JPS6031382A - Satellite broadcast receiver - Google Patents

Abstract

PURPOSE:To obtain voice surely at power-on by switching forcibly the mode to a specific selecting state where a voice output is obtained when the contents of control bit at power-on are different from the reception selecting state at power- off. CONSTITUTION:The information of memories 31A, 31B for modes A and B is fed to a comparator circuit 34 through a gate circuit. On the other hand, a decoder 36 discriminates the reception mode at that time by means of the control bit in a PCM voice signal extracted by a control bit extracting circuit 35. Then the decoder 36 feeds the information of the memories 31A, 31B selectively to the comparator circuit 34 by the discriminating output. When the contents of said memory and the output of the decoder 36 are different in the comparator circuit 34, the mode is decided forcibly by a prescribed priority and the voice is outputted depending on the mode. Further, the contents of said memory is rewritten into the contents of the forcible mode by the output of the comparator circuit 34.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite broadcast receiving apparatus that receives television signals transmitted using artificial satellites. BACKGROUND TECHNOLOGY AND PROBLEMS Satellite television broadcasting using artificial satellites in geostationary orbit and transmitting television signals as SHF band signals is on the way. In this satellite television broadcasting, the television audio signal in the television signal is converted into a PCM signal so that high quality reproduced audio can be obtained. FIG. 1 shows a receiving system for this SHF satellite television broadcast wave. Here, the transmitted SHF' signal is as follows. That is, the television audio signal is converted into a PCM signal, and this PCM audio data is divided into blocks for each predetermined time period, an error correction code is formed, and the data is added to the PCM signal.
After that, this PCM signal is subjected to four-phase phase modulation using 5.73 MHz as a subcarrier frequency, and is made into a signal that occupies the high frequency side of the analog video signal, as shown in Figure 2, and this modulated PCM signal and The analog video signal is synthesized, and the synthesized signal is FM modulated to generate 12 GH2H2O.
3) (F signal). This SHF broadcast wave is received by the receiving parabolic antenna (1) of the receiving system shown in Fig. 1.
) The SHF' band signal received by the outdoor unit) 12
+, the frequency is converted into a signal in the UHF' band of, for example, IGHz as a first intermediate frequency signal. And this UH17' band signal is transmitted via coaxial cable (3)
The signal is supplied to the tuner aD of the indoor unit aα through the channel. This tuner (111) is supplied with a channel selection signal according to the viewer's channel selection operation from the channel selection circuit iuz, and this tuner (111) receives the broadcast wave (UHF' signal) of the selected station from the tuner (111). This second intermediate R-wave signal is supplied to a second intermediate frequency amplifier a41 via bandpass filters a and iv.The output of this amplifier a41 is supplied to the AGC voltage detection circuit (151 is supplied to the &GC voltage, which is fed back to the amplifier (A) so that the output of this amplifier α becomes constant.
GC is applied. The output of the second intermediate frequency amplifier α is FM demodulated by the FM demodulation circuit Kasumi, and the FM demodulated output is sent to the video amplifier a.
D, and a video signal is derived from the output terminal (181).
11 and the audio subcarrier component is extracted;
