JP3110945B2 - Digital demodulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital demodulator capable of performing demodulation using the same circuit regardless of whether an AM signal or an FM signal is input.

[0002]

[Prior art]

Conventional example 1. First, as one of the conventional examples of performing AM demodulation,
An NTSC color demodulator that performs color demodulation of an NTSC color television signal will be described.

FIG. 12 is a block diagram showing a main part of a television receiver including a conventional NTSC color demodulation circuit. In FIG. 12, reference numeral 1 denotes an antenna for receiving a television broadcast wave; The tuner 3 demodulates the received radio wave, 3 is an external input terminal for inputting an external television signal such as a VTR, and 4 is whether to receive a television broadcast or an external television signal such as a VTR. AV selector for selecting, 5 is AV
An A / D converter for A / D converting the television signal input from the selector 4, 6 a is a Y / C separation circuit for performing Y / C separation of the digital television signal output from the A / D converter 5, and 7 a is A sync separation circuit that separates a sync signal from a luminance signal (hereinafter, referred to as a Y signal) input from the Y / C separation circuit 6a, and 8 deflects the beam of the CRT 10 according to the sync signal output from the sync separation circuit 7a. The deflection system 9 performs Y output from the Y / C separation circuit 6a.
A luminance signal processing circuit for performing luminance signal processing on a signal, 11
a is a color signal (hereinafter, referred to as a color signal) output from the Y / C separation circuit 6a.
C signal), an NTSC color demodulation circuit for performing color demodulation based on a pulse (hereinafter, referred to as a burst position pulse) for specifying a burst position from the sync separation circuit 7a, and 12 an NTSC color demodulation circuit. A TINT adjustment circuit that performs TINT adjustment on the two types of color difference signals output from the TINT adjustment circuit 11a.
A COLOR adjustment circuit 14 for performing COLOR adjustment on the two types of color difference signals after the INT adjustment, and a color difference signal RY signal, a BY signal output from the COLOR adjustment circuit 13, and an output from the luminance signal processing circuit 9. An RGB matrix circuit 15 for obtaining an R signal, a G signal, and a B signal based on the Y signal. Reference numeral 15 denotes an R matrix input from the RGB matrix circuit 14.
Signal, G signal, and B signal are converted into analog R signal, G signal, and B signal.
A D / A converter 10 for converting the signal into a signal is a CRT for displaying an image based on the analog R signal, G signal, and B signal from the D / A converter 15.

Next, the operation of the conventional example 1 will be described. The video signal received by the antenna 1 and output from the tuner 2 and the video signal from the external input terminal 3 are output to the AV selector 4, one of which is selected and output to the A / D converter 5.

An A / D converter 5 converts a video signal output from the AV selector 4 into a digital signal,
Output to the separation circuit 6a. Y / C separation circuit 6a is A / D
The video signal output from the converter 5 is separated into a Y signal and a C signal, the Y signal is output to the synchronization separation circuit 7a and the luminance signal processing circuit 9, and the C signal is output to the NTSC color demodulation circuit 11
output to a. The synchronization separation circuit 7a includes a Y / C separation circuit 6
a from a Y signal output from a.
YSYNC) and a vertical synchronizing signal (hereinafter, referred to as VSYNC) are separated and output to the deflection system 8, and further, based on HSYNC, a burst position pulse is transmitted to the NTSC color demodulation circuit 1.
1a.

The deflection system 8 generates a horizontal deflection current and a vertical deflection current from HSYNC and VSYNC output from the synchronization separation circuit 7a, and outputs them to the CRT 10. The luminance signal processing circuit 9 performs an operation on the Y signal input from the Y / C separation circuit 6a to adjust image quality and brightness. NTS
The C color demodulation circuit 11a demodulates the color of the C signal with a 4Fsc clock of burst synchronization and a burst position pulse input from the synchronization separation circuit 7a, and a red difference (hereinafter referred to as RY) signal and a blue difference (hereinafter referred to as "RY") signal. , BY) are output to the TINT adjustment circuit 12.

The TINT adjustment circuit 12 performs an operation on the RY signal and the BY signal output from the NTSC color demodulation circuit 11a to adjust the TINT. COLOR
The adjustment circuit 13 outputs the R output from the TINT adjustment circuit 12.
The operation is performed on the -Y signal and the BY signal, and COLOR
Make adjustments. The RGB matrix circuit 14 controls the Y signal output from the luminance signal processing circuit 9 and the COLOR adjustment circuit 1
3 is operated on the RY signal and the BY signal output from the D / A converter 15.
Output to The D / A converter 15 converts the primary color RGB signals output from the RGB matrix circuit 14 into analog signals and outputs the analog signals to the CRT 10. The CRT 10 performs a deflection operation using the horizontal deflection current and the vertical deflection current input from the deflection system 8, and projects the primary color RGB signals output from the D / A converter 15.

Next, the color demodulation circuit 1 for NTSC shown in FIG.
The operation of 1a will be described. FIG. 13 shows the configuration of the NTSC color demodulation circuit 11a, and FIG. 14 shows a diagram explaining the operation principle.

In FIG. 13, reference numeral 16 denotes an NTSC arrangement discriminating circuit for judging the arrangement based on the C signal and the burst position pulse, and 17 denotes an inversion of the C signal when the inverted signal output from the NTSC arrangement discriminating circuit 16 is at H level. An RY / BY separation circuit 18 separates the RY signal and the BY signal from the C signal inverted by the inversion circuit 17 based on the separation signal output from the NTSC arrangement discrimination circuit 16. Is shown.

The NTSC color demodulation circuit 11a thus constructed operates with a 4 Fsc clock synchronized with the burst signal, and the C signal input from the Y / C separation circuit 6a is composed of the RY signal and the B signal. As shown in FIG. 14, the -Y signal is represented by-(RY), BY, RY,-(BY),-(R
−Y),... Are multiplexed in the order of
The value of the burst signal is a local maximum at-(BY),
The minimum value is obtained at BY, and 0 is obtained at RY and-(RY). That is, the target pixel of the sampled C signal is-(RY), BY, RY,-(BY).
Is determined by referring to the value of the burst signal and further by the number of pixels from the reference position to the target pixel.

The NTSC alignment discriminating circuit 16 of FIG. 13 refers to the value of the burst signal based on the burst position pulse, and further counts the number of pixels from the referenced position to the pixel of interest, as shown in FIG. -Y),-(BY)
At the position (1), a signal for inverting these signals is output to the inversion circuit 17, and a separation signal for separating RY and BY is output to the RY and BY separation circuit 18. The inversion circuit 17 outputs-(R
-Y) signal and-(BY) signal are inverted, and RY,
Output to the BY separation circuit 18. The RY and BY separation circuit 18 separates these into an RY signal and a BY signal by a separation signal and outputs the separated signals.

Conventional Example 2. Next, as another conventional example of performing AM demodulation, a PAL color demodulator that performs color demodulation of a PAL color television signal will be described.
FIG. 15 is a block diagram showing a main part of a television receiver including a conventional PAL color demodulation circuit.
Reference numeral 11b denotes a PAL color demodulation circuit, and the other configuration is shown in FIG.
Therefore, the same reference numerals are given and the description is omitted.

Next, the PAL color demodulation circuit 11 shown in FIG.
The operation of b will be described. FIG. 16 shows the PA of FIG.
FIG. 17 shows a configuration of the color demodulation circuit for L, and FIG. In FIG. 16, reference numerals 17a and 17b denote inverting circuits, similar to those used in the NTSC color demodulating circuit of FIG. The output is inverted. Reference numeral 19 denotes 1 which delays the C signal by 1H period.
An H delay line memory, 20 is an adder for adding the C signal delayed by 1H period by the 1H delay line memory 19 and the original C signal, and 21 is a 1H period from the original C signal by the 1H delay line memory 19. A subtractor 22 for subtracting the delayed C signal is a PAL arrangement discriminating circuit 22 for judging the arrangement based on the C signal, the burst position pulse and the line switching signal.

In the PAL color demodulation circuit 11b configured as described above, the PAL arrangement determination circuit 22 operates with a 4Fsc clock synchronized with the burst, and outputs the C signal input from the Y / C separation circuit 6a. The sequence of data is n
The line, the (n + 1) th line, the (n + 2) th line, and the (n + 3) th line are multiplexed as shown in FIG. In addition, as shown in FIG.
As for the −Y component, the RY component can be extracted by subtraction, and FIG.
In the PAL color demodulation circuit of FIG.
And the adder 20 and the subtractor 21 perform this extraction processing.

The BY and RY components extracted by the adder 20 and the subtractor 21 are obtained by multiplexing inverted data and non-inverted data as shown in FIG.
Only the inverted data is again inverted by the two inverting circuits 17a and 17b and the PAL arrangement discriminating circuit 22 to obtain the RY signal and the BY signal of the demodulated signal. The PAL arrangement determining circuit 22 refers to the value of the burst signal by the burst position pulse, and further counts the number of pixels from the referenced position to the pixel of interest, and as shown in FIG. 17, − (BY).
An inversion signal is output, and the line switching signal and the reference value and the number of pixels up to the pixel of interest are used to calculate-(R-
Y) Output an inversion signal.

Conventional Example 3. Next, as still another example of the conventional FM demodulation, a SECAM color demodulator for performing color demodulation of a SECAM color television signal will be described.

FIG. 18 is a block diagram showing a main part of a television receiver including a conventional SECAM color demodulation circuit. In FIG. 18, reference numeral 6b denotes a Y separation circuit for separating and outputting a Y signal from a composite video signal. Are HSYNC and VSYNC
And a sync separation circuit that outputs a signal for identifying the RY component and the BY component that are line-sequential (hereinafter, this identification signal is referred to as a line switching pulse), and 11c is a SECAM. The other configuration of the color demodulation circuit for use is the same as that of FIG.

Next, the operation of the SECAM color demodulation circuit 11c will be described. FIG. 19 is a diagram showing the configuration of the SECAM color demodulation circuit 11c of FIG. In the figure,
23 is a bell filter to which a composite video signal is inputted, 24 is a 1H delay line memory for delaying the output signal of the bell filter 23 for 1H period, 27 is a color order determination circuit for determining a color order based on a line switching pulse, 25 Is a 1H delay line memory 24 according to the output of the color order determination circuit 27.
And the output signal of the original bell filter 23 at 4.406 MHZ frequency discriminators 26a and 4.250.
A line-sequential switch 26a that outputs to the MHZ frequency discriminator 26b or vice versa.
The 4.406 MHz frequency discriminator 26b discriminates the MHZ signal. The 4.250M frequency discriminator 26b discriminates the 4.250 MHz signal from the other output signal of the line sequential switch 25.
HZ frequency discriminator.

In the SECAM color demodulation circuit 11c thus configured, the bell filter 23 has a characteristic opposite to that used at the time of modulation for the video signal output from the A / D converter 5, 1 after correcting the amplitude
H delay line memory 24 and line sequential switch 2
5 is output.

The line-sequential switch 25 switches between a current signal and a 1H delay signal for a signal having an RY component and a signal having a BY component in a line-sequential manner and outputs the signal as a continuous output. A signal having the RY component
The color order discriminating circuit 2 is used to obtain a signal having a Y component.
7. The signal having the RY component output from the line sequential switch 25 is 4.406 MH
FM detection is performed by the Z discriminator 26a to obtain an RY signal. A signal having a BY component output from the line sequential switch 25 is subjected to FM detection by a 4.250 MHz discriminator 26b to obtain a BY signal.

[0021]

A conventional color demodulation circuit for a television receiver or the like is constructed as described above.
The TSC color demodulation circuit and the PAL color demodulation circuit perform AM demodulation, and the SECAM color demodulation circuit performs FM demodulation.

In general, the circuit configuration of an AM demodulation circuit differs greatly from that of an FM demodulation circuit, and few circuits can be shared. The same applies to the color demodulation circuit of a television receiver or the like. The color demodulation circuits of the NTSC system and the PAL system, which are AM demodulated, have similar circuit configurations, and most of the circuits must be shared. However, there are few circuits that can be shared with the color demodulation circuit of the SECAM system in which the FM demodulation is performed.
Circuits corresponding to all of the AL and SECAM systems are large-scale circuits. And NTSC, PAL, S
For a circuit corresponding to all of the ECAM methods, a method discrimination circuit for discriminating which of these signals is input is also required separately.

Further, when the circuit is digitized, N
In the TSC and PAL systems, a frequency that is an integral multiple of the burst synchronization clock is often used as the operation clock. For example, when 4Fsc is used as the operation clock, the frequency on the RY axis and the BY axis is used. This is because data is handled, and the RY signal and the BY signal can be separated only by distributing the data using the selector, and the circuit can be simplified. However, if it is attempted to input a non-standard signal such as a home VTR, the number of clocks in one horizontal period is not constant, so that it is difficult to configure a 1H delay line, and this causes deterioration of video. There was a problem.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is possible to demodulate an AM signal and an FM signal with the same device without increasing the circuit scale, and to digitize the device. And a digital demodulation device capable of performing color demodulation without causing signal degradation even when a non-standard signal is input when applied to a color demodulation circuit of a television receiver or the like. Aim.

