JPS59219029A - Television picture signal transmission system - Google Patents

Abstract

PURPOSE:To reduce uniformly the effect of noise even on a luminance level region by FM-modulating a television picture signal via an emphasis circuit having a prescribed normalized transfer function after the amplitude of the low level of the signal is expanded. CONSTITUTION:A picture signal from a picture signal generator 1 is A/D-converted 25, this digital signal is inputted to a digital nonlinear amplitude correcting circuit 35, and after the signal amplitude of the low level part is expanded, the result is inputted to a phase linear LIP pre-emphasis circuit 12. The circuit 12 has a normalized transfer function expressed in an equation I , where tau is the unit delay time, n is a natural number, omega is an angular frequency of an input signal, and an is a coefficient and consists of plural pairs of delay elements tau, 2tau, amplitude correcting devices 53-3, 53-4 and a synthesizing device 54-2. An output of the circuit 12 is D/A-converted 45 and transmitted with FM modulation. The signal FM-demodulated is A/D-converted 26 through the reverse path at the reception side, after the signal passes through an LIP de-emphasis circuit 14, the amplitude is restored by a digital nonlinear amplitude restoring circuit 36, D/A-converted 46 and displayed 5 as a picture.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television image signal transmission system that transmits a television image signal in the form of a frequency modulation signal, and in particular, transmits each component signal by time-base compression and time division multiplexing. This system is designed to reduce the influence of noise mixed into color television image signals.

In general, each component signal is time-base compressed and time-division multiplexed (T(:
When transmitting a composite color television image signal combined by iI) in the form of a frequency modulation signal, conventionally, the image signal is processed in the frequency domain by pre-emphasis, so that the so-called triangular image signal associated with one frequency variation n1θ is transmitted. Only the influence of noise, such as noise, in which the frequency spectrum is not uniform, is reduced. Therefore, this type of conventional television image signal transmission system has the following drawbacks: It is not possible to uniformly reduce the influence of noise, which varies depending on the brightness level of the television image signal.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks and to transmit a television image signal in the form of a frequency modulated signal;
In particular, it is an object of the present invention to provide a color television image signal transmission system that can uniformly reduce the influence of noise on a color television image signal not only in the frequency domain but also in the luminance level domain.

In other words, in the television image signal transmission system of the present invention, even if the noise power is the same, the shadow of the noise that affects the television image in a portion with a low brightness level is -3. Taking advantage of the characteristic of visual perception that noise is much more noticeable than noise, we apply nonlinear amplitude processing to the television image signal before transmitting it in the form of a frequency modulation signal to eliminate the influence of noise on the television image in the entire frequency range. In a transmission method that transmits a television image signal in the form of a frequency modulation signal, the signal amplitude of the low level part of the input signal is reduced uniformly in both the The expanding nonlinear amplitude correction circuit and n'
6 natural numbers, ω is the angular frequency of the input signal, τ is the unit delay time, and an is the coefficient. a plurality of pairs of delay elements each having a plurality of pairs of delay elements, a plurality of pairs of amplitude correctors each having a plurality of types of correction amounts respectively corresponding to the plurality of sequentially different types of delay times, and the delay elements and the amplitude correction corresponding to each other. a synthesizer for mutually synthesizing the input signals passed through each set of receivers, and converting the television image signal into a frequency modulated signal via the emphasis circuit having a transfer characteristic represented by the scaled transfer function. It is characterized by the following.

EXAMPLES Below, the present invention will be described in detail by way of examples with reference to the drawings.

First, the conventional television image signal frequency modulation (FM)
The schematic configuration of the transmission signal processing system is shown in Figure 1. In the conventional configuration shown in the figure, for example, a high-quality television image signal from a television image signal generation device 1 such as a television image pickup device fff is guided to a pre-emphasis circuit 2 of CC engineering R standard, and the high frequency of the image signal is After the signal is fully boosted and the frequency spectrum distribution is corrected, it is sent to the transmission line 8 via an FM modulator (not shown). The FM signal with noise added is received on the transmission line 3, and the F
The eight primary color signals R, G, and B are restored from the image signal, which has been corrected to have a frequency spectrum distribution opposite to that on the sending side, through an M demodulator (not shown), and are then led to the de-emphasis circuit 4 for image display. The image is supplied to a device 5 to display a color image.

