JPH01288192A - Broadcast receiver and reception system and color signal recording/reproducing device and system therefor - Google Patents

Abstract

PURPOSE:To obtain a reproduced image with high picture quality even in the reception of a weak electric field by suppressing a change in the S/N of a chrominance signal due to noise (triangle noise) proportional to a base band frequency generated in FM demodulation in a receiver for satellite broadcast (NTSC TV receiver). CONSTITUTION:An intermediate frequency stage generates an inverted phase IF signal whose polarity is inverted to a base band signal. The IF signal (in phase) or the inverted phase IF signal are demodulated and a subcarrier burst signal are extracted from the demodulation signal by using a synchronizing signal in the demodulation signal to generate a 1st consecutive subcarrier signal. A 2nd subcarrier signal consecutive and orthogonal to the subcarrier is generated, and a 1st switching process where the IF signal and the inverted IF signal are switched alternately based on the 1st subcarrier signal and the 2nd switching process where the IF signal and the inverted IF signal are switched alternately based on the 2nd subcarrier signal are provided, the output of the 1st switching process is demodulated to extract an E1 signal and the output of the 2nd switching process is demodulated to extract an EQ signal.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention particularly relates to an NTSC satellite broadcast receiving apparatus and receiving system.

The present invention further relates to an NTSC color television signal recording/reproducing apparatus and recording/reproducing method.

B0 Summary of the Invention According to the present invention, in a satellite broadcast receiving device that modulates and broadcasts an NTSC signal as a baseband signal, the intermediate frequency signal is converted into a baseband signal in addition to the normal normal phase signal. Create a reverse-phase IF in which the polarity of
Switch the positive phase and negative phase with the inωsct pulse,
The outputs are each demodulated by a demodulator to form a signal of Er+EQ, which is combined with the luminance signal Ev to be output from the S terminal.

Also, E! .

Eal EV is matrixed to output the three primary colors Ep, Ec, and Ea.

Further, in the color signal recording/reproducing apparatus according to the present invention, the FM modulated wave of the NTSC color television signal is used for recording, and during FM demodulation, (1) the demodulator-1 converts the FM modulated wave (baseband signal positive polarity ) to generate a subcarrier with a phase corresponding to the time axis fluctuation of one line period from the burst subcarrier. (2) A frequency converter generates an FM modulated wave in which the baseband signal has the opposite polarity. (3) Two positive and opposite polarities at baseband
The outputs of the various FM modulated waves switched with the reference carrier wave for each line obtained in (1) (actually two orthogonal signals cosωsct and sinωset) are sent to each FM demodulator.
2 and -3 to obtain a baseband signal, and a low-pass filter to obtain two chromaticity signals, which are combined with the luminance signal Ev obtained from (1) and output from the S terminal. Further, it is matrixed into three primary color signals of ER, Ea, and Ea.

C0 Prior Art In satellite broadcasting using the NTSC system, which is the Japanese standard system, the frequency distribution of the baseband signal of the video signal is as shown in FIG. The NTSC signal consists of a luminance signal EY, a chromaticity signal EC, and a subcarrier (frequency 3.579545 M7).
are multiplexed using balanced modulation (AM) L. The baseband signal EM is expressed by equation (1).

EM = Ey + Ec cos (ωs
ct 10 )== Ey + EI co
sωsct+EQ sin ωsct・・・・・・
... (1) ωsc: Subcarrier frequency In satellite broadcasting, equation (1) is frequency modulated and transmitted. Therefore, in principle, the receiver performs FM demodulation of the FM modulated wave to restore the baseband signal of equation (1), and the color receiver performs color demodulation.

Ec (E s + Ea) is restored and further matrixed with the luminance signal Ev to form three primary color signals of ER, Ea, and Ea. By demodulating this FM modulated wave, the formula (
When obtaining the EM of 1), so-called triangular noise, which has a frequency distribution of noise amplitude proportional to the frequency of the baseband signal specific to FM demodulation, is generated.

For this reason, the amplitude of the high frequency component is increased by pre-emphasis on the transmitting side, and the amplitude of the high frequency component is decreased by de-emphasis on the receiver side. However, as can be seen from the emphasis characteristics shown in FIG. 8, the SN ratio of a single chromaticity signal is worse than that of a luminance signal. In FIG. 8, the solid line represents the characteristics of the pre-emphasis circuit, and the broken line represents the distribution of FM demodulation noise. This is also mentioned in "Broadcasting Satellite Technology" edited by Japan Broadcasting Corporation, 2.8 Special Transmission Methods, page 63.

