JPH0544854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a direction adjustment device for a receiving antenna of a satellite broadcast receiving device.

[Conventional technology]

In the case of satellite broadcasting that broadcasts television using artificial satellites in geostationary orbit, the satellite broadcast radio waves are radio waves in the SHF band of about 12 GHz, where the television signal is an FM signal. This shows an example of a television broadcast wave reception system.

Here, the transmitted SHF signal is as follows. In other words, the TV audio signal is
This PCM audio data is converted into a PCM signal, and this PCM audio data is blocked at predetermined time intervals, and an error correction code is formed and added to it, and then this PCM signal is subjected to four-phase phase modulation using 5.73MHz as a subcarrier frequency. As shown in Figure 5, this is a signal that occupies the high frequency side of the analog video signal, and this modulated PCM signal and analog video signal are combined,
The composite signal is FM modulated and SHF of about 12GHz is generated.
It was a signal.

This SFH broadcast wave is received by the receiving parabolic antenna 1 of the receiving system shown in FIG. The SHF band signal received by the antenna 1 is sent to the outdoor unit 2 as a first intermediate frequency signal, for example.
The frequency is converted to a UHF band signal of about 1GHz.
This UHF band signal is then supplied to the tuner 11 of the indoor unit 10 through the coaxial cable 3. This tuner 11 is supplied with a channel selection signal according to the viewer's channel selection operation from the channel selection circuit 12, and the tuner 11 transmits the broadcast wave (UHF signal) of the selected station to the second intermediate frequency. It is obtained by converting it into a signal. This second intermediate frequency signal is passed through a bandpass filter 13 to a second intermediate frequency amplifier 1.
4. The output of this amplifier 14 is AGC
The voltage is supplied to the voltage detection circuit 15 to form an AGC voltage, which is fed back to the amplifier 14 and subjected to AGC so that the output of the amplifier 14 is constant.

The output of the second intermediate frequency amplifier 14 is FM demodulated by an FM demodulation circuit 16, and the FM demodulated output is supplied to a video amplifier 17, and a video signal is derived to an output terminal 18.

The output of the FM demodulation circuit 16 is also supplied to a bandpass filter 21 to extract an audio subcarrier component, which is supplied to a 4-layer phase demodulation circuit 22 to demodulate an audio PCM signal, and then supplied to a digital decoder 23. . In this decoder 23
After correctable errors in the PCM signal are corrected by an error correction code, the PCM signal is returned to its original time sequence and converted back into an analog audio signal. The analog audio signal from this decoder 23 is led out to an audio output terminal 24.

Further, this audio signal and the video signal from the video amplifier 17 are supplied to the AM modulation circuit 19, from which a signal modulated into the television broadcast wave of a specific open channel of VHF television broadcasting is obtained. This is led out to the output terminal 20.

Therefore, if the signal obtained at this output terminal 20 is supplied to the antenna terminal of a television receiver commonly used in ordinary homes, satellite television broadcasting can be viewed on a specific open channel of this receiver. .

By the way, in this satellite broadcast receiving system, the direction must be adjusted so that the receiving parabolic antenna 1 is correctly oriented toward the artificial satellite. The accuracy of this antenna adjustment requires high precision of one decimal place, so unlike the adjustment of VHF and UHF TV antennas, it cannot be adjusted while checking the screen image quality, and it is not possible to adjust while watching the image quality of the screen. It is necessary to adjust the position so that it can be secured at or above the level. For this reason, it is usually carried out accurately by a professional using a measuring device. However, antennas are susceptible to wind and aging, so it would be useful if the user could adjust them. Therefore, the present applicant has previously proposed a technology that allows the received signal level to be displayed on the screen of the monitor receiver of the receiving device, and allows the user to adjust the antenna using this display (Utility Application No. 1983-
No. 113542).

As described above, the antenna adjustment method is generally performed by measuring the received signal level, whether the antenna is precisely adjusted by a contractor when installing the antenna or simply performed by the user. In other words, when adjusting the antenna, the operator selects the channel that is likely to be broadcasting on the indoor unit, measures the received signal level using a measuring instrument, and the user For example, they make adjustments while looking at a level meter to find the optimal azimuth and suppression angle of the antenna.