As mentioned above, in the conventional image signal processing system for FM transmission, the correction conversion of the frequency spectrum distribution characteristics of the image signal is carried out exclusively, and the high frequency part of the image signal, such as FM noise, is Image signal processing was performed to completely reduce the influence of noise for transmission systems that increase noise. Therefore, in the conventional image signal transmission system of this type, no signal processing to reduce the influence of noise is performed in the luminance level region of the image signal.

In contrast, in the television image signal transmission system of the present invention, even if the noise power is the same, the noise in the low brightness level part of the image signal is more noticeable than the noise in the high purity level part, and the noise interferes with the entire image. After applying corrections to the entire image signal regarding the signal amplitude region to compensate for the characteristic of visual perception that governs the degree of visual acuity, the signal is transmitted and received by a conventional 1FM transmission system with the configuration shown in Figure 1, and the color image signal is converted into a color image signal. When performing full restoration, before performing the signal processing described above for the FM repeating cycle, signal processing is performed to perform the opposite correction to that performed on the transmitting side regarding the amplitude domain of the image signal, and then the transmission This is intended to reduce the effects of road noise.

As mentioned above, an example of a schematic configuration of an image signal processing system 1 based on an uninvented image transmission method that applies amplitude domain correction to image signals in addition to conventional frequency domain correction is shown in Figure 2. show. The configuration example shown in the second diagram differs from the conventional configuration shown in the first diagram in that the nonlinear amplitude correction circuit 15 on the transmitting side is
and a nonlinear amplitude restoration circuit 16ff on the receiving side.

In addition, the above-mentioned amplitude domain correction can be applied to the digitized image signal by digital signal processing.
In case j, by performing phase linear pre-emphasis and de-emphasis according to the present invention as described later in the digital signal processing, an efficient FM transmission system can be constructed by 2 degrees. In such a case, as shown in FIG. 3, the nonlinear amplitude correction circuit 15 and the nonlinear imaging (LIP) de-emphasis circuit 14 added to the conventional configuration shown in the first diagram are added to the configuration example shown in the second diagram.

Next, a signal processing process for FM transmission according to the present invention using the signal processing system having the schematic configuration shown in FIGS. 2 and 3 will be described. In the configuration shown in the second diagram, the image signal generating device 1
When the image signal e from is led to the nonlinear amplitude correction circuit 15,
In this correction circuit 15, the correction output signal "15
A nonlinear correction is applied to the signal amplitude such that E = eγ 1 s (1). E'M
In the case of transmission, each corrected output E15 is sent to the transmission path 3 in the form of an FM signal by an FM modulator (not shown) via the pre-emphasis circuit 2. Since noise with an amplitude value Δn is added to the transmission line 3, the receiver signal e
r becomes er20+Δn(2).

The received signal er is corrected in the opposite manner to that on the transmitting side by the nonlinear amplitude restoration circuit 16, and the signal processing according to the following formula (8) is performed in contrast to the signal processing according to the above-mentioned formula (1) on the transmitting side. Then, a restored output signal E□6 is obtained.

E = eT(a) 6 r Here, it is assumed to be F-14.

Substituting equations (1) and (2) into equation (3), we get E
□6=(er+In)'-:8(1+” An/er)
(4) The component of the second term in equation (3) representing the restored output signal E□6 appears on the screen as noise, and this noise component for vision, that is, the amount of sensory noise Pn, is pn=I' -i γ (5).

The amount of sensory noise Pno in the case where the nonlinear amplitude correction according to the present invention is not performed is P-ΔR1(6)n for the above-mentioned equation (5).