In the recording/reproduction signal processing system for the NTSC color television signal, the NTSC signal multiplexes the luminance signal EY with the chromaticity signal Ec (consisting of Et and Ea) by AM modulating the subcarrier. When the NTSC transmission signal is EM, the frequency distribution of equation (2) is as shown in equation (2) (%) θ: phase of color carrier wave.

The recording/reproducing method of NTSC signals in VTRs is to perform FM (frequency modulation) modulation in order to avoid the influence of fluctuations in the time axis and the influence of time fluctuations in the gain of electromagnetic conversion of the tape head.

During demodulation of FM modulation, transmission system noise is added as triangular noise that increases in proportion to the frequency of the baseband signal (EM in this case) (FIG. 15).

Current VTRs are broadly classified into the following two systems.

(1) EM of the NTSC signal is directly FM modulated and recorded/reproduced.

(2) NTSC color carrier Ec cos ((+)Se
j + θ), FM modulates only EY, converts ωsc to a low carrier wave, and adds it to the EY FM modulated wave. During playback, separates the low carrier color signal and converts it to subcarrier ωsc. and add it to the FM demodulated EY.

D0 Problems to be Solved by the Invention As a countermeasure to the deterioration of the S/N ratio of chromaticity signals in NTSC broadcast reception, the chromaticity signals are not multiplexed with the luminance signals in the baseband, and EY and Ec are temporally transmitted in one horizontal scanning line. It is compressed and transmitted, and on the receiver side, it is expanded for each purpose (IH).
A method has also been proposed. In this case, a circuit for expanding the time axis is required in the receiver, which has the disadvantage of increasing costs.

The method (1) described in the recording/playback signal processing system for NTSC color television signals is used for business purposes, and reduces noise accompanying recording/playback in order to suppress noise in color signals. This has the disadvantage of increasing the amount of tape used. (2) is used for home use and converts the color signal into a low carrier wave, so the noise of the color signal is reduced. However, it is a recording method based on amplitude modulation, and has the disadvantage that it is easily affected by nonlinear effects of recording/reproduction and time fluctuations in the sensitivity of electromagnetic conversion.

[Object of the Invention] A first object of the present invention regarding NTSC broadcast reception is to provide a satellite broadcast reception device (NTSC television) that
Suppresses changes in the S/N ratio of chromaticity signals due to noise proportional to the baseband frequency (triangular noise) generated during FM demodulation, and obtains high-quality reproduced images even when receiving weak electric fields (including the effects of rain). An object of the present invention is to provide a broadcast receiving device and a receiving method that make it possible to do this.

A second object of the present invention regarding the recording/reproduction of color signals is to improve the SN ratio of the color signal when recording and reproducing the second transmission signal in the recording/reproduction of NTSC color television signals, thereby achieving high quality. An object of the present invention is to provide a color signal recording/reproducing device and a recording/reproducing method that make it possible to obtain a reproduced image.

E3 Means for Solving Problems In order to achieve the above first object, the broadcast receiving device according to the present invention generates an anti-phase IF multiplied signal in which the polarity of the signal is reversed with respect to the baseband signal at the intermediate frequency signal stage. means and
a demodulator for demodulating an IF signal (positive phase) or a negative phase IF signal; a means for extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; and a means for generating a continuous subcarrier signal; means for generating a continuous second subcarrier signal orthogonal to the IF; first switching means for alternately switching the IF multiplied signal and the opposite phase IF signal based on the subcarrier signal;
a second switching means for alternately switching the double signal reverse phase IF signal based on the second subcarrier signal; a means for demodulating the output of the first switching means and extracting the EI double signal; demodulating the output of the means;
The gist of the present invention is to include means for extracting an EQ signal.

A broadcast receiving system for achieving the first object of the present invention includes a step of generating an opposite-phase IF multiplied signal in which the polarity of the signal is reversed with respect to a baseband signal at an intermediate frequency signal stage;
A step of demodulating the signal (positive phase) or negative phase IF multiplied signal;
a step of extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; a step of generating a continuous second subcarrier signal orthogonal to the subcarrier; Above IF double signal reverse phase I
A first switching step in which the F-fold signal is alternately switched based on the above-mentioned subcarrier signal, and the above-mentioned IF-fold signal has a reverse phase.
a second switching step of alternately switching the signal based on the second subcarrier signal; a step of demodulating the output of the first switching step and extracting the ET multiplied signal;
demodulating the output of the switching means and extracting the Eα signal.

