JPH01276895A - Nonlinear signal processor - Google Patents

Abstract

PURPOSE:To stably realize a nonlinear feature in a simple constitution by digitizing the color difference signal of a baseband, supplying it through a high pass filter and a limitter to an adder (or a subtracter), and directly supplying it to the adder (or the subtracter). CONSTITUTION:One digitized color difference signal R-Y is directly supplied to one adder 22R or the subtracter. Simultaneously, the one color difference signal is supplied through one high pass filter means 30R and a limitter means 40R to the one adder or the subtracter, the other digitized color difference signal B-Y is directly supplied to another adder 22B or the subtracter, and the other color difference signal is supplied through another high pass filter means 30B and a limitter means 40B to the other adder or the subtracter. Thus, the necessary nonlinear feature can be stably realized in a simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.・ Δ Industrial application field B Invention A Existing necessity C Prior art D Problem to be solved by the invention E Means for solving the problem (Fig. 1) 1-゛ Effect G Example G1 One example Configuration (Figures 1 and 2) G2 Operation of one embodiment (Figures 1 to 5) G3 Configuration of another embodiment (Figure 6) G4 Operation of another embodiment (Figures 6 and 5) Figure 7) Effect A of the H invention Industrial application field The present invention relates to a nonlinear signal processing device using digital signal processing.

B. Summary of the Invention The present invention digitizes a baseband color difference signal and passes it through a high-pass filter and a limiter to an adder (or lfc).
This is a nonlinear signal processing device that can stably realize desired nonlinear characteristics with a simple configuration by supplying the signal to the adder (or subtracter) as well as directly to the adder (or subtracter).

C. Prior Art Conventionally, in a video tape recorder (V'l''R), emphasis processing has been performed in order to improve the S/N of the high frequency component of the luminance signal Y. The non-linear emphasis circuit has been praised for its ability to increase the amount of emphasis for crystal-level signals and reduce the amount of emphasis for crystal-level signals to prevent problems caused by excessive emphasis such as overmodulation and inversion. There is.

V 'I' Depending on H, carrier color signal (chroma signal)
In order to improve the signal-to-noise ratio of C, some devices perform non-linear emphasis processing on sideband waves.

Conventional non-linear emphasis circuit for Nori I frame signal (
10) is an adder (12) inserted in the main transmission line (main line) (11) and a main transmission line (11), as shown in Fig. 8, for example.
A bandstop filter (
(13), a limiter (14) and an attenuator (15) inserted between the trap (13) and the adder (12).

Note that the limiter (14) is configured by, for example, a pair of diodes connected in parallel with opposite polarities.

As is well known, the voltage-current characteristics of a diode are non-linear characteristics that bend at the so-called knee potential. In a conductive state where a signal current flows sufficiently, the diode operates as a switch with a small internal resistance, and the signal Amplitude is limited.

When the signal current is weak, the internal resistance of the diode becomes large and the limiter (14) operates as a compressor.

When no signal current flows through the diode, its internal resistance becomes infinite, and the trap (3) is not affected by the limiter (14).

Therefore, the fundamental frequency characteristic of the emphasis circuit (10) is determined by the trap (13), the amount of emphasis is determined by the attenuator (15), and the emphasis characteristic for the signal level is determined by the limiter (14). As shown in Fig. 9, the frequency characteristics of the nonlinear emphasis circuit (1o) become as the human power No. 13 level becomes lower.
The characteristic is that the high-frequency components of both sidebands are emphasized.

Also, by connecting the above-mentioned non-linear emphasis circuit between the output terminal and the inverting input terminal of the operational amplifier,
A nonlinear emphasis circuit with reverse characteristics is constructed.

Specific configuration examples of the emphasis circuit and de-emphasis circuit are shown in FIGS. 10 and 11.

In FIG. 1O, a trap consisting of a capacitor C11, a coil Lll, and an adjusting resistor R11 is connected to the base of a transistor Q12, and the next stage transistor Q13 is connected to the base of a transistor Q12.
The output of the emitter of is connected in antiparallel to the diode Dl
It is foot-punctured to the base of transistor Q12 through a gate consisting of l and υ12. The output of this emphasis circuit is from the emitter of transistor Q14.
It is derived through diode 1''D13.