This is supplied to the 4-phase phase demodulation circuit (22) and the audio PC
The M signal is demodulated and fed to the digital decoder@. In this decoder (c), correctable errors in the PCM signal are corrected by an error correction code, and then the signal is returned to its original time series and converted back into an analog audio signal. This decoder (
The analog audio signal from the gain control circuit (c) is led out to the audio output terminal Q51 through the gain control circuit (2 outputs). Also, this audio signal and the video signal from the video amplifier □η are supplied to the AM modulation circuit 9. It has been said that V) I
A signal modulated to the television broadcast wave of the empty channel of P television broadcasting is obtained, and this signal is led out to the output terminal. Therefore, if the signal obtained from this output terminal (201) is supplied to the antenna terminal of a television receiver that is popular in ordinary households, it is possible to watch satellite television broadcasting on the open channel of this receiver. By the way, there are two types of PCM audio in this satellite TV broadcast: B mode, which allows relatively high quality audio to be obtained, and A mode, which has a low bit number in the normal state but allows multi-channel audio. There is a mode of 0, i.e.
The input mode compresses the 14 bits per sample of the TV audio signal to 10 bits to enable multi-channel audio within a limited band, while the B mode converts the signal to 16 bits per sample. Furthermore, it is possible to obtain high-quality audio. N mode is a mono-chill 4 channel consisting of the 1st to 4th audio (stereo 2nd channel),
The B mode is a mono-sil 2 channel (stereo 1st channel) consisting of the first audio and the second audio, and allows broadcasting according to the content of the transmission signal of the broadcasting station for each of the two channels. If these are summarized as one, it will be explained as shown in Fig. 3. That is, among the four channels of A mode, the first audio and the second audio are called TV audio, and the third audio and fourth audio are called additional audio. There are 1-channel broadcasts, 2-channel monaural broadcasts, and no broadcasts. When broadcasting on a mono-sil 2 channel, the broadcast mode is similar to that of current television audio multiplexing, and the first audio, the second audio, the third audio, and the fourth audio can be selected, respectively. As for the B mode, as with the IC & mode, there are stereo broadcasts, monaural 1-channel broadcasts, monaural 2-channel broadcasts, and no broadcasting, and in the case of mono-sil 2 channels, the first audio and You will have to choose between two voices. By the way, the recipient does not have to select all the combinations of reception modes shown in FIG. 3, but the bold lines in FIG. -2. Selection of television sound and additional sound in N mode as shown, and selection of first sound and second sound or third sound and fourth sound when broadcasting mono-sil 2 channels in N mode and B mode. Selection meets SELECT on the receiving side. The others are automatically switched on the receiving side by the "control" bit in the PCM television audio signal, as will be described later. That is, the PCM television audio signal constitutes 1 frame of data with a predetermined time as a unit time, and this 1 frame of data is preceded by 16 frames of data as shown in FIG.
A 32-bit frame synchronization signal is added, followed by a 16-bit control bit, then a 32-bit range bit, and a BCH code, which is an error correction code, is added after the PCM audio data. Ru. Currently, the first 1 bit of the 16 bits controls the broadcast program mode.

