JPH05122636A - Switching device for satelite brodcasting receiver - Google Patents

Abstract

PURPOSE:To automatically selecting and switching the appropriate sound demodulation output of a satelite broadcasting receiver receiving the BS of a DPSK whose audio signal modulation system is in four-phase and the CS of an FM or MSK and to display whether the sound is PCM or FM sound. CONSTITUTION:As to the changeover of a first switching circuit 8 between a DPSK demodulation circuit 6 and an MSK demodulation circuit 3, a controlling microcomputer 11 monitors the frame synchronization state of a high-order error correction part 7 after MSK demodulation and in the case of synchronization, it selects the side of the MSK demodulation circuit 3. As to the changeover of a second switching circuit 9 between an FM demodulation circuit 4 and the output of a scramble decoder 5, the controlling microcomputer 11 monitors the frame synchronization state at the time of low-order error correction and in the case of synchronization, it selects the output side of the scramble decoder 5. Furthermore, a display signal 26 linked with a second switching signal 25 displays whether the sound is the PCM or FM sound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a BS (broadcast satellite) having a four-phase DPSK (Differential Phase Shift Keying) modulation method for an audio signal, and an FM or MSK (Minimum Shif).
satellite broadcasting reception that automatically selects and switches the audio demodulation output of a satellite broadcasting receiver that receives CS (communication satellite) of t Keying) and displays PCM audio or FM audio. A switching device for a machine.

[0002]

2. Description of the Related Art At present, it is considered that a single receiver receives all the audio signals of the above-mentioned modulation method has not been commercialized.

[0003]

BS and C are used for satellite broadcasting.
Some of the modulation methods are used for transmitting these audio signals. Therefore, in order to be able to receive all broadcast signals of such different modulation systems, a demodulation circuit suitable for each system is provided, and the demodulation output from the demodulation circuit corresponding to the system is selected for each selected channel. Must be selected. If such selection switching is performed manually, the complexity cannot be endured. The present invention discriminates a modulation method of an audio signal from a received broadcast signal and automatically selects a normal audio demodulation output and a PC.
It is an object of the present invention to provide a switching device that also displays M audio or FM audio.

[0004]

The present invention provides a control microcomputer, a 4-phase DPSK demodulated signal, and an MSK after high-order error correction.
A first demodulation signal and a first switching signal based on a first switching signal from the control microcomputer, and input to the scramble decoder
And a second switching circuit for switching between the FM demodulated signal and the scramble-decoded voice signal from the scramble decoder based on the second switch signal from the control microcomputer to output a voice signal. , The MSK demodulation signal is selected when the frame synchronization state in the high-order error correction after the MSK demodulation is synchronized, and the four-phase DPSK demodulation signal is selected when the frame synchronization state is asynchronous. The switching circuit is switched so that the signal from the scramble decoder is selected when the frame synchronization state at the time of low-order error correction in the scramble decoder is synchronized, and the FM demodulation signal is selected when the frame synchronization state is asynchronous. The second switching circuit is switched to the display unit while the display unit is provided. When the frame synchronization state at the time of the low-order error correction is synchronous, PCM is displayed, and when the frame synchronization state is asynchronous, FM is displayed. A switching device for a satellite broadcast receiver is provided.

[0005]

The first switching circuit is connected to the DPSK demodulation circuit side or M
The switching to the SK demodulation circuit side is made by the first switching signal output by the control microcomputer based on the frame synchronization state at the time of high-order error correction after MSK demodulation. That is, if the frame synchronization state is synchronized, MSK
The demodulation circuit side is selected, and if asynchronous, the DPSK demodulation circuit side is selected. Whether the second switching circuit is switched to the FM demodulation circuit side or the scramble decoder output side is output by the control microcomputer based on the frame synchronization state at the time of low-order error correction in the scramble decoder. It is made by the switching signal of. That is,
If the frame synchronization state is synchronous, the scramble decoder output side is selected, and if not, the FM demodulation circuit side is selected.

Further, a PCM voice or FM voice is displayed by a display signal linked to the second switching signal. As a result, a normal demodulation signal is automatically obtained as a voice output. High-order error correction is an error correction method using a convolutional code (constraint length k = 4, coding rate r = 1/2), and low-order error correction is BCH (63,56) SEC.
-An error correction method that uses the DED code. Both methods correct bit errors in data transmission.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A satellite broadcast receiver switching device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts showing an embodiment of a switching device for a satellite broadcast receiver according to the present invention, and FIG. 2 is a flow chart for explaining the operation of a control microcomputer. In FIG. 1, 1 is a tuner section for selecting a channel from radio waves received from BS or CS antennas, and 2 is a non-scrambled FM audio signal by demodulating an FM wave (BS), or scrambled video and audio. An FM demodulation circuit that outputs either each signal or a DPSK audio signal, 3 is an MSK demodulation circuit that demodulates an MSK modulated wave [audio multiplex broadcasting by CS (no video)], and 4 is the FM audio signal FM demodulation circuit for demodulation, 5 a scramble decoder for descrambling, 6 a DPSK demodulation circuit for demodulating the DPSK audio signal, 7 high-order error correction and program selection (normally 6 programs are broadcast per channel. (Hereinafter, referred to as a high-order error correction unit), 8 is a first switching circuit (hereinafter, referred to as SW1), and 9 is a second Switching circuit (hereinafter,
SW2), 10 is a display unit, and 11 is a control microcomputer (hereinafter referred to as a microcomputer).

