JPS6351704A - Orientation device for satellite broadcast receiving antenna - Google Patents

Abstract

PURPOSE:To perform the adjustment of an antenna when a signal receiving level is low, by using the lower limit value of the dynamic range of an AGC as a calibration value, when an AGC voltage lovers below the lower limit value, at time of detecting a noise level. CONSTITUTION:When the adjustment of an antenna direction is performed by the detection of a receiving level, the noise level of a channel, that is not a broadcasting channel, is detected, and an offset value to eliminate the influence of a cable length, etc., is detected and stored in advance, and the receiving level is calibrated by the above value. Therefore, it is possible to surely and easily set antenna direction possible to obtain a satisfactory audio visual condition without being affected by a weather at time of setting, when the antenna direction is set. Also, when the receiving level is low, and an offset voltage is below the lover limit value of the dynamic range of an AGC characteristic, the lower limit value is used as the offset voltage. In this way, it is possible to well perform the adjustment of the antenna even when the receiving level is low.

Description

[Detailed description of the invention] The invention will be explained in the following order.

A. Field of industrial application B. J Existing requirements of the invention Fig. 1) Explanation of the setting of G2 lower limit value Am1n (Fig. 3) Explanation of G3 antenna sub-alignment mode (Fig. 4) Regarding equipment.

B. Summary of the Invention This invention provides a system for selecting a channel that is not being broadcast and adjusting its reception output when detecting the received signal level from its AGC voltage and adjusting the antenna direction in an indoor unit for receiving satellite broadcasting. Is the noise level obtained based on the AGC at that time? In a device that detects from the ti pressure and uses this noise level to calibrate the received signal level and adjust the antenna direction, when the noise level is detected, the AGC voltage is
When the value is below the lower limit of the GC dynamic range,
Instead of using the AGC voltage as a calibration value, the lower limit of the dynamic range is used as a calibration value, making it possible to adjust the antenna when the signal reception level is low.

C. Prior Art Satellite broadcasting is known in which television broadcasting is carried out using artificial satellites in geostationary orbit.

This satellite broadcast radio wave is an SHF band radio wave of about 12 Gllz, for example, in which the TV signal is converted into an FM signal.

FIG. 5 shows an example of a receiving system for this SHF satellite television broadcast wave.

Here, the transmitted SHF signal is as follows. That is, a television audio signal is converted into a PCM signal, and this PCM audio data is divided into blocks for every predetermined time, an error correction code is formed and added, and then this PCM signal is converted into a PCM signal with 5.73 MHz as a subcarrier frequency. is subjected to four-phase phase shifting to produce a signal that occupies the high frequency side of the analog video signal as shown in FIG. 6, and this modulated PCM signal and the analog video signal are combined,
The composite signal is FM-transformed and SH of about 12 GIIz
It was made into an F signal.

This SHF broadcast wave is received by the receiving parabolic antenna (11) of the receiving system shown in FIG.
The SHF band signal received at 1 is converted into a first intermediate frequency 1η in the outdoor unit (2) and frequency-converted to a UHF band signal of about 1 GHz, for example.

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 tuning signal from the tuning circuit (12) in response to the viewer's tuning operation, and from this tuner (11), the broadcast wave (
(UHF signal) is converted into a second intermediate frequency signal. This second intermediate frequency signal is passed through a bandpass filter (13)
is supplied to the second intermediate frequency amplifier (14) via. The output of this amplifier (14) is the AGC voltage detection circuit (15)
is supplied to the amplifier (1) to form an AGC voltage.
4), and AGC is applied so that the output of this amplifier (14) becomes constant.

Is the output of this second intermediate frequency amplifier (14) FM? ! The signal is rMiH modulated in a field circuit (16), and its 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 the audio subcarrier component, which is supplied to a 4-phase demodulation circuit (22) to demodulate the audio PCM signal. Digital decoder (23)
supplied to In this decoder (23), correctable errors in the PCM signal are corrected using an error correction code, and then the PCM signal is restored to its original time series 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).

In addition, this audio signal and the video signal from the video amplifier (17) are supplied to the AM conversion circuit 19), which modulates them into television broadcast waves of a specific open channel of VHF television broadcasting. A signal is obtained, which is routed to the state power terminal (20).

Therefore, if the signal obtained from this output terminal (20) is supplied to the antenna terminal of a television receiver that is popular in ordinary households, satellite television broadcasting can be viewed on a specific open channel of this receiver. Become.

By the way, in this satellite broadcasting receiving system, the direction of the receiving parabolic antenna (1) must be adjusted so that it correctly faces the direction of the artificial satellite.