[0025]

A digital demodulator according to the present invention (Claim 1) receives an AM signal or an FM signal sampled by a sampling clock of an arbitrary frequency as an input, and outputs a 90-degree signal to the input signal. A Hilbert transformer that performs a phase shift, a first arithmetic circuit that receives the input signal and the output signal of the Hilbert converter as inputs, and calculates amplitude information of the input signal; A second arithmetic circuit for calculating phase information of the input signal with an output signal as an input, the demodulation AM corresponding to the input AM signal or the input FM signal
It is configured to output a signal or demodulated FM signal.

The digital demodulator according to the present invention (Claim 2) is an NTSC or PSC which is an AM signal.
An input is a carrier color signal of the SECAM system, which is an AL system or an FM signal, and the input signal is NTSC or
In the case of the PAL system, it operates with an arbitrary sampling clock, obtains a phase angle of a burst for each line from the second arithmetic circuit, and obtains a phase angle of a current line obtained from the second arithmetic circuit,
A digital burst synchronous oscillator that compares the angular velocity of the sampling clock with the phase angle of the current line obtained by calculation from the phase angle of the previous line, and feeds back the difference to the angular velocity of the sampling clock; The output of the arithmetic circuit is
NTSC / PAL RYs for separating into a red difference (hereinafter, referred to as RY) signal and a blue difference (hereinafter, referred to as BY) signal by a burst synchronization clock output from the digital burst synchronization oscillator. A BY separation circuit is provided at the RY output of the RY and BY separation circuits. When the input signal is of the PAL system, the signal is inverted for each line and output. In case, output as it is, R
-Y line inversion circuit and SECAM RY, which are provided at the output of the second arithmetic circuit and switch the output for each line to separate the SECAM system demodulated signal into RY and BY. A BY separation circuit is provided so that color demodulation can be performed even if any carrier color signal of the NTSC, PAL, or SECAM system is input at an arbitrary sampling clock.

The digital demodulator according to the present invention (Claim 3) is a digital demodulator (NTSC or PSC) which is an AM signal.
It receives a carrier color signal of the AL system, operates at an arbitrary sampling clock, obtains a burst phase angle for each line from the second arithmetic circuit, and obtains a phase angle of a current line obtained from the second arithmetic circuit. And the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line,
A digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock; a COLOR adjusting adder that adds a value set arbitrarily from the outside to the amplitude of the carrier color signal obtained from the first arithmetic circuit; A TINT adjustment adder for adding a value arbitrarily set from the outside to the phase of the carrier chrominance signal obtained from the second arithmetic circuit, and outputting the output of the first arithmetic circuit to the digital An NTSC / NTC / RB that separates into a red color difference (hereinafter, referred to as RY) signal and a blue color difference (hereinafter, referred to as BY) signal by a burst synchronization clock output from a burst synchronization oscillator.
RY, BY separation circuit for PAL;
Provided at the RY output of the Y separation circuit,
In the case of the system, the signal is inverted and output for each line, and PA
In the case other than the L system, an R-Y line inverting circuit is provided to output as it is, and color density adjustment (hereinafter, referred to as COLOR adjustment) and hue adjustment (hereinafter, referred to as TINT adjustment)
It is configured to be able to.

The digital demodulator according to the present invention (claim 4) automatically determines whether an input signal is NTSC, PAL or SECAM based on the output of the first and second arithmetic circuits. An automatic discrimination circuit for discriminating
The color demodulation can be automatically performed even if any of the TSC, PAL, and SECAM carrier color signals is input.

In the digital demodulator according to the present invention, the first arithmetic circuit may receive the input signal and the output signal of the Hilbert transformer as inputs, and may take the square root of the sum of the squares of the respective squares. And the second
In which the input signal and the output signal of the Hilbert transformer are input, and the inverse tangent of each ratio is calculated.

The digital demodulator according to the present invention (Claim 6) is an NTSC or PSC which is an AM signal.
An input is a carrier color signal of the SECAM system, which is an AL system or an FM signal, and the input signal is NTSC or
In the case of the PAL system, it operates with an arbitrary sampling clock, obtains a phase angle of a burst for each line from the second arithmetic circuit, and obtains a phase angle of a current line obtained from the second arithmetic circuit,
A digital burst synchronous oscillator that compares the angular velocity of the sampling clock with the phase angle of the current line obtained by calculation from the phase angle of the previous line, and feeds back the difference to the angular velocity of the sampling clock; The output of the arithmetic circuit is
An RY / BY separation circuit for NTSC / PAL for separating an RY signal and a BY signal by a burst synchronization clock output from the digital burst synchronization oscillator; and an RY / BY separation circuit. An RY line inverting circuit provided at the RY output of the circuit, inverting the signal for each line when the input signal is of the PAL system, and outputting as it is when the input signal is other than the PAL system; 2 is provided at the output of the arithmetic circuit 2 and the output is switched for each line.
SE for separating the CAM demodulated signal into RY and BY
A RY / BY separation circuit for CAM is provided, and color demodulation can be performed even if any carrier color signal of the NTSC, PAL, or SECAM system is input at an arbitrary sampling clock.

The digital demodulator according to the present invention (Claim 7) is a digital demodulator (NTSC or PSC) which is an AM signal.
It receives a carrier color signal of the AL system, operates at an arbitrary sampling clock, obtains a burst phase angle for each line from the second arithmetic circuit, and obtains a phase angle of a current line obtained from the second arithmetic circuit. And the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line,
A digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock; a COLOR adjusting adder that adds a value set arbitrarily from the outside to the amplitude of the carrier color signal obtained from the first arithmetic circuit; A TINT adjustment adder for adding a value arbitrarily set from the outside to the phase of the carrier chrominance signal obtained from the second arithmetic circuit, and outputting the output of the first arithmetic circuit to the digital An NTSC / NTC / RB that separates into a red color difference (hereinafter, referred to as RY) signal and a blue color difference (hereinafter, referred to as BY) signal by a burst synchronization clock output from a burst synchronization oscillator.
RY, BY separation circuit for PAL;
Provided at the RY output of the Y separation circuit,
In the case of the system, the signal is inverted and output for each line, and PA
In the case other than the L system, an R-Y line inverting circuit is provided to output as it is, and color density adjustment (hereinafter, referred to as COLOR adjustment) and hue adjustment (hereinafter, referred to as TINT adjustment)
It is configured to be able to.

The digital demodulator according to the present invention (claim 8) automatically determines whether the input signal is NTSC, PAL or SECAM based on the output of the first and second arithmetic circuits. An automatic discrimination circuit for discriminating
The color demodulation can be automatically performed even if any of the TSC, PAL, and SECAM carrier color signals is input.

Also, in the digital demodulating apparatus according to the present invention (claim 9), the first arithmetic circuit stores a logarithmic conversion table for converting the input signal and the output signal of the Hilbert transformer into logarithms. A third and a second logarithmic conversion storage circuit, and a third for calculating amplitude information of the input signal in logarithmic expression using outputs of the first and the second logarithmic conversion storage circuits.
And a first exponential conversion storage circuit that stores an exponential conversion table that converts the output of the third arithmetic circuit into an exponent. A fourth arithmetic circuit for calculating phase information of the input signal in logarithmic expression using an output of the second logarithmic conversion storage circuit, and an exponential conversion table for converting an output of the fourth arithmetic circuit into an exponent. And a second exponential conversion storage circuit.

A digital demodulator according to the present invention (Claim 10) is an NTSC or AMSC signal.
When a carrier color signal of the SECAM system, which is a PAL system or an FM signal, is input, and when the input signal is of the NTSC or PAL system, it operates at an arbitrary sampling clock, and the second arithmetic circuit operates every one line. The phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line, A digital burst synchronization oscillator that feeds back the difference to the angular velocity of the sampling clock, and outputs the RY signal and the B-Y signal by the burst synchronization clock output from the digital burst synchronization oscillator. Y
A RY / BY separation circuit for NTSC / PAL for separating signals and a RY output of the RY / BY separation circuit. An RY line inverting circuit for inverting and outputting a signal and outputting as it is in a case other than the PAL system, and an output of the second arithmetic circuit are provided.
A SECAM RY and BY separation circuit for separating the SECAM demodulated signal into RY and BY signals, and any of the carrier color signals of the NTSC, PAL, and SECAM systems can be output at an arbitrary sampling clock. The configuration is such that color demodulation can be performed even when input.

A digital demodulator according to the present invention (claim 11) is an NTSC or PAL which is an AM signal.
A carrier chrominance signal is input, the operation is performed at an arbitrary sampling clock, a burst phase angle is obtained for each line from the second arithmetic circuit, and a phase angle of a current line obtained from the second arithmetic circuit is obtained. A digital burst synchronous oscillator that compares the angular velocity of the sampling clock with the phase angle of the current line obtained by calculation from the phase angle of the previous line, and feeds back the difference to the angular velocity of the sampling clock; A COLOR adjustment adder for adding a value arbitrarily set from outside to the amplitude of the carrier color signal obtained from the circuit, and arbitrarily setting the phase of the carrier color signal obtained from the second arithmetic circuit from outside And a TINT adjustment adder for adding the calculated value. The output of the first arithmetic circuit is controlled by a burst synchronization clock output from the digital burst synchronization oscillator to generate a red color difference signal. Hereinafter referred to as R-Y) signal and blue color difference (hereinafter, referred to as B-Y) for separating the signal NTSC / PA
The RY / BY separation circuit for L and the RY output of the RY / BY separation circuit are provided. When the input signal is a PAL system, the signal is inverted every line and output. In the case other than the PAL system, an R-Y line inverting circuit that outputs the image as it is is provided, and color density adjustment (hereinafter, referred to as COLOR adjustment) and hue adjustment (hereinafter, referred to as TINT adjustment) can be performed. It is configured as follows.

The digital demodulator according to the present invention (claim 12) automatically determines whether the input signal is NTSC, PAL, or SECAM based on the output of the first and second arithmetic circuits. Equipped with automatic discrimination circuit, NTS
The color demodulation can be automatically performed even if any of the C, PAL and SECAM carrier color signals is input.

In the digital demodulation device according to the present invention, the fourth arithmetic circuit constituting the second arithmetic circuit subtracts the output of the first and second logarithmic conversion storage circuits. A first subtraction circuit, and an exponential inverse tangent conversion storage circuit that stores conversion information within a predetermined range and stores an exponential inverse tangent conversion table that converts an output of the subtraction circuit into an exponential arc tangent. A third sine logarithmic conversion storage circuit storing a sine logarithmic conversion table for converting an output of the exponential arc tangent conversion storage circuit into a sine logarithm; And a second subtraction circuit for subtracting the output of the sine logarithmic conversion storage circuit corresponding to the output of the logarithmic conversion storage circuit from the above and outputting the result to the first exponential conversion storage circuit, respectively. Exponential conversion notation The circuit, in which consisted of the exponential inverse tangent converting storage circuit.

The digital demodulator according to the present invention (claim 14) is an NTSC or PAL which is an AM signal.
Or a carrier color signal of the SECAM method, which is an FM signal, and the input signal is NTSC or PA
In the case of the L system, it operates with an arbitrary sampling clock, obtains a phase angle of a burst for each line from the second arithmetic circuit,
The phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular speed of the sampling clock and the phase angle of the previous line, and the difference is calculated. NTSC / PAL for separating the output of the first arithmetic circuit into an RY signal and a BY signal by a burst synchronization clock output from the digital burst synchronization oscillator. RY / BY separation circuit and the RY output of the RY / BY separation circuit. When the input signal is a PAL system, the signal is inverted and output for each line. , Other than the PAL system, output as it is,
A RY line inversion circuit and an output of the second arithmetic circuit are provided.
SECAM which separates the demodulated signal of R-type into RY and BY
And a RY / BY separation circuit for color demodulation even if any carrier color signal of the NTSC, PAL, or SECAM system is input at an arbitrary sampling clock.

A digital demodulator according to the present invention (claim 15) is an NTSC or PAL which is an AM signal.
A carrier chrominance signal is input, the operation is performed at an arbitrary sampling clock, a burst phase angle is obtained for each line from the second arithmetic circuit, and a phase angle of a current line obtained from the second arithmetic circuit is obtained. A digital burst synchronous oscillator that compares the angular velocity of the sampling clock with the phase angle of the current line obtained by calculation from the phase angle of the previous line, and feeds back the difference to the angular velocity of the sampling clock; A COLOR adjustment adder for adding a value arbitrarily set from outside to the amplitude of the carrier color signal obtained from the circuit, and arbitrarily setting the phase of the carrier color signal obtained from the second arithmetic circuit from outside And a TINT adjustment adder for adding the calculated value. The output of the first arithmetic circuit is controlled by a burst synchronization clock output from the digital burst synchronization oscillator to generate a red color difference signal. Hereinafter referred to as R-Y) signal and blue color difference (hereinafter, referred to as B-Y) for separating the signal NTSC / PA
The RY / BY separation circuit for L and the RY output of the RY / BY separation circuit are provided. When the input signal is a PAL system, the signal is inverted every line and output. In the case other than the PAL system, an R-Y line inverting circuit that outputs the image as it is is provided, and color density adjustment (hereinafter, referred to as COLOR adjustment) and hue adjustment (hereinafter, referred to as TINT adjustment) can be performed. It is configured as follows.