In Fig. ti, capacitor (, :2L, coil L2
1 and an adjustment resistor) < 21 is connected to the base of the transistor Q22, and the output of the emitter of the next stage transistor Q23 is connected to the transistor Q22 through a limiter consisting of anti-parallel connected diodes D21 and D22. will be fed back to the base. The output of this de-emphasis circuit is derived from the collector of transistor Q21.

D Problems to be Solved by the Invention The analog nonlinear emphasis circuit described above has unstable emphasis characteristics because its nonlinearity depends on the nonlinear characteristics of semiconductor elements such as diodes. .

There were problems such as the need for adjustments.

To solve this problem, for example, digitization using bilinear transformation can be considered.

However, if the band-stop filter characteristics shown in Figure 9 above are digitized as they are, the transfer function of the band-stop filter generally becomes a quadratic function of z-1, resulting in a complex configuration. There is one living.

Furthermore, although the bandwidth of the chroma signal is relatively narrow at around ±500kHz, the subcarrier frequency f sc is 3.5
Since the frequency is relatively low at 8 MIIz, the sampling link frequency is set to 2.
It has to be set to a higher value than fsc, which causes problems such as a complicated circuit configuration and high power consumption.

When reproducing v″l″H, a comb-shaped filter with a center frequency of E sc is used to remove crosstalk of chroma signals from adjacent tracks, and digital encoder is used in the frequency domain of the low-frequency converted chroma signal. It is difficult to perform fan processing.

In view of the above, an object of the present invention is to provide a nonlinear signal processing device with a simple configuration, low power consumption, and stable characteristics.

E Means for Solving the Problems The present invention supplies one digitized color difference signal (H-Y) directly to one adder (22) 1) or subtracter, and also supplies one color difference signal (H-Y) directly to one adder (22) 1) or subtracter. High-pass filter means (
30R) and a limiter means (40R) to one adder or subtracter, and the other digitized color difference signal CB-Y) is directly supplied to the other adder (22B') or subtracter. At the same time, the other color difference signal is passed through the other high-pass filter means (30B) and limiter means (40B).
) to the other adder or subtracter.

According to this configuration, the required nonlinear characteristics can be stably realized.

G. Embodiment Hereinafter, an embodiment in which a nonlinear signal processing device according to the present invention is applied to chroma emphasis of a VTR will be described with reference to FIGS. 1 to 5.

Structure of an embodiment of G1 The structure of an embodiment of the present invention is shown in FIG.
The configuration of < is shown in Figure 2.

In FIG. 1, (30R) and (30B) are digital high-pass filters, and (40R) and (40B) are digital limiters, each of which is configured as shown in FIG.

The carrier color signal C is supplied to a color demodulator (51) to
The paired color difference signals (R-Y) and (B-Y) are adjusted to tM. /11) Converter (23)? ), the red difference signal (R-Y) passes through the main line (21)1) and is sent to the adder (22R
), and is also supplied to the adder (22) 1) via a high-pass filter (30R) and a limiter (40R). Similarly, the blue difference signal (B-Y) that has passed through the A-D converter (23B) is supplied to the adder (22B) via the main line (21B), and is also supplied to the high-pass filter (30B).
) and limiter (40B), adder (22B
). The outputs of both adders (22R) and (22B) are converted to 1)- to converters (24R) and (24B), respectively.
1 to a color modulator (52), from which a non-linear enfaunulated carrier color signal Cempb is output.

As described above, in this embodiment, a high-pass filter is used in place of the trap shown in FIG. 8, etc., in order to perform non-linear emphasis processing on the color difference signal, which is the base hand signal.

As shown in Figure 2, the high-pass filter (30) is connected to the main line (2
first and second coefficient multipliers (31) and (32) to which the input signal from 1) is commonly supplied;
) and (32) are respectively supplied to the adder (3
3) and a unit delay device (34), the delay device (34)
The output of is supplied to an adder (33) to form 'ζ'.

