JPS6388988A - Spread energy signal generating circuit - Google Patents

Abstract

PURPOSE:To make synchronism adjustment of symmetric triangular wave signals by making symmetric triangular wave signals synchronously with vertical synchronizing signals when there is synchronizing signal, and basing on pulse string of specified frequency when there is no synchronizing signal. CONSTITUTION:A synchronizing separator circuit 1 detects synchronizing signals form television video signals e1 and sends them to a vertical synchronism detecting circuit 2 and a synchronism discriminating circuit 8. The vertical synchronism detecting circuit 2 detects vertical synchronizing signals from inputted synchronizing signals and sends them to a frequency divider circuit 3. The frequency divider circuit 3 divides into a half frequency and sends to a selector circuit 9. On the other hand, a synchronism discriminating circuit 8 judges presence of synchronizing signals from inputted signals, and sends the result of judgement to the selector circuit 9. When output of the synchronism discriminating shows presence of synchronizing signals, the selector circuit 9 selects output of the frequency divider circuit 3, and in case of absence of synchronizing signal, selects output of a pulse generator, and sends them to an integrating circuit 12. When synchronizing signal is present, the integrating circuit 12 forms symmetric triangular wave signals synchronous to vertical synchronizing signals, and when there is no synchronizing signal forms the signals basing on pulse string of specified frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an energy spread signal generation circuit that generates an energy spread signal used in a satellite television video line.

(Prior art) In satellite communication lines that use FM modulated waves, in order to prevent intermodulation distortion noise in earth station transmitters and satellite repeaters, as well as interference with terrestrial microwave lines that share frequencies, It is necessary to disperse the energy of the station's transmitted waves, and for this purpose so-called energy spreading techniques are used.

To spread the energy of the FM modulation wave: All you have to do is to inject a spread signal with a frequency lower than the lower limit frequency into the baseband signal, effectively increasing the modulation index.
Various types of spreading signals have been considered, but a symmetrical triangular wave is said to be the most excellent in terms of spreading effect and practicality.

By the way, Intelsat (International Telecommunication Satellite 8i Structure: IN) uses symmetrical triangular waves synchronized with the field frequency to insert energy diffusion signals into the television video line by satellites in order to avoid affecting the video.
5AT). That is, Intelsat uses a triangular wave whose apex coincides with the vertical blanking period, and its frequency is 30H2 for the 525/60 system and 251 for the 625150 system.
It is 1z.

FIG. 7 shows a conventional energy spread signal generation circuit that generates a symmetrical triangular wave signal which is an energy spread signal inserted in a television video line. This energy spread signal generation circuit basically includes a synchronization separation circuit 1, a vertical synchronization detection circuit 2, a frequency division circuit 3, a phase comparator 4, a low-pass filter 5, and a voltage controlled oscillator 6. Be prepared.

Next, the operation of the conventional energy diffusion signal generation circuit will be briefly described. The synchronization separation circuit 1 detects the synchronization signal e2 from the input television video signal e1. This synchronization signal e
The vertical synchronization signal e3 included in the voltage control oscillator 6 is detected by the vertical synchronization detection circuit 2, and its frequency is divided into 1/2 by the next frequency division circuit 3. 4. It constitutes a PLL (phase locked loop) together with the low-pass filter 5, and generates a symmetrical triangular wave signal e7.

That is, the 1/2 frequency-divided signal e4 of the vertical synchronization signal e3 mentioned above and the output signal e8 of the voltage controlled oscillator 6 are input to the phase comparator 4, and the phase error signal e5 is passed through the low-pass filter 5 and converted into a voltage. The oscillation frequency of the controlled oscillator 6 is controlled. Due to this PLL looseness, a symmetric triangular wave signal e7 which is phase synchronized with the 1/2 frequency divided signal e4 of the vertical synchronizing signal e3 is obtained.

(Problem to be Solved by the Invention) However, in such a conventional energy diffusion signal generation circuit, when the input is a video signal, that is, when there is a synchronization signal, the equalization pulse of the input video signal is Alternatively, it is necessary to adjust the phase when locking the PLL loose so that the peak of the symmetrical triangular wave signal is within the interval where the vertical synchronization signal exists.