In this case, the adjustment method can be done precisely by a contractor when installing the antenna, or simply by the user.
A common method is to measure the received signal level. In other words, the user selects the channel that is likely to be broadcasting on the indoor unit at the time of the antenna national adjustment, and measures the received signal level using a measuring device in the case of a vendor. In this case, for example, the optimum azimuth and elevation angles of the antenna are found by making adjustments while looking at a level meter.

By the way, with satellite broadcasting, the reception level 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 to watch even in the worst conditions. This is considered to be suggested. In this case, the lowest level value given is an absolute value that ignores features such as the length of the cable. However, the actual received signal level is affected by differences in the length of the cable (3) that leads the signal from the outdoor unit to the indoor unit when each receiving device is installed. Therefore, if you measure the received signal level when adjusting the antenna, it will include the offset due to the difference in the length of this cable (3), and the measured value will be higher than the minimum allowable level, but in reality There is a possibility that it is below that level.

Therefore, the applicant previously proposed a method that automatically removes the offset caused by the influence of the cable length, etc., to ensure the setting of the optimum antenna direction (Japanese Patent Application No. 59-108123 s- reference).

In this future invention, first, select a channel that is not broadcasting, detect the offset m pressure for the received signal level from the noise level obtained in the received output, convert this offset pressure into a digital signal, and store it in memory. Then, the system selects a broadcasting channel, calibrates the received signal level on the broadcasting channel using the offset voltage read from the memory, and adjusts the direction of the antenna based on this. This is a method for adjusting the direction of a fyl broadcast receiving antenna, in which the offset is automatically removed when the antenna is adjusted, and the received signal level is calibrated.

D Problems to be solved by the invention By the way, detection of the received signal level and noise level is
When a user performs this simply using a satellite broadcast receiving device, the fact that the AGC voltage from the AGC voltage detection circuit (15) corresponds to these levels is utilized.

This AGC voltage has a polygonal characteristic as shown in FIG. 7, and the range of the linear part is the dynamic range of the AGC. The calibration of the received signal level using the noise level described above can be explained as follows. In other words, the signal level is considered to be the sum of the noise level and the pure signal component, and as shown in FIG. 7, the difference d between the AGC voltage A1 corresponding to the signal level and the AGC voltage A2 corresponding to the noise level is
becomes a pure signal component, and if the antenna reception signal level is obtained from this difference d, then the accurate antenna tl? In other words, it is possible to perform II adjustment. However, since the value of this difference d is small, the antenna reception signal level is obtained after being amplified by a DC amplifier.

However, due to reasons such as the small diameter of the receiving parabolic antenna, the antenna input signal level is small, resulting in a level like A i' in Figure 7, and the noise level is lower than the dynamic range as shown by level A7 in the figure. There are cases where it becomes lower than the lower limit Am1n.

In such a case, as is clear from the figure, the slope of the AGCfi pressure outside the dynamic range is very large, and due to the relationship with the gain of the DC amplifier for amplifying the difference value mentioned above, the antenna reception The disadvantage is that the signal level becomes saturated and ζ, making it impossible to measure the level accurately.

This invention aims to improve this drawback.

E. Steps to Solve the Problem In this invention, a storage means is provided for storing the lower limit value Awin of the dynamic range of the AGC voltage, and when detecting the noise level, the AGC'di pressure at that time is set to the lower limit value Awin. A
When it is smaller than m1n-, this limit value Am1n is used as an offset voltage for calibrating the signal level.

F Working antenna reception level is low (AG corresponding to noise level
When the C voltage is out of the dynamic range, the signal level is calibrated using the lower limit value A win, so when it is amplified by the DC amplifier, it will not reach the saturation level, and the signal level will be adjusted to the lower antenna reception level. A corresponding value can be obtained.

G Embodiment G Description of block diagram of essential parts of embodiment G FIG. 1 shows the configuration of essential parts of an embodiment of the present invention. In this example, as shown in the figure, AGC is applied to the received signal in the indoor unit (10);
The output of the C voltage detection circuit (15) corresponds to the received signal level.

The AGC voltage from this AGC voltage detection circuit (15) is used for offset removal and as an operational amplifier (3) as a DC amplifier.
1). This operational amplifier (3
The other input terminal of 1) is supplied with an offset voltage obtained as described below. Therefore, this operational amplifier (3
From 1), a signal corresponding to the received signal level is obtained by removing the offset due to the influence of cable length, etc., and this is converted to a digital signal by the A/D converter (32) and sent to the microcomputer (35). supplied to

A start tom end switch (34) in antenna adjustment mode is connected to this microcomputer (35). This switch (34) is, for example, a push-button switch, and is controlled by the microcomputer (35) so that it repeats the start and end of the antenna adjustment mode every time it is pressed.

The calibrated antenna reception level is then supplied to the monitor (38) via the character generator (36) and the switch circuit (37), and as described later, the monitor (38)
38) is displayed on the screen as shown in Figure 2.