The limiter (40) includes first and second nonlinear conversion circuits (
)<OM) (41) and (42) and the main line (43)
)<OM(41) is inserted upstream of the adder (4
4) and a unit delay device (45) that feeds back the output of 120M (42) to the adder (44), and the output of the adder (44) is commonly supplied to both ROMs (41) and (42). The output of the ROM (41) is derived and configured.

-ゝ-ゝ＼, G2 Operation of the Embodiment Next, the operation of the present embodiment will be explained with reference to FIGS. 3 and 4.

As mentioned above, in this embodiment, since the non-linear emphasis processing is performed using the base band, the trap (13) in the analog non-linear emphasis circuit shown in FIG.
As shown in FIG. 3A, the limiter (14) and attenuator (15) include a high-pass filter (3) in which a coil L and a resistor Re are connected in series, and a diode pair (4) connected in reverse series.
) are connected in parallel. and,
By replacing the internal resistance of the diode pair (4) with a transformer resistor Rv, its equivalent circuit can be expressed as shown in FIG.

Further, the emphasis characteristic is based on the characteristic in the frequency region shown in FIG. 9 above.

The transfer function of the circuit shown in FIG. 3B is expressed as the following equation (1).

Rv (sl, +Re) L 1 + τ2S where r t =L/RIL” (la) τ2 =
L/ (Rg + Rv) ... (lb)
By subjecting this equation (1) to the bilinear transformation shown by the following equation (2), a digital filter having the characteristics shown by equation (3) can be obtained.

Here l゛ is the sampling period 1+ - l゛1゛■+□ Here 8 (Rv) -He /Rv/ (1+2 r
2/'l”) ...(3ωB (Rv)
-(12r2 /'l') / (1+21'2 /l
') ... (3b) C-= 1 + 2 r1/T
”...(
3c) 1)=1-2τr/l”
(3d) In this equation (3), the numerator (C+ Dz -s) is configured in the form of a high-pass filter (30) in Figure 2, and C and D are multipliers (31) and It becomes the coefficient of (32). Also, the denominator 1
-B (Rv) z-” is the glue transmitter (40) in the same figure.
Among them, the second ROM (42), the addition te+v(4
4) and a delay device (45) in the form of a feedback loop. Furthermore, the molecule A(Rv) is the first ROM (
41).

Since the internal resistance Rv of the diode pair (4) changes non-linearly depending on the input signal level, the ROM (
By storing data corresponding to equations (3a) and (3b) in 41) and (42), a digital limiter (40) with stable characteristics is configured without requiring any adjustment.

In this case, the numerator A(Rv) mainly represents the amplitude characteristics, the denominator +31ν) mainly represents the frequency characteristics,
The characteristics of the nonlinear emphasis circuit shown in FIG. 1 change as shown in FIG. 4 with respect to changes in Rv.

As shown in FIG. 5A, the digital limiter (40) in FIG. 2 moves the ROM (42) to the main line (43) within the feedback loop, and also moves the ROM (42) to the main line (43) downstream of the feedback loop. A, (Rv)/B(Hv
) (OM(41)1)
may be replaced with a limiter (4011) inserted. Or, as shown in Figure B, the RO of the main line (43)
While moving M(41) into the feedback loop on the main line (43), B (Rv ) /A (Hν)
It may be replaced with a limiter (40J) that foot-banks the output of the ROM (42J) in which data corresponding to is stored to the ζ adder (44) via the unit delay device (45).

However, in the limiters (40H) and (40J) of FIG. 5, the dynamic range of data to be stored in the ROM (41H) or (42J) becomes large.

The embodiments in which the present invention is applied to V 1' H chroma emphasis have been described above, but when the present invention is applied to chroma emphasis, the adder (22R) in FIG.
and (22B), a subtracter may be used in place of the adder (22) in FIG.