The digital demodulator according to the present invention (claim 16) automatically determines whether the input signal is NTSC, PAL, or SECAM based on the output of the first and second arithmetic circuits. Equipped with automatic discrimination circuit, NTS
The color demodulation can be automatically performed even if any of the C, PAL and SECAM carrier color signals is input.

[0041]

According to the present invention (claim 1), with the above-described configuration, both the AM modulation signal and the FM modulation signal sampled at an arbitrary sampling clock by the same circuit using a digital circuit. A principle configuration of a digital demodulator capable of demodulating a signal is realized.

In the present invention (claim 2),
With the above-described configuration, the NTSC, PA can be used by using the above-described principle configuration of the digital demodulator.
A digital demodulator capable of executing most of the L and SECAM color demodulation processes with the same circuit is realized.

In the present invention (claim 3),
With the above-described configuration, in the above-described digital demodulation device, only by adding an adder, CO
LOR adjustment and TINT adjustment functions are realized.

Further, in the present invention (claim 4),
With the above-described configuration, in the above-described digital demodulator, NTSC, PAL, SECAM
A digital demodulator capable of automatically determining the system is realized.

Further, in the present invention (claim 5),
With the above-described configuration, the basic configuration of a digital demodulator that can demodulate both the AM modulation signal and the FM modulation signal sampled with an arbitrary sampling clock in the same circuit using a digital circuit is provided. Is achieved.

In the present invention (claim 6),
With the above-described configuration, NTSC and PA can be used by using the basic configuration of the digital demodulator as described above.
A digital demodulator capable of executing most of the L and SECAM color demodulation processes with the same circuit is realized.

In the present invention (claim 7),
With the above-described configuration, in the above-described digital demodulation device, only by adding an adder, CO
LOR adjustment and TINT adjustment functions are realized.

In the present invention (claim 8),
With the above-described configuration, in the above-described digital demodulator, NTSC, PAL, SECAM
A digital demodulator capable of automatically determining the system is realized.

In the present invention (claim 9),
With the above-described configuration, the same circuit using a digital circuit that performs demodulation operation that can be used at a high operation speed can be used for both the AM modulation signal and the FM modulation signal sampled at an arbitrary sampling clock. A digital demodulator capable of actually demodulating a signal is put to practical use.

Further, according to the present invention (claim 10), with the above-described configuration, NTSC, PAL, S
A digital demodulator capable of performing most of the ECAM color demodulation processing with the same circuit is realized.

Further, according to the present invention (claim 11), with the above-described configuration, in the above-described digital demodulation apparatus, only by adding an adder,
A COLOR adjustment and a TINT adjustment function are realized.

Further, according to the present invention (Claim 12), the digital demodulation apparatus as described above has the NTSC, PAL, SEC
A digital demodulator capable of automatically determining the AM system is realized.

Further, according to the present invention (claim 13), with the above-described configuration, the same circuit as a digital circuit that performs demodulation operation that can withstand practical use at a higher operation speed can arbitrarily sample any signal. A digital demodulator capable of actually demodulating both the AM modulation signal and the FM modulation signal sampled by the coded clock is put into practical use.

Further, according to the present invention (claim 14), with the above-described configuration, the NTSC, PAL, and SAL can be realized by using the configuration of the digital demodulator as described above.
A digital demodulator capable of performing most of the ECAM color demodulation processing with the same circuit is realized.

Further, according to the present invention (claim 15), with the above-described configuration, in the above-described digital demodulation device, only by adding an adder,
A COLOR adjustment and a TINT adjustment function are realized.

Further, according to the present invention (claim 16), the digital demodulation apparatus as described above has the NTSC, PAL, SEC
A digital demodulator capable of automatically determining the AM system is realized.

[0057]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. The first embodiment is an example showing a circuit that demodulates both the AM signal and the FM signal with a common circuit.

FIG. 1A is a block diagram showing a main part of a digital demodulator according to the first embodiment of the present invention. In the figure, reference numeral 28 denotes an input of an AM signal or an FM signal to be demodulated by the present demodulator. The input terminal 29 is connected to the AM terminal or the FM signal input to the input terminal 28 by 90.
The Hilbert converter 30 for performing the phase shift, and 30 is a delay time required for performing the 90 ° phase shift by the Hilbert converter 29.
A delay compensating register 31 for compensating the original AM signal or the original FM signal, and receives the output signal of the delay compensating register 30 and the output signal of the Hilbert transformer 29 as inputs and calculates the square root of the sum of the respective squares. An arithmetic circuit 1 for digitally calculating the amplitude information of the input signal.
Reference numeral 32 designates the output signal of the delay compensation register 30 and the output signal of the Hilbert transformer 29 as inputs, calculates the time differential of the arc tangent of each ratio, calculates the phase information of the input signal, and further differentiates the phase information. Shows an arithmetic circuit 2 for digitally calculating angular velocity information.

Next, the operation will be described. Input terminal 28
, An AM signal or an FM signal is input, and the input signal is input to the Hilbert transformer 29 and the delay compensation register 3.
0 is given. The Hilbert transformer 29 outputs a signal obtained by applying a 90 ° phase to the input signal.

Here, the Hilbert transformer 29 used in the circuit of FIG. 1A will be described. FIG. 1B shows an example of the configuration of the Hilbert transformer 29. In the figure, 29
a to 29l are 8-bit registers connected in series, and 29m is a coefficient H2 (= 0.
0174), a coefficient unit 29n is a register 29c
Is multiplied by a coefficient H4 (= 0.1151), and 29o is a coefficient unit that multiplies the output of the register 29e by a coefficient H6 (= 0.151).
5974) is multiplied by 29p.
Is multiplied by a coefficient H8 (= −0.5974). 29q is a coefficient unit that multiplies an output of the register 29i by a coefficient H10 (= −0.5974).
0.1151), 29r is a register 2
This is a coefficient unit that multiplies the output of 9k by a coefficient H12 (= −0.0174), and each of these coefficient units digitally multiplies the coefficient. An adder 29s digitally adds the outputs of the coefficient units 29m to 29r and outputs a signal obtained by performing a 90 ° phase shift on the input signal of the register 29a.

The Hilbert converter 29 is an FIR (Finit)
e Impulse Response) filter, and the delay compensation register 30 compensates for the steady delay caused by the FIR filter. Therefore, the output signal of the Hilbert transformer 29 and the output signal of the delay compensation register 30 are always 90 °. Has a phase difference. The arithmetic circuits 1 and 31 are Hilbert converters 2
9 and the output signal of the delay compensation register 30, and outputs a signal corresponding to the square root of the sum of the squares of the respective signals. The arithmetic circuits 2 and 32 receive the output signal of the Hilbert transformer 29 and the output signal of the delay compensation register 30 as inputs, and calculate the inverse tangent (tan) of the ratio of the respective signals.
^-1 x) is output.

The above will be described using equations. First, assuming that the amplitude of the signal x (t) output from the delay compensation register 30 is A and the angular velocity is ω,

(Equation 1) X (t) = A sin ωt

On the other hand, the signal Y (t) output from the Hilbert transformer 29 has a phase that is 90 ° ahead of X (t).

(Equation 2) Y (t) = A sin (ωt−90 °) = − A cos ωt

In the arithmetic circuits 1 and 31, X (t), Y
Since the square root of the sum of the squares of (t) is calculated,
As shown in (Equation 3), the amplitude of the input signal is obtained.

(Equation 3)

(Equation 1)

In the arithmetic circuits 2 and 32, X (t), Y
Since the inverse tangent of the ratio of each signal of (t) is output,
As shown in (Equation 4), the phase angle of the input signal is obtained.

(Equation 4)

(Equation 2)

The angular velocity ω can be determined by differentiating -ωt obtained by (Equation 4) with a differentiating circuit in the arithmetic circuit 2. Therefore, the circuit of the first embodiment can obtain the amplitude A and the angular velocity ω, that is, the AM demodulation output and the FM demodulation output by a common circuit.

As described above, according to the circuit of the first embodiment, the Hilbert converter, the delay compensation register for performing the delay compensation for performing the delay compensation, the digital signal processing for these output signals, and the amplitude information and the phase information are performed. Further, since the apparatus is constituted by two digital arithmetic circuits for calculating angular velocity information, even if an AM modulated signal or an FM modulated signal sampled by a sampling clock of an arbitrary frequency is input, an AM demodulated signal corresponding to each of the signals is input. Alternatively, the FM demodulated signal can be obtained by the same circuit, and A
It is possible to demodulate both the M-modulated signal and the FM-modulated signal.

Embodiment 2 FIG. Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. The second embodiment is an embodiment in which not only the demodulation of both the AM signal and the FM signal can be executed by a common circuit, but also a circuit capable of executing a demodulation operation at a small circuit scale and at a high speed.

FIG. 2 is a block diagram showing a main part of a digital demodulator according to a second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. 33
Is an absolute value circuit 1 for calculating the absolute value of the output signal of the delay compensation register 30; 34 is an absolute value circuit 2 for calculating the absolute value of the output signal of the Hilbert transformer 29; Logarithmic ROMs 1 and 3 for calculating logarithms of signals
6 is a logarithmic ROM 2 for calculating the logarithms of the output signals of the absolute value circuits 2 and 34, and 37 is a subtraction circuit 1 for subtracting the output signals of the logarithmic ROMs 2 and 36 from the output signals of the logarithmic ROMs 1 and 35.
38 is an absolute value circuit 3 for calculating the absolute value of the output signal of the subtraction circuits 1 and 37; 39 is an exponential inverse tangent ROM for calculating the exponential arc tangent of the output signal of the absolute value circuit 3;
In accordance with 1, 37 and the code data output from the Hilbert transformer 29, the angle data which is the output signal of the exponential arc tangent ROM is output as it is or is converted into data obtained by subtracting this angle data from 90 ° and then output. The data conversion circuit 41 converts the output signal of the data conversion circuit 40 into 90 according to the code data output from the Hilbert converter 29.
Adder or adds the output signal of the data conversion circuit 40 as it is. A 90 ° adder 42 inverts the sign of the output signal of the 90 ° adder 41 in accordance with the sign data output from the delay compensation register 30. Or 90 °
A sign inverting circuit for outputting the output signal of the adder 41 without inverting the sign; 43, an angular velocity calculator for calculating the angular velocity from the output signal of the sign inverting circuit 42;
Logarithmic ROM 1 according to the code data output from 37,
A selector for selecting and outputting one of the output signals of an output signal 35 and logarithmic ROMs 2 and 36;
Sine logarithm RO for calculating sine logarithm of output signal of M39
M and 46 are sine logarithmic ROMs from the output signal of the selector 44
The subtraction circuits 2 and 47 for subtracting the 45 output signals are exponent ROMs for calculating the exponents of the output signals of the subtraction circuits 2 and 46. The selector 44, the sine logarithmic ROM 45, and the subtraction circuit 46 constitute arithmetic circuits 3, 31a for calculating the amplitude information of the input signal in logarithmic expression.
Are absolute value ROM1, 33, absolute value ROM2, 34, logarithmic ROM1, 35, logarithmic ROM2, 36, exponent ROM47.
Together, they constitute the arithmetic circuits 1 and 31. Further, subtraction circuits 1 and 37, an absolute value circuit 38, an exponential arc tangent ROM 39
Form arithmetic circuits 4 and 32a for calculating phase information of the input signal in logarithmic expression. These arithmetic circuits 4 and 32a are absolute value ROMs 1 and 33, absolute value ROMs 2 and 34, logarithmic ROMs.
1, 35 logarithmic ROMs 2, 36, data conversion circuits 40, 9
The arithmetic circuits 2 and 32 are configured together with the 0 ° adder 41, the sign inversion circuit 42, and the angular velocity calculator 43.

Next, the operation will be described. As in the case of the first embodiment, an AM signal or FM
The output signal of the Hilbert transformer 29 and the output signal of the delay compensation register 30 are always 90 °.
With a phase difference of Absolute value circuits 1 and 33 and absolute value circuit 2,
Reference numeral 34 outputs the absolute value of the output signal of the delay compensation register 30 and the output signal of the Hilbert transformer 29, respectively. The output signals of the absolute value circuits 1 and 33 are shown in (Equation 5), and the output signal from the absolute value circuit 2 is shown in (Equation 6).