With respect to the interference noise Δn added in the transmission path 3, the lower the signal level of the image e, that is, the lower the luminance level, the lower the perceived noise amount Pn0 when the amplitude is not corrected.
becomes larger. Therefore, the disturbing noise Δn is most noticeable in the low brightness level portion of the image, and the signal-to-noise ratio of the entire image is dominated by the amount of perceived noise in this low brightness level portion.

Therefore, in the nonlinear amplitude correction circuit 15 in the signal processing system shown in FIG.
In a signal level region where the image signal level e is low, the sensory noise amount PnQ value expressed by equation (5) becomes a value smaller than the sensory noise amount Pno when amplitude is not corrected expressed by equation (6), and the noise of the entire image is reduced. It becomes much less conspicuous than when using the 11 emotionless correction.

FIG. 4 shows how such sensory noise is reduced by nonlinear amplitude correction applied to the image signal in the transmission system of the present invention. FIG. 4 shows the mode of sensory noise reduction, with the horizontal axis representing the image signal level e and the vertical axis representing the relative value of the amount of noise interference, with γ as a harameter. That is, as shown in the figure, the signal-to-noise ratio of the entire image is determined by the perceived noise ratio of the low luminance level part, and compared to the case of conventional signal processing where γ = 1.0, the signal-to-noise ratio of the entire image is γ = 0.70. ,0.
50.

When the signal processing according to the present invention is performed with a value of 0.30, the signal-to-noise characteristics of the entire image are significantly improved.

An example of the actual configuration of the signal processing system of the transmission system of the present invention, which achieves the remarkable sensory noise reduction effect as described above, is shown in Figure 5 (a).
) to ((1), and examples of their operating characteristics are shown in Section 6.
and FIG. 7, respectively.

In the transmitting side signal processing system shown in FIG. supply

This digital nonlinear amplitude correction circuit 85 is composed of a only memory (ROM) in which the digital amount of the correction output signal is stored in advance according to the above-mentioned equation (1) for the entire range of digital image signal levels. The input digital image signal level is used as an address, and a corrected output signal having a digital amount corresponding to the input image signal level is extracted. The digitally corrected output signal k is guided to a normal pre-emphasis circuit 2 via a D/A converter 45, and then converted into an FM signal by an FM modulator (not shown) and sent to a transmission line 3.

- On the receiving side, as shown in FIG. 5 (1)), the received and demodulated input image signal is sent to the emphasis circuit 4.
The signal is guided to the A/D converter 26 via the A/D converter 26, digitized again, and then led to the digital nonlinear amplitude restoration circuit 36. This digital nonlinear amplitude restoration circuit 86 is configured with a read-only memory (ROM) similarly to the digital nonlinear amplitude correction circuit 35 on the transmission side, and performs the opposite conversion of the digital signal level to that on the transmission side. Nonlinear amplitude restoration is performed using the above-mentioned equation (3), and a digitally restored output signal corresponding to equation (4) is extracted and guided to the /A converter 46 to restore an image signal with noise interference reduced in the amplitude domain. .

The nonlinear amplitude correction characteristic that performs noise interference reduction processing in the amplitude domain as described above is achieved by time-base compression/time-division multiplexing (
For the composite color image signal subjected to TOj, l'i, the low-range luminance signal component (Y10Y2J/2 is determined by the level range from 0 to 1 of the normalized input signal level, as shown in Figure 6). is converted by the function shown in equation (1) to obtain a nonlinear correction output signal, and the reed, h-range luminance signal component (Y
l-Y2)/2, for bipolar input signals such as wideband color signal component Cw and narrowband color signal component ON,
As shown in Figure 7: Normalized hexagonal signal level range 0
Nonlinear amplitude correction is performed on an input signal at a level of 0.5 centering on the intermediate value of 0.5 k with positive and negative symmetrical characteristics. The symmetrical characteristics of the nonlinear amplitude correction in this case can be expressed by the following equation.