The switch circuit (37) is a microcomputer (35)
In the antenna adjustment mode, the control signal is switched to the character generator (36) side, and in the normal mode, it is switched to the video and audio system (100) side.

(39) is the lower limit A of the AGC voltage dynamic range.
This is a non-volatile memory for storing l1in, and is connected to the microcomputer (35).

Although not shown, a channel selection key is connected to a microcomputer (35 channels), and when a channel selection operation is performed,
The channel selection signal is supplied to the channel selection circuit (12) so that the selected channel is received and selected.

Description of setting the G2 lower limit value A min Prior to the antenna adjustment mode, the lower limit value A sin is set. FIG. 3 is a flow chart thereof.

When setting this lower limit value, first, the indoor unit (1
Set the input level of 0) to -65dB+w.

For example, if the outdoor unit is separated from the indoor unit (10), the human power of the tuner (11) is 65 dB.
The input signals of m may be supplied by the state regulator.

In this state, for example, the microcomputer (35)
When the key connected to is pressed, the lower limit value setting mode starts (step (201)).

Then, the indoor unit (10) performs a receiving operation,
The AGC@ pressure at this time, that is, the lower limit value Am1n is obtained from the AGC voltage detection circuit (15) (step (20)
2) ), this lower limit value All1in is the amplifier (31
) is supplied to the A/D converter (32) and converted into a digital signal, which is then sent to the microcomputer (35).
is man-powered. Then, the digital value of this lower limit value Am1n is written into the nonvolatile memory (39) by the microcomputer (35) (step (203)).
When the above steps are completed, this mode ends (step (204)).

Description of G3 antenna 11m mode Next, a flowchart of the antenna adjustment mode based on the operation of the switch (34) is shown in FIG.

First, when the switch (34) is pressed, the antenna adjustment mode starts (step (101)).

In this antenna adjustment mode, even if the channel selection key is operated on the channel selection circuit (12), it is invalidated.

In other words, the tuner is prohibited from tuning (step (102)
)).

Next, the non-broadcast channels are set to the microcomputer (
0 artificial satellite lBs-2 tuned by the signal from 35)
Since two channels, channel 11 and channel 15, are broadcast channels, channel 16, for example, is selected (step (103)).

Therefore, the noise level will be detected in these 16 channels. This noise level varies depending on the length of the cable (3) in each household, etc., and is detected as an offset value.

That is, first, the contents of the built-in memory (35M) of the microcomputer (35) are reset, and the D/A
The output of the converter (33) is set to O(V) (step (104'l). Then, the AGC voltage ■N corresponding to the noise level in the 16 channels is obtained at the output of the operational amplifier (31). This is converted into a digital signal by the A/D converter (32), and this is corrupted into the RAM (35M) as the memory of the microcomputer (35) (step (105)).Next, the RAM
(Voltage VN written in 35M> and lower limit value A wi
Step (106)) When the voltage V is equal to or higher than the lower limit value Awin, the process proceeds to step (107), where the offset m of the output of the D/A converter (33) is set as the voltage VOFF from the RAM (35M). AGC voltage VN of
get. On the other hand, when the voltage vN is smaller than the lower limit value Awin, the process proceeds to step (108), and off-sef+1 voltage ■o
The lower limit value Am1n read from the nonvolatile memory (39) is obtained as an FF.

When this offset value is detected, the selection shifts to the channel where the broadcast is, for example, channel 15 (step (1)
09)), it is determined whether there is a broadcast on the 15 channels (step (110)).

Note that if there is a channel that was being received and viewed before entering the antenna adjustment mode, that channel (the last channel that was viewed) is selected.

At this 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, the switch (34) is operated and antenna 1! It is determined whether or not the mode is set to end (step (111)), and if an end command is issued, antenna 1! The illumination adjustment mode is canceled (step (118)), and the tuning circuit (12) returns to a state in which the current tuner can select a tune (step (119)).
, step (111) is necessary, for example, when no channel is broadcasting at that time.

If the antenna self-sustaining mode end command has not been issued, another broadcasting channel, for example channel 11, is selected (step (112)), and the presence or absence of broadcasting is determined in the same manner as described above.
111 will be separated. Once it is detected that there is a broadcast, the tuner (11) selection is fixed at the channel with the broadcast, and the direction of the antenna is changed so that the reception level is the same as when there is no broadcast. (step (113)).

Then, in the reception state of a certain channel of this broadcast, the direction of the antenna is changed and adjusted, and the AGCi pressure V^ corresponding to the reception level at that time is adjusted by the operational amplifier (31).
The detection output is sent to a microcomputer (
35) (step (114)), this voltage vA is calibrated by the aforementioned offset voltage VOFF to a value that is not affected by cable length, etc. (step (115)).