In order to achieve the above-mentioned second object, the color signal recording/reproducing apparatus according to the present invention includes means for generating an inverse phase FM signal whose polarity is reversed with respect to the baseband signal of the reproduced FM signal, and a reproduced IF signal. a demodulator for demodulating a (normal phase) or anti-phase FM signal; a means for extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; and a means for generating a continuous subcarrier signal; death,
means for generating a continuous second subcarrier signal; first switching means for alternately switching between the reproduced FM signal and the reverse phase FM signal based on the subcarrier signal; and the reproduced FM signal and the reverse phase FM signal. and second switching means for alternately switching the subcarrier signals based on the second subcarrier signal.

The gist is to include means for demodulating the output of the first switching means and extracting the EQ signal, and means for demodulating the output of the second switching means and extracting the EQ signal.

A color signal recording/reproducing method for achieving the second object of the present invention includes a step of generating an inverse phase FM signal having a polarity reversed with respect to the baseband signal of the reproduction FM signal;
a step of demodulating the reproduced IF signal (normal phase) or a negative phase FM signal; a step of extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; and a step of generating a continuous subcarrier signal; a first switching step of alternately switching between the reproduced FM signal and the opposite-phase FM signal based on the subcarrier signal; a second switching step of alternately switching the anti-phase FM signal based on the second subcarrier signal, a step of demodulating the output of the first switching step and extracting the Et times signal, and a second switching step of Demodulate the output and convert it to EcL
and a step of extracting the signal.

F9 Operation The broadcast receiving apparatus and reception method of the present invention operate as follows.

(1) Create positive and negative baseband signals at the IF (intermediate frequency) stage (referred to here as positive-phase IF and negative-phase IF).

(2) Demodulate the positive or negative phase IF with an FM demodulator, extract the subcarrier burst, control the phase of the subcarrier oscillator, and further calculate cosωset and sinωsc
Output mutually orthogonal components of t.

(3) Switch between positive and negative phase IF using pulses based on the subcarrier (cosωset and sinω5ct), demodulate the output with an FM demodulator, and extract the low frequency of the baseband signal (Ec).

(4) The luminance signal Ev, which is the low frequency component of the FM demodulator obtained in (2), and the chromaticity signal Ec obtained in (3) are output. Or ER, Ec, in matrix from EV and Ec,
The three primary color signals of Ea are used.

The color signal recording/reproducing apparatus and recording/reproducing method of the present invention operate as follows.

(1) FM demodulate the reproduced signal and extract the luminance Ev and subcarrier reference signal (burst).

(2) Setting a reference for the phase of the subcarrier of the reproduced signal that fluctuates on the time axis for each line.

(3) Reproduction Creates an FM signal (positive polarity at baseband is called positive phase) and its opposite phase signal (reverse polarity at baseband).

(4) Two orthogonal switching signals (cos ωset and sinω
5et) and switch the positive phase and negative phase FM of (3).

(5) The two FM modulated waves in (4) are each FM demodulated to obtain two chromaticity signals.

(6) EV and two types of Ec (Et-EQ) are used as output signals.

G. EXAMPLES The present invention will be explained in more detail below using examples with reference to the drawings, but these are merely illustrative and various modifications and improvements can be made without going beyond the scope of the present invention. Of course it is possible.

FIG. 1 is a block diagram showing the configuration of a broadcast receiving device according to the present invention. In the figure, 1 is a high frequency amplification section, 2 is a frequency converter, 3 is a local oscillator, 4 is a frequency converter (negative phase generation), and 5 is a fixed Oscillator, 6 is FM demodulator-1, 7
is a synchronous separator, 8 is a burst gate, 9 is a subcarrier generator (3°58 MHz) cos ωsct, ・1
0 is the EY separation filter, 11.12 is the electronic switch,
13.14 is an FM demodulator, 2, 3, and 15 are 90'' phase shifters, 16.17 is a low-pass filter, 18.19 is a delay line, and 20, 21, and 22 are S terminal outputs.