Moreover, when the input is other than a video signal, that is, when there is no synchronization signal, there is no input signal e4 of the phase comparator 4, so P
The LL loop is in a free run state, and the frequency of the symmetric triangular wave signal is determined by the free running frequency of the voltage controlled oscillator 6 that generates the symmetric triangular wave signal. The frequency of the energy spread signal in the absence of this synchronization signal is selected to be several 10112 because it can be easily removed by the stabilizing amplifier in the receiving system, but it is necessary to adjust the free-running frequency of the voltage controlled oscillator 6 to that frequency. be.

Furthermore, since its free-running frequency also fluctuates depending on temperature, etc.
It is difficult to obtain a stable energy diffusion signal generation circuit.

In addition, the input video signal is 525/60 format and 62515 format.
In both cases, there are various problems such as the need to adjust the phase of the symmetrical triangular wave signal generated due to the difference in repetition frequency of the vertical synchronization signal.

The present invention has been made in view of these conventional problems, and its purpose is to provide an energy dispersion signal generation circuit that makes it possible to make adjustments to the presence or absence of synchronization signals and differences in television video signal formats. Our goal is to provide the following.

(Means for Solving the Problems) In order to achieve the above object, the energy diffusion circuit of the present invention has the following configuration.

That is, the energy spread signal generation circuit of the present invention is a circuit that generates a symmetrical triangular wave signal as an energy spread signal in a television video line by a satellite; and a synchronization separation circuit that detects a synchronization signal from a television video signal. and; a vertical synchronization detection circuit that detects a vertical synchronization signal from the detected synchronization signal; and a frequency division circuit that divides the repetition frequency of the vertical synchronization signal into half the frequency;
a synchronization determination circuit that determines the presence or absence of the synchronization signal; a pulse generator that generates a pulse train of a predetermined frequency; and an output of the synchronization determination circuit that indicates the presence of the synchronization signal.

a selection circuit that selects the output of the frequency dividing circuit when indicating "no synchronizing signal" and selects the output of the pulse generator when indicating "no synchronizing signal"; an integrating circuit for forming a symmetrical triangular wave signal; and an integrating circuit for forming a symmetrical triangular wave signal;
a 5 25/625 detection circuit for detecting either the 25150 system or the 525/60 system;
This is an energy diffusion signal generation circuit characterized by comprising: a gain switching circuit that adjusts according to the output content of the 25/625 detection circuit;

(Function) Next, the function of the energy diffusion signal generation circuit of the present invention having the above-mentioned configuration will be explained.

The synchronization separation circuit detects a synchronization signal from the television video signal and sends it to the vertical synchronization detection circuit and the synchronization determination circuit.

The vertical synchronization detection circuit detects a vertical synchronization signal from the input synchronization signal and sends it to the frequency dividing circuit.

The frequency dividing circuit divides the feedback frequency of the input vertical synchronization signal into half the frequency and sends it to the selection circuit.

On the other hand, the synchronization determination circuit determines the presence or absence of a synchronization signal from the input signal, that is, determines whether the input signal is a video signal or not, and sends the determination result to the selection circuit.

The selection circuit selects the output of the frequency divider circuit when the output of the synchronization determination circuit has a synchronization signal, and selects the output of the pulse generator when there is no synchronization signal, and sends each to the integration circuit.

As a result, in the integrating circuit, a required symmetrical triangular wave signal synchronized with the vertical synchronization signal is formed if there is a synchronization signal. Furthermore, when there is no synchronization signal, a required symmetrical triangular wave signal is formed based on a pulse train of a predetermined frequency.

Further, in the present invention, a 525/625 detection circuit receives the output of the frequency dividing circuit and detects whether the television video signal is in the 625150 system or the 525/60 system, and the gain switching circuit However, the signal level of the symmetrical triangular wave signal outputted by the integrating circuit is
Adjust according to the output content of the 625 detection circuit, 525/6
The level difference that occurs in the symmetric triangular wave signal due to the difference between the 0 system and the 625150 system is automatically compensated for.

