JP2978175B2 - Direction control device for satellite signal receiving antenna - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a direction control device for a satellite signal receiving antenna.

[Prior Art] In recent years, satellite broadcasting and satellite communication using artificial satellites have been realized and have reached the level of practical use.
Since a z-band microwave is used, a dedicated antenna such as a parabolic antenna (hereinafter referred to as a receiving antenna) is required to receive a signal from an artificial satellite (hereinafter referred to as a satellite signal). In order to receive satellite signals efficiently, it is necessary to adjust the elevation angle and azimuth angle of the receiving antenna (hereinafter collectively referred to as receiving angle) to the direction of the satellite. In particular, in a moving body such as a ship or a train, the receiving angle of the receiving antenna shifts with the movement, so that the receiving angle must be constantly adjusted during the movement in order to receive the satellite signal satisfactorily.

Therefore, a reception angle control device that adjusts a reception angle of a reception antenna so as to obtain an optimal reception state has been developed. This type of control apparatus includes a receiving satellite based on an automatic gain signal output from an automatic gain adjustment circuit that automatically adjusts the gain of an intermediate frequency amplification circuit (hereinafter, referred to as an IF circuit) in a receiver that receives a satellite signal. There is a configuration in which a reception angle of a reception antenna is adjusted so that a signal level is maximized.

[Problems to be Solved by the Invention] However, in a state where it is difficult to distinguish between noise and satellite signals, such as when a ship or a train enters under a rain cloud or thundercloud, the above-described device has a maximum noise level. In some cases, the receiving angle may be adjusted, and satellite broadcasting cannot be received.

In order to solve this problem, a reception angle control device that adjusts the reception angle of the reception antenna so that the ratio (C / N ratio) between the signal level and the noise level in the output signal of the IF circuit is maximized has been proposed. ing.

However, in order to detect the C / N ratio, it is necessary to separate only the noise component from the output signal of the IF circuit through a band-pass filter that extracts noise outside the reception band. And the number of parts increases.

Therefore, an object of the present invention is to provide a satellite signal receiving antenna direction control apparatus capable of appropriately controlling the antenna receiving angle in accordance with a reception state.

[Means for Solving the Problems] That is, the gist of the present invention is, as exemplified in FIG. 1, a satellite signal reception for receiving a satellite signal transmitted from a satellite and including at least a pulse code modulation signal component. A direction control device for a satellite signal receiving antenna M1 for adjusting an elevation angle and an azimuth angle of a satellite signal receiving antenna M1, a satellite signal received by the satellite signal receiving antenna M1, And an automatic gain adjusting means M4 for automatically adjusting the gain, and an amplifying means for amplifying the intermediate frequency signal input from the tuning means M3 to a predetermined signal level. M5, based on the gain adjustment signal of the automatic gain adjustment means M4, the reception angle adjustment so that the signal level of the intermediate frequency signal input from the tuning means M3 to the amplification means M5 is maximized. A first antenna direction control means M6 for controlling the stage M2, and a code error signal representing a code error of the demodulated signal while demodulating a pulse code modulation signal component from the intermediate frequency signal amplified by the amplification means M5. Demodulation method to create
M7, a code error amount detecting means M8 for converting the created code error signal into a voltage signal representing a code error amount, and a code error amount minimizing based on an output from the code error amount detecting means M8. A second antenna direction control means M9 for controlling the reception angle adjusting means M2, based on the output from the code error amount detection means M8, determine whether the code error amount is a predetermined amount or more, the code When the error amount is less than a predetermined amount, the receiving angle adjusting unit M2 is controlled by the first antenna direction control unit M6, and when the code error amount is equal to or more than a predetermined amount, the second antenna direction control unit And a control switching means M10 for controlling the reception angle adjusting means M2 by M9. A direction control device for a satellite signal receiving antenna, comprising:

[Operation] According to the present invention, the tuning means M3 inputs the satellite signal received by the satellite signal receiving antenna M1, and converts the satellite signal into a predetermined intermediate frequency signal. Subsequently, the gain of the amplifying means M5 is automatically adjusted by the automatic gain adjusting means M4, and the tuning means M3 is selected.
To a predetermined signal level. Therefore, the demodulation means M7 demodulates the pulse code modulation signal component from the intermediate frequency signal amplified by the amplification means M5, and outputs the demodulated signal to, for example, a television receiver and creates a code error signal representing a code error of the demodulated signal. I do.