In addition, a nonlinear amplitude restoration circuit 86 with opposite characteristics on the receiving side
In this case, nonlinear amplitude restoration is performed using a conversion characteristic opposite to the conversion characteristic on the transmitting side described above with reference to FIGS. 6 and 7.

On the transmitting side, before FM modulation for FM transmission, for image signals processed by the nonlinear amplitude restoration circuit as described above, a correction system for frequency spectral distribution characteristics, generally referred to as Brien-Fascist, is applied. As the pre-emphasis circuit, it is internationally recommended to use a lumped constant Toba circuit as shown in FIG. 9, which has a frequency characteristic of high-frequency boost.

However, the conventional pre-emphasis circuit with such a circuit configuration has a phase characteristic of 1r+' with respect to frequency.
Since the image signal is not linear, if the image signal is corrected using such a conventional glimmering circuit, a waveform distortion as shown in FIG. 10(a) will occur. As such, it always appears asymmetrically only at the trailing edge of the amplitude change portion, and the maximum amplitude between the peak values of the signal waveform increases significantly, making it impossible to use the 2M transmission band effectively.

On the other hand, in the transmission system of the present invention, as described above, all of the linear phase (LIP) type brienphat cis circuits are used to prevent such waveform distortion from occurring. In other words, the conventional general pre-emphasis circuit
The illustrated configuration uses 11 high-frequency boosters, making it difficult to compensate for high-frequency phase characteristics.However, in a linear phase (LIP) l-type pre-emphasis circuit, the phase characteristics of the input signal are %, gender @ low frequency boost that is easy to compensate) 'i = subtract the applied from the input signal with a flat characteristic, r,,! l11 It is possible to relatively boost high frequencies with good phase characteristics. 1° Therefore, if such a phase MlflJ type pre-emphasis circuit is used, the overshoot that was occurring only at the trailing edge of the square waveform as shown in FIG. 10(a) can be reduced to the preshoot at the leading edge and the The corrected output waveform as shown in FIG. 10(b) can be obtained by dividing the waveform into two waves and giving the same frequency-amplitude characteristics at the front and rear edges of the rectangular waveform.

Therefore, since the amplitude between the peak values of the pre-emphasis output signal waveform corresponds to the required transmission bandwidth of the FM transmission line, the pre-emphasis output signal waveform shown in FIGS. 10(a) and ('b) The transmission bandwidth required to obtain the same signal-to-noise ratio through F14 transmission is significantly different, and depending on the output waveform in Figure (a), the transmission bandwidth is significantly different compared to the output waveform in Figure ('b). The total bandwidth needs to be significantly wider.

Furthermore, if the FM transmission bandwidth is constant, Fig. 11(a)
, As shown in comparison with (b), in the output waveform of the conventional general pre-emphasis circuit shown in (a) of the same figure, the frequency deviation amount ΔFQ representing the FM modulation degree of the low frequency mantissa part is
is small, and the frequency deviation amount ΔFL in the output waveform of the phase linear pre-emphasis circuit shown in FIG.

The phase linear pre-emphasis circuit described above has a linear phase characteristic and a flat delay characteristic, as shown in FIG. 12(a).
It can be realized by combining basic delay circuits in units of which the principle configuration is shown in 1 and the actual configuration is shown in 1), and the respective delay times are made different in total order. That is, in order to fully realize a phase linear pre-emphasis circuit having such a configuration for a digitized image signal, the illustrated delay element is constructed with a shift register to provide a normalized transfer function expressed by the following equation.

Here, n is a natural number, an is a coefficient, and ω is the angle of the input signal)
τ is the delay time exhibited by the delay element.

In addition, the phase linear de-emphasis circuit similarly used on the receiving side has the standardization 11. expressed by the following equation. .

, transfer functions, and can be realized by combining basic delay circuits of units similar to those shown in FIGS. 12(a) and (1)).

Here, m is a natural number.

