JP2708938B2 - Automatic tracking antenna system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic tracking antenna system for receiving radio waves from broadcast satellites and communication satellites.

[Related Art] Recently, a receiving system for receiving a radio wave from a broadcasting satellite or a communication satellite is used in a moving object such as a train or an automobile. In this case, a general receiving antenna mounted on the moving object is used. Has a narrow band with a half value width of 1 to 2 degrees of directivity, so that it is necessary to control the receiving direction so as to always face the satellite. Conventionally, this type of automatic tracking antenna system for receiving radio waves from a broadcasting satellite or a communication satellite includes a receiving antenna mounted on a mobile object and receiving a radio wave from a broadcasting satellite or a communication satellite, and a receiving antenna for receiving the radio wave from the receiving antenna. A tracking control means for automatically controlling the direction to always face the satellite. The tracking control means includes an azimuth sensor control mode for controlling the direction of the receiving antenna based on the azimuth output sensor, and a tracking sensor output mode. And a tracking control mode for controlling the direction of the receiving antenna on the basis of the following. First, as shown in FIG. 5, a rough satellite direction is detected in the azimuth sensor control mode. Swing the antenna left and right several degrees to detect the correct satellite direction in the tracking control mode and control the direction of the receiving antenna. The satellite was supposed to automatic tracking.

However, in the above-described conventional example, the same output signal is obtained when the receiving antenna accurately faces the satellite and the radio wave is normally received, and when the radio wave is interrupted for some reason. Even if the radio wave is cut off, the direction control of the receiving antenna is performed in the tracking control mode,
There is a problem that the relative position of the receiving antenna with respect to the moving object is fixed and the receiving antenna is directed in a direction irrelevant to the position of the satellite. In this case, the direction of the receiving antenna is completely different from the direction of the satellite even if the moving body escapes from the radio wave blocking area and enters the receivable area, so that the radio wave from the satellite cannot be received thereafter. there were. However,
It goes without saying that when the direction of the receiving antenna is substantially opposite to the satellite due to a change in the direction of the moving object and enters the controllable area in the tracking control mode, radio waves can be received. Also, if it is confirmed that the radio wave is not received by the receiving antenna, the radio wave can be received by exiting the tracking control mode and entering the azimuth sensor control mode.

Therefore, in order to solve the above-described problems of the conventional example, a method of determining whether or not the signal received by the receiving antenna is a satellite broadcast radio wave is considered. As a method of judging whether or not the signal passes, a band-pass filter 20 for passing only a satellite broadcast channel is provided, and a signal passing through the band-pass filter is detected by a diode 21 as shown in FIG. As shown in FIG. 6 (b), a method for detecting the detection signal level,
From the intermediate frequency stage (bandpass filter 23 and intermediate frequency amplifier 24) to high frequency amplifier 22 with gain control
A method of monitoring the level of the gain adjustment signal Vg fed back via 25 is conceivable.

[Problems to be Solved by the Invention] However, in the conventional example shown in FIG. 6 (a), even when satellite broadcasting is cut off, there are unnecessary waves due to noise or the like in the signal band of satellite broadcasting radio waves, There has been a problem that thermal noise when the antenna 1 is directed toward the sun is judged as a satellite broadcast wave and malfunctions.

In the conventional example shown in FIG. 6 (b), if the time constant is set relatively large so as to prevent the gain control from successively changing in response to a fast signal level change, it is determined whether or not the satellite broadcast radio wave is cut off. It takes a long time to
There is a problem that it takes time to resupplement the broadcasting satellite.

The present invention has been made in view of the above points, and its object is to prevent unnecessary operation in a signal band and malfunction due to thermal noise of the sun, and furthermore, to cut off satellite broadcast radio waves. An object of the present invention is to provide an automatic tracking antenna system that can quickly determine the presence / absence and can perform resupplement in a short time.

[Means for Solving the Problems] An automatic tracking antenna system according to the present invention includes a receiving antenna mounted on a mobile object for receiving radio waves from a broadcasting satellite or a communication satellite, and a receiving direction of the receiving antenna always set to a satellite. Tracking control means for automatically controlling to face each other,
The tracking control means is formed so as to have a direction sensor control mode for controlling the direction of the receiving antenna based on the direction sensor output and a tracking control mode for controlling the direction of the receiving antenna based on the tracking sensor output. After detecting the direction in the azimuth sensor control mode, in an automatic tracking antenna system in which the satellite is automatically tracked by detecting the accurate satellite direction in the tracking control mode, a signal received by the receiving antenna A synchronization detection circuit for detecting whether or not a synchronization signal is included; and a control mode changing means for changing a control mode according to whether or not the synchronization detection signal is output from the synchronization detection circuit. Synchronous detection by detecting the satellite direction in the direction sensor control mode when the It is obtained so as to direction control receiving antenna in issue tracking control mode at the time of output.

