JPH0654270A - Satellite broadcast reception equipment - Google Patents

Abstract

PURPOSE:To provide the satellite broadcast reception equipment which reports the normal reception state of a MUSE signal with a simple circuit constitution. CONSTITUTION:A C/N detection voltage value is led out by a video signal processing circuit 1 of the satellite broadcast reception equipment, and the presence or the absence of a frame synchronizing signal is detected by a PCM demodulating circuit 2, and a decoder 3 is provided which discriminates the reception state of the MUSE signal based on the C/N detection voltage value and the detection output of the presence or the absence of the frame synchronizing signal, and a display device 5 is operated by the output of this decoder 3, thus reporting the normal reception state of the MUSE signal.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to MUS in satellite broadcasting.
E (Multiple Sub-Nyquist Sa)
The present invention relates to a satellite broadcast receiving device capable of discriminating and reporting a plumbing encoding signal.

[0002]

2. Description of the Related Art Currently, there are NTSC system and MUSE system for high-definition television in satellite broadcasting, but when a satellite broadcasting receiver compatible with NTSC system receives a MUSE system signal,
Since the signal conditions are different in both of the above methods, synchronization cannot be achieved, and the screen is in a synchronous flow state.

[0003]

When the MUSE signal is received by the satellite broadcasting receiver compatible with the NTSC system, the screen synchronization becomes disturbed and the screen becomes a noise state. This is not a malfunction but the horizontal synchronization circuit. There was a problem that it was mistaken for a system failure. In view of the above problems, the present invention provides a satellite broadcast receiving apparatus that uses a signal obtained from a conventional satellite broadcast receiving apparatus and can notify that a MUSE signal is being received by simply adding a simple circuit. The purpose is to get.

[0004]

In order to achieve the above-mentioned object, the present invention provides a satellite broadcast receiving apparatus provided with a video signal processing circuit for processing a video signal and a PCM demodulation circuit for demodulating an audio signal. A C / N voltage value detecting means for detecting a C / N detection voltage value obtained from the video signal processing circuit, a frame synchronization signal detecting means for detecting a frame synchronization signal obtained by the PCM demodulation circuit, and the C /
A discriminating means for discriminating the MUSE signal based on the detection outputs of the N voltage value detecting means and the frame synchronizing signal detecting means, and a notifying means for notifying the discriminating result of the discriminating means are provided.
It is configured to notify the reception state of the signal.

[0005]

When the satellite broadcasting receiving apparatus receives the MUSE signal and the signal level of the received MUSE signal becomes a predetermined value or more, the C / N detection voltage value obtained from the video processing circuit becomes a predetermined value or more. The C / N voltage value detecting means detects this. When MUSE signal is received, MUS
Since the E signal has no voice frame synchronization, the frame synchronization signal detecting means cannot detect the voice frame synchronization in the PCM demodulation circuit and detects a signal without frame synchronization.

Therefore, when the C / N voltage value detection means and the frame synchronization signal detection means have a C / N detection voltage value higher than a predetermined value and a signal without frame synchronization is output, the determination means is the MUSE signal. It is determined that the result is notified by the notification means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment of the present invention, showing a configuration from receiving satellite broadcast to deriving a composite signal. In the figure, the parts other than the circuit surrounded by the dotted line are the same as those of the conventional satellite broadcast receiving apparatus.

The received signal of the satellite broadcasting received by the BS antenna is converted into a baseband (BB) signal by the DBS tuner, then amplified by the amplifier circuit Q ₁ , and converted by the video level adjusting circuit VR ₁ It is adjusted and guided to the video signal processing circuit 1. The video signal processing circuit 1 has C /
There is an N detection circuit, and FIG. 2 is a block diagram thereof.

In FIG. 2, the video level adjusting circuit VR
The baseband output whose signal level has been adjusted in 1 is guided to the video signal processing circuit 1, is amplified by the amplifier, is then output once from the IC 2 that constitutes the video signal processing circuit 1, and is converted into a low impedance by the impedance conversion circuit Q _2. To be converted.
After that, the band pass filter (BPF) extracts the 8 MHz component, returns it to the IC2 again, amplifies the high frequency component by the amplifier, and after peak detection, non-linearly amplifies by the non-linear amplifier to C
Derive the / N detection output voltage.

VR2 is a circuit for adjusting the C / N detection output voltage. FIG. 3 is a graph showing the relationship between the C / N of the input signal and the C / N detection output voltage.
Is 14 dB, which is the practical minimum, the adjusting circuit VR2 is adjusted so that the C / N detection output voltage is 2.1 V, and when the C / N detection output voltage is 2.1 V or more, a good reception state is obtained. To indicate that.

On the other hand, in FIG. 1, the baseband output of the DBS tuner input to the video signal processing circuit 1 is amplified and then QPSK (4 Phase Shift Key).
ing) is guided to the demodulation circuit to demodulate the audio subcarrier,
2.08 Mbps serial PCM (Pulse Co
de Modulation) data is transmitted to the PCM demodulation circuit 2 and subjected to PCM demodulation and supplied to a digital filter to perform decoding processing necessary for generating digital audio data, determination of a BS broadcast mode, and selection of an audio mode.

In this case, since the PCM demodulation circuit always performs signal processing for each frame, the presence or absence of voice data and the state of the signal can be determined by checking the frame synchronization, and the received signal is In the case of MUSE signal, it becomes an asynchronous signal without frame synchronization and the received signal is NT
In the case of the SC system, it becomes a synchronization signal.