23 represents a matrix, and 24 represents R, G, and B outputs.

The operation of the above embodiment will be explained below.

The received signal is added to the frequency converter 2 from the high frequency amplification section 1 and is converted into an IF signal with an FM modulated wave by the difference frequency with the output of the local oscillator 3.

The output of frequency converter 2 is transferred to frequency converter 4.
In addition, a difference component from the frequency of the fixed frequency oscillator 5 is created, and the output of the frequency converter 2 is converted into a positive-phase IF.
Then, the output of frequency converter 4 is in reverse phase I
Let it be F.

If the output frequency of the frequency converter 2 corresponding to the unmodulated FM wave is flO, the output frequency f of the frequency converter 2 is expressed by equation (3).

f+=fto+△f (positive phase IF)...
...(3) If the frequency of the fixed oscillator 5 is 2f+o and the single frequency converter 4 is a balanced modulation type frequency converter, then the frequency of the output of the frequency converter 4 is f+'
becomes equation (4).

f+' = 2 f+o (f+o+△f)
= f + o - Δf (negative phase IF) ...... (4) The output of frequency converter 2 is made into a baseband signal by FM demodulator - 16, synchronous separator 7, burst gate 8
, via the subcarrier generator 9.

Obtain cos ωsc t. Figure 2 shows this fsc
=3°579545 M-Explain the occurrence.

FIG. 2(a) shows the baseband signal of the FM demodulator-16, and FIG. 2(b) shows the output of the sync separator 7, which is a horizontal sync pulse. By delaying (b) to create a burst gate pulse (c) and gating (a) with this, the subcarrier burst shown in (d) is extracted. By (d), the fsc oscillator 9 is phase-coupled and continuous cos
Obtain ωset.

The positive phase IF of the output of frequency converter 2 and the negative phase IF of the output of frequency converter 4 are
cos ω5 in Figure 3, shown by the solid line and broken line in Figure (a).
5 shows switching by et (output of subcarrier generator 9). That is, the electronic switch 11 in FIG. In Figure 3 (b), T/2 = 1/2 f
The outputs of the frequency converters 2 and 4 are switched every sc and used as the output of the electronic switch 11. Figure 3(a)
The output is shown as a thick line. This signal is added to the FM demodulator 213 to demodulate it into a baseband signal, and then passed through the low-pass filter 16.
3 (c,), which is the signal E modulated by cos ωset of the NTSC chromaticity signal.

can be taken out.

CO8ωset of the output of subcarrier generator 9 is set to 90
”In addition to 15 phase shift circuits, 5in (115Ct
The positive phase and negative phase IF outputs of frequency converters 2 and 4 are added to electronic switch 12, switched by 90" phase shifter 15, and the output is
The FM demodulator 314 outputs the baseband signal, and the low-pass filter 17 outputs the NTSC SI signal as a low-pass component.
A signal EQ modulated by nωsct is extracted.

On the other hand, the output of the FM demodulator-16 is added to the EY separation low-pass filter 10 to take out EY, and the delay line 18
In addition to , we get the output 2o.

The EQ also obtains an output 21 through a delay line 19.

Together with the EQ output 22, the output 20°21.
22 becomes a so-called S terminal output signal, which becomes an NTSC transmission signal.

In order to drive a display device such as a color CRT, a low pass filter 17 and delay lines 18 and 19 are required.
Adding the output of to matrix 23, Ey, El,
EQ is converted into three primary color signals ER+EG+EB and output 24.

NTSC chromaticity signal E cos ω orthogonal to Fig. 4
set and E(Isin ωset IF
Showing separation in steps. In Figure 4(a), Ey is omitted and EH
The distribution of signals at the IF stage is shown in a state (dashed line) where cos ω5ct (solid line) and Ecsin ω5ct (broken line) coexist. Figures 4(a) and (b) are cosω
square wave pulses corresponding to sct and sin ωsct that control the electronic switch.

Figure 4(d) shows a pulse of cos ωsc t (a
) is an example in which the signal (IF) is switched. To be exact, if Fig. 4(a) is the positive phase IF signal, and the opposite phase IF is switched in (b), Fig. 4(d) is obtained.
This is the output of the IF. In FIG. 4(d), the solid line corresponds to EQ, and the broken line corresponds to EQ. In this example, EY exists on the positive side (Δf>O) with respect to fIp, while EQ has a distribution in which the positive and negative values cancel each other out with respect to flO. Therefore, when (d) is demodulated into a baseband signal by the FM demodulator-2, only the EY component in the solid line remains, and by passing this through the low-pass filter 16 in FIG. 1, the signal in FIG. 4(e) is obtained. EY is obtained.