As described above, according to the energy spread signal generation circuit of the present invention, the presence or absence of a synchronization signal is detected, and if there is a synchronization signal, the signal is synchronized with the vertical synchronization signal, and if there is no synchronization signal, it is synchronized with a predetermined frequency. 3 symmetrically based on the pulse train of
Since a square wave signal can be formed, there is no need to synchronize the symmetrical triangular wave signal when there is a synchronization signal, and there is no need for special adjustment regarding the generation of the symmetrical triangular wave signal even when there is no synchronization signal. be able to.

In addition, video signal input is 525/60 format and 6251 format.
50 system and automatically compensates for the signal level difference of the symmetrical triangular wave signal based on the difference in the repetition frequency of the vertical synchronization signal in both systems, so the conventional adjustment is not necessary. It can be made completely unnecessary.

In addition, in the case of no synchronization signal, various excellent effects such as frequency fluctuation of the symmetrical triangular wave signal due to temperature etc. can be suppressed to an almost negligible level by determining the frequency of the pulse train using a crystal oscillator. can get.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
The figure shows an energy spread signal generation circuit according to an embodiment of the present invention. , a synchronization determination circuit 8, a selection circuit 9, a comparator 11, an integration circuit 12, a pulse generator 13, a 525/625 detection circuit 14, and a gain switching circuit 7.

The synchronization separation circuit 1 receives the input television image (a signal e
! A synchronization signal e2 is detected from the vertical synchronization detection circuit 2 and a synchronization determination circuit 8. Note that the satellite communication line is multiplexed and handles signals other than television video signals such as audio signals. That is, in reality, non-video signals such as audio signals are also input to the synchronization determination circuit 1, and in this case, the synchronization signal e2 is not output.

The vertical synchronization detection circuit 2 detects only the vertical synchronization signal e from the synchronization signal e2 and supplies it to the frequency dividing circuit 3. The vertical synchronization signal e, as shown in FIG. 2 (1), is a signal that repeats at a constant period, and its repetition frequency is 525/
It is well known that the 60 format and the 625/50 format are different.

The frequency dividing circuit 3 is composed of a D-type flip-flop.
The repetition frequency of the vertical synchronizing signal e3 is divided by 1/2, and as shown in FIG.
% square wave is formed, and this is used as the frequency divided signal e12 and connected to one input terminal of the AND gate 91 of the selection circuit 9 and 525/6.
25 and the detection circuit 14.

The synchronization determination circuit 8 determines whether or not there is a synchronization signal e2 in the input signal, and sends the signal elo, which is the determination result, to the other input terminal of the AND gate 91 of the selection circuit 9, and also outputs the signal elo that is the determination result to the other input terminal of the AND gate 91 of the selection circuit 9. The signal is applied to one input terminal of the AND gate 93 through the signal.

Specifically, this synchronization determination circuit 8 has a retriggerable monostable multi-by-break, and this mono-stable multi-by break generates a pulse slightly wider than the repetition period of the horizontal synchronization signal in response to the rising edge of the input pulse. Therefore, as long as the synchronization signal is present, that is, as long as the television video signal is input, the output will be
It is always "'1", and if there is no synchronization signal, it is "0".
becomes.

This is the content of the discrimination signal elO.

The pulse generator 13 generates a pulse train e of an arbitrary number Lol12.
tt and selects it from the AND gate 9 of the selection circuit 9.
3 to the other input terminal.

The selection circuit 9 is composed of the AND gates 91 and 93, an inverter 92, and an OR gate 94 which receives the outputs of the AND gates 91 and 93 as inputs. This selection circuit 9
selects the divided signal e12 when the discrimination signal elG is "1", that is, when there is a synchronization signal, and selects the pulse train ei when the discrimination signal elO is "0", that is, when there is no synchronization signal.
t is selected and sent to the comparator 11.

The comparator 11 receives the output e1. of the OR gate 94. (either the frequency-divided signal e12 or the pulse train all) is converted to a signal level at which the integrating circuit 12 can operate sufficiently.For example, the frequency-divided signal e12 is as shown in FIG.
As shown in the figure, the "1n level is converted to a positive potential +■, and the 0" level is converted to a negative potential -■, respectively, and the integration circuit 1
2.