However, as mentioned above, if the adjuster has the right to select the channel when adjusting the antenna, there may be cases where he or she accidentally selects a channel that is not broadcasting, or when the selected channel is If there is no broadcast, it may be impossible to set the antenna direction forever.

Therefore, the applicant of the present invention previously proposed an invention that improved this drawback in Jiken No. 12440/1983.

In future inventions, when adjusting the antenna direction, the receiver does not have the right to select a channel to the adjuster, but searches for and finds a channel that is broadcasting, and when the channel that is broadcasting is found, that channel is fixed. , the direction of the antenna is adjusted based on the level of the received signal in the fixed channel, which is useful for shortening the time for adjusting the direction of the antenna.

At this time, the received signal level is displayed on the screen of the monitor receiver of the receiving device using the technology of the above-mentioned utility model registration application so that the user can easily adjust it. Problem] In this case, the channel search is always started from a certain predetermined channel.

Installing or reinstalling the antenna for the first time,
This is fine when adjusting the direction, but you may want to know the reception level after the adjustment or at a later date, such as to confirm that the direction of the antenna has not shifted. In this case, if you set the receiving device to antenna adjustment mode and measure the level while watching a certain broadcasting channel CH ₁ , if the channel at the beginning of the channel search is different from the channel you were watching up to that point, the channel you were watching up to that point will be canceled. The selected channel is fixed on a broadcast channel different from the channel that was previously used, and the received signal level on the fixed channel CH ₂ is displayed on the screen.

Therefore, when the level measurement is finished, the fixed channel CH ₂ is selected, and if you want to continue the previous broadcast channel CH ₁ , select that channel CH ₁ again. There is a need.

However, normally when you want to check the received signal level from the state you were watching,
This is often done to check whether the antenna direction has shifted due to poor image quality, etc., and it is more convenient to return to the original broadcast channel that was being viewed after checking. Also,
There are many requests to do so.

Therefore, it would be more convenient to automatically return to the original broadcast channel that was being viewed, but as described above, in the conventional case, it is necessary to reselect the channel, which is inconvenient to use.

This invention improves this drawback.

[Means for solving problems]

When the antenna adjustment mode is set, this invention prohibits channel selection by the adjuster, and when finding a channel that is broadcasting by channel search, the channel at the beginning of the search is always the channel that was being received until then. .

[Effect]

When you switch to antenna adjustment mode while watching a broadcast,
Since you always select the broadcasting channel that you have been watching up to that point, you are fixed on that channel and can adjust the antenna and check the reception level on the channel that you have been watching. However,
When the adjustment mode is canceled, the original channel is in the receiving state.

〔Example〕

Fig. 1 shows the main part of an example of the device of this invention.In the indoor unit 10, AGC is applied to the received signal, and the output of this AGC circuit 15 is the one corresponding to the received signal level. It is becoming. Therefore, in this example, this AGC circuit 1
5 is supplied to one input terminal of a differential amplifier 31 for offset removal. This differential amplifier 31
The other input terminal of is supplied with an offset voltage obtained as described below. Therefore, a signal corresponding to the received signal level is obtained from the differential amplifier 31 with offsets due to the influence of cable length etc. removed, and this is converted into a digital signal by the A/D converter 32 and sent to the microcomputer. 3
5. This microcomputer 35
A start and end switch 34 for antenna adjustment mode is connected to the antenna adjustment mode start and end switch 34. This switch 34
For example, a push switch is used and is controlled by the microcomputer 35 so that the antenna adjustment mode starts and ends repeatedly each time it is pressed. A flowchart of the antenna adjustment mode based on the operation of the switch 34 is shown in FIG.

First, it is determined whether or not the switch 34 has been pushed to enter the antenna adjustment mode (step [101]).

When the switch 34 is not operated and the adjustment mode is not set, the tuning circuit 12 allows the user to perform normal tuning. (Step [115]).

When the switch 34 is operated to enter the adjustment mode, the tuning operation by the adjuster in the tuning circuit 12 is invalidated by a signal from the microcomputer 35. In other words, the coordinator is prohibited from selecting channels (step [102]).

