JPH0620187B2 - Directional adjustment device for satellite broadcasting reception antenna - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a direction adjusting device for a receiving antenna of a satellite broadcast receiving device.

2. Background Art and Its Problems Sanitary broadcasting, which is a satellite broadcasting that uses satellites in geostationary orbit, is being realized.

This satellite broadcast radio wave is a radio wave in the SHF band of about 12 GHz in which the television signal is an FM signal.

FIG. 1 shows an example of a receiving system for this SHF satellite television broadcast wave.

Here, the transmitted SHF signal is the following signal. That is, the television audio signal is converted into a PCM signal,
Then, this PCM audio data is divided into blocks at predetermined time intervals, and after an error correction code is formed and added, this PCM is set to 5.73 MHz as a subcarrier frequency.
The signal is quadrature phase modulated to be a signal occupying the high frequency side of the analog video signal as shown in FIG. 2, the modulated PCM signal and the analog video signal are combined, and the combined signal is FM-modulated. The SHF signal is about 12 GHz.

This SHF broadcast wave is received by the receiving parabolic antenna (1) of the receiving system shown in FIG. The signal in the SHF band received by the antenna (1) is frequency-converted in the outdoor unit (2) into a UHF band signal of, for example, about 1 GHz as a first intermediate frequency signal. Then, the UHF band signal is supplied to the tuner (11) of the indoor unit (10) through the coaxial cable (3). The tuner (11) is supplied with a tuning signal from the tuning circuit (12) according to the tuning operation of the viewer, and the tuner (11) receives the broadcast wave (UHF signal) of the selected station. ) Is converted into the second intermediate frequency signal and obtained. The second intermediate frequency signal is supplied to the second intermediate frequency amplifier (14) through the bandpass filter (13). The output of this amplifier (14) is the AGC voltage detection circuit (1
It is supplied to 5) to form an AGC voltage, which is fed back to the amplifier (14) and AGC is applied so that the output of the amplifier (14) becomes constant.

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

The output of the FM demodulation circuit (16) is also supplied to the bandpass filter (21) to extract the audio subcarrier component, which is supplied to the four-phase phase demodulation circuit (22) to output the audio P.
The CM signal is demodulated and supplied to the digital decoder (23). In this decoder (23), the PCM signal is corrected to an error that can be corrected by an error correction code, and then returned to the original time series to be returned to an analog voice signal. The analog audio signal from this decoder (23) is output from the audio output terminal (2
4) is derived.

Also, the audio signal and the video signal from the video amplifier (17) are supplied to the AM modulation circuit (19), and X
A signal modulated into a television broadcast wave of a specific open channel of HF television broadcast is obtained, and this signal is led to the output terminal (20).

Therefore, if the signal obtained at the output terminal (20) is supplied to the antenna terminal of a television receiver which is widely used in general households, satellite television broadcasting can be viewed on a specific open channel of this receiver. .

By the way, in this satellite broadcast receiving system, it is necessary to adjust the direction of the receiving parabolic antenna (1) so as to correctly face the artificial satellite. The adjustment method in this case is if the vendor makes accurate adjustments when installing the antenna,
Even if the user simply performs the method, the method of measuring the received signal level is generally used. In other words, in the case of the user, while selecting the channel that seems to be broadcasting at the time of the antenna adjustment in the indoor unit and measuring the received signal level using a measuring instrument in the case of a dealer, For example, the optimum azimuth angle and elevation angle of the antenna are found by adjusting while looking at the level meter.

By the way, since the precision of this antenna adjustment requires a high precision of one digit below the decimal point, it seems that a considerable amount of time is spent as compared with the adjustment of the TV antennas of VHF and UHF.

However, if the coordinator has the right to select a channel when adjusting the antenna as described above, if a channel that does not have a broadcast is selected by mistake, or if the selected channel is broadcast during the time when the antenna is adjusted. If not,
The antenna direction may not be set forever.