Another example of the actual configuration of the signal processing system according to the transmission method of the present invention in the case where the above-mentioned phase linear type pre-emphasis and de-emphasis are performed is shown in FIG.
C), shown in (d). In the signal processing system with the configuration shown in the figure, when nonlinear amplitude correction and nonlinear amplitude restoration are both performed by digital processing, pre-emphasis and de-emphasis for FM transmission are performed. In place of the normal pre-emphasis circuit 2 and de-emphasis circuit 4 in the configuration example shown above, a phase shifter #+! which both performs digital processing! This circuit uses a pre-emphasis circuit 12 and a de-emphasis circuit 14, as shown in FIG.
, ■) It is possible to realize an ideal signal processing system that is much superior to the configuration example shown in □.

The linear phase (LIP) type emphasis circuit whose principle configuration is shown in FIG. 12(a) and whose actual unit circuit configuration is shown in FIG. ] 1975 s-13g, Publication No. 212 ``Emphasis method'' 1 As mentioned above, the first (
7) Basic type transfer function A(jω) expressed by equation
have.

A (koω) = 1+ a(εJ″″r+ ε−j″′?
)=1+2a OO8ωr' (7
) Here, the coefficient a is a (1 means that when the polarity is negative, a characteristic in which the high frequency is boosted relative to the low frequency, that is, a pre-emphasis characteristic for FM transmission is obtained,
Further, when the coefficient a has a positive polarity, a de-emphasis characteristic for FM transmission in which the low frequency is boosted with respect to the surface frequency is obtained, and no delay distortion based on the nonlinear phase characteristic occurs. Note that the phase advancing circuit 51 having a negative delay time -τ shown by the dotted line in FIG. 12(a) cannot be realized, so in an actual circuit configuration,
As shown in b), by inserting a delay circuit 60 with a delay time τ in the signal system with a nine-delay in FIG. Construct a progressive system. In addition, the transfer function in such an actual circuit configuration can be expressed only by multiplying equation (7) by ε-j6)7, and it is sufficient to assume that the signal itself appears delayed by the time τ. As in equation (7), no delay distortion occurs.

Furthermore, in an actual phase linear (LIP) wrinkle pre-emphasis circuit, the total number n of basic circuits in units shown in FIGS. 'lvA, and its transfer function Ap(jω) is expressed by the following equation (8).

Ap (-1ω) = 1 +X an (t-I"
"" + ε-ko"") (sln
=1 An actual linear phase (LIP) type de-emphasis circuit is constructed in the same manner and is expressed by equation (9) of its transfer function Ad(jω).

Ad(jω) = '/Ap(jω) (9) Actual phase line (LIP) resulting from a combination of such n unit circuits
Realize the type emphasis circuit (C is shown in Figure 12 (1)
) As shown in Equations (8) and (9), the maximum phase advance time nτ is actually set to no delay, and relatively symmetrical phase advances and lags are calculated based on the median value of each delay time. This can be realized by a combination of various delay circuits so that the phase can be obtained.

In the linear phase (LIP) type emphasis realized as described above, delay distortion unlike in conventional conventional emphasis circuits does not occur, so it is possible to use the linear phase (LIP) type emphasis realized as described above. During transmission, the amplitude amplification port of the transmitted signal is minimized.

The signal waveform of FIG. 10(a), Φ) described above has a phase difference of 1
．． 1. Compare the signal waveforms that express the above-mentioned effects obtained when using a linear emphasis circuit with the signal waveforms when using a conventional normal emphasis circuit shown in the same figure (al). It is shown in Figure 0:l),
This clearly shows that the increase in the amplitude of the signal waveform is small, so that the emphasis effect is significant, and that the desired emphasis effect can be achieved and the total FM modulation can be increased.

Next, the overall configuration of a high-definition television satellite broadcasting system using the transmission method of the present invention is capable of efficiently transmitting FM television image signals with good characteristics by applying the aforementioned nonlinear amplitude correction and phase linear emphasis. The entire figure is shown in Figure 13 (a) and (t)).