(Equation 5) | X (t) | = A | sin ωt | That is, when ωt = 0 ° to 180 °, | X (t) | = Asin ωt | X (t) | = Asin ωt ωt = When 0 ° to -180 ° | X (t) | = -Asin ωt

(Equation 6) | Y (t) | = A | cos ωt | That is, when ωt = 0 ° to 90 ° and 0 ° to −90 °, | Y (t) | = Acos ωt ωt = 90 ° １８０180 °, -90 ° to -180 ° | Y (t) | = -Acos

Logarithmic ROMs 1 and 35 and Logarithmic ROMs 2 and 36
Are absolute value circuits 1 and 33 and absolute value circuits 2 and 34, respectively.
Output the natural logarithm of the output signal. Logarithmic ROM 1, 35
(Equation 7) and the output signals of the logarithmic ROMs 2 and 36 are shown in (Equation 8).

(Expression 7) log | X (t) | = log (A | sin ωt |) That is, when ωt = 0 ° to 180 °, log | X (t) | = log (Asin ωt) ωt = 0 When | ° -−180 ° log | X (t) | = log (−A sin ωt)

(Equation 8) log | Y (t) | = log (A | cos ωt |) That is, when ωt = 0 ° to 90 ° and 0 ° to −90 °, log | X (t) | = log (Acos ωt) When ωt = 90 ° to 180 ° and −90 ° to −180 °, log | X (t) | = log (−Acos ωt)

The subtraction circuits 1 and 37 are connected to logarithmic ROMs 1 and 35
Are subtracted from the output signals of the logarithmic ROMs 2 and 36. The absolute value circuits 3 and 38 output the absolute value of the result of the subtraction. The output Z (t) of the absolute value circuits 3 and 38 is shown in (Equation 9).

(Equation 9) log | X (t) | ≧ log | Y (t) | That is, ωt = 45 ° to 135 °, −45 ° to −135 °
, Z (t) = log | X (t) | −log | Y (t) | = log (A | sin ωt |) −log (A | cos ωt
|) Log | X (t) | <log | Y (t) | That is, ωt = 0 ° to 45 °, 135 ° to 180 °, 0 °
Z- (t) = log | Y (t) | -log | X (t) | = log (A | cos ωt |) -log (A | sin ωt)
｜)

(Equation 9) can be transformed into (Equation 10) by applying (Equation 7) and (Equation 8).

(Equation 10) When ωt = 0 ° to 45 °, Z (t) = log (tan ωt) When ωt = 45 ° to 90 °, Z (t) = log (cot ωt) ωt = 90 At 135 ° to 135 °, Z (t) = log (−cot ωt) at ωt = 135 ° to 180 °, Z (t) = log (−tan ωt) at ωt = 0 ° to −45 °, Z (t) = log (−tan ωt) When ωt = −45 ° to −90 °, Z (t) = log (−cot ωt) When ωt = −90 ° to −135 °, Z (t) = Log (cot ωt) When ωt = −135 ° to −180 °, Z (t) = log (tan ωt)

The exponential arc tangent ROM 39 stores the absolute value circuit 3,
An exponent (exp x) based on e of the 38 output signal is calculated, and its arc tangent (tan ^-1 x) is output. First,
By taking the exponent of Z (t), (Equation 10) becomes (Equation 1)
1).

(Equation 11) When ωt = 0 ° to 45 °, exp [Z (t)] = tan ωt When ωt = 45 ° to 90 °, exp [Z (t)] = cot ωt ωt = 90 At 135 ° to 135 °, exp [Z (t)] = − cot ωt ωt = 135 ° to 180 °, exp [Z (t)] = − tan ωt at ωt = 0 ° to −45 °, exp [Z (t)] = − tan ωt When ωt = −45 ° to −90 °, exp [Z (t)] = − cot ωt ωt = −90 ° to −135 °, exp [Z ( t)] = cot ωt When ωt = −135 ° to −180 °, exp [Z (t)] = tan ωt

FIG. 3 is a graph of Equation (11). To obtain the value of ωt from (Equation 11), tan ^-1 x, cot ^-1 x, and-(tan ^-1 x) are required as tables, but in this circuit, the tables used are minimized. In order to do so, as shown in the graph of FIG. 3, the symmetry of the function is used. After all, exponential arc tangent RO
As the output ωt ′ of M39, a value of 0 ° to 45 ° is output, and this is expressed by an equation (Equation 12).

(Equation 12) tan ⁻¹ ωt ′ = tan ⁻¹ [exp Z (t)]

That is, to obtain an accurate value of ωt, ωt
In the area shown in FIG. 4 and an operation corresponding to the area must be performed on the output ωt ′ of the ROM 38. A description will be given of a method of determining a region and a calculation in each region. The following three conditions are used as conditions for determining the region.

Condition 1: sin ωt ≧ 0 Condition 2: cos ωt ≧ 0 Condition 3: | sin ωt | ≧ | cos ωt |

The condition 1 is determined by referring to the sign of the output signal of the delay compensation register 30, and when the condition 1 is satisfied, ωt = 0 ° to 180 °. The condition 2 is determined by referring to the sign of the output signal of the Hilbert transformer 29. When the condition 2 is satisfied, ωt = 0 ° to 90 °, 0 °
~ -90 °. Condition 3 is determined by referring to the sign of the output signal of the subtraction circuits 1 and 37. When Condition 3 is satisfied, ωt = 45 ° to 135 °, −45 ° to -135 °
It is. Next, (Equation 12) shows the calculation of each area.

(Equation 12) Region 1: Conditions 1 and 2 are satisfied ωt = ωt ′ Region 2: Conditions 1, 2, and 3 are satisfied ωt = 90 ° −ω
t 'region 3: Conditions 1 and 3 are satisfied ωt = 90 ° + ω
t ′ region 4: Condition 1 is satisfied. ωt = 180 ° −ω
t ′ region 5: condition 2 is satisfied ωt = −ωt ′ region 6: conditions 2 and 3 are satisfied ωt = − (90 ° −
ωt ′) Region 7: Condition 3 is satisfied ωt = − (90 ° +
ωt ′) Region 8: All conditions are not satisfied. ωt = − (180 °
-Ωt ')

The circuitization of (Equation 12) is realized as follows in FIG. First, when both condition 2 and condition 3 are satisfied or when both are not satisfied (region 2, region 4, region 6, region 8), data conversion circuit 40 outputs ωt ′ output from exponential arc tangent ROM 39. And outputs 90 ° -ωt ′. If only one of the conditions 2 and 3 is satisfied (region 1, region 3, region 5, region 7), ωt ′ is output as it is. When the output of the data conversion circuit 40 is shown for each area, it is as shown in (Equation 13).

(Equation 13) Region 1: ωt 'Region 2: 90 ° -ωt' Region 3: ωt 'Region 4: 90 ° -ωt' Region 5: ωt 'Region 6: 90 ° -ωt' Region 7: ωt 'Region 8: 90 ° -ωt'

Next, if condition 2 is not satisfied (region 3, region 4, region 7, region 8), 90 ° addition circuit 41 adds 90 ° to the signal output from data conversion circuit 40 and outputs the result. When the condition 2 is satisfied (region 1, region 2,
The data is directly output to the areas 5 and 6). If the output of the 90 ° adder 41 is shown for each area, it is as shown in (Equation 14).

(Equation 14) Region 1: ωt 'Region 2: 90 ° -ωt' Region 3: 90 ° + ωt 'Region 4: 180 ° -ωt' Region 5: ωt 'Region 6: 90 ° -ωt' Region 7 : 90 ° + ωt 'Region 8: 180 ° -ωt'

If the condition 1 is not satisfied (region 5, region 6, region 7, region 8), the sign inversion circuit 42
° The signal output from the adder 41 is inverted with respect to the sign and output, and when the condition 2 is satisfied (area 1, area 2, area 3, area 4), the signal is output as it is. Sign inversion circuit 4
If the output of the second area is shown for each region, it becomes as shown in the above (Equation 12), and ωt can be obtained. The angular velocity calculator 43 calculates ωt
To calculate the angular velocity, that is, output the FM demodulated waveform.

The angular velocity calculator 43 can be realized by a circuit as shown in FIG. 5, for example. In FIG. 5, reference numeral 48 denotes a register for holding an input signal indicating a phase angle; 49, a subtractor for subtracting the input signal from the output signal of the register 48; 50, a 360 ° adder for adding 360 ° to the output signal of the subtractor 49; , 51 are the output signal of the subtractor 49 and 360 according to the sign of the input signal and the sign of the output signal of the register 48.
° A selector which selects and outputs one of the output signals of the adder 50, and 52 denotes an absolute value circuit which calculates the absolute value of the output signal of the selector 51.

Next, the operation of the angular velocity calculator 43 will be described. Ωt is input from the phase angle input terminal, and is subtracted from the phase angle of one sample before stored in the register 48 to obtain the amount of change of the phase angle per unit time. Since the phase angle at the time of input is a value of -180 ° to 180 °, a selector 51, a 360 ° adder 50 and an absolute value circuit 52 are provided to obtain a value of 0 ° to 360 ° as an angular velocity output. Is negative and the phase angle input is positive, 360 ° is added; otherwise, 360 ° is not added, and the absolute value is taken at the final stage.

By performing such an operation, FM demodulation of an input signal can be performed. On the other hand, the sine log ROM 45 of FIG. 2 obtains a sine for ωt ′ input from the exponential arc tangent ROM 39, and further calculates and outputs the natural logarithm. The output of the sine log ROM 45 is shown in (Equation 15).

(Equation 15) log (sin ωt ′)

By applying (Equation 12) to (Equation 15) and expressing it as a function of ωt, (Equation 16) is obtained.

(Equation 16) Area 1: log (sin ωt ′) = log (sin ωt) Area 2: log (sin ωt ′) = log (cos ωt) Area 3: log (sin ωt ′) = log (− cos ωt) area 4: log (sin ωt ′) = log (sin ωt) area 5: log (sin ωt ′) = log (−sin ωt) area 6: log (sin ωt ′) = log (cos ωt) area 7: log (sin ωt ′) = log (−cos ωt) Region 8: log (sin ωt ′) = log (−sin ωt)

The selector 44 switches the signals represented by the above-mentioned (Equation 7) and (Equation 8) inputted from the logarithmic ROMs 1 and 35 and the logarithmic ROMs 2 and 36 according to the condition 3, and outputs the signals. The output of the selector 44 is shown in (Equation 17).

(Equation 17) Region 1: log (Asin ωt) Region 2: log (Acos ωt) Region 3: log (-Acos ωt) Region 4: log (Asin ωt) Region 5: log (-Asin ωt) region 6: log (Acosωt) region 7: log (−Acosωt) region 8: log (−Asinωt)

The subtraction circuits 2 and 46 subtract the output signal of the sine log ROM 45 from the output signal of the selector 44. The output signals of the subtraction circuits 2 and 46 are shown in (Equation 18).

(Equation 18) logA

The exponent ROM 47 calculates the exponent of the signal input from the subtraction circuits 2 and 46, and outputs the amplitude A, that is, the AM demodulated wave. The output signal of the exponent ROM 47 is expressed by (Equation 19)
Shown in

(Equation 19) exp (logA) = A

Therefore, in the circuit of the second embodiment, the amplitude A and the angular velocity ω, that is, the AM demodulation output and the FM demodulation output can be obtained by a common circuit.

As described above, according to the circuit of the second embodiment, the logarithm of the output signal of the Hilbert transformer and the delay compensation register that performs the delay compensation for performing the delay compensation is calculated, and the digital operation is performed in the logarithmic expression. After calculating the exponent, the device is composed of two arithmetic circuits for digitally calculating the amplitude information, the phase information, and the angular velocity information by returning the expression to the original expression. The conversion into addition and subtraction can be performed at a high speed, and even if an AM modulation signal or an FM modulation signal sampled by a sampling clock of an arbitrary frequency is input, the corresponding A
The M demodulated signal or the FM demodulated signal can be obtained by the same circuit, and the demodulation of both the AM modulated signal and the FM modulated signal can be performed on a small circuit scale at a speed that can be practically used. Further, since the table for calculating the phase information is configured to store only a minimum area using the symmetry of the function representing the conversion performed by the table, the circuit can be configured in a smaller scale. It becomes possible.
Further, since the circuits for performing various operations are configured by the ROM, the operations can be performed at high speed.

Embodiment 3 FIG. Example 3 uses NTSC, PAL,
In any of the color television systems of the SECAM system, this is an embodiment in which color demodulation can be performed not only with the burst synchronization clock but also with an arbitrary clock. Generally, NTSC and P
In the case where the signal of the AL system is subjected to digital processing to perform color demodulation, a burst synchronization clock of an integer multiple of the color subcarrier such as 4Fsc is often used as a system operation clock. .5M
A description will be given using HZ as a system operation clock.

Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram showing a main part of a television receiver including a digital color demodulation circuit according to a third embodiment of the present invention. In FIG. 6, reference numeral 6c denotes a Y / C for performing Y / C separation.
The separation circuit separates the composite video signal output from the A / D converter 5 into a Y signal and a C signal. However, SECAM
In the case of the system signal, only the Y signal is used and the C signal is not used. A synchronization separation circuit 7c separates and outputs HSYNC and VSYNC from the Y signal output from the Y / C separation circuit 6c, and further outputs a line switching pulse and a burst position pulse. A mode selector 53 selects one of the output signal of the bell filter 23 and a C signal output from the Y / C separation circuit 6c and outputs the selected signal.
The M / FM demodulation circuit is the same as the circuit of the first or second embodiment. 55 is an AM / FM demodulation circuit 5
Synchronization separation circuit 7c for the FM demodulated wave demodulated by
RY, using the output line switching pulse
The SECAM RY / BY separation circuit 56a for performing the B / Y separation, 56a outputs the burst position pulse output from the synchronization separation circuit 7c with respect to the AM demodulated wave and the phase angle demodulated by the AM / FM demodulation circuit 54. RY and BY separation circuit for NTSC / PAL for performing RY and BY separation using
57 is an RY / BY separation circuit 56 for NTSC / PAL
a sync separation circuit 7c for the RY signal separated by
A PAL RY line inversion circuit for inverting a line using the output line switching pulse, a reference numeral 58a denotes a SECAM RY / BY separation circuit 55 according to a mode switching signal, and a PAL RY line. Inverting circuit 57, NT
The mode selectors 2 and 58b for selecting and outputting any one of the RY signals output from the RY / SC / PAL R / Y separation circuit 56a are provided for the SECAM RY,
BY separation circuit 55, NTSC / PAL R-Y, B-
Mode selectors 2, 59 for selecting and outputting any one of the BY signals output from the Y separation circuit 56a.
Denotes a mode switching signal input terminal to which a mode switching signal is input. Others are the same as the conventional example 1, the conventional example 2, and the conventional example 3, so that the reference numerals are attached and the description is omitted.

Next, the operation will be described. One of the input terminals of the mode selectors 1 and 53 has an NT modulated wave NT
The carrier color signal of the SC system or the PAL system is input to the other input terminal, and the signal of the SECAM system video signal which is the FM modulation wave after passing through the bell filter 23 is input to the other input terminal. One of the signals is selected and output to the AM / FM demodulation circuit 54.

In the circuit of the third embodiment, the AM / FM demodulation circuit 54 performs the demodulation operation described in the second embodiment, and outputs the output signal of the angular velocity calculator 43 of FIG. The output signal of the inversion circuit 42 is output as a phase angle, and the output signals of the subtraction circuits 2 and 46, which are logarithmic expressions, are output as AM demodulated waves. The FM demodulation wave output from the AM / FM demodulation circuit 54 is a demodulation wave of a signal of the SECAM system, in which the RY signal and the BY signal are line-sequentially arranged. The signal is separated into an RY signal and a BY signal by a Y separation circuit 55. AM /
The AM demodulated wave output from the FM demodulation circuit 54 is PAL
And R-Y signal and B
−Y signal is a composite signal, and the subsequent NTS
The R / Y and BY signals are separated by a C / PAL RY / BY separation circuit 56a. However, in the case of the PAL signal, the RY signal and the-(RY) signal are separated into a line-sequential signal and a BY signal. For this reason,
In the case of the signal of the PAL system, the RY line inversion circuit 57 for PAL further inverts only the-(RY) signal. With the circuit described above, the RY signal is input to the input terminals of the mode selectors 2 and 58a, and the input terminals of the mode selectors 2 and 58b are input regardless of whether any signal of SECAM, PAL, or NTSC is input. BY signals can be obtained respectively. Mode selectors 2, 58a and 58
b is controlled by a mode switching signal, and switches between the RY signal and the BY signal in accordance with the input signal.
Output to the INT adjustment circuit 12.

Here, the RY and BY separation circuit 55 for SECAM used in the circuit of FIG. 6 will be described. FIG. 7 shows the configuration of the RY and BY separation circuit 55 for SECAM. In the figure, reference numeral 24 denotes a 1H delay line memory for delaying an FM demodulated wave by 1H period, and 25 denotes an FM demodulated wave or 1H delay line memory 24 in accordance with a line switching pulse.
Is a line sequential switch for sequentially switching and outputting the output signal as an RY signal, a BY signal or the reverse signal.

Next, the operation will be described. The input FM demodulation wave is a line-sequential signal of the RY signal and the BY signal. Therefore, the signal of the current line and the signal delayed by 1H by the 1H delay line memory 24 are switched line-sequentially. By switching at 25, the FM demodulated wave is separated into the RY signal and the BY signal, and continuous signals are obtained.

In the circuit of the third embodiment, since the free-running 13.5 MHz is used as the system operation clock, the AM demodulation wave output from the AM / FM demodulation circuit 54 is composed of the RY signal and the BY vector. Is the absolute value of the sum of Therefore, the RY signal and the BY signal are obtained from the AM demodulated wave.
In order to obtain the signal, the phase difference of the AM demodulated wave currently being referred to is determined from the burst, and vector decomposition into a sin component and a cos component is performed according to the phase difference.
Separate into -Y signal and BY signal. The separation of the above-mentioned RY signal and BY signal is performed for NTSC / PAL RY and BY signals.
This is done in the separation circuit

Next, the NTSC / PAL used in the circuit of FIG.
The RY and BY separation circuit 56a will be described. FIG. 8 shows a RY / BY separation circuit 56a for NTSC / PAL.
Is shown. 8, the burst position pulse input terminal burst position pulse is input 61, 1 59 is the phase angle input terminal of the phase angle signal is input, 63 a register for holding the data from the adder 62, 64 is a register A subtractor for subtracting the output signal of the register 70 from the output signal of 63, a coefficient unit 65 for multiplying the output signal of the subtractor 64 by a predetermined coefficient, and a reference numeral 60 for the output signal of the coefficient unit 65 an adder for adding, 66 register for holding an output signal of the adder 6 0 at a timing synchronized with the burst position pulse, 67 denotes an adder for adding the output signals of the register 69 of the register 66, 68 is an adder 67 is a data converter for performing data conversion on the output signal of 67, and 69 is a data converter for holding the output signal of data converter 68 in synchronization with the system operation clock. Star, 70 register for holding an output signal of the register 69 at a timing synchronized with the burst position pulses, 71 to more than 63 no 70
This is a burst synchronous oscillation unit composed of 73b
Is a subtractor for subtracting the output signal of the register 69 from the output of the adder 62, 74 is a sine log ROM for calculating the sine log for the output signal of the subtractor 73, and 75 is a cosine for calculating the cosine log for the output signal of the subtractor 73. Log ROM, 76
Is a multiplexer that switches and outputs the output of the sine log ROM 74 and the output of the cosine log ROM 75; 78 is an amplitude input terminal to which amplitude data as an AM demodulated wave is input;
a is an adder for adding the amplitude data from the amplitude input terminal 78 and the output signal of the multiplexer 76;
An exponent ROM for calculating an exponent for the output signal of 9a, 8
Reference numeral 1 denotes a demultiplexer for demultiplexing the output signal of the exponent ROM 80.

Next, the operation will be described. The burst synchronous oscillator 71 compares the phase angle of the input burst with the phase angle of the burst calculated from the angular velocity, and feeds back the comparison result to the angular velocity again.
It is an L circuit. Phase angle input from the phase angle input terminal 1 59 takes a value of -180 ° to 180 ° but, by adding the 180 ° by the adder 62, it is converted into data of 0 ° to 360 °. The output θnow of the adder 62 is latched as a burst part phase angle θb every horizontal period by a burst position pulse and stored in the register 63. The subtractor 64 subtracts the calculated burst part phase angle θsum stored in the register 70 from the burst part phase angle θb, and the coefficient unit 65 multiplies the result of the subtraction by a coefficient k to obtain an angular velocity correction value Δω to the adder 60. Output. The relationship among θb, θsum, Δω, and k is shown in (Equation 20).

(Equation 20) Δω = k (θb−θsum)

The adder 60 adds the angular velocity correction value Δω to the burst part angular velocity ωb stored in the register 66,
The addition result is stored again in the register 66 as a new burst portion angular velocity. Accordingly, the data shown in (Equation 21) is updated in the burst portion angular velocity stored in the register 66 every horizontal period.

(Equation 21) ωb = ωb + Δω

The adder 67 operates the system operation clock clk.
The output θnowb of the register 69 operating in synchronism with the above and the burst portion angular velocity ωb output from the register 66 are added. This addition is performed in synchronization with the system operation clock clk. The data converter 68 converts the result of addition by the adder 67 so as to always have a value of 0 ° to 360 °. The register 69 stores the current phase angle of the burst synchronization clock, that is, θnowb, which can be expressed by an equation (Equation 22). Note that the value of θnowb is regulated by the data converter 68 so as to always be a value of 0 ° to 360 ° as described above.

(Equation 22)

(Equation 3)

The register 70 stores the value of θ at the burst position pulse.
By latching nowb, the calculated burst phase angle is stored. The subtractor 73b, as shown in (Equation 23),
The phase difference θ from the burst of the AM demodulation wave currently being referenced
dif is output.

(Equation 23) θdif = θnow−θnowb

Θdif is the sine log ROM 74 and the cosine log R
The data is converted into data of (Expression 24) and (Expression 25) by the OM75.

(Equation 24) log (sin θdif)

(Equation 25) log (cos θdif)

The data shown in (Equation 24) and (Equation 25) are time-division multiplexed by the system operation clock in the multiplexer 76, and the amplitude input terminal 78 in the adder 79a.
Is added to the amplitude logA input from. Adder 79
The output of a is shown in (Equation 26).

(Equation 26) log (sin θdif) + logA = log (Asin θdi
f) log (cos θdif) + logA = log (Acos θdi
f)

In the output of the adder 79a, these two components are time-division multiplexed. After the data shown in (Equation 26) is converted into an exponent by the exponent ROM 80, the data that has been time-division multiplexed by the demultiplexer 81 is separated into an RY signal and a BY signal. The outputs RY and BY of the demultiplexer 81 are shown in (Equation 27).

(Equation 27) RY = Asin θdif BY = Acos θdif

(Equation 27) determines the phase difference of the AM demodulated wave currently being referenced from the burst, and performs vector decomposition into a sin component and a cos component according to the phase difference. The RY and BY separation circuit for NTSC / PAL of the AM / FM demodulation circuit 54
This shows that the demodulated wave is separated into an RY signal and a BY signal.

As described above, according to the circuit of the third embodiment, the AM / FM demodulation circuit of the first or second embodiment has the NTS
Television compatible with NTSC, PAL, and SECAM by adding a RY / BY separation circuit for C / PAL, a RY inversion circuit, and a RY / BY separation circuit for SECAM. Most of the color demodulation processing of the John receiver can be performed by the same circuit, and the circuit scale can be reduced as compared with the conventional one, and color demodulation can be performed not only by the burst synchronous clock but also by any clock, Even when color demodulating a non-standard signal, it is possible to prevent image degradation from occurring.

Embodiment 4 FIG. In the fourth embodiment, only by adding an adder, the COLOR adjustment circuit and the TI
This is an embodiment in which the NT adjustment circuit can be omitted. Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 9 is a block diagram showing a main part of a television receiver including a digital color demodulation circuit according to Embodiment 4 of the present invention. In FIG.
The signals HSYNC and VSYNC are separated and output from the signal, and a line switching pulse and a burst position pulse are further output. 56b is R- with TINT, COLOR adjustment function
Y, BY separation circuits, 58c and 58d are mode selectors 3, 82 are TINs to which TINT adjustment data is input.
A T input terminal 83 indicates a COLOR input terminal to which COLOR adjustment data is input. The other parts are the same as those of the third embodiment, and thus the reference numerals are given and the description is omitted.

Next, the operation will be described. The AM / FM demodulation circuit 54 receives a carrier color signal of the NTSC system or the PAL system. In the circuit according to the fourth embodiment, the AM / FM demodulation circuit 54 performs the demodulation operation described in the second embodiment, outputs the output signal of the sign inversion circuit 42 in FIG. 2 as a phase angle, and further expresses a logarithmic expression. The output signals of the subtraction circuits 2 and 46 are output as AM demodulated waves. The AM demodulated wave output from the AM / FM demodulation circuit 54 is based on the PAL system and N
The signal is a demodulated wave of the signal of the TSC system, and is a signal in which the RY signal and the BY signal are combined.
RY and BY separation circuit 56b with LOR adjustment function
The signal is separated into a -Y signal and a BY signal, and TINT and COLOR are adjusted according to values set from a TINT input terminal 82 and a COLOR input terminal 83. However, PAL
When a signal of the system is input, the RY signal and-(R-
Y) signal is separated into a line-sequential signal and a BY signal. For this reason, in the case of the signal of the PAL system, only the-(RY) signal is inverted by the RY line inversion circuit 57 for PAL. With the above circuit, PAL, NT
Regardless of which of the SC signals is input, the RY signal can be obtained at the input terminals of the mode selectors 3 and 58c, and the BY signal can be obtained at the input terminals of the mode selectors 3 and 58d. Mode selectors 3, 58c and 58
d is controlled by a mode switching signal, and switches between the RY signal and the BY signal in accordance with the input signal.
Output to the GB matrix circuit 14.