[0] or B mode [1]
The next two bits are for the first audio and the second audio, and the next two bits are for stereo

[00] or mono-sil 1 channel [
10], mono-sil 2 channel [01], or no broadcasting [11]. 6
The 15th bit (1) after the 1st bit is considered an extension bit, and the last 1 bit is, for example, when the program source changes from N mode to B mode.
It is defined as a voice control bit that serves as a command to suppress noise that occurs when switching modes. Therefore, the first pit and the second to fifth pits in the control bit
The reception mode is specified to some extent by the bit, and the receiver simply selects whether the additional audio is TV audio or monophonic when in N mode.
In the case of 2-channel broadcasting, the user selects the first audio, the second audio, the third audio, or the fourth audio. As mentioned above, there are various broadcasting modes in satellite broadcasting, so unlike conventional television receivers, satellite broadcasting receivers can not only select channels but also select TV audio and additional audio in N mode, mono- It is necessary to select a complex receiving mode, such as selecting the first audio, the second audio, the third audio, or the fourth audio in the case of two-channel broadcasting. By the way, when using an electronically tuned tuner, in order to avoid a situation where the signal cannot be received at all when the power is turned on after the power is turned off, it is necessary to set the channel, volume value, etc. when the power is turned off. There is a function to memorize the information, but since satellite broadcast receivers have a wide variety of broadcasting modes as mentioned above, this function alone may cause images to be displayed on the screen but no sound to be output. There is a possibility that the receiver may mistake it for a malfunction.For example, if the reception state is in N mode when the power is turned off,
When the fourth audio, that is, the additional audio stereo broadcast is being received, the next time the power is turned on, if the program source being transmitted at that time is B mode and the broadcast is in two languages, it will be stored when the power is turned off. What used to be done becomes completely invalid. Furthermore, since the selection status of the main and sub languages for bilingual broadcasting has not yet been determined, the situation is unstable. For this reason, the conventional so-called last memory function, which stores the channel selection state when the power is turned off, is insufficient for satellite broadcast receiving apparatuses. Purpose of the Invention In view of the above-mentioned problems peculiar to satellite broadcasting, this invention provides a system that does not have the above-mentioned inconveniences when the power is turned on.
The aim is to provide a device that is devised so that audio can be obtained stably and reliably. Summary of the Invention In this invention, the contents of a memory circuit that stores the reception selection state when the power is turned off are compared with the contents of a control bit, and if the contents match, the sound is generally determined by the output of the memo + 1 circuit. The selection is made, and if the selection is different, the takuma is forced to switch to a specific selection state in which the sound is produced. EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. In this example, when the power is turned off, a memory is provided to store the reception selection state immediately before that. In this case, as shown in FIG. 5, the memory is a memory for N mode (
31N) and a memory for B mode (31B) are prepared. The memory for N mode (31A) is stored only when the received signal is in N mode, and the memory for B mode I7 (31B) is stored only when the received signal is in 8 mode. Therefore, the contents of the N mode memory (31A) include information on whether the reception mode is A mode, TV audio or additional audio, and selection of 1st audio or 2nd audio when TV audio is mono-sil 2 channels. In addition, information on the above three modes of selecting the third audio or the fourth audio in the case of the additional audio and the mono-sil 2 channel is stored. On the other hand, B mode memory (3
1B), the reception mode is B mode, and
Information on selection of the first audio or the second audio is stored in the hole of the mono-sil 2 channel. The information in these two memories (31A) and (31B) is supplied to the comparator circuit C3a through gate circuits (32A) and (32B) 44, respectively, and an OR gate (33). On the other hand, the control bits in the PCM audio signal are extracted in the control bit extraction circuit C'15) provided in the digital decoder (C).
How much is the program lease at that time?
It is determined whether the receiving mode is set. The decoded output is supplied to the comparison circuit 134) and also to these two memos TI (31PL) and (31B). Of the decoded outputs of the decoder (g), N
A gate circuit (32A
) and (32B) are controlled, and when the receiving mode is N mode, the information from the memory (31A) is selected, and when the receiving mode is B mode, the information from the memory (31B) is selected by the comparator circuit (34). Supplied with Memo IJ
The information and the decoder output are compared. Then, if there is no unreasonableness in the comparison, the audio output selection circuit 437) is controlled by the comparison output. That is, if the receiving mode is N mode, Memo I+ (31
Based on the selection information of A:, if the receiving mode is B' mode, the audio output mode is switched and audio is output based on the selection information of the memories (31, 8). Memory (31A) (31B) in the comparison circuit (34)
When the content of the decoder differs from the output of the decoder (to), causing an unreasonable situation, the mode is forcibly determined with priority as described later, and the audio is output according to the forcibly set mode. be made to be In addition, when irrationality is detected in the comparator circuit (2), the output is used to store the memory (31N) or (
31B) is rewritten to the forced mode content. In this way, when the power is turned on, if the contents differ from the last memory, the forced mode allows audio output to be obtained. Further, when the channel selection state is changed in the channel selection circuit +13 by key operation, the contents of the memory are changed to the mode state after the key operation. That is, the contents of each memory (31A) or (31B) are changed depending on the output state of the decoder example. The above operations are actually controlled by a microcomputer, and a flowchart in that case is shown in FIG. In this case, Memo'J (31A) and (31B)
