, and the sample points are arranged on a grid. The arrow inside the circle indicates the sampling phase of the color signal at the sampling point, and the vertical direction is one horizontal line period (11
35 ri〇" riff period), the horizontal direction is 1 ri 0 riff period. nth lie, 7 (sample points 30, 31, 32, ...)
In this case, the color signal is sent as U, -V signals, and on the n+lth line (sample points 4o, 41, 42, etc.), the color signal is U.
, +V signal. It is assumed that the luminance signal has a high vertical phase difference and takes approximately the same value in the vertical direction. However, since the color signal is band-limited, it is considered that the U, V, and signals around the sample point are almost the same. Since the signal is four times as large as the chrominance subcarrier and is synchronous with the chrominance subcarrier, the single chrominance signal component is sampled and immediately decoded on the U and V axes to obtain a value of t. ΔSkin lV is an error component due to phase distortion.

Color subcarriers or U signals are in the same phase at 1186
riDtsuk cycle interval, that is, sample point (a)G]) (L
42, it shifts to the right by 190' per line.

The V signals have the same phase at intervals of 1134 cycles, that is, at sampling points (LtC1→(4)), which shift to the left by 10 degrees every line. Since the color signal is in reverse phase, it will be erased by adding it.Also, the color signal is the sum of the sample points diagonally above), and if you take the difference, it will be U, V, aU or JV. You can get this.

FIG. 4 is a diagram of one embodiment of the present invention.

The input signal may be a sampled analog human power input (here, it is a sampled and quantized PAL digital color television signal.The D/T signal is generated by a clock generation circuit not shown). It is synchronized with the color printing carrier wave burst and has a frequency four times that of the color printing carrier wave burst.

The input signal (control) passes through the 1135th stage, 1134th stage, and 1st stage shift register (51)), is added to the input signal amount by an adder c, and is output as a luminance signal F34u).

In FIG. 3, if the input is sample point (4]), shift 1.・The output of Jister□□□ is sample point 12+),
The ■ and ΔV signals are added together, and the luminance signal component 2 is
It becomes YI.

Furthermore, the operation of the signal switching circuit r1 is such that when the sampling phase is 0 degrees and 180 degrees (that is, the U signal), the 2271st stage delayed output (that is, the output of the shifted register (i7)) is selected, and the sampling phase is 90 degrees and 270 degrees (i.e. V signal)
At this time, the 2269th stage delayed output (the output of the Zunara shift register) is selected, so when the manual input is sample point 0 in Figure 3), the circuit subtracts (a) from sample point (11). Subtract by 1, output 2TJ, input or sample point 0 →
When , subtract shi J) from the sample point - profit and get 2V. When the input is the sample point a, it is -2U, and when the input is the sample point a, it is -2V, and the output of the subtraction circuit 69 is the nth
+15in human power: 2U, 2V, -2U
, -2V, etc., and when it is the 0th +2nd line, the polarity of ■ is inverted and output.

The bandpass filter (200) mixes the difference components of the luminance signals and passes the color signals U, ±V from the output of the one-subtraction circuit 6. As described above, the luminance signal and color id @ minute 1#I
#, color signals are averaged.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a diagram of another embodiment of the present invention. The principle is the same as that shown in Fig. 4.

The difference is that the color signal is averaged using 35 pixels. Dividing the shift register ('', I) in Fig. 4 into the 52 wheels of the shift register (b),
A signal switching circuit and an adding circuit (support) are added.

To explain this with reference to Figure 3, if the input is the sampling point (b), the adder circuit (to) calculates the sum of the sample points CD and c2D and outputs it as 2Y1, and the adder circuit (i9 is the sample point θQ and (2) ) and subtracting 1/2 from the sample point 61) to obtain a color signal output of 2U. Further, when the input is the sample point 83, a color signal of 2v is obtained from the sample point G71).

As described above, the luminance signal and color signal are separated and the color signals are averaged. Compared to the embodiment shown in FIG. 4, this is characterized in that the comb characteristic becomes sharper and the separation between the U signal and the V signal becomes better because the color signal is calculated from three lines of sample points. In the embodiment shown in FIG. 4, since the color signal passes only through the comb-shaped filter characteristic shown in (2), there is a drawback that the high-frequency component of the luminance signal is mixed with the color signal.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a schematic diagram of another embodiment of the present invention. (71) CnQ Kousai 1184 dan, 2 dan each,
It is a shifted register with 1184 steps. (7f9 is a signal switching circuit, QQ (c) is a subtraction circuit, (74)ff→ is an addition circuit, and the ring is a bandpass filter.