Regarding the component of EQsinωsct, (a) is also expressed as (C
) to obtain the EQ acid component.

FIG. 5 shows Ey, E in the baseband signal according to the present invention.
It shows changes in the spectral distribution of Y and EQ.

FIG. 5(a) is the NTSC signal shown in equation (1),
EY is ECcos (ωs
ct + θ) are multiplexed.

In Figure 5(a), ECcos (ωsct 10)
The chromaticity signal component of is located at a high frequency in the baseband signal. FIG. 5(b) shows changes in the baseband due to switching of IF, where Ec is a low frequency and the luminance signal EV is a modulated wave centered on Ey cos C+)5ct and fsc. Due to this IF switching, Ec becomes a low frequency component.

Figure 5(c) shows a low-pass filter that extracts Ec, which is 1.5 MHz for EY and 0.5M1 (z for EQ. In the simple method, both El and EQ are 0.5 MHz is used. In this case, the delay line 19 in FIG. 1 is unnecessary.

FIG. 6 illustrates the reduction in the noise level of the chromaticity signal EC according to the present invention. In Koki, both EY and EQ are 0.5
Let us take a simple method for the MHz band as an example.

Figure 6(a) shows the noise distribution for the NTSC signal when a normal positive-phase IF is demodulated by FM demodulator-1.Since the noise generated by FM demodulation is proportional to the frequency of the baseband signal, The distribution is triangular as shown in Figure (a), and the chromaticity signal exists at fsc '' 3.58 MHz, so the noise in the shaded area shown in (a) L will be affected.In contrast, the present invention When the positive-phase and negative-phase IFs are switched at ωsc, the frequency distribution of the baseband signal in this case becomes as shown in FIG. 5(b), and the noise is also reduced to the shaded area in FIG. 6(b).

FIG. 9 is a block diagram showing the configuration of a color signal recording/reproducing apparatus according to the present invention, in which 31 is an NTSC input;
2 is an FM modulator, 33 is a recording amplifier, 34 is a recording head, 35 is a magnetic tape, 36 is a reproduction head, 37
is a regenerative amplifier equalization circuit, 38 is an FM demodulator-1, 39
4o is a synchronous separator, 4o is a burst gate, 41 is a 1 line length fsc oscillator, 42 is a 90'' phase shift circuit, 43.
44 is an electronic switch, 45 is an FM demodulator-2, 46
is an FM demodulator-3, 47 is a delay line, 48 is a YC separation circuit, and 49 is a delay line.

50 is Ey output, 51 is E! output, 52 is EQ small output 53 is matrix, 54 is ER output, 55 is Ea
Specific output 56 is EB output, 67° is fixed oscillator (2f+
o ), 68 is a frequency converter (negative phase FM generation)
represents. For the sake of explanation, the recording system and the reproducing system are separated from the head in this case, but in many recording/reproducing apparatuses, the head is shared, and the circuit is switched between the recording mode and the reproducing mode.

The operation of the above embodiment will be explained below.

The NTSC signal 31 is converted into an FM modulated wave by an FM modulator 32, converted into a signal suitable for recording by a recording amplifier 33, and supplied to a recording head 34. Recording is performed while tracing a magnetic tape 35 with a recording head 34. In the playback mode, the playback head 36 reads the pattern recorded on the magnetic tape 35, and the playback amplifier equalization circuit 37 reads the recorded FM pattern.
Reproduce the modulated wave. The input of the FM demodulator-138 is expressed by the formula (2
) is a positive phase FM modulated wave with the baseband signal. The horizontal synchronization signal is extracted from the output of the FM demodulator 138 by the synchronization separation circuit 39, and the output of the FM demodulator 138 is gated by the burst gate 1-40, and the burst 1 of the subcarrier is gated by the burst gate 1-40.
- Take out. Figure 10(a) shows the output of the FM demodulator-138, and the output of the sync separator 32J is shown in Figure 10(a).
b), and the output of burst game 1-40 is shown in Figure 10 (
c). The output of burst gate 40 is 1 line long
fsc oscillator 41. The oscillator 41 will be explained later with reference to FIG.