Since the integration time constant of the integration circuit 12 is set to be sufficiently longer than the period length of the repetition period of the vertical synchronization signal e3, the integration circuit 12 has a symmetrical three-dimensional structure with extremely excellent linearity as shown in FIG. 2 (4).
An angular wave signal e15 is formed and sent to the gain switching circuit 7.

Here, the apex of the symmetrical triangular wave signal e15 is automatically synchronized with the rising and falling portions of the frequency-divided signal e12, that is, the rising portion of the vertical synchronizing signal e3.

Next, FIG. 3 shows that when the video signal input is either the 525/60 system or the 625150 system, the integration circuit 12
FIG. 3 is a diagram showing that the signal levels of the symmetrical triangular wave signal e15 formed by the symmetrical triangular wave signals e15 are different.

That is, if the level of the peak of the symmetrical triangular wave signal obtained in the case of the 625150 system is A, then in the 525/60 system, it decreases by the ratio of the repetition frequency of the vertical synchronization signal, and becomes 0.83 A. .

In the present invention, a 525/625 detection circuit 14 and a gain switching circuit 7 are provided to compensate for the difference in signal level between the symmetrical triangular wave signals between the 525/60 system and the 625/50 system.

FIG. 4 shows a specific example of the configuration of the 525/625 detection circuit 14. In FIG. 4, 16 is a monostable multivibrator and 17 is a voltage comparator.

The monostable multi-bi break 16 generates a pulse with a fixed time width in response to the rising edge of the input signal, but the frequency-divided signal e12 input to the monostable multi-bi break 16 is generated when the video signal e1 is of the 625/50 format. This is a pulse train with a pulse period of 40 m5 (Fig. 5 (1)), and in the case of the 525/60 system, the pulse period is 33.3 m5.
s pulse train. Therefore, by adjusting the time constant of the monostable multivibrator, the width of the generated pulse can be set to, for example, 3
Set to 5rns. Then, the output of the monostable multivibrator 16 is turned on and off in the interval "1" of <35 m5 and the interval "0" of 5 ms as shown in Figure 5 (3) for the signal in Figure 5 (1). However, for the signal shown in FIG. 5 (2), the monostable multivibrator 16 repeats re-triggering, so it always becomes "1''. Therefore, the output of this monostable multivibrator 16 is connected to the resistor R2. It is smoothed by the capacitor C2 and input to the voltage comparator 17, but the input voltage of the voltage comparator 17 is 62
The voltage is higher than that of the 5/50 system.

Therefore, the reference voltage V ref of the voltage comparator 17 is 52
It is set to an intermediate value between the input voltage in the 5/60 system and the input voltage in the 625/50 system.

As a result, the output e16 of the voltage comparator 17 is 525/6
0 method, the negative power supply voltage level is 625150
When using this method, it becomes the positive power supply voltage level. Note that when there is no synchronization signal, the output of the monostable multivibrator 16 is "0", so the output e16 of the voltage comparator 17 is at the positive power supply voltage level.

Further, FIG. 6 shows a specific example of the configuration of the gain switching circuit 7. As shown in FIG. In FIG. 6, 18 is an OP amplifier, and the OP amplifier 18 has an inverting input terminal to which the output of the integrating circuit 12, that is, a symmetrical triangular wave signal e15, is input via a resistor R3, and an inverting input terminal and an output. A resistor R5 is provided between the terminals, and a series circuit of a resistor R6 and a transistor TRI is provided in parallel with the resistor R5, forming an inverting amplifier as a whole.

Note that the output e16 of the 525/625 detection circuit 14 is applied to the transistor TRI.

Now, assume that the resistance value of the resistor R5 is R (Ω), and the resistance value of the resistor R6 is selected to be 4.88R (Ω).

The output voltage e16 of the 525/625 detection circuit 14 is 525
When using the /60 method, since the power supply voltage level is negative,
Transistor TRI is turned off. OP amplifier 1
The negative feedback resistor of No. 8 is only R5, and its resistance value is R.

On the other hand, since the output voltage e16 is at the positive power supply voltage level in the 625150 system, the transistor TRI is turned on.
state. ○Negative feedback resistance of P amplifier 18 is R5 and R6
The parallel resistance is 0.83R, and the combined resistance is 0.83R.