Then, in this antenna adjustment mode, the reception level is displayed on, for example, a monitor receiver instead of or superimposed on the reproduced video by the reception signal (step (
116)). Then, while looking at the displayed level, determine the direction of the antenna that will result in a minimum allowable level or higher. Once that direction is found, fix it in that direction, press the switch (34), and send the antenna adjustment end command to the micro combinator (35). ).

1'', that is, the switch (34) is pressed and it is determined whether or not the adjustment is at the end (step (117)), and if it is not at the end, steps (114) to [117
is repeated, and if the end is reached, the antenna adjustment monitor is canceled (step (1181)), and the channel selection circuit (12) returns to a state in which a normal user can select a channel (step (119)).

The antenna group adjustment method in this case is made simple and easy for the user as follows.

That is, the RAM (
35M) also stores the highest level value of the peak value of the received signal level. That is, when in antenna adjustment mode, the level detection output is monitored, the previously stored peak value is compared with the detection level value of the received signal level at that antenna direction, and the detection level value at that time is compared. is large, the stored contents are rewritten to the large detection level value, and the highest level value of the received signal level is stored in the RAM (35M).
It is intended to be stored in memory.

Then, this microcomputer (35) outputs this highest level value along with the detection output of the received signal level in the antenna direction, and these are supplied to the character generator (36), whose output is sent to the switch circuit ( 37) via the monitor receiver (&v!1 (38)
supplied to When adjusting the antenna, the output of the character generator (36) is supplied to the monitor receiver (38) in place of the video and audio signals of the receiving channel from the video and audio signal system (100). A level display as shown in FIG. 2 is displayed on the display screen (39). Zunawara, the screen (
39), the reception level is displayed as a bar graph. In this case, the shaded area in Figure 2 is bright (the part that lights up; 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. The reception level at that time is displayed on the left side of both sides, 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 angle of the receiving antenna are set. From this position, for example, by changing the azimuth, the peak value at the azimuth where the strongest radio waves were received is stored and displayed on the display screen (40). Find the azimuth angle where the input level matches the peak value by going back in the opposite direction so that the input level matches the peak value.

Once that position is found, at that azimuth angle, change the elevation angle and calculate the elevation angle that reaches the peak value on the screen (4).
Find it while looking at 0). 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 process, 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 adjuster finds the channel with the broadcast, and the direction is self-sufficient in that channel selection state, so there is no broadcast on all channels. You can always set the antenna direction except when

When adjusting the antenna direction by detecting the reception level as described above, the noise level in a channel other than the broadcast channel is detected and the effect of cable length etc. is detected. Detect and store the offset value for removing I in advance,
By calibrating the reception level with this,
When setting the antenna direction, it is possible to reliably and easily set the antenna direction that provides almost sufficient viewing conditions that are not affected by the weather or the like at the time of setting.

Furthermore, when the receiving level is low and the offset voltage is lower than the lower limit of the dynamic range of the AGC characteristic, by using the lower limit as the offset voltage, the antenna can be properly aligned even when the receiving level is low.

In addition, in the above example, the antenna adjustment can also be made by the user while receiving and watching the bell display. Furthermore, in this case, the offset voltage is automatically obtained according to processing by the microcomputer, and the received signal level is automatically calibrated when adjusting the antenna direction.

In addition, in the above example, the reception level is displayed on the monitor reception@! Alternatively, a separate display device may be provided.

H Effects of the Invention According to this invention, the received signal level is detected by detecting the AGC voltage at the intermediate frequency stage of the indoor unit of the satellite broadcasting receiver, and the noise level is also detected, thereby determining the received signal level. When calibrating and accurately adjusting the antenna direction, it is possible to prevent saturation of the measured value of the reception level even when the noise level is below the limit value of the AGC dynamic range, allowing for good antenna adjustment. It can be done.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an example of the essential parts of the device of this invention;
Figure 1 shows an example of a monitor display, Figures 1, 3 and 4 are flowcharts for explaining antenna adjustment operations, Figure 5 is a system diagram of an example of a satellite broadcast receiving system, and Figure 6 shows satellite broadcast radio waves. A diagram for explanation, FIG. 7, is an AGC characteristic diagram. (10) is an indoor unit, (15) is an AGC voltage detection circuit, (35) is a microcomputer, and (39) is a nonvolatile memory.

Claims (1)

[Claims] When adjusting the antenna direction by detecting the received signal level from the AGC voltage in an indoor unit for satellite broadcast reception, the noise obtained in the received output when a channel with no broadcast is selected. The apparatus detects the noise level from the AGC voltage at that time, calibrates the received signal level using the noise level, and uses the noise level to adjust the antenna direction, further comprising means for storing a lower limit value of the dynamic range of the AGC voltage. , when detecting the noise level, if the AGC voltage at that time is below the lower limit of the dynamic range, the lower limit value from the storage means is used as the noise level for the calibration; Orientation device.