The output of the oscillator 41 is added to the 90° phase shifter 42 and the output cosωsct of the oscillator 41 and the phase shifter 42
Obtain two orthogonal switching signals of sin ωsct of the output of .

Now, the positive phase FM modulated wave (frequency f+o when no modulation) output from the regenerative amplifier equalization circuit 37 is converted to a frequency converter.
Add to 68. A fixed frequency of 2 f to from a fixed oscillator 67 is added to the frequency converter 68, and the difference frequency is outputted. Of course, in principle, the frequency converter 68 is of a balanced modulation type, and the output of the regenerative amplifier equalization circuit 37 is prevented from becoming the output of the frequency converter 68 directly.
Equivalently, the output of the frequency converter 68 or the output of the regenerative amplifier equalization circuit 37 and the baseband signal have opposite polarities, so to speak.For this reason, if the frequency change due to the baseband signal in positive phase is Δf, then the reproduction The frequency f of the positive-phase FM modulated wave output from the amplifier equalization circuit 37 is expressed by equation (3).

f = f,. +△f・・・・・・・・・
...(3) The frequency f' of the anti-phase FM modulation wave is expressed by the formula (
4).

f””2f+of =flo−△f ・・・・・・・・・(4) First
The solid line in Figure 2 (a) is the positive phase FM modulated wave, and the broken line is the negative phase FM modulated wave. Electronic switch 43 in FIG.
．． 44, add the positive phase and negative phase FM modulation waves of the regenerative amplifier equalization circuit 37 and the frequency converter 68,
cosωset of the oscillator 41 and si of the phase shifter 42
Switching between positive phase and negative phase is performed by nωsct, and the output is made into a baseband signal by FM demodulator-235 and FM demodulator-336. This situation can be seen by switching the positive-phase FM modulated wave shown by the solid line in Fig. 12 (a) and the FM modulated wave shown by the broken line using the switch pulse shown in Fig. 12 (b). Output. FM this
The signal is demodulated to a baseband signal, and a chromaticity signal EC (for example, El) shown in FIG. 12(c) is obtained by using a low-pass filter.

Figure 12 shows an example of cosωset, but si
The same applies to n ωsct.

Now, the output of the FM demodulation (positive phase) of the FM demodulator 138 is converted to E by the YC separation circuit 48 (for example, a low-pass filter).
. is taken out and passed through a delay line 49 to become an EY output 50.

On the other hand, the output E! of the FM demodulator-245! The signal also passes through the delay line 47 and becomes the output EQ51. FM demodulator-346
The output becomes \output 52 as it is. Delay line 4
7.49 is E. , El.

This compensates for the difference in delay due to the difference in EQ bands.

Therefore, without distinguishing between Ex and Ec, both are 0
．． In the simple method of setting the frequency to 5 MHz, the delay line 47 is not required. EY 501 El 51. EQ 52 becomes a so-called S terminal output signal. 53 is EY, El
, Ec to ER54,Ea 55°EB56, and R,G.

Suitable for type B monitors.

FIG. 11 shows an example of the 1-line fsc oscillator 41 shown in FIG. In a recording/reproducing system such as a VTR, there are fluctuations in the time axis, and in particular, the phase of sub-transport changes significantly. FIG. 11 shows an example of a circuit for absorbing such changes. In FIG. 1, reference numbers common to those in FIG. 9 represent parts that are the same as or correspond to those in FIG.
8 is a 90° phase shift circuit, 59.60 is a synchronous detection circuit,
61.62 is an IH holding circuit, 63.64 is a multiplication circuit, 65 is an addition circuit, and 66 is an output.

The burst gate 4o in FIG. 11 is a subcarrier burst. Crystal oscillator 57 (fsc = 3°579
545 MHz) (7) The phase is constant for the time period of VTR (7) time fluctuation. This is cosωset
shall be. The output of the 90" phase shift circuit 58 is sin C
L) SCt.

Since the reproduced signal of the FM demodulator-138 has time fluctuations,
Let the burst signal be COS (ωsct+Δ). Δ indicates a time-varying phase change.

Therefore, since the output signal of the crystal oscillator 57 matches the phase of the long burst, it becomes CO8ωset.