By this gain switching, 625150 system and 525/6
It is possible to output a symmetrical triangular wave signal e7 of a required level, which completely compensates for the difference in level of the symmetrical triangular wave signal e15 due to the 0 method.

(Effects of the Invention) As described in detail above, according to the energy diffusion signal generation circuit of the present invention, the presence or absence of a synchronization signal is detected, and if the synchronization signal is present, it is synchronized with the vertical synchronization signal, and the synchronization signal is In the case without a synchronization signal, each symmetrical triangular wave signal can be formed based on a pulse train of a predetermined frequency, so the synchronization adjustment of the symmetrical triangular wave signal in the case of a synchronization signal is unnecessary, and in the case of a thirsty case without a synchronization signal. It is also possible to eliminate the need for special adjustments regarding symmetrical triangular wave signal generation.

In addition, video signal input is available in 525/60 format and 625/50 format.
It is possible to automatically compensate for the signal level difference of the symmetrical triangular wave signal based on the difference in the delay frequency of the vertical synchronization signal in both systems, so the conventional adjustment is no longer necessary. It can be made completely unnecessary.

In addition, in the case of no synchronization signal, various excellent effects such as frequency fluctuation of the symmetrical triangular wave signal due to temperature etc. can be suppressed to an almost negligible level by determining the frequency of the pulse train using a crystal oscillator. can get.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram of an energy diffusion signal generation circuit according to an embodiment of the present invention, FIG. 2 is a waveform diagram of each part, and FIG.
The figure shows symmetry 3 using the 525/60 method and 625/50 method.
Waveform diagram showing differences in angular wave signals, Figure 4 is 525/625
A circuit diagram showing a specific example of a detection circuit, Fig. 5 is an input/output waveform diagram of a monostable multivibrator, Fig. 6 is a circuit diagram showing a specific example of a gain switching circuit, and Fig. 7 is a conventional energy diffusion signal generation circuit. FIG. 1... Synchronization separation circuit, 2... Vertical synchronization detection circuit, 3... Frequency division circuit, 4...
...Phase comparator, 5...Low pass filter, 6...
...Voltage controlled oscillator, 7... Gain switching circuit, 8... Synchronization determination circuit, 9... Selection circuit, 11... Comparator, 12...
Integrating circuit, 13...Pulse generator, 14...
...525/625 detection circuit, 16...
Monostable multi-bi break, 17... Voltage comparator, 18... OP amplifier, R1-R6...
...Resistance, CI, C2...Capacitor,
TR1...Transistor, 91.93...
...AND gate, 92...Inverter,
94...OR gate. Agent Yoshihiro Patent Attorney Yoshihiro Yahata
Figure 1: Painting cycle signal, 's-d/)-3γ trace rate 2 Figure 3 Figure 10V Adar-4Lfp Marunatsu ＼゛Fray Z Flowing θth 7 pickled melon rotation Takeshi Otomizo: Figure 4

Claims (1)

[Claims] A circuit for generating a symmetrical triangular wave signal as an energy diffusion signal in a television video line by a satellite; comprising: a synchronization separation circuit for detecting a synchronization signal from the television video signal; and a vertical synchronization signal for detecting a vertical synchronization signal from the detected synchronization signal. a vertical synchronization detection circuit for detecting; a frequency dividing circuit for dividing the repetition frequency of the vertical synchronization signal into a half frequency; a synchronization determination circuit for determining the presence or absence of the synchronization signal; generating a pulse train of a predetermined frequency. a pulse generator that selects the output of the frequency divider circuit when the output of the synchronization determination circuit indicates "synchronization signal present", and selects the output of the pulse generator when it indicates "no synchronization signal"; a selection circuit; an integration circuit that receives the output of the selection circuit and performs an integration operation to form a desired symmetrical triangular wave signal; and a selection circuit that receives the output of the frequency division circuit and converts the television video signal into a 625/50 format signal; 525/6
525/62 to detect which of the 0 methods
5 detection circuit; and a gain switching circuit that adjusts the signal level of the symmetric triangular wave signal outputted by the integration circuit according to the output content of the 525/625 detection circuit. generation circuit.