Then, the created code error signal is converted into a voltage signal indicating the code error amount by the code error amount detection means M8, and is output to the control switching means M10. Then, based on this signal, the control switching means M10 determines whether or not the amount of code error is equal to or more than a predetermined amount, and when the amount of code error is less than the predetermined amount, the control antenna M10 receives the signal by the first antenna direction control means M6. When the code error amount is equal to or more than the predetermined amount, the second antenna direction control unit M9 controls the reception angle adjustment unit M2.

For this reason, in the present invention, when the code error amount is less than the predetermined amount, the first antenna direction control unit M6 inputs from the channel selection unit M3 to the amplification unit M5 based on the gain adjustment signal of the automatic gain adjustment unit M4. The received angle adjusting means M2 is controlled so that the signal level of the intermediate frequency signal to be obtained is maximized, and when the amount of code error is equal to or more than a predetermined amount, the second antenna direction control means M9 is controlled by the code amount detecting means M8. Based on the output from the receiving angle adjusting means M2 so that the amount of code error is minimized.
And the satellite signal receiving antenna M1 is
It will always be adjusted to the optimal direction (elevation and azimuth).

That is, when the code error amount is equal to or more than the predetermined amount and the reception state is poor, the noise level of the intermediate frequency signal increases,
When the antenna direction control by the first antenna direction control unit M6 cannot be satisfactorily performed, and conversely, when the amount of code error is less than a predetermined amount and the reception state is good, the antenna by the second antenna direction control unit M9 is used. Than the direction control, the antenna direction control by the first antenna direction control means M6,
Since the antenna side can be controlled with high accuracy, in the present invention, the satellite signal receiving antenna M1 is always adjusted to the optimal direction by switching the control means used for controlling the antenna direction according to the amount of code error as described above. We are doing it.

Note that, when the reception state is good, the first antenna direction control means M6 can control the antenna direction with higher accuracy than the second antenna direction control means M9. This is because errors hardly occur, and the amount of code error hardly changes even if the antenna direction is slightly shifted from the artificial satellite.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing the configuration of the entire satellite broadcast receiving system to which the present invention is applied. This satellite broadcast receiving system is installed on a ship (not shown) or the like.

As shown in the drawing, the satellite broadcast receiving system 1 includes a receiving antenna unit 3, a receiver 5, a direction control unit 7, and a monitor television 9.

First, the receiving antenna unit 3 is a BS antenna (in this embodiment, an offset parabolic antenna is used).
The reception angle of the BS antenna 20 is adjusted (however, the elevation angle is adjusted by an elevation angle adjustment unit 26 described later, and the azimuth angle is adjusted by an azimuth angle adjustment unit 24 described later). Consists of

The BS antenna 20 collects a 12 GHz radio wave from a satellite at its focal point by a reflecting mirror 20a, receives the radio wave at a primary radiator 20b, and receives a first intermediate frequency signal (hereinafter, referred to as a first IF signal) of 1035 to 1335 MHz by a frequency converter 20c. And output to the receiver 5.

As shown in FIG. 3, the receiving angle adjusting mechanism 22 includes a motor.
The azimuth adjustment unit 24 and the motor MT that change the azimuth of the BS antenna 20 by rotating the antenna azimuth adjustment mechanism 20d by MT1
2 to move the antenna elevation adjustment mechanism 20e to the reflector 20a.
An elevation angle adjustment unit 26 that changes the elevation angle of the camera is constituted as a main part. The respective rotation direction switching units 28 and 30 are operated by a control signal from a direction control unit 7 described later, and the azimuth angle adjustment unit 24 and the elevation angle The operation and moving direction of the adjustment unit 26 are controlled.