The luminance signal al) is separated in a manner similar to that of FIG. 4 and FIG. That is, it is Y-14-Z-2270. The subgroups of color signals will be explained with reference to FIG.

When the input is a sampling point (good) (sampling phase is 90 degrees), the adder circuit (1) is 1, -z-1136, 21134, respectively.
, -Z-2270. That is, the trowel is subtracted from the sample point 0υ, and ρυ is subtracted from the sample point (1). As a result, the error component is canceled in both cases, resulting in a value of 2V, and the output of the adder circuit 179 becomes 4V. If the input is the sample point θ, similarly adder 9 C4n It 1z-11, 3 respectively
4, Z-11, 36, and z-2270 are calculated, and the adder circuit Q→ outputs 4U. Similarly, color signal components are output at each sample point.

In this embodiment, when calculating the luminance signal, for example, if you use tooth 4 of sample point 6 in Fig. 3, you are predicting the luminance signal at sample point 0η, and when calculating the color signal, , its sample point O
This means that n @2 is entangled with the sample a @ (3]) around a. In the case of this embodiment, the separation characteristics of the luminance signal and chrominance signal are better than those of the embodiments shown in FIGS. 4 and 5, since both the luminance signal and the chrominance signal are 2H comb-shaped filters.

FIG. 7 is a block diagram of still another embodiment of the present invention.

The operating principle is exactly the same as the embodiment shown in FIG. The luminance signal is exactly the same as above. The output of the adder circuit Q barrel in Fig. 6 is as follows: When the input is the U signal: t-Z +Z -2 ~ When the human input is the V signal: 1+Z -Z -Z. 2270) King (z 1134 z +-1,
36), and depending on the sampling phase of the input signal, the latter 1
Just invert the sign of 100. This is the principle shown in FIG. 7, where the subtraction circuit 6 calculates Z-2270, and the subtraction circuit 6→ calculates z 1134 z 1136.

The sign inversion circuit (2) has its sign inverted controlled by the sampling phase of the input. This can be done by synchronizing one color subcarrier table and controlling the exclusive OR gate of 152 times the frequency. The adder circuit (c) outputs the U or V signal, the pad pasta (3) removes the luminance signal U component outside the '4iJ- range, and the color signal 0 is then output.

As described above, in this embodiment, the signal switching circuit shown in FIG. 6 is not used, but the same function is achieved by using a sign inverting circuit.

The deviation in the timing between the luminance signal and the chrominance signal due to the bandpass filter can be corrected by inserting a delay circuit into the luminance signal.

Effects of the Invention As is clear from the above explanation, the 7t-invention inputs a PAL color television signal sampled with a 90-riff signal at four times the color subcarrier frequency synchronized with the color subcarrier. 1+Z using a maximum of 2272 stages of delay circuits
- outputs a luminance signal by calculating z-1,135(1
The color signal is output by the calculation of z-1135 1).
This configuration has an excellent effect in that YC separation and a color signal with phase error corrected can be obtained with a small number of delay circuits. This has increased the possibility of introducing comb filters into PAL receivers.

Furthermore, by configuring the configuration to output the color signal by calculating z (1 (zl135 upper 14z - 4,135 hands))/2), the separation of the color signal U is further improved, and the transient characteristics of the color signal are improved. It has the effect of being improved.

Sara 1 Otsu (1z 2270) hand y 1135 (z+1
By configuring to output the color signal by calculating z~1), both the luminance signal and the chrominance signal can have a 2H comb filter configuration, and the separation of the luminance signal and the chrominance signal is further improved. Moreover, it is possible to obtain an excellent effect of simultaneously obtaining a color signal whose phase distortion has been corrected.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional PAL comb filter device, Fig. 2 is an explanatory diagram showing the frequency characteristics of the comb filter and the frequency distribution of a PAL color television signal, and Fig. 3
The figure is sampled using four times as many color subcarriers.
The figure is a glue lock diagram of one embodiment of the present invention, FIG. FIG. 7 is a block diagram of still another embodiment of the present invention. φ1) ~ q) η, (71) ~ (y3/delay circuit, Q'
i194i! l ljika (i 荀 (7 (all tri) < letter) (i) (foundation) arithmetic circuit, (W) i! Hiroshi Figure 1 Figure 2 Effect -----fH-----÷ Figure 3 Yo Y (Y2 Y3 Y4 Time Figure 4 Figure 5 Figure 7