Next, the tuning information of the channel currently being received is written and stored in, for example, a memory provided in the tuning circuit 12 (step [103]). next,
Channels without broadcasting are microcomputer 3
The channel is selected by the signal from 5. Satellite BS−
In 2, channels 11 and 15 are broadcast channels, so channel 16, for example, is selected (step [104]).

Then, the noise level is detected in those 16 channels. This noise level detection is performed in each household, etc., because the received signal level is affected by differences in the length of the cable 3, etc., so the influence of the length of the cable 3, etc. is detected as an offset value by noise level detection. By subtracting this offset value from the reception level, the reception level without that influence is measured (step [105]). This is because the reception level of satellite broadcasting is affected by the weather, for example, so it is necessary to adjust the direction of the antenna so that the reception level is sufficient even in bad conditions. This may be suggested, but in this case, the value is the overall value ignoring the influence of cables, etc., so it is necessary to detect the offset value and detect the reception level as an absolute value. .

When this offset value is detected, the channel that was being received up to that point is read out from memory, and
Change the tuning to that channel (step [106]),
It is determined whether there is a broadcast on that channel (step [107]). At this time, when installing the antenna for the first time, the direction of the antenna is adjusted by the adjuster. The presence or absence of broadcasting is determined, for example, by monitoring the detection output of the reception level.

When there is no broadcast on that channel,
It is determined whether the switch 34 has been operated to end the antenna adjustment mode (step [108]), and if an end command has been issued, the antenna adjustment mode is canceled (step [114]), and the tuning circuit 12 returns to the state in which a normal tuner can select a channel (step [115]). Step [108] is necessary, for example, when no channel is broadcasting at that time. If the antenna adjustment mode end command is not issued in step [108], another broadcasting channel, for example channel 11, is selected (step [109]), and the presence or absence of broadcasting is determined in the same manner as described above. Once it is detected that there is a broadcast, tuner 11's tuning is fixed to the channel with that broadcast, and even if the antenna direction changes and the reception level becomes the same as when there is no broadcast, it will remain tuned to that channel. (Step [110]).

Then, in the reception state of a certain channel of this broadcast, the direction of the antenna is changed and adjusted,
The reception level at that time is detected in a calibrated state by the differential amplifier 31, and the detection output is taken into the microphone computer 35 (step [111]). This reception level is calibrated by the offset described above, and is a value that is not affected by cable length, etc., and when the reception level is in this antenna adjustment mode, it is displayed instead of or superimposed on the reproduced image by the reception signal. For example, it is displayed on a monitor receiver (step [112]). Then, when adjusting the antenna, look at the displayed level and determine the direction of the antenna that will result in a minimum allowable level or higher. Once you find that direction, fix it in that direction and press the switch 34 to give the antenna an adjustment end command. The microcomputer 35 outputs the data. That is, when the switch 34 is pressed, it is determined whether or not the adjustment is at the end (step [113]), and if it is not the end, steps [111] to [113] are repeated, and if it is the end, the antenna adjustment mode is changed. is released (step [114]),
Tuning circuit 1 ready for tuning by normal users
2 returns (step [115]).

When the antenna installation is completed and the switch 34 is set to antenna adjustment mode to check the received signal level, the channel that was being received and viewed up to that point is written in the memory, and the Then, when that channel is read out and selected in step [106], there will always be a broadcast, so in this case, in step [110], the channel that was being watched up to that time is always fixed. Therefore, when the received signal level is displayed and checked in step [112] and the adjustment mode is canceled, the original channel selection state of the channel being viewed is restored. Therefore, the viewer can check the received signal level by simply turning the switch 34 on and off, and the selected channel returns to the original viewing channel, so the program on the original channel can be continued. You can watch it.

The antenna adjustment method described above can be performed simply and easily by the user as follows.

That is, in the microcomputer 35
The highest level value of the peak value of the received signal level is stored in the RAM 35M. In other words, in the antenna adjustment mode, the level detection output is constantly monitored, and the previously stored peak value is compared with the detected level value of the received signal level at that antenna direction, and the detected level value at that time is determined. When the value is larger, the memory contents are rewritten to the larger detection level value,
The highest level value of the received signal level is stored in the RAM 35M.