When the burst subcarrier reproduced by the burst gate 40 is synchronously detected by the synchronous detection circuits 59 and 60, the output of the synchronous detection circuit 59 is a cos (ωsct+Δ)
X cosωset, and with a low-pass filter a
Take out cosΔ/2. Similarly, the synchronous detection circuit 60
-sin Δ is taken out as the output. The 1-line memory 61, 62 of CO5Δ and sinΔ holds data only during the IH period. The output of the corresponding one line of the multiplier circuits 63 and 64 becomes cosωsCt+CoS△ and sinωsct''sinΔ, and by adding (or subtracting) both in the adder circuit 65, cosωsct+CoSΔ壬sinω5Ctゝsin△
= cos (ωset±Δ) is obtained. Therefore, the output 66 becomes the reference subcarrier with a varied phase Δ between its lines.

Figure 13 shows the changes in the frequency distribution of the baseband signal due to positive-phase and negative-phase FM modulated waves.
As shown in (b), the chromaticity signal Ec is located at a low frequency.

Therefore, the triangular noise due to FM demodulation also becomes as shown in Fig. 14, and the noise of the chromaticity signal (Ex + Ea) is where the low frequency noise level is small, and the output of the FM demodulator-138 in Fig. 9 is The noise level is commensurate with the noise level of Ey50.

As explained in detail about the H0 invention, by using the broadcast receiving device according to the present invention, the IF stage of FM modulation creates a positive phase and negative phase IF, and converts this into T / 2 = 1 / 2 f sc
By switching with a pulse of period, the chromaticity signal can be converted to the baseband low frequency at the IF stage.
The noise generated during FM demodulation is significantly smaller than that of normal IF demodulation, and it has the advantage of being able to maintain the same S/N ratio as EY even when receiving weak electric fields, and reproduce images with less color noise. It will be done.

By using the color signal recording/reproducing device according to the present invention, it is possible to accurately switch the FM modulation wave by using a subcarrier wave that follows the fluctuations of the NTSC signal with time axis fluctuations, and it is possible to switch the FM modulation wave with positive phase and negative phase. By switching between orthogonal subcarriers and FM demodulating each of them, the chromaticity signal that was multiplexed on the subcarrier (3.58MHz) in the baseband is FM demodulated with a low frequency signal. It is possible to avoid the influence of high-level high-frequency noise accompanying demodulation, and the advantage is that the S/N ratio of the chromaticity signal can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a broadcast receiving device according to the present invention, Fig. 2 is a waveform diagram for explaining the generation of fsc, and Fig. 3 is a waveform diagram for explaining the switching between positive phase and negative phase IF. Waveform diagram, Figure 4 is a waveform diagram for explaining the separation of two orthogonal phases, Figure 5 is a frequency distribution diagram by FM demodulator-2, Figure 6 is a diagram showing changes in the noise component of Ec, Figure 7 The figure is N
FIG. 8 is a diagram showing the frequency distribution of the TSC baseband signal, FIG. 8 is a diagram showing the pre-emphasis characteristics of satellite broadcasting and the distribution of FM demodulation noise, FIG. 9 is a block diagram showing the configuration of the color signal recording/reproducing device according to the present invention, Fig. 10 is a waveform diagram showing the operation of the burst gate, Fig. 11 is a block diagram showing the specific configuration of a 1-line length fsc oscillator, and Fig. 12 is a positive phase,
Waveform diagram explaining anti-phase FM and its switching,
Figure 13 is a distribution diagram to explain the conversion of baseband frequency distribution, and Figure 14 is a distribution diagram after switching between positive and negative phases.
Noise distribution diagram of Ec in FM demodulation. FIG. 15 is a frequency distribution diagram of noise in FM demodulation. 1...High frequency amplification section, 2...Frequency converter, 3...Local oscillator, 4...
...... Frequency converter (reverse phase generation), 5.
......Fixed oscillator, 6...FM demodulator-1, 7......Synchronization separator, 8...
...burst gate, 9...subcarrier generator (3,58MHz) cos cvsct
, 10m--Ey separation filter, 11,1.2-
......Electronic switch, 13.14...
...FM demodulator-2,3゜1-5...
・90° phase shifter, 16.17...Low pass filter, 18,19...Delay line, 2
0゜21.22...S terminal output, 23.
・・・・・・・・・Matrix, 24・・・・・・・・・
R, G, B output, 31...NTSC input, 32...FM modulator, 33...
... Recording amplifier, 34... Recording head, 35... Magnetic tape, 36...
...Reproduction head, 37...Reproduction amplifier equalization circuit, 38...FM demodulator-1
, 39... Synchronous separator, 4o old...
・Burst gate, 41...1 line length fsc oscillator, 42...90° phase shift circuit, 43.44......electronic switch , 45
......FM demodulator-2゜46...
...FM demodulator-3,47...Mountain delay line, 4
8...Yc separation circuit, 49...
...Delay line, 50...EY output, 51
・・・・・・・・・E engineering output, 52・・・・・・・・・
EQ output, 53, old...Matrix, 54...
...ER output, 55...Ec output, 56th...E11 output, 57...
...Crystal oscillator, 58...Song...90' phase shift circuit, 59.60......Synchronized detection circuit, 61.
62...IH holding circuit, 63.64...
・・・・・・Multiplication circuit, 65・・・・・・Addition circuit, 66・・・・・・Output, 67・・・・・・・・・
・・Fixed oscillator (2f+o)-68・・・・・・・・・
Frequency converter (negative phase FM generation). Patent applicant Tararion Co., Ltd.