Claims (1)

[Claims] The 1135th stage, the 2269th stage, using as input a PAL color television signal synchronized with the color subcarrier and sampled with a clock signal of four times the color printing carrier frequency, A delay circuit having a delay output for each block period at the 2270th stage and 2271st stage, an addition circuit that adds the input and the delayed output at the 2270th stage and outputs a luminance signal, and a sampling phase of the color subcarrier burst at 180± 45 degrees, the signal switching circuit selects the 2271st stage delayed output when the input sampling phase is 0 degrees and 180 degrees, and selects the 2269th stage delayed output when the manual sampling phase is 90 degrees and 270 degrees. and 11
A comb filter device comprising a subtraction circuit for subtracting the selected output of the signal switching circuit from the delayed output of the 35th stage, and a D-mavand filter for outputting a color signal by inputting the output of the subtraction circuit. 2. Input a PAL color television signal sampled with a D.Tsuku signal at four times the color print carrier frequency synchronized with the color subcarrier, and then select the 1st, 2nd, 1136th, and 2270th stages. a delay circuit having clock cycle delay outputs at the 1st, 2271st, and 2272nd stages, and a first addition circuit that adds the 1st stage delay output and the 2271st stage delay output to output a luminance signal. , the sampling phase of the color subcarrier burst is 180 ± 45 degrees, and the manual sampling phase is 0 degrees and 1
When the input sampling phase is 80 degrees, the 2nd stage delay output and 2270th stage delay output are selected, and when the input sampling phase is 90 degrees and 270 degrees, two signal switches are selected to output the input and 2272nd stage delay output. a second addition circuit that adds the outputs of the two signal switching circuits; a subtraction circuit that subtracts 1/2 of the output of the second addition circuit from the 1136th stage delayed output; A comb-shaped filter device 08 having a band pass filter for extracting the color signal, and a PAL signal sampled at four times the color subcarrier frequency synchronized with the color subcarrier.
System color television system signal is used as human power, tiat
a delay circuit having black riff period delay outputs for each of the 1136th stage, 1136th stage, and 2270th stage; a first addition circuit that adds the input and the 2270th stage delayed output to output a luminance signal;
When the sampling phase of the color subcarrier burst is 180±45 degrees, and the manual sampling phase is 0 degrees and 180 degrees, the first signal switching circuit selects the 1134th stage delayed output, and the second signal switching circuit selects the 1134th stage delayed output. operates to select the 1186th stage delayed output, and when the sampling phase is 90 degrees and 270 degrees, the first signal switching circuit selects the 1186th stage delayed output, and the second signal switching circuit selects the 1134th stage delayed output. Two signal switching circuits that operate to select the second delayed output, a first subtraction circuit that subtracts the output of the first signal switching circuit from the input, and a second delay output from the output of the second signal switching circuit. A comb filter device comprising: a second subtraction circuit for subtracting , a second addition circuit for adding the outputs of the two subtraction circuits, and a zero band bus filter for extracting a color signal from the output. 4. Sampled with a D-scan signal at four times the color subcarrier frequency synchronized with the color subcarrier;7. m PAL system color television signal is input, the 1134th stage, 1136th stage, and the 2270th stage each have an O-riff period delay output, and the input and the 2270th stage delay output are added to calculate the brightness ( A first adder circuit that outputs the number N, and a 227
a first subtraction circuit that subtracts the 0th stage delay output, and 1184
A second step that subtracts the 1186th stage delayed output from the 1186th stage delayed output.
The subtraction circuit and the sampling phase of the color subcarrier)\-st are set to 1
80 ± 45 degrees, input sampling phase is 0 degrees and 180 degrees
When the sampling phase is 90 degrees and 270 degrees, the sign of the output of the second subtraction circuit is inverted, and when the sampling phase is 90 degrees and 270 degrees, it is passed through as is. A comb filter device having a second addition circuit for adding outputs, and a zero band pass filter for extracting a color signal from the output of the second addition circuit.