[Operation] The present invention is configured as described above, and includes a direction sensor control mode for controlling the direction of the receiving antenna based on the direction sensor output and a tracking control mode for controlling the direction of the receiving antenna based on the tracking sensor output. Automatic tracking in which a tracking control means is formed so as to have a first direction of a rough satellite detected in an azimuth sensor control mode, and then an accurate satellite direction is detected in a tracking control mode to automatically track a satellite. In an antenna system, a synchronization detection circuit that detects whether a signal received by a receiving antenna includes a predetermined synchronization signal, and a control mode is changed depending on whether a synchronization detection signal is output from the synchronization detection circuit. The control mode changing means and the tracking control means are provided, and the direction sensor control is performed when the synchronization detection signal is not output. The satellite direction is detected in the mode, and the direction of the receiving antenna is controlled in the tracking control mode when the synchronization detection signal is output, so that it is possible to reliably and quickly detect whether the radio wave from the satellite is being received. It does not malfunction due to unnecessary waves in the signal band or the thermal noise of the sun. Moreover, it is possible to quickly judge whether or not the radio wave from the satellite is interrupted, so that re-supplementation can be performed in a short time. I have.

[Embodiment] Fig. 1 shows an embodiment of the present invention. A reception signal of a reception antenna 1 mounted on a moving body 9 such as a train or an automobile and receiving radio waves from a broadcasting satellite or a communication satellite is converted by a converter. 2 and the first intermediate frequency (1.035
To 1.335 GHz) and input to a tuner module 8 for selecting a satellite broadcast channel. The signal of the first intermediate frequency is amplified by the amplifier 3 and then mixed with the oscillation output oscillated by the local oscillation circuit 4 by the mixing circuit 5 to obtain the second intermediate frequency (402.78 MHz or 134.26 MHz). Is converted. The signal of the second intermediate frequency is further amplified by the amplifier 6, and then band-limited by the band-pass filter 7 to remove unnecessary signals and noise outside a predetermined band (27 MHz). Each of the above circuits is connected to the moving body 9 via the fixed base 11.
It is mounted in a turntable 10 that is rotatably mounted on the
The satellite broadcast signal (1) selected by the tuner module 8
The channel signal) is sent from the turntable 10 to the mobile unit 9 via the fixed unit 11 as a signal of the second intermediate frequency.

On the side of the fixed base 11 receiving the signal of the second intermediate frequency, the signal is branched by the branch circuit 12, one of the branched signals is input to the monitor television 13 to receive the satellite broadcast, and the other Is input to the synchronization detection circuit 14 of the tracking control means (not shown) as a signal for tracking control.

By the way, the tracking control means for automatically controlling the receiving direction of the receiving antenna 1 to always face the satellite is based on the azimuth sensor control mode for controlling the direction of the receiving antenna 1 based on the azimuth sensor output and the tracking sensor output. It is formed so as to have a tracking control mode for controlling the direction of the receiving antenna 1, and first detects a rough satellite direction in the direction sensor control mode, and then detects an accurate satellite direction in the tracking control mode. The satellite is automatically tracked. Here, in the embodiment, a synchronization detection circuit for detecting whether a signal received by the receiving antenna 1 includes a predetermined synchronization signal or not.
14 and a control mode changing means (not shown) for changing a control mode according to whether or not a synchronization detection signal is output from the synchronization detection circuit 14 are provided in the tracking control means. The satellite direction is detected in the sensor control mode, and the direction of the receiving antenna 1 is controlled in the tracking control mode when the synchronization detection signal is output.

FIG. 2 shows the synchronization detection circuit 14. The signal of the second intermediate frequency, which is a frequency modulation signal having a maximum frequency shift of 27 MHz, is FM-detected by the FM detector 15, and the demodulated signal is converted to a video signal. While performing predetermined amplification in the amplifier 16,
The video signal and the audio signal are separated. Here, the demodulated signal has a maximum frequency component of 4.5 MHz, a video signal on which video pre-emphasis and an energy spread signal of 15 Hz are superimposed, and an audio signal subjected to 4-phase DPSK modulation with a subcarrier of 5.72727 MHz. In the video amplifier 16,
De-emphasis and removal of energy spread signals are performed on video signal components, and the output signal level is 1.0
Amplify to 0.2 Vpp (positive polarity and output impedance 75Ω). Synchronous extraction circuit to which this video signal is input
In 17, the presence / absence of a synchronization signal is detected, and a synchronization detection signal (“H”) is output when the synchronization signal is obtained.