OBJECT OF THE INVENTION The present invention is intended to provide an antenna adjusting apparatus which does not have the above-mentioned drawbacks.

SUMMARY OF THE INVENTION According to the present invention, when adjusting the antenna direction, the coordinator is not given the right to tune, the channel with the broadcast is searched for and found, and when the channel with the broadcast is found, the channel is fixed and the antenna is fixed. Direction adjustment is performed based on the received signal level in the fixed channel, which is useful for shortening the antenna direction adjustment time.

Embodiment FIG. 3 shows an essential part of an example of the device according to the present invention, in which an AGC is performed on a received signal in an indoor unit (10).
In this example, the bandpass filter (1
The signal from 3) is supplied to the level detection circuit (31) and its signal level is detected. The detected output is converted into a digital signal by the A / D converter (32) and supplied to the microcomputer (33). An antenna adjustment mode start & end switch (34) is connected to the microcomputer (33). The switch (34) is, for example, a push-push switch, and is controlled by the microcomputer (33) so as to repeat the start and end of the antenna adjustment mode each time it is pressed. FIG. 5 shows a flowchart of the antenna adjustment mode based on the operation of the switch (34).

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

When the switch (34) is not operated and the adjustment mode is not set, the channel selection circuit (12) allows normal channel selection by the user (step [117]).

When the switch (34) is operated to enter the adjustment mode, it is invalid even if the coordinator makes a tuning operation in the tuning circuit (12). That is, tuning of the coordinator is prohibited (step [102]).

Next, the channel without broadcasting is selected by the signal from the microcomputer (33). In the satellite BS-2
Since two channels, channel 11 and channel 15, are broadcast channels, for example, channel 16 is selected (step [103]).

Then, the noise level is detected on the 16 channels. In this noise level detection, the reception signal level is affected by differences in the length of the cable (3) in each household, etc., so the influence of the length of the cable (3) is detected as an offset value by noise level detection. Then, this offset value is subtracted from the reception level to measure the reception level having no influence (step [104]). In satellite broadcasting, for example, the reception level depends on the weather, so it is necessary to drive the antenna direction so that the reception level will be sufficient for viewing even in bad conditions, so the minimum acceptable level is suggested. It is thought that
This is because, in this case, the value is an absolute value that ignores the influence of the cable or the like, 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 shifts to a channel with broadcasting, for example, channel 15 (step [105
], And it is determined whether there is a broadcast on the 15th channel (step [106]). At this time, the direction of the antenna is adjusted by the adjuster. The presence or absence of broadcasting is determined by monitoring the detection output of the reception level, for example.

When there is no broadcast, it is judged whether or not the switch (34) is operated to set the antenna adjustment mode end (step [107]). If the end command is issued, the antenna adjustment mode is released (step). [114]), the tuning circuit (12) returns to the normal tuning enabled state by the coordinator (step [115]). The step [107] is necessary, for example, when broadcasting is not performed on any channel at that time.

If the antenna adjustment mode end command is not issued, another broadcasting channel, for example, channel 11 is selected (step [108]), and the presence or absence of broadcasting is determined in the same manner as described above. Now, once it is detected that there is a broadcast, the tuner (11) tuning is fixed on the channel with that broadcasting, and even if the direction of the antenna changes and the reception level becomes the same as that without broadcasting, that channel is selected. It is left as it is (step [109]).

And, in the channel receiving state of this broadcast,
The direction of the antenna is changed and adjusted, the reception level at that time is detected by the detection circuit (31), and the detection output is taken into the microcomputer (33) [110]. This reception level is calibrated by the offset amount described above to a value that does not affect the cable length and the like (step [111]), and the reception level is displayed on, for example, a monitor receiver (step [112]). . Then, while observing the displayed level, determine the antenna direction that is above the allowable minimum level, and if that direction is found, fix it in that direction and press the switch (34) to send the antenna adjustment end command to the microcomputer (33 ). That is, it is determined whether or not the switch (34) is pressed to reach the adjustment end (step [113]), and if not the end, steps [110] to [112] are repeated, and if it is the end, antenna adjustment is performed. The mode is released (step [114]), and the tuning circuit (12) returns to a normal user-selectable state (step [115]).