R- with TINT, COLOR adjustment function
The Y, BY separation circuit 56b will be described. FIG. 10 shows the configuration of an RY / BY separation circuit with a TINT and COLOR adjustment function. In the figure, reference numeral 72 denotes a TINT input terminal to which data for TINT adjustment is input, and 77 denotes a COL.
A COLOR input terminal to which data for OR adjustment is input,
73a is the TINT input from the TINT input terminal 72
The adder 79b adds the adjustment data and the signal input from the adder 62.
A three-input adder for adding the COLOR adjustment data input from the OLOR input terminal 77 and the amplitude data input from the amplitude input terminal 78 is shown. The other configuration is the NTSC / PAL RY shown in FIG. , BY separation circuit 56
Since they are the same as those described above, they are denoted by reference numerals and description thereof is omitted.

RY, B for NTSC / PAL of Example 3
(Equation 27) showing the output signal of the −Y separation circuit 56 is TI
In the RY / BY separation circuit 56b with the NT / COLOR adjustment function, the value set from the TINT input terminal 72 is set from the kt and COLOR input terminals by an equation that holds when the TINT and COLOR inputs are 0. Value kc
Then, RY with TINT, COLOR adjustment function,
The equation representing the output signal of the BY separation circuit 56b is (Equation 28)
become that way.

(Equation 28) RY = A * exp (kc) * sin (θdif + kt) BY = A * exp (kc) * cos (θdif + kt)

As described above, according to the circuit of Embodiment 4, the AM / FM demodulation circuit of Embodiment 1 or 2 is
By adding a RY / BY separation circuit for C / PAL, a RY inversion circuit, etc., it is possible to perform color demodulation in two systems, NTSC and PAL. By providing the addition circuit in the Y separation circuit, TINT and COLOR adjustment can be performed as can be understood from (Equation 28), whereby the COLOR adjustment circuit and TINT adjustment circuit at the subsequent stage of the color demodulation circuit can be omitted. The circuit scale can be reduced.

Embodiment 5 FIG. Example 5 is based on NTSC, PA
This is an embodiment in which the signal system of the L, SECAM system is automatically determined. Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a block diagram showing a main part of a television receiver including a digital color demodulation circuit according to Embodiment 5 of the present invention. In FIG. 11, reference numeral 84 denotes an AM demodulated wave and FM output from the AM / FM demodulation circuit 54. A mode automatic discrimination circuit for automatically discriminating which of NTSC, PAL and SECAM input signals is to be demodulated based on a demodulated wave and a burst position pulse which is an output signal from the sync separation circuit 7c. Since the third embodiment is the same as the sixth embodiment, the same reference numerals are given and the description is omitted.

Next, the operation will be described. In the circuit of the fifth embodiment, the input signals NTSC, PAL, SECA
Since the mode determination of M is performed by the automatic mode determination circuit 84, the mode switching input terminal 59 in the third embodiment of FIG. 6 is unnecessary. The mode automatic discrimination circuit 84 has an AM / F
AM demodulated wave, FM, which is an output signal from M demodulation circuit 54
A demodulation wave and a burst position pulse which is an output signal from the sync separation circuit 7c are input, and a mode switching signal is output. Since the waveforms of the AM demodulated wave and the FM demodulated wave at the burst position are uniquely determined by the mode of the input signal, the mode of the input signal can be determined by referring to the waveform at the burst position. Although the mode selectors 1 and 53 do not always match the mode of the input signal in the initial state,
If they do not match, the mode automatic determination circuit 84 determines that the referenced waveform does not apply to any mode and is undefined. If it is determined that the input signal is indeterminate, the mode of the mode selector 1 or 53 is changed to match the mode of the input signal.

As described above, according to the circuit of the fifth embodiment, the AM / FM demodulation circuit of the first or second embodiment has the NTS
By adding a RY / BY separation circuit for C / PAL, a RY inversion circuit, a RY / BY separation circuit for SECAM, etc., color demodulation in three systems of NTSC, PAL and SECAM can be performed. NTSC, PAL, SECAM by adding a mode automatic discrimination circuit
It is possible to automatically determine the mode of an input signal of a device capable of performing color demodulation with a small circuit scale using the three methods, and to automatically switch operation modes.

In the third to fifth embodiments, the television receiver has been described as an example.
The present invention can also be applied to the R tuner section and the video-integrated television receiver, and the same effects as in the above embodiments can be obtained. In the second embodiment and the third to fifth embodiments to which the AM / FM demodulator according to the second embodiment is applied, various operations are performed using the conversion table stored in the ROM. May use a RAM instead of a ROM and store the conversion table in the RAM when the power is turned on, and the same effects as in the above embodiments can be obtained.

[0147]

As described above, according to the digital demodulator according to the present invention (claim 1), an AM signal or an FM signal sampled by a sampling clock of an arbitrary frequency is used as an input. A Hilbert transformer for performing a 90-degree phase shift on a signal, a first arithmetic circuit that receives the input signal and an output signal of the Hilbert converter as input, and calculates amplitude information of the input signal; A second arithmetic circuit that receives the output signal of the converter as an input and calculates phase information of the input signal, so that the input AM signal or the input FM sampled with a sampling clock of an arbitrary frequency When a signal is input, the corresponding demodulated AM signal or demodulated FM
The signal can be obtained with the same circuit, and the AM
There is an effect that a principle configuration of a digital demodulation device capable of demodulating both a modulation signal and an FM modulation signal can be obtained.

Further, according to the digital demodulation apparatus according to the present invention (claim 2), SECAM which is an NTSC or PAL system which is an AM signal or an FM signal.
When the input color signal is an NTSC or PAL system, the system operates with an arbitrary sampling clock, obtains a burst phase angle for each line from the second arithmetic circuit, The phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line, and the difference is fed back to the angular velocity of the sampling clock. A digital burst synchronous oscillator, and outputs the output of the first arithmetic circuit in a red color difference (hereinafter referred to as R−R) by a burst synchronous clock output from the digital burst synchronous oscillator.
RY / BY separation circuit for NTSC / PAL for separating the signal into a Y signal and a blue difference (hereinafter referred to as BY) signal, and RY of the RY and BY separation circuit. An R-Y line inverting circuit, which is provided at the output and inverts the signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is other than the PAL system; The output is provided for each line, and the output is switched for each line.
SE for separating the CAM demodulated signal into RY and BY
A RY / BY separation circuit for CAM is provided so that color demodulation can be performed even if any carrier color signal of the NTSC, PAL, or SECAM system is input at an arbitrary sampling clock. Using the basic configuration of such a digital demodulator, it is possible to perform most of the color demodulation processing of a television receiver supporting the three systems of NTSC, PAL, and SECAM with the same circuit, and to use a non-standard signal. In the case where the color demodulation is performed, it is possible to prevent the image from being deteriorated.

Further, according to the digital demodulation device according to the present invention (claim 3), the carrier signal of the NTSC or PAL system, which is the AM signal, is input and operates with an arbitrary sampling clock. A second line, and obtains a phase angle of a burst for each line from the second operation circuit, and calculates a current line obtained by calculation from the phase angle of the current line obtained from the second operation circuit, the angular velocity of the sampling clock, and the phase angle of the previous line. And a digital burst-synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock and the amplitude of the carrier chrominance signal obtained from the first arithmetic circuit, and a value set arbitrarily from the outside. An adder for COLOR adjustment to be added;
To the phase of the carrier chrominance signal obtained from the second arithmetic circuit,
A TINT adjustment adder for adding a value set arbitrarily from the outside, wherein an output of the first arithmetic circuit is output by a burst synchronization clock output from the digital burst synchronization oscillator to generate a red color difference (hereinafter, referred to as a red difference). NT which is separated into an RY signal and a blue color difference (hereinafter, referred to as BY) signal.
An RY / BY separation circuit for SC / PAL;
The RY output is provided at the RY output of the Y, BY separation circuit. When the input signal is of the PAL system, the signal is inverted and output for each line.
Line inversion circuit to adjust the color density (hereinafter referred to as CO
Since the configuration is such that LOR adjustment and hue adjustment (hereinafter referred to as TINT adjustment) can be performed, COLOR adjustment and TINT adjustment are performed by simply adding an adder in the digital demodulator as described above. It is possible,
There is an effect that the COLOR adjustment circuit and the TINT adjustment circuit at the subsequent stage of the color demodulation circuit can be omitted.

Further, according to the digital demodulation device according to the present invention (claim 4), based on the output of the first and second arithmetic circuits, the input signal is NTSC, PAL, SEC.
An automatic discrimination circuit for automatically discriminating whether the signal is AM or not is provided. Therefore, in the digital demodulator as described above, the NTS is simply added by the automatic discrimination circuit.
There is an effect that color demodulation can be automatically performed even if any of the C, PAL and SECAM carrier color signals is input.

Further, according to the digital demodulation device according to the present invention (claim 5), the first arithmetic circuit receives the input signal and the output signal of the Hilbert transformer as inputs and sums the squares of the respective squares. Calculate the square root of
The second arithmetic circuit receives the input signal and the output signal of the Hilbert transformer as inputs and calculates the arc tangent of each ratio, so that the second arithmetic circuit is sampled with a sampling clock of an arbitrary frequency. Input AM signal or input FM
When a signal is input, the demodulated AM corresponding to each signal
A signal or a demodulated FM signal can be obtained by the same circuit, and a basic configuration of a digital demodulating device that can demodulate both an AM modulation signal and an FM modulation signal with a small circuit scale can be obtained. There is.

Further, according to the digital demodulation apparatus according to the present invention (claim 6), SECAM which is an NTSC or PAL system which is an AM signal or an FM signal.
When the input color signal is an NTSC or PAL system, the system operates with an arbitrary sampling clock, obtains a burst phase angle for each line from the second arithmetic circuit, The phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line, and the difference is fed back to the angular velocity of the sampling clock. And a RY signal and a BY signal in response to a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for NTSC / PAL for separating signals and a RY output of the RY / BY separation circuit. An RY line inverting circuit for inverting and outputting a signal and outputting as it is in a case other than the PAL system, and an output of the second arithmetic circuit are provided.
A SECAM RY and BY separation circuit for separating the SECAM demodulated signal into RY and BY signals, and any of the carrier color signals of the NTSC, PAL, and SECAM systems can be output at an arbitrary sampling clock. Since the color demodulation can be performed even when the signal is input, the basic configuration of the digital demodulator as described above can be used to generate the NTS signal at an arbitrary sampling clock.
There is an effect that color demodulation can be performed even if any of the C, PAL and SECAM carrier color signals is input.

Further, according to the digital demodulation device according to the present invention (claim 7), the carrier signal of the NTSC or PAL system, which is an AM signal, is input and operated with an arbitrary sampling clock. A second line, and obtains a phase angle of a burst for each line from the second operation circuit, and calculates a current line obtained by calculation from the phase angle of the current line obtained from the second operation circuit, the angular velocity of the sampling clock, and the phase angle of the previous line. And a digital burst-synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock and the amplitude of the carrier chrominance signal obtained from the first arithmetic circuit, and a value set arbitrarily from the outside. An adder for COLOR adjustment to be added;
To the phase of the carrier chrominance signal obtained from the second arithmetic circuit,
A TINT adjustment adder for adding a value set arbitrarily from the outside, wherein an output of the first arithmetic circuit is output by a burst synchronization clock output from the digital burst synchronization oscillator to generate a red color difference (hereinafter, referred to as a red difference). NT which is separated into an RY signal and a blue color difference (hereinafter, referred to as BY) signal.
An RY / BY separation circuit for SC / PAL;
The RY output is provided at the RY output of the Y, BY separation circuit. When the input signal is of the PAL system, the signal is inverted and output for each line.
Line inversion circuit to adjust the color density (hereinafter referred to as CO
Since the configuration is such that LOR adjustment and hue adjustment (hereinafter referred to as TINT adjustment) can be performed, COLOR adjustment and TINT adjustment are performed by simply adding an adder in the digital demodulator as described above. It is possible,
There is an effect that the COLOR adjustment circuit and the TINT adjustment circuit at the subsequent stage of the color demodulation circuit can be omitted.