When the control signal is not input to the terminals T1 and T2, the azimuth adjustment unit 24 is at rest because the contacts of the relays RL1 and RL2 are at the illustrated positions and the motor MT1 is stopped. When a control signal is input to the terminal T1, the relay coil L1 is energized, the contact of the relay RL1 is switched, the motor MT1 rotates forward, and the antenna azimuth adjustment mechanism 20d rotates clockwise.
On the other hand, when a control signal is input to the terminal T2, the relay coil
When L2 is energized, the contact of relay RL2 switches and motor M
T1 is reversed, and the antenna azimuth adjustment mechanism 20d rotates leftward. Similarly, when the control signal is input to the terminals T3 and T4 in the elevation angle adjustment unit 26, the contacts of the relays RL3 and RL4 are switched by the relay coils L3 and L4, and the motor MT2 rotates forward or reverse to rotate the antenna elevation angle adjustment mechanism 20e. Reciprocate.

Next, signal processing in the receiver 5 will be described with reference to FIG.

In the receiver 5, the high-frequency amplifier circuit 30 amplifies the first IF signal input from the frequency converter 20c of the BS antenna 20, and the tuning unit 32 including the mixer 34 and the variable transmission circuit 36
A desired television signal is converted from a 1IF signal into a second intermediate frequency signal of 400 MHz band (hereinafter, referred to as a second IF signal).

The converted second IF signal is amplified to a predetermined level by an intermediate frequency amplifier 40 whose gain is adjusted by an automatic gain adjustment circuit (hereinafter, simply referred to as an AGC circuit) 38. The intermediate frequency amplifying unit 40 includes a variable attenuator 41 and an intermediate frequency amplifying circuit 42, and the AGC circuit 38 includes a rectifying circuit 38a, a smoothing circuit 38b, and a DC amplifying circuit 38c, and outputs the amplified second IF signal. An automatic gain adjustment signal (hereinafter, simply referred to as an AGC signal) according to the level is output to the intermediate frequency amplifier 40. As shown in FIG. 5 (A), the AGC circuit 38 has such a characteristic that the higher the level of the second IF signal, the higher the level of the AGC signal. When the level of the AGC signal increases, the attenuation of the variable attenuator 41 increases, and the gain of the intermediate frequency amplifier 40 is reduced.

Subsequently, the amplified second IF signal is input to the FM demodulation circuit 44, where it is demodulated and separated and extracted into a composite video signal and a four-phase differential phase modulation signal (hereinafter, referred to as a four-phase DPSK signal). In the video signal processing block 46, the video filter 46
Only the video signal is extracted from the composite video signal through a and the clamp circuit 46b, amplified by the video amplifier circuit 46c, and output to the monitor television 9.

On the other hand, in the audio signal processing block 48, the 4-phase DPSK signal is input to the 4-phase DPSK demodulation circuit 48c through the band-pass filter 48a and the audio amplification circuit 48b, where the pulse code modulation audio signal (hereinafter referred to as PCM audio signal) ). Subsequently, the PCM audio signal is input to the PCM demodulation circuit 48d and demodulated into a digital audio signal.

The PCM demodulation circuit 48d demodulates the digital audio signal, detects an error using the transmitted error correction code (BCH code), and creates a code error signal. The code error signal is composed of a pulse signal of a number corresponding to the digital code error amount. The four-phase DPSK demodulation circuit 48c and the PCM demodulation circuit 48d are integrated into one IC (for example, TM421
8N, manufactured by Toshiba Corporation). In this embodiment, 4
The phase DPSK demodulation circuit 48c and the PCM demodulation circuit 48d correspond to the above-mentioned decoding means M7.

