JPH0698271A - Receiver - Google Patents

Abstract

PURPOSE:To attain the miniaturization and low cost for a receiver by A/D- converting a video signal in the state of composite signal by an A/D conversion means, and performing processing in the state of composite signal obtained by demodulating a wave. CONSTITUTION:The synchronizing signal of the composite signal that is the video signal which is demodulated signal of the wave received by an antenna is detected at a synchronizing signal detection circuit 4, and when it is decided that the S/N of the synchronizing signal is less than a prescribed reference level, a control signal which notifies the reduction of the electric field strength of the wave is outputted to a readout control part 8. In such a case, the control part 8 prohibits additional write on memory 2, and the composite signal stored in the memory 2 before the control signal is detected i.e., the video signal stored in the memory 2 before the electric field strength of the wave received by the antenna is decreased is read out successively, and it is outputted via a D/A converter 5 and a synchronizing signal attaching circuit 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver suitable for use in, for example, a satellite broadcast receiver.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing the configuration of an example of a conventional satellite broadcast receiver. The decoder 11 converts (decodes) a composite signal, which is a video signal obtained by demodulating radio waves received by an antenna (not shown), into an RGB signal. The A / D converters 12a to 12c of the A / D conversion unit 12 are controlled by the write control unit 14, and the decoder 11
R signal, G signal, and B of the RGB signal output from
The signals are respectively A / D converted. The switch 18 is controlled by the writing control unit 14 and controls the A / D converters 12a to 12a.
digitized R signal, G signal output from c,
And B signals are sequentially selected and supplied to the memory 13.

The memory 13 is a digitized R output from the A / D converters 12a to 12c via the switch 18 to the address output from the write control unit 14.
An RGB signal (video signal) including a signal, a G signal, and a B signal is stored in field units. Furthermore, memory 1
3 is an R signal stored under control of the read control unit 17;
The G signal and the B signal are supplied to the switch 19. The switch 19 is controlled by the read control unit 17 and controls the memory 13
Digitized R signal, G signal,
And B signals are supplied to the D / A converters 15a to 15c of the D / A converter 15, respectively. The encoder 16 is D
Analog signals R, G, and B (RGB signals) output from the / A converters 15a to 15c,
Also, a composite signal is generated (encoded) from the clock signal supplied from the synchronization generation circuit 6.

The synchronization generating circuit 6 supplies a clock signal to the write controller 14, the encoder 16 and the read controller 16. The write control unit 14 operates according to the clock signal supplied from the synchronization generation circuit 6 to the A / D conversion unit 1
2, controlling the memory 13 and the switch 18.

The synchronizing signal detecting circuit 4 detects the synchronizing signal of the composite signal which is a video signal obtained by demodulating the radio wave received by the antenna, and determines that the S / N of the detected synchronizing signal is below a predetermined reference level. In this case, the control signal notifying that the electric field strength of the radio wave received by the antenna has decreased is output to the read control unit 17. Read control unit 17
Is a memory 13, a switch 19, and a D / A converter 1.
5, the RGB signals stored in the memory 13 are read according to the clock signal supplied from the synchronization generation circuit 6, and are sequentially supplied to the D / A conversion unit 15 via the switch 19. Further, when the read control unit 17 detects the control signal supplied from the synchronization signal detection circuit 4, the read control unit 17 receives the RGB signal (video signal) stored in the memory 13 before the control signal is detected, that is, is received by the antenna. The video signal stored in the memory 13 is continuously read before the electric field strength of the radio wave decreases.

Next, the operation will be described. A composite signal, which is a video signal obtained by demodulating the radio wave received by the antenna, is supplied to the decoder 11 and the synchronization signal detection circuit 4. In the decoder 11, the composite signal is converted into an RGB signal and R of the converted RGB signal is converted.
The signal, the G signal, and the B signal component are transferred to the A / D converter 12
A / D conversion is performed by the A / D converters 12a to 12c. The digitized RGB signal is written (temporarily stored) in the memory 13 via the switch 18 in the write controller 14.

The RGB signals stored in the memory 13 are sequentially read by the read control unit 17 and the switch 1
It is supplied to the D / A conversion unit 15 via 9. In the D / A converters 15a to 15c of the D / A conversion unit 15, the R signal, G signal, and B signal component of the RGB signal read from the memory 13 via the switch 19 are D / A converted, It is supplied to the encoder 16. In the encoder 16, a video signal which is a composite signal is generated and output from the analog RGB signal and the clock signal output from the synchronization generation circuit 6.