Further, according to the digital demodulation device of the present invention (claim 8), based on the output of the first and second arithmetic circuits, the input signal is NTSC, PAL, SEC.
An automatic discrimination circuit is provided for automatically discriminating which of the two types is AM, so that color demodulation can be automatically performed even if any of the carrier color signals of the NTSC, PAL, or SECAM system is input. In a digital demodulator, NTSC, P
There is an effect that color demodulation can be automatically performed regardless of whether any of the AL and SECAM carrier color signals is input.

According to the digital demodulation device of the present invention, the first arithmetic circuit stores a logarithmic conversion table for converting the input signal and the output signal of the Hilbert transformer into logarithms. A first and a second logarithmic conversion storage circuit to perform, a third arithmetic circuit for calculating amplitude information of the input signal in logarithmic expression using an output of the first and the second logarithmic conversion storage circuit, A first exponential conversion storage circuit that stores an exponential conversion table that converts the output of the third arithmetic circuit into an exponent.
A fourth arithmetic circuit for calculating phase information of the input signal in logarithmic expression using outputs of the first and second logarithmic conversion storage circuits, and an exponent for converting an output of the fourth arithmetic circuit into an exponent Since it has the second exponential conversion storage circuit for storing the conversion table, the speed of the operation to be performed by the first and second arithmetic circuits can be increased, and the sampling can be performed with a sampling clock of an arbitrary frequency. When the input AM signal or the input FM signal is input, the corresponding demodulated AM signal or the demodulated FM signal can be obtained by the same circuit, and the demodulation of both the AM modulated signal and the FM modulated signal can be performed. Can be executed with a small circuit scale and at a speed that can withstand practical use, and the digital demodulator can be put into practical use.

Further, according to the digital demodulation apparatus according to the present invention (claim 10), the NTSC or PAL system which is an AM signal or the SECA which is an FM signal.
An M-type carrier color signal is input, and the input signal is NTSC
Alternatively, in the case of the PAL system, it operates with an arbitrary sampling clock, obtains a phase angle of a burst for each line from the second arithmetic circuit, and obtains a phase angle of a current line obtained from the second arithmetic circuit and a sampling angle. A digital burst synchronous oscillator that compares the angular velocity of the sampling clock with the phase angle of the current line obtained by calculation from the phase angle of the previous line, and feeds back the difference to the angular velocity of the sampling clock; The output of the circuit is connected to the RY signal and the B-signal by the burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for NTSC / PAL for separating into Y signals; and an RY output of the RY / BY separation circuit. A RY line inverting circuit, which outputs the signal as it is in the case other than the PAL system, and is provided at the output of the second arithmetic circuit. And a SECAM RY and BY separating circuit for separating the demodulated signal into RY and BY. Any of the carrier color signals of the NTSC, PAL, and SECAM systems is input at an arbitrary sampling clock. Therefore, the color demodulation can be performed by using the basic configuration of the digital demodulation apparatus as described above, and NTN can be performed at an arbitrary sampling clock.
There is an effect that color demodulation can be performed even if any of the SC, PAL, and SECAM carrier color signals is input.

Further, according to the digital demodulation device according to the present invention (claim 11), the carrier signal of the NTSC or PAL system, which is an AM signal, is input and operated with an arbitrary sampling clock. A second line, and obtains a phase angle of a burst for each line from the second operation circuit, and calculates a current line obtained by calculation from the phase angle of the current line obtained from the second operation circuit, the angular velocity of the sampling clock, and the phase angle of the previous line. And a digital burst-synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock and the amplitude of the carrier chrominance signal obtained from the first arithmetic circuit, and a value set arbitrarily from the outside. A COLOR adjustment adder for adding, and a TINT adjustment adder for adding a value arbitrarily set from the outside to the phase of the carrier color signal obtained from the second arithmetic circuit. An output of the first arithmetic circuit is converted into a red difference (hereinafter, referred to as RY) signal and a blue difference (hereinafter, referred to as BY) signal by a burst synchronization clock output from the digital burst synchronization oscillator. The RY / BY separation circuit for NTSC / PAL to be separated and the RY output of the RY / BY separation circuit are provided. When the input signal is a PAL system, a signal is output for each line. Invert and output, and output as it is in cases other than the PAL system.
-Y line inversion circuit for adjusting color density (hereinafter, referred to as
COLOR adjustment) and hue adjustment (hereinafter, TINT)
(Referred to as “adjustment”), so that in the above-described digital demodulation apparatus, COLOR adjustment and TINT adjustment can be performed simply by adding an adder. And TINT
There is an effect that the adjustment circuit can be omitted.

Further, according to the digital demodulation device of the present invention (claim 12), based on the output of the first and second arithmetic circuits, the input signal is NTSC, PAL, SE
An automatic discriminating circuit for automatically discriminating which of the CAMs is provided is provided so that color demodulation can be automatically performed even if any of the carrier color signals of the NTSC, PAL, and SECAM systems is input. In a digital demodulator, NTSC, P
There is an effect that color demodulation can be automatically performed regardless of whether any of the AL and SECAM carrier color signals is input.

Further, according to the digital demodulation device of the present invention (claim 13), the fourth arithmetic circuit constituting the second arithmetic circuit is replaced by the first and second logarithmic conversion storage circuits. One having a first subtraction circuit for subtracting an output, and an exponential inverse tangent conversion storage circuit for storing conversion information within a predetermined range and storing an exponential arc tangent conversion table for converting the output of the subtraction circuit into an exponential arc tangent. The third arithmetic circuit constituting the first arithmetic circuit, a sine logarithmic conversion storage circuit storing a sine logarithmic conversion table for converting the output of the exponential arc tangent conversion storage circuit into a sine logarithm; A second subtraction circuit for subtracting an output of the corresponding sine logarithmic conversion storage circuit from an output of the second logarithmic conversion storage circuit and outputting the result to the first exponential conversion storage circuit, The second Since the exponential conversion storage circuit is composed of the exponential arc tangent conversion storage circuit, it is possible to further speed up the operation to be performed in the first and second arithmetic circuits, and to perform sampling with a sampling clock of an arbitrary frequency. When the input AM signal or input FM signal is input, the corresponding demodulated AM signal or demodulated FM signal is input.
The signal can be obtained by the same circuit, and the AM modulated signal and F
Demodulation of both of the M-modulated signals can be performed on a small circuit scale at a speed sufficient for practical use, and there is an effect that the digital demodulator can be put to practical use.

Further, according to the digital demodulating apparatus according to the present invention (claim 14), the SECA, which is an NTSC or PAL system which is an AM signal or an FM signal.
An M-type carrier color signal is input, and the input signal is NTSC
Alternatively, in the case of the PAL system, it operates with an arbitrary sampling clock, obtains a phase angle of a burst for each line from the second arithmetic circuit, and obtains a phase angle of a current line obtained from the second arithmetic circuit and a sampling angle. A digital burst synchronous oscillator that compares the angular velocity of the sampling clock with the phase angle of the current line obtained by calculation from the phase angle of the previous line, and feeds back the difference to the angular velocity of the sampling clock; The output of the circuit is connected to the RY signal and the B-signal by the burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for NTSC / PAL for separating into Y signals; and an RY output of the RY / BY separation circuit. A RY line inverting circuit, which outputs the signal as it is in the case other than the PAL system, and is provided at the output of the second arithmetic circuit. And a SECAM RY and BY separating circuit for separating the demodulated signal into RY and BY. Any of the carrier color signals of the NTSC, PAL, and SECAM systems is input at an arbitrary sampling clock. Therefore, the color demodulation can be performed by using the basic configuration of the digital demodulation apparatus as described above, and NTN can be performed at an arbitrary sampling clock.
There is an effect that color demodulation can be performed even if any of the SC, PAL, and SECAM carrier color signals is input.

Further, according to the digital demodulation device according to the present invention (claim 15), the carrier signal of the NTSC or PAL system, which is an AM signal, is input and operated with an arbitrary sampling clock. A second line, and obtains a phase angle of a burst for each line from the second operation circuit, and calculates a current line obtained by calculation from the phase angle of the current line obtained from the second operation circuit, the angular velocity of the sampling clock, and the phase angle of the previous line. And a digital burst-synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock and the amplitude of the carrier chrominance signal obtained from the first arithmetic circuit, and a value set arbitrarily from the outside. A COLOR adjustment adder for adding, and a TINT adjustment adder for adding a value arbitrarily set from the outside to the phase of the carrier color signal obtained from the second arithmetic circuit. An output of the first arithmetic circuit is converted into a red difference (hereinafter, referred to as RY) signal and a blue difference (hereinafter, referred to as BY) signal by a burst synchronization clock output from the digital burst synchronization oscillator. The RY / BY separation circuit for NTSC / PAL to be separated and the RY output of the RY / BY separation circuit are provided. When the input signal is a PAL system, a signal is output for each line. Invert and output, and output as it is in cases other than the PAL system.
-Y line inversion circuit for adjusting color density (hereinafter, referred to as
COLOR adjustment) and hue adjustment (hereinafter, TINT)
(Referred to as “adjustment”), so that in the above-described digital demodulation apparatus, COLOR adjustment and TINT adjustment can be performed simply by adding an adder. And TINT
There is an effect that the adjustment circuit can be omitted.

Further, according to the digital demodulation device of the present invention (claim 16), based on the output of the first and second arithmetic circuits, the input signal is NTSC, PAL, SE
An automatic discriminating circuit for automatically discriminating which of the CAMs is provided is provided so that color demodulation can be automatically performed even if any of the carrier color signals of the NTSC, PAL, and SECAM systems is input. In a digital demodulator, NTSC, P
There is an effect that color demodulation can be automatically performed regardless of whether any of the AL and SECAM carrier color signals is input.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital demodulator according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a digital demodulation device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a graph of Expression 11.

FIG. 4 is a diagram showing division of ωt into regions.

FIG. 5 is a block diagram of an angular velocity calculator.

FIG. 6 is a block diagram of a television receiver including a digital color demodulation circuit according to Embodiment 3 of the present invention.

FIG. 7 is a block diagram of a RY and BY separation circuit for SECAM.

FIG. 8 is a block diagram of an RY / BY separation circuit for NTSC / PAL.

FIG. 9 is a block diagram of a television receiver including a digital color demodulation circuit according to Embodiment 4 of the present invention.

FIG. 10: TINT, RY with COLOR adjustment function,
It is a block diagram of a BY separation circuit.

FIG. 11 is a block diagram of a television receiver including a digital color demodulation circuit according to Embodiment 5 of the present invention.

FIG. 12 is a block diagram of a television receiver including an NTSC color demodulation circuit of Conventional Example 1.

FIG. 13 is a block diagram of a color demodulation circuit for NTSC.

FIG. 14 is a diagram illustrating the operation principle of an NTSC color demodulation circuit.

FIG. 15 is a block diagram of a television receiver including a PAL color demodulation circuit of Conventional Example 2.

FIG. 16 is a block diagram of a color demodulation circuit for PAL.

FIG. 17 is a diagram illustrating the operation principle of the NTSC color demodulation circuit.

FIG. 18 is a block diagram of a television receiver including a SECAM color demodulation circuit of Conventional Example 3.

FIG. 19 is a block diagram of a color demodulation circuit for SECAM.

[Explanation of symbols]

1 antenna, 2 tuner, 3 external input terminal, 4
AV selector, 5A / D converter, 6a, 6c Y
/ C separation circuit, 6b Y separation circuit, 7a, 7b, 7c
Sync separation circuit, 8 deflection system, 9 luminance signal processing circuit, 1
0CRT, 11a Color demodulation circuit for NTSC, 11b P
AL color demodulation circuit, 11c SECAM color demodulation circuit, 1
2 TINT adjustment circuit, 13 COLOR adjustment circuit, 1
4 RGB matrix circuits, 15 D / A converters,
16 NTSC alignment determination circuit, 17 inversion circuit, 18
RY, BY separation circuit, 19, 241H delay line memory, 20, 60, 62, 67, 73a, 79a
Adder, 2 1, 49,64,73b subtractor 23 bell filter, 25 lines sequentially SW, 26a 4.40
6 MHz frequency discriminator, 26b 4.250 MHz frequency discriminator, 27 color sequence discriminating circuit, 28 input terminals, 2
9 Hilbert transformer, 30 delay compensation register, 3
1 arithmetic circuit 1, 31a arithmetic circuit 3, 32 arithmetic circuit 2, 32a arithmetic circuit 4, 33 absolute value circuit 1, 34
Absolute value circuit 2, 35 log ROM1, 36 log ROM
2, 37 Subtraction circuit 1, 38 Absolute value circuit 3, 39 Exponential arc tangent ROM, 40 Data conversion circuit, 41 90 °
Adder, 42 sign inversion circuit, 43 angular velocity calculator, 4
4,51 selector, 45,74 sine log ROM, 46
Subtraction circuit 2, 47, 80 exponent ROM, 48, 63,
66, 70 registers, 50 360 ° adder, 52
Absolute value circuit, 53 mode selector 1, 54 AM / F
M demodulation circuit, RY / BY separation circuit for 55 SECAM, 56a RY / BY separation circuit for NTSC / PAL, 56b TINT, R-R with COLOR adjustment function
Y, BY separation circuit, 57 PAL RY line inversion circuit, 58a, 58b Mode selectors 2, 58c, 5
8d mode selector 3, 59 mode switching signal input terminal, 61 burst position pulse input terminal, 65 coefficient unit, 68 data converter, 71 burst synchronous oscillation
Part , 72, 82 TINT input terminal, 75 Cosine logarithm R
OM, 76 multiplexer, 77,83 COLOR
Input terminal, 78 Amplitude input terminal, 79b 3-input adder, 81 Demultiplexer, 84 Mode automatic discrimination circuit , 159 Phase angle input terminal .