Switching of SW1 and SW2 is performed as follows. The ST numbers in parentheses in the following description represent each step in FIG. When the channel which is the tuner 1 is selected, the microcomputer 11 initializes SW1 and SW2 to "a side" and "c side" in the figure (ST1). On the other hand, the tuner output is normally demodulated by either the FM demodulation circuit 2 or the MSK demodulation circuit 3. This is because the transmitted radio waves are either FM waves or MSK waves. Now
If the radio wave of the selected channel is an MSK wave, it is normally demodulated by the MSK demodulation circuit 3, and the demodulated output is further program selected by the high-order error correction section 7, and the high-order signal of the selected program program is selected. Error correction is made. Here, the program selection is selected by the program selection signal 21 output from the microcomputer 11 based on the program selection operation. The microcomputer 11 monitors the synchronization state of the frame synchronization at the time of the higher-order error correction with the data line 22 (ST2), and the switching signal (first switching signal 23) according to it.
Is output. For example, a high (H) level [or low (L) level] is output if the synchronization state of the frame synchronization is synchronous, and an L level (or H level) is output if the frame synchronization is asynchronous. Further, it is determined whether or not it is "synchronous" by determining the output voltage [high (H) level or "low (L) level" of the frame synchronization state monitoring terminal of the higher-order error correction circuit (integrated circuit).
Level], and the microcomputer 11 monitors the output voltage. Here, the H level or the L level depends on the circuit design, but if one (for example, H) is “synchronous”, the other (for example, L) is “asynchronous”. Naturally SW1
And the first switching signal 23 are made to correspond to each other. As a result, "synchronous" is selected as the first switching signal 23.
If it is “asynchronous”, it is output so as to switch to the b side, respectively. Therefore, if the radio wave of the selected channel is the MSK wave, the frame synchronization state is "synchronous", and therefore SW1 is maintained at the side a (ST3). The term "maintained" is set to the side a in the initial state. If it is not the MSK wave, it will be “asynchronous”, so SW1
Is switched to the b side (ST4).

Next, switching of SW2 will be described. The SW2
The reference of the switching signal (second switching signal 25) is the frame synchronization state in the scramble decoder 5.
Similar to the first switching signal 23, the frame switching state of the second switching signal 25 is monitored by the data line 24 (ST5), and if synchronized, H level (or L level) is changed to asynchronous. If so, L level (or H level)
Is output, and SW2 is switched to the c side in the case of synchronization, and SW2 is switched to the side of d in the case of asynchronous. Therefore, if the radio wave of the selected channel is the FM wave and the scrambled signal, the frame synchronization state is "synchronous", so that it is maintained on the c side (initial state) (ST6). In the case of a non-scrambled FM wave, it becomes "asynchronous" and is switched to the d side (ST8). Here, to determine whether or not it is “synchronous”, the output voltage [high (H) level or “low (L) level] of the frame synchronization state monitoring port of the scramble decoder 5 is used, and the microcomputer 11 determines the output voltage. The circuit design determines whether the level is H or L. However, if one (eg, H) is “synchronous”, the other (eg, L) is “asynchronous”.

PCM audio is used except for those which are normally demodulated by the FM demodulation circuit 4. That is, by linking with the second switching signal 25, the distinction between FM voice and PCM voice can be displayed. That is, when the microcomputer 11 outputs the signal to be set to the c side as the second switching signal 25, it simultaneously outputs the display signal 26 for PCM display to the display unit 10 (ST7). On the contrary, when the signal to be set to the d side is output, the display signal 26 for FM display is output at the same time (ST9). The video signals in the signals of the respective systems described above are output to the video output terminal 12 via the scramble decoder 5 (whether or not the scramble is released) except for the MSK wave (there is no video).

[0011]

As described above, according to the present invention, in a satellite broadcasting receiver that receives a BS having a four-phase DPSK and a CS having an FM or MSK as a modulation method of an audio signal, it is appropriate for each channel selection. The signal from the demodulation circuit is automatically selected and the PCM sound or FM sound is also displayed, which contributes to improving the function of the satellite broadcast receiver.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts showing an embodiment of a switching device for a satellite broadcast receiver according to the present invention.

FIG. 2 is a flow chart for explaining the operation of the control microcomputer 11.

[Explanation of symbols]

 1 Tuner section 2 FM demodulation circuit 3 MSK demodulation circuit 4 FM demodulation circuit 5 Scramble decoder 6 QPSK demodulation circuit 7 Higher-order error correction section 8 First switching circuit (SW1) 9 Second switching circuit (SW2) 10 Display section 11 Control microcomputer 23 First switching signal 25 Second switching signal 26 Display signal

Claims (2)

[Claims] 1. FM demodulation and 4-phase DPS in a voice signal
In the audio switching of the satellite broadcast receiver configured to perform K demodulation and MSK demodulation, the control microcomputer, the 4-phase DPSK demodulated signal, and the MSK demodulated signal after high-order error correction are used by the first control microcomputer. Switching circuit based on the second switching signal from the control microcomputer, and a first switching circuit for switching to the scramble decoder for switching based on the switching signal of 1) and the FM demodulation signal and the scramble-decoded audio signal from the scramble decoder A second switching circuit for outputting a voice signal as a voice signal is provided, and when the frame synchronization state at the time of high-order error correction after MSK demodulation is synchronized, the MSK demodulation signal is selected and the frame synchronization state is asynchronous. Sometimes, the first switching circuit is switched so as to select the 4-phase DPSK demodulated signal, and the low order signal in the scramble decoder is selected. The second switching circuit is switched so that the signal from the scramble decoder is selected when the frame synchronization state at the time of error correction is synchronized, and the FM demodulation signal is selected when the frame synchronization state is asynchronous. A switching device for a satellite broadcast receiver, characterized in that 2. A display unit is provided, and a display signal from the control microcomputer is used to display PCM when the frame synchronization state at the time of the low-order error correction is synchronized, and the frame synchronization state is displayed. 2. The switching device of the satellite broadcast receiver according to claim 1, wherein the display indicates that FM is active when is asynchronous.