JP3604105B2 - FPU device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of an FPU device.
[0002]
[Prior art]
When the input electric field strength decreases in the FPU device, for example, when the direction of the antenna is adjusted to about -85 dBm or less, the S / N ratio of the video signal output from the FPU receiving device deteriorates, and the connection to the FPU device is reduced. In the picture monitor or the waveform monitor, the synchronization is disturbed, and it becomes impossible to know what kind of signal is being transmitted. When adjusting the direction of the antenna, there are a method of looking at the meter indicating the input electric field strength, a method of looking at the picture monitor, and a method of looking at the waveform monitor. By looking at and judging whether or not the signal is a signal to be transmitted, the antenna is adjusted in the direction in which the meter indicating the input electric field strength swings most strongly.
[0003]
Before the direction adjustment of the antenna is started, the input electric field strength is low and the S / N ratio is deteriorated because the antenna direction is naturally not aligned. Therefore, the direction of the antenna is changed, and when the input electric field strength becomes -85 dBm or more, the synchronization of the picture monitor is fixed for the first time, and it is determined what kind of video is being received. Before the discrimination is possible (at -85 dBm or less), even if the video component is received and demodulated for the time being, the S / N ratio is poor and the synchronization of the picture monitor does not stop. Disturbance, cannot determine what kind of video is being received. This is the same as not receiving at all.
[0004]
In the prior art, a method has been used in which the input frequency band is narrowed by an input band-pass filter to improve the S / N ratio at the time of low input electric field strength, so that the synchronization of the picture monitor is easily fixed. However, even in this method, the degree of improvement of the S / N ratio is about 6 dB, which is equivalent to the reduction of the frequency band, and the synchronization of the picture monitor is disturbed when the input electric field is lower than that.
[0005]
[Problems to be solved by the invention]
In the above-mentioned conventional technique, when the S / N ratio is deteriorated to such an extent that the synchronization is impossible with a picture monitor or a waveform monitor due to a low input electric field, the screen is disturbed and it is difficult to know what is being received. Disadvantage. This is because the synchronization of the picture monitor on the receiving side is fixed only by the synchronization signal of the transmitted video signal.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to reproduce a synchronizing signal when a signal-to-noise ratio is deteriorated to the extent that synchronization of a picture monitor is disturbed, add a synchronizing signal having a regular waveform, and send the signal to the picture monitor.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises a circuit for detecting an input electric field intensity, a synchronizing signal separating circuit, a synchronizing signal generating circuit, and a synchronizing signal synthesizing circuit, wherein the input electric field intensity is about -85 dBm or less. Then, the synchronizing signal synthesizing circuit is operated, so that a signal having a good S / N ratio of the synchronous component can be transmitted from the FPU device even if the S / N ratio of the video component is low.
[0008]
As an effect of the present invention, no matter how bad the S / N ratio of the signal output from the FPU device is, the synchronization of the picture monitor is not disturbed, and it is possible to determine what is reflected on the screen.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIG.
The SHF signal input from the parabolic antenna 1 is amplified by the low noise amplifier 2 and converted into an IF signal by the down converter 3. The IF signal passes through an IF signal amplifier circuit 4 and is demodulated into a video signal by a demodulation circuit 5.
[0010]
On the other hand, the IF signal from the down converter 3 is input to the input electric field intensity detection circuit 6 and detects whether the input electric field intensity is equal to or more than -85 dBm or less. In this block diagram, when the voltage of the signal 7 is equal to or more than -85 dBm, it is LO, and when it is equal to or less than -85 dBm, it is HI. 8 is a synchronizing signal separation circuit, 9 is a circuit for reproducing and generating a synchronizing signal, and outputs 10 SYNC signals or black burst signals. It also generates 11 composite blanking signals. A switching circuit 13 switches between the video signal and the SYNC signal 10 according to the 12 composite blanking signals. When the voltage of the signal 7 is LO, that is, when the input electric field strength is -85 dBm or more, the composite blanking signal 12 is a no-signal, so that the SYNC switching is not performed.
[0011]
FIG. 2 shows a waveform of a video signal waveform monitor and a picture monitor screen. 2 are demodulated outputs when the input electric field strength is high, 1 in FIG. 2 is a waveform monitor waveform, and 1 'in FIG. 2 is a picture monitor screen. 2 and 2 'in FIG. 2 show demodulated output waveforms when the input electric field intensity is low and is -85 dBm or less, and shows a state where the synchronization of the waveform monitor and the picture monitor screen is disturbed, so that it is not clear what is being displayed. The waveforms 3 and 3 'in FIG. 2 are obtained when the synchronization signal is re-added from the state 2 in FIG. 2. The synchronization is fixed for both the waveform monitor 3 in FIG. 2 and the picture monitor 3' in FIG. Then, it is possible to determine what is reflected though it is noisy.
[0012]
Hereinafter, this operation will be described.
When the input electric field intensity is -85 dBm or less, the input electric field intensity detection circuit 6 makes a determination, and determines that the input electric field intensity is a low input electric field intensity, which is an S / N ratio that cannot be synchronously detected by the picture monitor. In this case, the video signal output from the demodulation circuit 5 has a poor S / N ratio, and when the signal is viewed on a picture monitor, synchronization is disturbed as shown at 2 'in FIG. Impossible.
[0013]
From this noisy video signal, a synchronizing signal is reproduced by a synchronizing signal separating circuit 8 and a synchronizing signal generating circuit 9 to output a SYNC signal 10 or a black burst signal. The SYNC signal 10 or the black burst signal and the video signal having a poor S / N ratio are switched by the composite blanking signal 12 and output, thereby re-attaching the synchronization signal. As a result, the output video signal becomes as shown at 3 and 3 'in FIG. 2, and it is possible to view the waveform signal on the waveform monitor and the picture monitor without disturbing the synchronization.
[0014]
【The invention's effect】
Conventionally, when the input electric field strength of the SHF signal input from the parabolic antenna is extremely low, for example, in a state before the antenna direction adjustment is performed, even when the demodulated video signal is viewed on the picture monitor, the synchronization is disturbed. It was impossible to determine what kind of video was being received.
[0015]
According to the present invention, even when the input electric field strength is extremely low, the synchronization between the picture monitor and the waveform monitor is less likely to be disturbed, and it is possible to determine what kind of video is being received. Thereby, the direction can be adjusted more quickly. Also, the character signal superimposed on the monitor output can be identified even if there is no SHF signal.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of the overall block configuration of the present invention. FIG. 2 is a waveform monitor and a picture monitor screen showing the effects of the present invention.
1: parabolic antenna, 2: low noise amplifier, 3: down converter, 4: IF signal amplifier circuit, 5: demodulation circuit, 6: input electric field strength detection circuit, 8: synchronization signal separation circuit, 9: synchronization signal generation circuit, 13 : Switching circuit.