On the other hand, the sync signal detection circuit 4 detects the sync signal of the composite signal which is a video signal obtained by demodulating the radio wave received by the antenna, and the S / S of the sync signal is detected.
When N is determined to be equal to or lower than the predetermined reference level, a control signal notifying that the electric field strength of the radio wave received by the antenna has decreased is output to the read control unit 17. When the read control unit 17 detects the control signal supplied from the synchronization signal detection circuit 4, new writing to the memory 13 is stopped, and the RGB signals stored in the memory 13 before the control signal is detected. The signal (video signal), that is, the video signal stored in the memory 13 before the electric field strength of the radio wave received by the antenna decreases is continuously read.
Therefore, also in the encoder 16, the video signal stored in the memory 13 is continuously output before the electric field strength of the radio wave received by the antenna is reduced, so that a still image is displayed on the screen.

[0009]

As described above, in the conventional device, when the electric field strength of the radio wave received by the antenna is lowered, that is, when the reception state of the radio wave is deteriorated, the data is stored in the memory 13. The image signal is prevented from being disturbed by continuously reading out the image signal of several frames (fields) before and displaying it on the screen. However,
In this device, a video signal demodulated from a received radio wave is converted into an RGB signal and the RGB signal is stored, so that the same processing is simultaneously performed on three signals of R, G and B. However, there is a problem that the number of circuits constituting the device increases and the cost increases.

The present invention has been made in view of such a situation, and it is possible to make the apparatus small in size and to reduce the cost.

[0011]

The receiving device of the present invention is an A / D converter 1 as A / D converting means for A / D converting a video signal in a receiving device for receiving radio waves and demodulating into a video signal. , A memory 2 as a storage means for storing the A / D converted video signal of at least one field, a synchronization signal detection circuit 4 as a detection means for detecting the reception state of the radio wave, and a reception state of the detected radio wave. Corresponding to memory 2
A D / A converter 5 as output control means for D / A converting the video signal stored in
And a read control unit 8, and the A / D converter 1 is characterized by A / D converting the video signal in the state of a composite signal.

[0012]

In the receiving device having the above structure, the video signal of at least one field which is A / D converted by the A / D converter 1 is stored in the memory 2 to detect the reception state of the radio wave and respond to the reception state of the radio wave. Then, the video signal stored in the memory 2 is D / A converted and output. Further, the A / D converter 1 performs A / D conversion on the video signal in the state of the composite signal.
Therefore, since the processing is performed in the state of the composite signal obtained by demodulating the radio wave, the device can be downsized.

[0013]

1 is a block diagram showing the configuration of an embodiment of a satellite broadcast receiver to which the receiving apparatus of the present invention is applied. A
The / D converter 1 is controlled by the writing control unit 3 and A / D converts a composite signal which is a video signal obtained by demodulating an electric wave received by an antenna (not shown). Memory 2 is
The digitized composite signal (video signal) output from the A / D converter 1 is stored in a field unit at the address output from the write control unit 3. further,
The memory 2 is controlled by the read control unit 8 and supplies the stored composite signal to the D / A converter 5.

The D / A converter 5 D / A converts the composite signal read from the memory 2. The sync signal adding circuit 7 converts the D / A converted analog signal into a sync signal such as a horizontal sync signal, a vertical sync signal, and a color burst signal according to the clock signal supplied from the sync generation circuit 6. Is newly added.

The sync generation circuit 6 supplies a clock signal to the write control unit 3, the sync signal adding circuit 7, and the read control unit 8. The write control unit 3 controls the A / D converter 1 and the memory 2 according to the clock signal supplied from the synchronization generation circuit 6.

The sync signal detection circuit 4 detects the sync signal of the composite signal, which is a video signal obtained by demodulating the radio wave received by the antenna, and determines that the S / N of the detected sync signal is below a predetermined reference level. In this case, the control signal notifying that the electric field strength of the radio wave received by the antenna has decreased is output to the read control unit 8. The read control unit 8 controls the memory 2 and the D / A converter 5, and the synchronization generation circuit 6
The composite signal stored in the memory 2 is read according to the clock signal supplied from the D / A converter 5
To supply to. Further, when the read control unit 8 detects the control signal supplied from the sync signal detection circuit 4, the read control unit 8 prohibits the update of the write data of the memory 2, and the composite stored in the memory 2 before the control signal is detected. The signal (video signal), that is, the video signal stored in the memory 2 is continuously read before the electric field strength of the radio wave received by the antenna decreases.