In either case, in this embodiment, the baseband color difference (No. 4) is digitally processed instead of the carrier color signal, so a sampling frequency of approximately Iz (for example, LM) is sufficient, which simplifies the circuit configuration. At the same time, power consumption is reduced.

G] Comparison of Other Embodiments Next, with reference to FIGS. 6 and 7, another embodiment in which the nonlinear signal processing device according to the present invention is applied to the chroma emphasis of a VTR will be described.

The configuration of another embodiment of the present invention is shown in FIG. In FIG. 6, parts corresponding to those in FIGS. 1 and 2 are given the same reference numerals, and redundant explanation will be omitted.

In FIG. 6, (601 and (60B)) are digital limiters, and are digital MyR filters (601 and (60B), respectively).
30)? ) and (30B) are supplied.

One digital limiter (60R) includes first and second multipliers (61R) and (62k), and an adder 6 inserted upstream of the main line (63k) multiplier (6111).
4) and the output of the multiplier (62R) to the adder (64R)
The output of the adder (64R) is connected to the square multiplier (61R) and (62).
1? ), and the output of the multiplier (61) is derived and configured.

The other digital limiter (60B) is configured similarly.

(71) and (72) are nonlinear conversion circuits (ROM), (
73) is a vector calculation circuit, which includes a limiter (60R
) and (60B), the signals of main lines (63R) and (63B) are supplied to a vector calculation circuit (73), and the output of this calculation circuit (73) is supplied to ROMs (71) and (72). The output of one ROM (71) is the limiter (6
It is commonly supplied to the multiplier (61R) and CBIB) of each one of the multipliers (61R) and (60B), and the ROM of the other
The output of (72) is commonly supplied to the other multipliers (62R) and (62B) of limiters (60R) and (60B). The rest of the structure is the same as that shown in FIGS. 1 and 2 above.

G4 Operation of other embodiments The operation of the embodiment of FIG. 6 is as follows.

Each main line (63R) of limiter (60R) and (60B)
and (63B), the high-frequency red difference signal (RY) with amplitude U
H and the high-frequency blue difference signal (B-Y))l with the amplitude V are supplied to a vector calculation circuit (73), where the amplitude n of the original high-frequency color signal is calculated. This calculation result is supplied to both ROMs (71) and (72), and the amplitude characteristic coefficient A (Rv) as shown in equation (3a) above is read out from one ROM (71), and the other A frequency characteristic coefficient B (Rv) as shown in the above equation (3b) is read from the ROM (72).

In the multipliers (61R') and (61B) on each side of the limiters (60R) and (60B), the amplitude characteristic coefficient A (
Rv) is multiplied, and each other multiplier (62R)
and (62B), each area color difference signal (RY)H
and (B-Y))l is multiplied by the frequency characteristic coefficient 3 (Rv) to obtain high-frequency color difference signals (R-Y)H and (B-Y)
H is the amplitude of the original high-frequency color signal / is 7;
Non-linear emphasis is applied.

The level of the carrier color signal C supplied to the color demodulator (51) is, for example, OdB, and its phase is, for example, as shown in FIG.
, H, if it is red or magenta,
Flesh color difference signal (R-
The composite vector of Y) and (B-Y) becomes the original color signal R4 or Mi as shown by the broken line in the figure.

The original color signal is at the upper limit of its signal band (500kHz)
When the frequencies are close to each other, the color difference signals (R-Y) and (B-Y) from the iM Mlld device (51) pass through the high-pass filters (30) and (30B) and are sent to the limiter (60). ) and (60B), supra No. 9
Referring to the figure, the signals are each compressed at the same rate of, for example, 6 dB, are supplied to a color converter (52), and are again converted into a color sending signal for use.

At this time, the composite vector of the compressed color difference signals is Rc or Mc, which has been compressed in fWII'fa (saturation) compared to the original color 4fj, number Ri or Mi, as shown by the solid line in Fig. 7. In the embodiment shown in FIG. 6, the hue does not change before and after compression.

On the other hand, in the embodiments shown in FIGS. 1 and 2, when a large amplitude general color feeding signal is supplied as described above,
The hue changes before and after compression.