Continuation of the front page (72) Inventor Fumio Suzuki 1 Baba Zoshosho, Nagaokakyo-shi, Kyoto Mitsubishi Electric Corporation Kyoto Works (56) References JP-A-58-1389 (JP, A) JP-A-58-14684 (JP, A) JP-A-58-14685 (JP, A) JP-A-61-131991 (JP, A) JP-A-5-347736 (JP, A) JP-A-64-7730 (JP, A) Kaisho 64-7731 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/16 H03D 5/00

Claims (16)

(57) [Claims] An amplitude-modulated signal (hereinafter, referred to as an AM signal) or a frequency-modulated signal (hereinafter, referred to as an FM signal) sampled by a sampling clock having an arbitrary frequency is input to the input signal. A Hilbert converter that performs a phase shift, a first arithmetic circuit that receives the input signal and an output signal of the Hilbert converter as input, and calculates amplitude information of the input signal; the input signal; and the Hilbert A second arithmetic circuit that receives the output signal of the converter and calculates the phase information of the input signal, the demodulated AM signal or the demodulated FM corresponding to the input AM signal or the input FM signal. A digital demodulation device characterized by being configured to output a signal. 2. The digital demodulator according to claim 1, wherein a carrier color signal of an NTSC or PAL system which is an AM signal or a SECAM system which is an FM signal is input, and the input signal is NTSC or PAL. In the case of the system, it operates with an arbitrary sampling clock, and 1 second from the second arithmetic circuit.
The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. Having a digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock,
An output of the first arithmetic circuit is converted into a red difference (hereinafter, referred to as RY) signal and a blue difference (hereinafter, referred to as BY) signal by a burst synchronization clock output from the digital burst synchronization oscillator. An RY / BY separation circuit for NTSC / PAL to be separated; and an RY output of the RY / BY separation circuit;
An R-Y line inversion circuit that inverts the signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is other than the PAL system; and an output of the second arithmetic circuit, An RY / BY separation circuit for SECAM that switches the output for each line to separate the SECAM system demodulated signal into RY and BY, and NTSC, PAL, SECAM
A digital demodulation device characterized in that color demodulation can be performed regardless of which carrier color signal is input. 3. The digital demodulation device according to claim 1, wherein a carrier chrominance signal of the NTSC or PAL system, which is an AM signal, is input, and is operated with an arbitrary sampling clock. The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. A digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock;
To the amplitude of the carrier color signal obtained from the first arithmetic circuit,
A COLOR adjustment adder for adding a value arbitrarily set from outside; and a T for adding a value arbitrarily set from outside to the phase of the carrier color signal obtained from the second arithmetic circuit.
And an INT adjustment adder. An output of the first arithmetic circuit is output by a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for NTSC / PAL for separating into a Y signal and a blue difference (hereinafter referred to as BY) signal; and an RY of the RY and BY separation circuit. Provided on the output,
An R-Y line inversion circuit that inverts and outputs a signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is not of the PAL system. A digital demodulator characterized in that the digital demodulator is configured to be capable of performing hue adjustment (hereinafter referred to as TINT adjustment). 4. The digital demodulator according to claim 2, wherein an automatic determination is made based on an output of said first and second arithmetic circuits as to whether the input signal is NTSC, PAL, or SECAM. A digital demodulation device comprising a circuit and configured to automatically perform color demodulation even when any of the carrier color signals of the NTSC, PAL, and SECAM systems is input. 5. The digital demodulator according to claim 1, wherein the first arithmetic circuit receives the input signal and the output signal of the Hilbert transformer as inputs and calculates a square root of a sum of squares of the input signal and the output signal of the Hilbert transformer. Wherein the second arithmetic circuit receives the input signal and the output signal of the Hilbert transformer as inputs and calculates an arctangent of a ratio between the digital signal and the digital signal. 6. The digital demodulator according to claim 5, wherein a carrier color signal of an NTSC or PAL system which is an AM signal or a SECAM system which is an FM signal is input, and the input signal is NTSC or PAL. In the case of the system, it operates with an arbitrary sampling clock, and 1 second from the second arithmetic circuit.
The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. Having a digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock,
NTSC / PA for separating an output of the first arithmetic circuit into an RY signal and a BY signal by a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for L, and a RY output of the RY / BY separation circuit;
An R-Y line inversion circuit that inverts the signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is other than the PAL system; and an output of the second arithmetic circuit, An RY / BY separation circuit for SECAM that switches the output for each line to separate the SECAM system demodulated signal into RY and BY, and NTSC, PAL, SECAM
A digital demodulation device characterized in that color demodulation can be performed regardless of which carrier color signal is input. 7. The digital demodulator according to claim 5, wherein an input is a carrier chrominance signal of the NTSC or PAL system, which is an AM signal, and is operated with an arbitrary sampling clock. The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. A digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock;
To the amplitude of the carrier color signal obtained from the first arithmetic circuit,
A COLOR adjustment adder for adding a value arbitrarily set from outside; and a T for adding a value arbitrarily set from outside to the phase of the carrier color signal obtained from the second arithmetic circuit.
And an INT adjustment adder. An output of the first arithmetic circuit is output by a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for NTSC / PAL for separating into a Y signal and a blue difference (hereinafter referred to as BY) signal; and an RY of the RY and BY separation circuit. Provided on the output,
An R-Y line inversion circuit that inverts and outputs a signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is not of the PAL system, and adjusts color density (hereinafter referred to as COLOR) A digital demodulator characterized in that the digital demodulator is configured to be capable of performing hue adjustment (hereinafter referred to as TINT adjustment). 8. The digital demodulator according to claim 6, wherein an automatic discrimination is made based on the output of the first and second arithmetic circuits to determine whether the input signal is NTSC, PAL, or SECAM. A digital demodulation device comprising a circuit and configured to automatically perform color demodulation even when any of the carrier color signals of the NTSC, PAL, and SECAM systems is input. 9. The digital demodulator according to claim 1, wherein the first arithmetic circuit stores a logarithmic conversion table for converting the input signal and the output signal of the Hilbert transformer into a logarithm. A third logarithmic conversion storage circuit, a third arithmetic circuit that calculates the amplitude information of the input signal in logarithmic expression using outputs of the first and second logarithmic storage circuits, and an output of the third arithmetic circuit And a first exponential conversion storage circuit that stores an exponential conversion table that converts into an exponent. The second arithmetic circuit uses an output of the first and second logarithmic conversion storage circuits to logarithmically. A fourth arithmetic circuit for calculating phase information of the input signal in expression; and a second exponential conversion storage circuit for storing an exponential conversion table for converting an output of the fourth arithmetic circuit into an exponent. It is characterized by Digital demodulator. 10. The digital demodulator according to claim 9, wherein an input is a NTSC or PAL carrier color signal, which is an AM signal, or an SECAM carrier color signal, which is an FM signal. In the case of the system, it operates with an arbitrary sampling clock, and 1 second from the second arithmetic circuit.
The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. Having a digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock,
NTSC / PA for separating an output of the first arithmetic circuit into an RY signal and a BY signal by a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for L, and a RY output of the RY / BY separation circuit;
An R-Y line inversion circuit that inverts the signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is other than the PAL system; and an output of the second arithmetic circuit, An RY / BY separation circuit for SECAM that switches the output for each line to separate the SECAM system demodulated signal into RY and BY, and NTSC, PAL, SECAM
A digital demodulation device characterized in that color demodulation can be performed regardless of which carrier color signal is input. 11. The digital demodulation device according to claim 9, wherein a carrier chrominance signal of the NTSC or PAL system, which is an AM signal, is input, operated with an arbitrary sampling clock, and output from the second arithmetic circuit. The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. A digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock;
To the amplitude of the carrier color signal obtained from the first arithmetic circuit,
A COLOR adjustment adder for adding a value arbitrarily set from outside; and a T for adding a value arbitrarily set from outside to the phase of the carrier color signal obtained from the second arithmetic circuit.
And an INT adjustment adder. An output of the first arithmetic circuit is output by a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for NTSC / PAL for separating into a Y signal and a blue difference (hereinafter referred to as BY) signal; and an RY of the RY and BY separation circuit. Provided on the output,
An R-Y line inversion circuit that inverts and outputs a signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is not of the PAL system, and adjusts color density (hereinafter referred to as COLOR) A digital demodulator characterized in that the digital demodulator is configured to be capable of performing hue adjustment (hereinafter referred to as TINT adjustment). 12. The digital demodulator according to claim 10, wherein an automatic discrimination is made based on the output of said first and second arithmetic circuits to determine whether the input signal is NTSC, PAL, or SECAM. A digital demodulation device comprising a circuit and configured to automatically perform color demodulation even when any of the carrier color signals of the NTSC, PAL, and SECAM systems is input. 13. The digital demodulator according to claim 9, wherein said fourth arithmetic circuit constituting said second arithmetic circuit is configured to subtract an output of said first and second logarithmic conversion storage circuits. And an exponential inverse tangent conversion storage circuit that stores conversion information within a predetermined range and stores an exponential inverse tangent conversion table that converts an output of the subtraction circuit into an exponential arc tangent. A third sine-logarithmic conversion storage circuit that stores a sine-logarithmic conversion table that converts an output of the exponential arctangent conversion storage circuit into a sine-logarithm; and the first and second arithmetic circuits. A second subtraction circuit for subtracting the corresponding output of the sine logarithmic conversion storage circuit from the output of the logarithmic conversion storage circuit and outputting the result to the first exponential conversion storage circuit, wherein the second Exponential change Storage circuit, a digital demodulation device, characterized in that is made of the exponential inverse tangent converting storage circuit. 14. The digital demodulation apparatus according to claim 13, wherein a carrier color signal of an NTSC or PAL system, which is an AM signal, or a SECAM system, which is an FM signal, is input, and the input signal is NTSC or PAL. In the case of the system, it operates with an arbitrary sampling clock, and 1 second from the second arithmetic circuit.
The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. Having a digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock,
NTSC / PA for separating an output of the first arithmetic circuit into an RY signal and a BY signal by a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for L, and a RY output of the RY / BY separation circuit;
An R-Y line inversion circuit that inverts the signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is other than the PAL system; and an output of the second arithmetic circuit, An RY / BY separation circuit for SECAM that switches the output for each line to separate the SECAM system demodulated signal into RY and BY, and NTSC, PAL, SECAM
A digital demodulation device characterized in that color demodulation can be performed regardless of which carrier color signal is input. 15. The digital demodulation device according to claim 13, wherein a carrier chrominance signal of the NTSC or PAL system, which is an AM signal, is input, operated with an arbitrary sampling clock, and output from the second arithmetic circuit. The phase angle of the burst is obtained for each line, and the phase angle of the current line obtained from the second arithmetic circuit is compared with the phase angle of the current line obtained by calculation from the angular velocity of the sampling clock and the phase angle of the previous line. A digital burst synchronous oscillator that feeds back the difference to the angular velocity of the sampling clock;
To the amplitude of the carrier color signal obtained from the first arithmetic circuit,
A COLOR adjustment adder for adding a value arbitrarily set from outside; and a T for adding a value arbitrarily set from outside to the phase of the carrier color signal obtained from the second arithmetic circuit.
And an INT adjustment adder. An output of the first arithmetic circuit is output by a burst synchronization clock output from the digital burst synchronization oscillator.
A RY / BY separation circuit for NTSC / PAL for separating into a Y signal and a blue difference (hereinafter referred to as BY) signal; and an RY of the RY and BY separation circuit. Provided on the output,
An R-Y line inversion circuit that inverts and outputs a signal for each line when the input signal is of the PAL system and outputs the signal as it is when the input signal is not of the PAL system. A digital demodulator characterized in that the digital demodulator is configured to be capable of performing hue adjustment (hereinafter referred to as TINT adjustment). 16. The digital demodulator according to claim 14, wherein an automatic discrimination is made on the basis of an output of said first and second arithmetic circuits to determine whether the input signal is NTSC, PAL, or SECAM. A digital demodulation device comprising a circuit and configured to automatically perform color demodulation even when any of the carrier color signals of the NTSC, PAL, and SECAM systems is input.