A non-volatile memory such as MNOS is used. Next, the selection in forced mode will be explained. First, it is determined whether the reception mode can be selected on the receiver side based on the information of the control bit when the power is on. That is, selection of the first and second audio in the case of mono-sil 2 channels in N mode,
The selection of the third and fourth voices and the selection of the first and second voices in the B mode are aspects that are problematic in mode selection. Furthermore, selection of the second stereo channel in N mode is also a case in which the receiving side has the selection right. In this case, when the receiving side has the right to choose, the contents of memo I7 (31A) (31B) are followed first. That is, when the control bit information indicates N mode,
First, television audio or additional audio is selected depending on the contents of the memory (31A). Next, in the state of the TV sound or additional sound, in the case of mono-sil 2 channel broadcasting, the selection of the first sound or the second sound, or the selection of the third sound or the fourth sound is stored in the memory (31A). It will be done accordingly. Even when the control bit information indicates B mode, the first audio and the second audio are selected depending on the contents of the memory (31B) in the case of mono-sil 2 channels. In addition,
In the case of N mode and B mode, when the receiving mode, that is, the state of the control bit is in a state where there is no audio information, there is no selection right on the receiving side, and the mode with the audio program is determined according to the priority order described later. It will be done. Note that the memories (31A) and (31B) operate independently, so if the state of the received signal when the power is turned on is B mode, the memory for N mode (31A) will store the previous state. 11 continues to memorize, and the memory for B mode (3
The selection is made only according to the contents of 1B). Next, in the case of a program source for which the receiving side does not have the above-mentioned selection authority, that is, for example, in the case of A-mode or B-mode stereo broadcasting, the audio output is selected according to the information of the control bits. The contents of the above control bits and memo I+ (3i) and (3
If the audio output is still not determined depending on the storage contents of 1B), the selection state is determined according to the priority order as follows. That is, as mentioned above, the modes that require selection on the receiving side are (1) In mode A, selection of TV audio or additional audio. (2) In A mode, TV audio and mono-sil 2
Selection of 1st audio or 2nd audio when using channel. (3) In k mode, selection of third or fourth audio when additional audio and mono-sil 2 channels are used. (4) In B mode, selection of first audio or second audio when using mono-sil 2 channels. The above four ways are possible. Here, in the satellite broadcasting currently being considered, in the A mode, the television sound consisting of the first and second sounds is the main one. Kata, seven naural 2 channel and taste, eight, eight
In both modes, the first audio is the main audio. In the case of the third and fourth voices, the third voice becomes the main voice. From the above, in the case of (1) above, select the first and second TV sounds, in the case of (21, (4), select the first sound, and in the case of (3), select the third sound. Priority is set so that the selection is made.However, in consideration of the fact that in A mode, the first and second audio may not be broadcast and there is no audio, in that case, the control bit at that time will prioritize the first and second audio. 3. Give priority to the 4th audio. The priority is determined by the above, the mode is forcibly determined, and a stable audio output can be obtained from the receiver. Figure 7 shows the program source. It shows the temporal change in content, the on/off state of the receiver's power, and the selection state of the receiving side at that time.In the above example, Memo+7 (3]A), (
31B) uses non-volatile memory, so by making it possible to preset the reception mode of the program source the next time the power is turned on in this memory, it can be used in combination with a timer to It becomes possible to record and reserve programs. That is, in this case, the receiver makes the preset while looking at the TV program guide, so when the power is turned on, the control bits and the contents of the memory will always match, so the audio will be output in the audio reception mode set by the receiver. You will be able to
This allows you to record your answering machine and make program reservations. Effects of the Invention As described above, in this invention, not only the reception selection state is set the next time the power is turned on based on the contents of the memory when the power is turned off, but also the reception selection state is set when the power is turned on next time. By comparing the contents of the control bits in the received signal with the contents of its memory, if the contents of the two differ, the device is forced to switch to a mode that provides stable audio output, so when the power is turned on. Since there is no possibility that the sound cannot be obtained or the output state is unstable, the viewer will not be given an unpleasant image. This is because in a normal reception state, it is possible to select the most flexible mode by selecting the forced selection state with priority.

[Brief explanation of drawings]

Figure 1 is a system diagram of an example of a satellite television broadcast receiving system.
Figure 2 is a diagram for explaining satellite television broadcast signals, Figure 3
FIG. 4 is a diagram for explaining a PCM audio signal, and FIGS. 5 and 6 are diagrams for explaining an embodiment of the present invention. A system diagram and a flowchart, and FIG. 7 is a time chart for explaining the present invention in detail. Figure 3 Figure 4 Figure 6°” Separate

Claims (1)

[Claims] It has a memory circuit that stores the last selection state when the power is turned off, and a comparison circuit that compares the control bit extracted from the received signal when the power is turned on with the contents of the memory circuit, A satellite broadcast receiving device that is configured to forcibly switch to a specific selection state in which audio is output when the two are different.