In FIG. 1, reference numeral 3 is an input of a C / N detection output voltage derived from the signal processing circuit 1 and a frame synchronization detection signal derived from the PCM demodulation circuit 2 indicating the presence or absence of frame synchronization. A decoder for deriving an AND output, 4 amplifies the output of the decoder 3 and outputs L
A driver for driving the display device 5 such as an ED, and the decoder 3, the driver 4 and the display device 5 constitute a discrimination circuit 6 shown by a dotted frame.

FIG. 4 is a specific circuit diagram of the discriminating circuit 6, and the display operation at the time of receiving the MUSE signal will be described below with reference to this circuit diagram. If the C / N of the input signal input from the BS antenna is 14 dB or more, which is said to be the worst value in practical use, the C / N detection output voltage of 2.1 V or more and 5 V or less is detected by the graph shown in FIG. It is supplied from the circuit 1 to the input terminal T ₁ and applied to the cathode of the Zener diode D ₁₀ having a Zener voltage of about 2V.

[0015] As a result, the transistor Q ₁₀ is turned on, the base potential of the transistor Q ₁₁ decreases, the transistor Q ₁₁ becomes a cutoff state, the diode D ₁₁ the terminals of the diode D ₁₁ is a + B voltage is interrupted It becomes a state.

On the other hand, in the case of the MUSE signal, since the voice frame synchronization cannot be detected, the PCM demodulation circuit 2 inputs the "H" level signal indicating the state without the frame synchronization to the input terminal T ₂ . As a result, the transistor Q ₁₂ is rendered conductive to lower the base potential of the transistor Q _13, to both terminals of the diode D ₁₂ and the transistor Q ₁₃ to the blocking state + B
An electric potential is applied to bring the diode D ₁₂ into the cutoff state.

When both the diodes D ₁₁ and D ₁₂ are cut off, a + B potential is applied to the base of the transistor Q ₁₄ via the resistor R ₁₉ , and the transistor Q ₁₄ is turned on to turn on the light emitting diode D _13. To notify that the MUSE signal is being received.

The received signal input from the BS antenna is weak and is derived from the video signal processing circuit 1, and the C / N detection output voltage applied to the input terminal T ₁ becomes 2.1 V or less, or broadcasting other than the MUSE signal is broadcast. To receive the PCM demodulation circuit 2
More frame showing the state of there sync "L" level signal is applied to the input terminal T _2, either of the transistors Q ₁₀ or Q ₁₂ is a cut-off state, since the collector potential becomes the + B voltage following Stage transistor Q ₁₁ or Q
Any one of ₁₃ becomes conductive, and the collector potential of the transistor drops.

Therefore, the diode D ₁₁ connected to the collector of the lowered voltage of the transistor Q ₁₁ or Q _13.
Or D ₁₂ conducts, lowering the base potential of the transistor Q _14, a result of the transistor Q ₁₄ in cut-off state, no current flows through the light emitting diode D _13, the light emitting diode D
₁₃ is turned off. This is the state when the MUSE signal is not normally received, specifically, when there is no antenna input or it is extremely weak, or when an NTSC signal other than the MUSE signal is received and demodulated. Is shown.

It is also possible to take out the operation content of the transistor Q ₁₄ as a signal and use it as a control signal for other related equipment. FIG. 5 is an example thereof,
The output signal of the transistor Q ₁₄ controls the power supply of other MUSE-related equipment.

In FIG. 5, the output signal of the transistor Q ₁₄ shown in FIG. 4 is applied to the input terminal T ₃ . Now, when the satellite broadcast receiver 6 is receiving the MUSE signal in a normal state, the "H" level signal is derived from the transistor Q ₁₄ shown in FIG. 4, and the signal is applied to the input terminal T _3. . As a result, the relay circuit 8 becomes conductive via the relay drive circuit 7, supplies power to another MUSE-related device 9, and brings the MUSE-related device 9 into an operating state.

When the MUSE signal is not received or is not received in the normal state, the signal from the transistor Q ₁₄ becomes "L" level, the relay circuit 8 is cut off, and the other MUSE-related equipment 9 is sent. The power supply to the MUSE-related device 9 is stopped, and the operation of the MUSE-related device 9 is stopped.

[0023]

Since the present invention has the above-described structure, it is possible to detect and inform whether or not the MUSE signal is normally received by simply adding a simple circuit to the existing circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a main part of the present invention.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is a circuit diagram of a main part of the present invention.

FIG. 5 is a block diagram of another embodiment of the present invention.

[Explanation of symbols]

 1 video signal processing circuit 2 PCM demodulation circuit 3 decoder 5 display device

Claims (1)

[Claims] 1. A satellite broadcast receiving device comprising a video signal processing circuit for processing a video signal and a PCM demodulation circuit for demodulating an audio signal, wherein a C / N detection voltage obtained from the video signal processing circuit. C / N voltage value detecting means for detecting a value, frame synchronizing signal detecting means for detecting a frame synchronizing signal obtained by the PCM demodulation circuit, and C / N
The MUS is provided with a discriminating means for discriminating the MUSE signal based on the detection outputs of the N voltage value detecting means and the frame synchronizing signal detecting means, and an informing means for informing the discrimination result of the discriminating means.
A satellite broadcast receiving device, characterized in that the reception state of an E signal can be notified.