This is the red difference signal (R-Y) from the color demodulator (51).
) and (B-Y) are limiters (40R) and (40B
), compression is performed at different rates depending on the magnitude of the amplitude.

In the example shown in Figure 7, the large amplitude red difference signal (R-Y) is 6
dB compression, whereas the small amplitude blue difference signal CB-
Y) is compressed by about 2 dB, and the composite vector of the compressed color difference signals becomes Rd, which has a different hue from the original color signal Ri, as indicated by the dashed line in the figure. In addition, in the example of FIG. 7B,
The large amplitude red color difference signal (R-Y) is compressed by 6 dBEE, while the small amplitude color difference signal (B-Y) is reduced by about 4.5 dBEE.
The composite vector of the compressed color difference signal is 1 in the same figure.
As shown by the dotted chain line, the hue is different from the original color signal Mi.
becomes Md.

As can be easily understood from FIGS. 7A and 7B, in the embodiments shown in FIGS. 1 and 2, the closer the hue of the original color signal is to either one of the color difference signal axes, the more As the difference in compression ratio increases °ζ, the hue shift of the compressed color signal increases.

By the way, the digital limiter (40) shown in Figure 2 above is
As shown in FIG. 5A or B, ROM (41).

(42) in the feedback loop or on the main line, and in response to this movement,
It was possible to change the coefficient data stored in the other ROM.

Similarly, the digital limiter (60R) and (60R) in FIG.
0B) is each multiplier (61K), (62R) and (6
1B) and (62B) in the feedback loop or on the main line, and in response to this movement, the coefficient data stored in the ROM connected to the other multiplier is changed to the above-described embodiment. can be changed in the same way.

In the embodiment shown in FIG. 6 as well, as in the actual AI example shown in FIG.
A sampling frequency of about MHz is sufficient.

In addition, in the embodiment shown in Fig. 6, by calculating the vector sum of the flesh color difference signals, non-linear emphasis is performed according to the amplitude of the original (shell feeding color signal), so the hue is kept constant before and after the emphasis. It is possible to maintain the ROM (71) and (72) as a flesh color difference signal (R-Y
) and (B-Y), the circuit configuration can be further simplified.

1. Effects of the Invention As detailed above, according to the present invention, a baseband color difference signal is digitized and sent to an adder (or -Nc′!j#″a) via a high-pass filter and a limiter. Since the signal is supplied directly to the adder (or subtracter), a nonlinear signal processing device that can stably realize the required nonlinear characteristics with a simple configuration can be obtained.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing an embodiment of the nonlinear signal processing device according to the present invention and the configuration of its essential parts, FIG. 3 is a wiring diagram for explaining the present invention, and FIG. 4 is a block diagram showing the configuration of the main parts thereof. FIG. 5 is a block diagram showing the configuration of the main part of the embodiment of the present invention. FIG. 6 is a block diagram showing the configuration of another embodiment of the present invention. The figure is a diagram for explaining the operation of another embodiment of the present invention, FIGS. 8 and 9 are block diagrams and characteristic curve diagrams showing a configuration example of a conventional nonlinear emphasis circuit, and FIGS. FIG. 11 is a wiring diagram showing a conventional nonlinear emphasis circuit and a specific configuration example of the nonlinear emphasis circuit. (30), (30R>, (30B) are digital area filters, (40), (40R)
, (40B), (60)? ). (6011) is a digital limiter, (41), (
42). (71) and (72) are nonlinear conversion circuits (ROM)
, (61)1), (61B), (62
R), (6211) is a multiplier, and (73) is a hector arithmetic circuit.

Claims (1)

[Claims] One of the digitized color difference signals is directly supplied to one of the adders or subtracters, and one of the color difference signals is added to the one of the above through one of the high-pass filter means and the limiter means. the digitized color difference signal is directly supplied to the other adder or subtracter, and the other color difference signal is passed through the other high-pass filter means and limiter means to the other color difference signal. A nonlinear signal processing device characterized in that the signal is supplied to an adder or a subtracter.