Claims (4)

[Claims] (1) (a) Means for generating an anti-phase IF signal in which the polarity of the signal is reversed with respect to the baseband signal at the intermediate frequency signal stage; (b) A demodulator for demodulating the IF signal (positive phase) or the anti-phase IF signal. (c) means for extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; (d) a second continuous subcarrier signal orthogonal to the subcarrier; (e) a first switching means for alternately switching the IF signal and the anti-phase IF signal based on the subcarrier signal; (f) switching the IF signal and the anti-phase IF signal to the second sub-carrier signal; a second switching means that alternately switches based on the carrier signal; (g) demodulating the output of the first switching means;
means for extracting the signal; and (h) demodulating the output of the second switching means and e.g.
A broadcast receiving device comprising: means for extracting a signal. (2) (a) A step of generating an anti-phase IF signal in which the polarity of the signal is reversed with respect to the baseband signal at the intermediate frequency signal stage, (b) A step of demodulating the IF signal (positive phase) or the anti-phase IF signal, (c) extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; (d) generating a continuous second subcarrier signal orthogonal to the subcarrier; (e) a first switching step of alternately switching the IF signal and the anti-phase IF signal based on the subcarrier signal; (f) switching the IF signal and the anti-phase IF signal to the second subcarrier; a second switching step that alternately switches based on the signal; (g) demodulating the output of the first switching step and e.g.
extracting the signal, and (h) demodulating the output of the second switching step to obtain E_Q
A broadcast reception method characterized by including a step of extracting a signal. (3) (a) Means for generating an anti-phase FM signal whose polarity is reversed with respect to the baseband signal of the reproduced FM signal, (b) Reproducing IF
(c) means for extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; (d) means for generating a continuous second subcarrier signal orthogonal to the subcarrier; (e) first switching means for alternately switching the reproduced FM signal and the opposite phase FM signal based on the subcarrier signal; f) a second switching means that alternately switches the reproduced FM signal and the anti-phase FM signal based on the second subcarrier signal; (g) demodulates the output of the first switching means, and
means for extracting the signal; and (h) demodulating the output of the second switching means and e.g.
A color signal recording/reproducing device characterized in that it includes means for extracting a signal. (4) (a) A step of generating an anti-phase FM signal whose polarity is reversed with respect to the baseband signal of the reproduced FM signal, (b) A step of demodulating the reproduced IF signal (normal phase) or an anti-phase FM signal, ( c) extracting a subcarrier burst signal from the demodulated signal using a synchronization signal in the demodulated signal to generate a continuous subcarrier signal; (d) generating a continuous second subcarrier signal that is orthogonal to the subcarrier. (e) a first switching step of alternately switching the reproduced FM signal and the reverse phase FM signal based on the subcarrier signal; (f) switching the reproduced FM signal and the reverse phase FM signal to the second subcarrier signal; a second switching step that alternately switches based on the carrier signal; (g) demodulating the output of the first switching step and e.g.
extracting the signal, and (h) demodulating the output of the second switching step to obtain E_Q
A color signal recording/reproducing method characterized by including a step of extracting a signal.