Finally, the digital audio signal is converted into an analog signal by the D / A converter 48e and output to the monitor television 9.

Next, as shown in FIG. 6, the direction control unit 7 is composed of a code error level detection circuit 50 as a code error amount detection means constituted mainly by a well-known integration circuit, and an electronic control circuit 60. ing.

The code error signal generated by the PCM demodulation circuit 48d is converted by the code error level detection circuit 50 into a voltage signal that is inversely proportional to the number of pulses (in other words, the amount of code error). Fig. 5 (B)
As shown in (1), this voltage signal (hereinafter, referred to as a code error level signal) has characteristics corresponding to the C / N ratio indicating the degree of reception quality. That is, the C / N ratio increases as the code error level signal increases, and decreases as the code error level signal decreases. Generally, in a good reception state (image quality evaluation value 4), a C / N ratio of 14 dB or more is required.
When the / N ratio is 9 dB or less (image quality evaluation value 2), the reception state deteriorates.

The above-mentioned code error level signal is input to the electronic control circuit 60.

The electronic control circuit 60 is configured as a logical operation circuit around the CPU 62, the ROM 64, and the RAM 66, and includes a code error level detection circuit 50.
A / D converter 68 converts the bit error level signal output from
And the AGC signal from the AGC circuit 38 is input from the input / output port 72 via the A / D converter 70.

The input / output port 72 receives latitude and longitude data from a gyrocompass (not shown) installed on the ship, and the input / output port 72 outputs a control signal to the reception angle adjustment mechanism 22.

In the direction control unit 7 configured as described above, the antenna direction control processing is repeatedly executed according to the reception state of the satellite signal.

As shown in FIG. 7, in this antenna direction control process, first, step 100 is executed, and based on the latitude and longitude data input from the gyro compass, a reference azimuth and a reference elevation angle are set using a preset data map. Is calculated. In step 110, a control signal is output to the reception angle adjusting mechanism 22 so that the BS antenna 20 is located at the reference azimuth and reference elevation, and the BS antenna 20 is moved so as to face the reference azimuth and reference elevation. Then, in step 120, code error level signal data (hereinafter simply referred to as error level) is read, and the process proceeds to step 130. In step 130, the read error level is set to a first predetermined value (for example, C /
Whether the reception state is good or not is determined based on whether the voltage is equal to or more than a voltage value corresponding to the N ratio of 9 dB). When the error level is smaller than the predetermined value, it is determined that the reception state is bad, and the process proceeds to step 150,
When the error level is equal to or higher than the first predetermined value, it is determined that the reception state is good, and the process proceeds to step 140. In step 140, AGC signal data is set as level data, and step 1
Go to 70.

On the other hand, when the process proceeds to step 150, it is determined whether or not the error level is equal to or more than a second predetermined value (for example, a voltage value corresponding to a C / N ratio of 4 dB) smaller than the first predetermined value. If it is determined that the error level is smaller than the second predetermined value, the process is temporarily terminated. In other words, the reception condition is extremely poor,
Even if the elevation angle and the azimuth angle of the BS antenna 20 are changed, no improvement in the reception state is expected, so the BS antenna 20 is kept at the current position moved in step 100 or steps 170 and 190 described later. When the error level is equal to or higher than the second predetermined value, the process proceeds to step 160. In step 160, the error level is set as the level data, and the process proceeds to step 170.
In the present embodiment, a series of processing from step 130 to step 160 corresponds to the control switching unit M10 described above.

In step 170, an azimuth adjustment routine for adjusting the azimuth of the BS antenna 20 is executed so that the read level data becomes maximum.

That is, as shown in FIG.
Then, the value 0 is set in the counter CNT, the current elevation and azimuth data of the BS antenna 20 are stored in a predetermined area of the RAM 66 in step 172, and the flow advances to step 173. In step 173, the level data set in step 140 or step 160
RD (n) (n is the value of the counter CNT) is read, and the level data RD (n) is stored in a predetermined area of the RAM 66. Next, at step 174, the receiving angle adjusting mechanism 2 is moved so that the BS antenna 20 is moved rightward by a predetermined angle (for example, 0.2 degrees).
The control signal is output to 2 to rotate the BS antenna 20 to the right by a predetermined angle.