Next, the operation will be described. In the A / D converter 1, a composite signal, which is a video signal obtained by demodulating radio waves received by the antenna, is A / D converted, and the digitized composite signal is written in the memory 2 by the write control unit 3. (Temporarily stored).

The composite signal stored in the memory 2 is sequentially read by the read control unit 8 and supplied to the D / A converter 5. In the D / A converter 5, the composite signal read from the memory 2 is D / A converted and supplied to the synchronization signal adding circuit 7. In the sync signal adding circuit 7, an analogized composite signal
A synchronization signal is newly added according to the clock signal output from the synchronization generation circuit 6 and output as a video signal.

On the other hand, the sync signal detection circuit 4 detects the sync signal of the composite signal which is a video signal obtained by demodulating the radio wave received by the antenna, and the S / S of the sync signal is detected.
When N is determined to be equal to or lower than the predetermined reference level, a control signal notifying that the electric field strength of the radio wave received by the antenna has decreased is output to the read control unit 8. When the read control unit 8 detects the control signal supplied from the synchronization signal detection circuit 4, new writing to the memory 2 is prohibited, and the composite stored in the memory 2 before the control signal is detected. The signal (video signal), that is, the video signal stored in the memory 2 before the electric field strength of the radio wave received by the antenna is lowered is continuously read out, and the D / A converter 5 and the synchronization signal adding circuit 7 are read. Is output via.

Here, normally, the color burst signal has one sequence in four fields as shown in FIG. On the other hand, when the sync signal detection circuit 4 determines that the S / N of the sync signal of the composite signal, which is a video signal obtained by demodulating the radio wave received by the antenna, is equal to or lower than a predetermined reference level, the memory as described above is used. Since the video signal of one field read out from No. 2 is continuously output, as shown in FIG. 2, the color burst signal of this video signal causes a phase difference of 90 degrees at the beginning and end of the field. . Therefore, in the sync signal adding circuit 7, not only the process of adding the sync signal to the video signal output from the D / A converter 5 but also the process of correcting the 90-degree phase difference is performed. There is.

The case where the receiving apparatus of the present invention is applied to a satellite broadcast receiver has been described above, but the present invention is applicable not only to the satellite broadcast receiver but also to an apparatus for receiving radio waves having a remarkable directivity. You can

[0022]

As described above, according to the receiving apparatus of the present invention, at least one signal which is A / D converted by the A / D converting means.
The video signal of the field is stored in the storage unit, the reception state of the radio wave is detected, and the video signal stored in the storage unit is D / A converted and output corresponding to the reception state of the radio wave. further,
The A / D conversion means A / D converts the video signal in the state of a composite signal. Therefore, since the processing is performed in the state of the composite signal obtained by demodulating the radio wave, the device can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a satellite broadcast receiver to which a receiving device of the present invention is applied.

FIG. 2 is a waveform diagram showing a color burst signal when a video signal of one field is continuously reproduced.

FIG. 3 is a waveform diagram illustrating that the color burst signal has one sequence in four fields.

FIG. 4 is a block diagram showing a configuration of an example of a conventional satellite broadcast receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 A / D converter 2 Memory 3 Writing control section 4 Sync signal detection circuit 5 D / A converter 6 Sync generation circuit 7 Sync signal addition circuit 8 Read control section 11 Decoder 12 A / D conversion section 12a to 12c A / D Converter 13 Memory 14 Write Control Unit 15 D / A Converter 15a to 15c D / A Converter 16 Encoder 17 Read Control Unit 18, 19 Switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Ojima 2-6-3 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation (72) Masahiro Uematsu 2--6, Otemachi, Chiyoda-ku, Tokyo No. 3 within Nippon Steel Corporation

Claims (1)

[Claims] 1. A receiving device for receiving a radio wave and demodulating into a video signal, an A / D conversion means for A / D converting the video signal, and at least one field A / D converted by the A / D conversion means. Storage means for storing the image signal of the radio wave, detection means for detecting the reception state of the radio wave, and D / A for the video signal stored in the storage means corresponding to the reception state of the radio wave detected by the detection means. A receiving device, comprising: an output control unit for converting and outputting, wherein the A / D conversion unit performs A / D conversion of the video signal in a composite signal state.