Then, the microcomputer 35 outputs this highest level value together with the detection signal of the received signal level for that antenna direction.
These are supplied to a character generator 36, the output of which is supplied to a monitor receiver 38 via a switch circuit 37, and a level display as shown in FIG. 2 is made on the display screen 37. During this antenna adjustment, the output of this character generator 36 is sent to the monitor receiver 3 instead of the video signal and audio signal of the reception channel from the video and audio signal system 100.
8, and the level is displayed on the display screen 39 as shown in FIG. That is, the reception level is displayed in the upper part of the screen 39 as a bar graph. In this case, the shaded area in the figure is the part that lights up brightly, and the figure shows that the reception level at that time is 20 dB, and the maximum value of the peak value of the reception level up to that point is 30 dB. There is. The left side of the screen shows the reception level at that time, and the right side shows the maximum peak value.
Each is displayed with a number.

Using this display, the direction of the receiving antenna 1 can be adjusted as follows.

First, since the position of the artificial satellite is fixed, the approximate azimuth and elevation angle of the receiving antenna are set. From this position, first,
For example, as the azimuth is changed, the peak value at the azimuth where the strongest radio waves are received is stored and displayed on the front screen 39. Therefore, this time, we return to the opposite direction so that the peak value is reached and find the azimuth where the input level matches the peak value. Once that position is found, at that azimuth angle, change the elevation angle and find the elevation angle that gives the peak value in the same way while looking at the screen 39. Once this elevation angle is found, the azimuth angle at that elevation angle is changed to find the position where the peak value becomes even larger. By successively repeating this operation, the optimal azimuth and elevation angles at which the reception level is higher than the permissible level are found.

In the above example, while adjusting the antenna direction, the adjuster is not given the right to select the channel, and the channel with the broadcast is found, and the direction adjustment is made while the channel is selected, so the drawbacks mentioned at the beginning are avoided. There is no antenna direction, so you can always set the antenna direction on all channels except when there is no broadcasting.

In addition, when adjusting the antenna direction by detecting the reception level as in the above example, it is necessary to detect the noise level in a channel that is not a broadcast channel and detect an offset value in advance to eliminate the influence of cable length, etc. If you calibrate the reception level using this, you can set the antenna direction to obtain almost sufficient viewing conditions that are not affected by the weather at the time of setting.
It's easy to do.

Therefore, in the above example, the user can easily adjust the antenna while looking at the reception level display.

In the above example, the reception level may not be displayed on the monitor receiver, but another display device may be provided.

Effects of the Invention In this invention, when the antenna adjustment mode is set, the previously received channel is memorized and the channel search is started from the memorized channel. If you check the received signal level or adjust the antenna while in antenna adjustment mode, this will be done on the channel that you were receiving and watching up to that point, so when you cancel antenna adjustment mode, that channel will be used. The original channel can be received and viewed as is, making it convenient for users.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the main parts of an example of this invention;
3 and 3 are diagrams for explaining the same, FIG. 4 is a system diagram of an example of a satellite broadcast receiving system, and FIG. 5 is a diagram for explaining satellite broadcast radio waves. 31 is a differential amplifier as a detection circuit for calibrating and detecting the level of the received signal; 35 is a microcomputer; 38 is a monitor receiver as an example of a display that displays the received signal level and its peak value; This is the screen.

Claims (1)

[Claims] 1 In an indoor unit for receiving satellite broadcasting
In a device for adjusting the direction of an antenna by detecting a received signal level before AGC is applied, means for prohibiting a channel selection by an adjuster in an antenna direction adjustment mode;
It has means for sequentially searching channels to find a channel with a broadcast, and means for fixing the tuning at that channel when a channel with a broadcast is found, so that the above-mentioned antenna direction adjustment is performed in this fixed channel. 2. A direction adjustment device for a satellite broadcast receiving antenna, which is configured to perform a channel search as described above, and is configured to start the search from a channel that has been received up to that point.