Then, in step 175, the counter CNT is incremented. In step 176, it is determined whether or not the value of the counter CNT exceeds the value 5. When the value of the counter CNT is 5 or less, the process returns to Step 173, and Steps 173 to 173 are performed.
The process of 175 is repeatedly executed, and when the value of the counter CNT reaches 6, the process proceeds to step 177.

In step 177, the position of the BS antenna 20 is
The control signal is output to the reception angle adjusting mechanism 22 so as to return to the initial position stored in the step (1). Subsequently, at step 178, -1 is set to the counter CNT, and then at step 179, a control signal is output to the reception angle adjusting mechanism 22 so that the BS antenna 20 moves to the left by a predetermined angle (for example, 0.2 degrees). And BS
The antenna 20 is moved leftward by a predetermined angle. Then, in step 180, the level data RD (n) is read, and the level data is stored in a predetermined area of the RAM.

In step 181, the counter CNT is decremented,
In the following step 182, it is determined whether or not the value of the counter CNT is smaller than -5. When the value of the counter CNT is equal to or more than -5, the process returns to step 179 and returns to steps 180 and 18.
The process of 1 is repeated, and when the value of the counter CNT becomes -6, the process proceeds to step 183.

In step 183, the read level data RD (0),
RD (1), RD (2), RD (3), RD (4), RD (5), RD
(-1), RD (-2), RD (-3), RD (-4), RD (-
The largest one among 5) is searched, and a control signal is output to the reception angle adjusting mechanism 22 so that the BS antenna 20 moves to the position of the BS antenna 20 in the maximum state.

Thus, in the azimuth adjustment routine of step 170, B
The azimuth of the S antenna 20 initially moves rightward by a predetermined angle five times, then returns to the original azimuth, moves leftward five times by a predetermined angle, and then the level data read at each moving position Are compared, and the BS antenna 20 is moved to the position of the highest level.

Next, when the azimuth of the BS antenna 20 is adjusted by the process of step 170, the process proceeds to step 190. step 1
In 90, the BS antenna 20 is used to maximize the level data.
Execute the elevation angle adjustment routine for adjusting the elevation angle of the camera.

That is, as shown in FIG. 9, similarly to the azimuth angle adjustment routine, the elevation angle of the BS antenna 20 is first moved up five times by a predetermined angle in a series of steps 191 to 202, and then the initial After returning to the elevation angle, the camera is moved downward by a predetermined angle five times, and the level data is read at each movement position. Then, in subsequent steps 203 and 204, the level data read at the respective movement positions are compared, and the BS antenna 20 is moved to the position having the highest level.

Then, when the elevation angle of the BS antenna 20 is adjusted in the elevation angle adjustment routine in step 190, the process returns to step 120 again, and the subsequent processing is repeatedly executed.

As described above, in the satellite broadcast receiving system 1 of the present embodiment, when the noise is relatively small and the receiving state is good, the BS antenna 20 is moved to the receiving angle where the level of the AGC signal is maximum, and the comparison is made. When the reception condition is poor due to a large amount of noise, the BS antenna 20 is moved to the reception angle at which the C / N ratio is maximized.
The BS antenna 20 can be controlled.

Conventionally, to detect the C / N ratio, the device configuration became complicated and the number of parts increased, but in this embodiment, the PCM
Since the code error signal generated by the demodulation circuit 48d is used, the C / N ratio can be detected with a simple circuit configuration (that is, an integration circuit).