Claims (3)

In an FPU device that modulates a video signal and wirelessly transmits the radio wave by radio waves,
A synchronizing signal generating circuit for reproducing and generating a synchronizing signal from a video signal received and demodulated on the receiver side of the wireless transmission, a switching circuit for switching the output of the reproduced synchronizing signal and the output of the received demodulated video signal, And controlling the switching operation of the switching circuit so that when the reception electric field strength at the receiver side of the wireless transmission is reduced, the reproduced synchronizing signal is reattached to the video signal whose S / N ratio is degraded and output. Circuit,
When the received electric field strength is reduced, the received demodulated video signal with the re-attached synchronization signal is output to the display unit located at the subsequent stage of the switching circuit, so that the synchronization displayed on the display unit is not disturbed. An FPU device wherein the direction of an antenna is adjusted based on a received and demodulated video. The FPU device according to claim 1,
An FPU having at least one of a waveform display unit for displaying a waveform of the video signal output from the switching circuit and a video display unit for displaying a video corresponding to the video signal, as the display unit. apparatus. The FPU device according to claim 1,
A circuit for controlling the switching operation of the switching circuit, an electric field intensity detection circuit for detecting the received electric field intensity, and the synchronization signal generating circuit when the received electric field intensity detected by the electric field intensity detection circuit becomes a predetermined value or less. And a control signal for controlling a switching operation of the switching circuit based on the signal.

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