In the signal processing system on the transmission side 1 shown in FIG. 1(a), three primary color image signals R from a television camera (not shown),
G, B' are led to a transmission component conversion circuit 100 to be converted into each component signal of the composite color television information, that is, a luminance signal Y and a wideband color signal Ow1 and a narrowband color signal ON. D converter 101
9 After digitizing, nonlinear signal processing circuit 1
．． 08 and 10.2, respectively, and undergo nonlinear amplitude correction as shown in FIGS. 6 and 7, respectively.

Each component signal Y, cap, 0Nf subjected to nonlinear processing
j/: TOI-LSO forming circuit 104, each component signal Y.

After compressing the time axes of Ow and ON, the wide and narrow band chrominance signal is converted into an 'I'CI-LSO signal in which the face is time-division multiplexed on the luminance signal Y in alternating lines, and then the first
2 Basic circuit configuration shown in FIG.D After pre-emphasis syllables are performed by the phase linear (L'P) type pre-emphasis circuit 105 having the transfer function Ap(jω) expressed by equation (8), the D/A converter 1061c performs pre-emphasis. The signal is converted back to an analog signal and guided to the FMM modulator 107, where it is converted into an FM wave and broadcast.

10,000, the signal processing system on the receiving side shown in FIG. L engineering P) type emphasis circuit 115,
After performing phase linear de-emphasis and 1° bias using the transfer function expressed by equation (9), the nonlinear amplitude restoration circuit 1
13, each component signal Y is subjected to amplitude correction having a characteristic opposite to that on the transmitting side to restore the amplitude characteristic, and further restored by the TC knee LSC-component conversion circuit 114.

The signals are supplied to the OW and ON k matrix circuit 110 to restore the three primary color image signals, and a Q-reproduced color image is displayed on a television receiver 120 or the like.

The random noise received by the FMM transmission signal due to the transmission path intervening between the transmitting and receiving signal processing systems as described above increases in the high brightness level areas where the noise is originally difficult to notice in the reproduced color image, but the noise is noticeable. Since the noise is significantly reduced in the low luminance level portion where noise interference is easy to occur, it is possible to reproduce a high-quality color image with extremely little noise interference on the screen as a whole.

Nonlinear amplitude compression for a television image signal in a signal format in which a scanning synchronization signal is added in the negative direction in an amplitude region below the black level of the image signal is performed according to the nonlinear amplitude correction custom order shown in FIG. Therefore, the spectral distribution of noise added in the FM transmission of the television image signal is so-called triangular noise, which increases as the frequency range of image 1a increases. - Since the scanning synchronization signal need only be capable of reproducing the scanning phase information with high precision, it is sufficient that the signal bandwidth for separating and reproducing the synchronization signal is narrow. Moreover, the signal-to-noise ratio of reproduction synchronization No. 1g obtained in FM transmission of television image signals is sufficiently higher than in the case of AM transmission, so the synchronization signal amplitude is sufficient to provide peace of mind for ordinary AM transmission. is not required. Therefore, in FM transmission of television image signals, compared to AM transmission, the synchronization signal amplitude can be compressed to about 1/2 to 1/3 of the total amplitude, and FMM transmission can be used to transmit image information. Bandwidth can be used more effectively.

Effects As is clear from the above explanation, according to the invention, prior to FM transmission of a television image signal, the maximum signal amplitude of 111iI is unchanged, and for low luminance -.1 level areas, Expands the signal amplitude and suppresses the signal amplitude for high luminance level regions, and suppresses the signal amplitude for high frequency components (H2-(Yl+Y2)/2) in the second Hadermal transform of color signal components and luminance signals. , performs nonlinear amplitude processing that makes the signal components symmetrical in both positive and negative polarities around the 0 level, and further performs phase linear pre-emphasis and de-emphasis signal processing that does not cause delay distortion. FM of the image signal
It is possible to construct a television image signal transmission system that minimizes all damages.