Figure 3 is shows a concrete circuit example of the sync extraction circuit 17, the transistors Q ₁ to Q _3, is formed by the capacitor C ₁ -C ₃ and the resistor R ₁ to R _5, 4 (a the video signal component of the signal Va shown in), by erasing by utilizing the saturation of the transistor Q ₁ (negative polarity synchronizing signal is left due to the cut-off region), as shown in FIG. 4 (b) A signal Vc as shown in FIG. 4 (c) is formed by an integrating amplifier circuit comprising a resistor R ₂ , a capacitor C ₂ and a transistor Q ₂ , and a resistor R ₄ and a capacitor. A second integration circuit composed of C ₃ and transistor Q ₃ outputs a flat signal Vd as shown in FIG. 4 (d) in which the synchronization signal is completely complemented. Va to Vd are A to V in FIG. 3, respectively.
It is a signal voltage waveform of a point D.

Hereinafter, the operation of the embodiment will be described. Now, when the radio wave from the satellite is no longer received by the receiving antenna 1 whose direction is controlled in the tracking control mode, the synchronization detection signal is not output from the synchronization detection circuit 14 (the signal Vd is "L"). Immediately recognized that the interruption was,
Control of the direction sensor control mode is performed. In this case, even if an unnecessary wave exists in the signal band, no malfunction occurs unless a synchronization signal having substantially the same period is included. Needless to say, no malfunction occurs due to the thermal noise of the sun.

On the other hand, when a radio wave from a satellite is received by the receiving antenna 1, a synchronization detection signal is immediately output from the synchronization detection circuit 14 (the signal Vd is "H"). And the time required to recapture the satellite can be shortened.

[Effects of the Invention] The present invention is configured as described above, and has an azimuth sensor control mode for controlling the direction of the receiving antenna based on the output of the azimuth sensor, and tracking control for controlling the direction of the receiving antenna based on the tracking sensor output. A tracking control means is formed so as to have a mode, and after a rough satellite direction is first detected in the direction sensor control mode, an accurate satellite direction is detected in the tracking control mode to automatically track the satellite. In an automatic tracking antenna system, a synchronization detection circuit that detects whether a signal received by a reception antenna includes a predetermined synchronization signal, and a control mode that depends on whether a synchronization detection signal is output from the synchronization detection circuit. The tracking control means is provided with a control mode changing means for changing the direction, and when the synchronization detection signal is not output, the azimuth sensor is The satellite direction is detected in the satellite control mode, and the direction of the receiving antenna is controlled in the tracking control mode when the synchronization detection signal is output, so that it is possible to quickly and surely check whether a radio wave from the satellite is being received. It can be detected and does not malfunction due to unnecessary waves in the signal band or thermal noise of the sun. Moreover, it is possible to quickly determine whether or not the radio wave from the satellite is interrupted, and it is possible to recapture in a short time There is.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of one embodiment of the present invention, FIG. 2 is a block diagram of a main part of the above, FIG. 3 is a specific circuit diagram of a main part of the same, FIG. FIGS. 6 (a) and 6 (b) are main part block circuit diagrams of other conventional examples. 1 is a receiving antenna, 9 is a moving body, and 14 is a synchronization detecting circuit.

Claims (1)

(57) [Claims] 1. A receiving antenna mounted on a mobile body for receiving a radio wave from a broadcasting satellite or a communication satellite, and tracking control means for automatically controlling the receiving direction of the receiving antenna to always face the satellite. The tracking control means is formed so as to have a direction sensor control mode for controlling the direction of the receiving antenna based on the direction sensor output and a tracking control mode for controlling the direction of the receiving antenna based on the tracking sensor output. In the automatic tracking antenna system that detects the correct satellite direction in the direction sensor control mode and then detects the accurate satellite direction in the tracking control mode to automatically track the satellite, the signal received by the receiving antenna A synchronization detection circuit that detects whether a predetermined synchronization signal is included, and a synchronization detection from the synchronization detection circuit Control mode changing means for changing the control mode depending on whether or not the signal is output is provided in the tracking control means so that the satellite direction is detected in the azimuth sensor control mode when the synchronization detection signal is not output, and the output of the synchronization detection signal An automatic tracking antenna system, wherein the direction of a receiving antenna is sometimes controlled in a tracking control mode.