In this case, the antenna adjustment method is designed so that the user can easily and easily perform it as follows.

That is, the maximum level value of the peak value of the received signal level is stored in the RAM in the microcomputer (33). 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 detection level value of the received signal level in that antenna direction, and the detection level value at that time is compared. When it is larger, the stored contents are rewritten to the larger detection level value, and the highest level of the received signal level is stored in the RAM.

Then, this microcomputer (33) outputs the highest level value together with the detection output of the received signal level in the direction of the antenna, supplies these to the character generator (35), and the output is a monitor in this example. It is supplied to the receiver (36) and the level display as shown in FIG. 4 is made on the display screen (37). That is, the reception level is displayed as a bar graph in the upper part of the screen (37). In this case, the shaded area in the figure is the brightly lit part, and the figure shows that the reception level at that time is 20 dB and the maximum peak value of the reception level up to that point is 20 dB. There is. Then, the reception level at that time is displayed on the left side of the screen, and the maximum peak value is displayed on the right side with numbers.

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 of the receiving antenna are set. From this position, first, for example, when the azimuth angle is changed, the peak value at the azimuth angle at which the strongest radio wave is received is stored and displayed on the display screen (37). Therefore,
This time, the azimuth angle at which the input level matches the peak value is found by returning in the opposite direction so that this peak value is reached.
When that position is found, at that azimuth angle, change the elevation angle this time, and in the same way, display the elevation angle that becomes the peak value (3
7) Find while looking. When 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. Hereinafter, by repeating this operation in sequence, the optimum azimuth angle and elevation angle at which the reception level is higher than the allowable level can be found.

As described above, during adjustment of the antenna direction, the coordinator is not given the right to select a channel, a channel with a broadcast is found, and the direction is adjusted in the channel selection state. There is no, and the antenna direction can be set without exception unless there is no broadcast on all channels.

Further, when the antenna direction is adjusted by detecting the reception level as in the above example, the noise level in the channel other than the broadcast channel is detected, and the offset value for eliminating the influence of the cable length or the like is detected in advance. ,
If you calibrate the reception level with this, when setting the antenna direction, you can set the antenna direction so that you can obtain almost sufficient viewing conditions that are not affected by weather etc. at the time of setting.
It can be done easily.

Therefore, in the case of the above example, the user can easily adjust the antenna while watching the reception level display.

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

EFFECTS OF THE INVENTION According to the present invention, the antenna direction can be set without exception except when there is no broadcast on all broadcast channels, and the antenna direction setting time will not be unnecessarily lengthened due to erroneous channel selection or the like.

[Brief description of drawings]

FIG. 1 is a system diagram of an example of a satellite broadcast receiving system, FIG. 2 is a diagram for explaining satellite broadcast radio waves, and FIG. 3 is a system diagram of essential parts of an example of the present invention, FIGS. 4 and 5. Is a diagram for explaining it. (31) is a level detection circuit for detecting the level of the received signal, (33) is a microcomputer, (36) is a monitor receiver as an example of a display for displaying the received signal level and its peak value, (37) Is the screen.

Claims (1)

[Claims] 1. An indoor unit for receiving satellite broadcasting, comprising:
In an apparatus for detecting a received signal level before applying GC and adjusting the direction of an antenna, a means for prohibiting a channel selection by an adjuster in an antenna direction adjustment mode, and a means for finding a broadcast channel in the mode. A direction adjusting device for a satellite broadcast receiving antenna, which has means for fixing a channel selection when a certain channel of broadcasting is found, and the antenna direction adjustment is performed on the fixed channel.