In the above embodiment, the azimuth angle and the elevation angle are adjusted by moving the BS antenna 20 five times in the left and right or up and down directions, and moving the BS antenna 20 to the position where the reception state is best at each position. But
It may be moved three times at a time. Also, each time the BS antenna 20 is moved, the previous reception state is compared with the reception state after the movement, and if the reception state is improved, the BS antenna 20 is moved again based on the position after the movement, and the procedure is as follows.
The azimuth and the elevation may be adjusted while gradually moving the BS antenna 20.

Further, in the above embodiment, a satellite broadcast receiving system using a broadcast satellite has been described, but it goes without saying that the present invention can be applied to a satellite communication receiving system using a communication satellite.

[Effects of the Invention] As described above, according to the present invention, when the code error amount is less than the predetermined amount and the reception state is good, the elevation angle and the azimuth at which the signal level of the intermediate frequency signal is maximized based on the gain adjustment signal. The satellite signal receiving antenna is controlled at a corner, and when the amount of code error is equal to or more than a predetermined amount and the reception state is poor, the satellite signal receiving antenna is controlled at an elevation angle and an azimuth at which the amount of code error is minimized. Therefore, according to the present invention, it is possible to always control the satellite signal receiving antenna in an optimal direction according to the reception state at that time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating the present invention, FIG. 2 is a schematic configuration diagram showing the entire configuration of a satellite broadcast receiving system of an embodiment, FIG. 3 is a schematic configuration diagram of a reception angle adjusting mechanism, and FIG. FIG. 5 (A) is a graph showing a relationship between an input signal and an AGC signal, FIG. 5 (B) is a graph showing a relationship between a code error level signal and a C / N ratio, and FIG. FIG. 7 is a block diagram of a direction control unit, FIG. 7 is a flowchart showing an antenna direction control process executed by the direction control unit, FIG. 8 is a flowchart showing an azimuth adjustment routine, and FIG. 9 is a flowchart showing an elevation angle adjustment routine. It is. M1,20: Satellite signal receiving antenna M2: Receiving angle adjusting means (22: Receiving angle adjusting mechanism) M3: Tuning means (32: Tuning unit) M4: Automatic gain adjusting means (38: AGC circuit) M5: amplifying means (40: intermediate frequency amplifying unit) M6: first antenna direction control means M7: demodulating means (48c: 4-phase DPSK demodulation circuit, 48d: PCM demodulation circuit) M8: code error detection Means (50: Code error level detection circuit) M9: Second antenna direction control means M10: Control switching means 60: Electronic control circuit

Claims (1)

(57) [Claims] A direction control device for a satellite signal receiving antenna for receiving a satellite signal transmitted from a satellite and including at least a pulse code modulation signal component, wherein the direction control device controls an elevation angle and an azimuth angle of the satellite signal receiving antenna. Angle adjusting means, a channel selecting means for inputting a satellite signal received by the satellite signal receiving antenna and converting the satellite signal into a predetermined intermediate frequency signal, and an automatic gain adjusting means for automatically adjusting a gain, Amplifying means for amplifying the intermediate frequency signal input from the tuning means to a predetermined signal level, based on a gain adjustment signal of the automatic gain adjusting means, First antenna direction control means for controlling the reception angle adjustment means so that the signal level is maximized; and a pulse signal based on the intermediate frequency signal amplified by the amplification means. Demodulation means for demodulating a code modulation signal component and generating a code error signal representing a code error of the demodulated signal; and detecting a code error amount for converting the generated code error signal into a voltage signal representing the code error amount. Means, a second antenna direction control means for controlling the reception angle adjusting means so as to minimize the code error amount based on an output from the code error amount detection means, and an output from the code error amount detection means. Based on the, it is determined whether the code error amount is equal to or more than a predetermined amount, when the code error amount is less than a predetermined amount, the first antenna direction control means to control the reception angle adjusting means, the code Control switching means for controlling the reception angle adjusting means by the second antenna direction control means when the error amount is equal to or more than a predetermined amount, the satellite comprising: Direction control device of Patent receiving antenna.