Therefore, by introducing the transmission method of the present invention, as a high-definition television satellite broadcasting system, extremely excellent television image signal transmission can be achieved, which can transmit high-definition television image information using a narrow transmission band with extremely low satellite power consumption. A special effect can be obtained in that the system can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a conventional preview image signal transmission system, and FIGS. 2 and 3 are block diagrams showing an example of a schematic configuration of a television image signal transmission system according to the present invention. 41 is a characteristic curve diagram showing an example of image noise improvement by nonlinear amplitude correction of an image signal in the transmission method of the present invention, and FIG. FIG. 6 is a block diagram showing examples, and FIG. 6 is a characteristic curve diagram showing the nonlinear amplitude correction characteristic for each luminance component of the image signal in the transmission system of the present invention and the pressure processing mode of the synchronous 1g signal. FIG. A characteristic curve diagram showing an example of the nonlinear amplitude correction characteristics for the color signal and Hadamard Hadamard transform signal components in a composite color image signal of time axis compression/time division multiplexing in a transmission method. A diagram showing an example of the structure of a multiplexed composite color image signal, FIG. 9 is a circuit diagram showing the structure of a conventional conventional emphasis circuit, and FIGS. 10 (a) and (1)) show the conventional system and the present invention. Figure 11 (a) and ('b) are the same waveform diagrams showing the sidetones of the image signal waveform transmitted by the conventional method and the method of the present invention, respectively. Waveform diagrams, Figures 12(a) and Φ) are block diagrams showing examples of the theoretical configuration and actual configuration of the phase linear emphasis circuit in the transmission system of the present invention, respectively, and Figure 18(a)
Figures 1 and 2 are block diagrams illustrating side sounds respectively on the transmitting side and receiving side of a television image signal FM transmission system to which the transmission system of the present invention is applied. DESCRIPTION OF SYMBOLS 1... Image signal generator 2... Pre-emphasis circuit 3... Transmission line 4... De-emphasis circuit 5... Display device 12... Phase linear pre-emphasis circuit 14...
Phase linear deen 7 assist circuit, 15...Nonlinear amplitude correction circuit 16...Nonlinear amplitude restoration circuit 25, 26...A/D converter 85...Digital nonlinear amplitude correction circuit 36...Digital nonlinear amplitude restoration Circuits 45, 46...D/A converter 51...phase advance circuit 52, 60', 6
1...Delay circuit 53...Attenuator 54.
...Adder 101...A/D converter 1 (12, 103...Nonlinear processing circuit 104,...'l"cI-LS (E shaping circuit 105...
... Phase linear pre-emphasis circuit] 06...D/
A converter 107...FM modulator 110...Matritus circuit 113...Nonlinear amplitude restoration circuit] 14...TC knee LSO-component conversion circuit 1.15--Phase, ? [f-linear de-emphasis circuit] 1
6... A/D converter 117... FM demodulator 12
0 Television receiver. Suga 8 cough λki beme ＾ Ha to 8~ ・0 0 ℃ oath V, /v

Claims (1)

[Claims] ], a transmission method for transmitting a television image signal in the form of a frequency modulated signal, a nonlinear amplitude correction circuit for expanding the signal amplitude of a low level part of one input signal;
A plurality of different delay time sounds are sequentially related to each other in relation to a normalized transfer function of the form where n is a natural number, ω is the angular frequency of the input signal, τ is a unit delay time, and an is a coefficient. A plurality of pairs of symmetrical delay elements, a plurality of pairs of amplitude correctors each having a plurality of types of correction amounts each corresponding to a plurality of different delay times, and a plurality of pairs of amplitude correctors each having a plurality of types of correction amounts respectively corresponding to a plurality of different delay times; An emphasis circuit is provided which includes a synthesizer that combines the input signals that have passed through the set of the delay element and the amplitude corrector, respectively, and has a transfer characteristic expressed by the normalized transfer function. 1. A television image signal transmission system characterized in that the television image signal is converted into a frequency modulated signal.