JPH04286425A - Antenna system - Google Patents

Abstract

PURPOSE:To prevent the generation of power loss in a down-converter by sending a signal bidirectionally and multiplexingly on a coaxial cable, supplying power, transmitting a control signal through the coaxial cable only and using the control signal as a frequency signal. CONSTITUTION:A plane antenna 1 capable of receiving a radio wave from plural satellites X with different polarization systems and a turner 2 are interconnected by one coaxial cable 3. A tuner 2 sends a control signal to the antenna 1 through the coaxial cable 3 in frequency multiplex. The control signal is used for the adjustment of a reception direction, the adjustment of a received polarized angle and the reception polarization system. Moreover, a reception signal of the antenna 1 is fed to the tuner 2 though the coaxial cable 3 to implement bindirectional signal transmission through the coaxial cable 3. Since the tuner 2 supplies the power to an LNB(low noise down- converter) 4, the generation of a power loss due to the control signal is not caused in the down-converter.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an antenna system for receiving satellite broadcasting or satellite communication, in which the receiving direction, receiving polarization angle, polarization method switching, etc. can be adjusted on the antenna side. .

0002

[Prior Art] Recently, satellite broadcasting using the SHF band (12 GHz) by a geostationary satellite in a geostationary orbit 36,000 km above the equator has been put into practical use, and radio waves not only from one satellite but also from multiple satellites have been put into practical use. Antenna systems capable of receiving radio waves are being developed mainly in the United States.

By the way, when receiving radio waves from a plurality of satellites as described above, each satellite has a different stationary position and a different polarization method of the radio waves. Note that, as the polarization method, a horizontal polarization method, a vertical polarization method, a right-handed circular polarization method, a left-handed circular polarization method, etc. are used. Therefore, in the case of the above antenna system, as shown in FIG. 8, the antenna 1 installed outdoors and the tuner 2 installed indoors are connected using a coaxial cable 3 and a multicore cable 15. A control signal for adjusting the receiving direction is sent to the antenna 1 side through the cable 15, and a motor (not shown) provided on the antenna 1 side is driven to adjust the receiving direction of radio waves. .

However, this system requires a cable 15 for transmitting control signals, making the wiring work troublesome. Therefore, in order to improve this point, there is a system in which a control signal for switching the receiving direction is transmitted through the coaxial cable 3. An antenna system as an example is shown in FIG. This antenna system is based on the European communications satellite Astra (AS).
Amstrad (AMS) receives radio waves from TRA)
It is called TRAD (trade name).

In the case of the communication satellite Astra, radio waves are transmitted from the satellite using horizontally polarized waves on odd-numbered channels and vertically polarized waves on even-numbered channels. Therefore, in the antenna system described above, when a desired channel is selected on the tuner 2 side, the reception polarization method of the antenna 1 is switched according to the selected channel. The control signal for switching the polarization method is a high/low voltage signal shown in FIG. 9(b), and this control signal is sent from the tuner 2 to the antenna 1 through the coaxial cable 3. Note that the antenna 1 is provided with a low noise down converter (hereinafter referred to as LNB) 4 that lowers the frequency of the received signal to, for example, 1 GHz, and the above control signal is given to the LNB 4.
At step 4, the polarization method is switched.

[0006]

[Problems to be Solved by the Invention] However, with this method of sending a voltage signal from the tuner 2 to the LNB 4, when the control signal is at a high level, an unnecessary Voltage is supplied, and the amount of this control signal becomes a power loss, which increases the amount of heat generated. For this reason, the temperature of the HEMT used as a microwave amplification element in this type of LNB 4 increases, which has the drawback of deteriorating the NF (noise figure), which is an important characteristic for this type of amplification element.

The present invention has been made in view of the above-mentioned points, and its object is to reduce the number of cables to be wired between the antenna and the tuner to one, and to control the electric power on the antenna side using a control signal. An object of the present invention is to provide an antenna system that does not cause loss.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention connects an antenna equipped with a down converter for lowering the reception frequency and a tuner with a coaxial cable, and transmits a reception signal from the antenna through the coaxial cable. In addition to sending the signal to the tuner, power for the down converter is supplied from the tuner side, and a control signal for controlling the operation of the antenna side is sent from the tuner by frequency multiplex transmission.

[0009]

[Operation] By configuring the present invention as described above,
By transmitting signals in both directions and multiplexing on a coaxial cable, as well as supplying power and making it possible to transmit control signals using only the coaxial cable, and converting the control signal into a frequency signal, the power loss due to the control signal is reduced by down converter. This is to prevent this from occurring.

0010

[Example] As shown in Fig. 1, the antenna system of this example uses one coaxial cable between a flat antenna 1 that can receive radio waves from a plurality of satellites X with different polarization systems and a tuner 2. A control signal is sent from the tuner 2 to the antenna 1 by frequency multiplexing through the coaxial cable 3, and the control signal is used to adjust the receiving direction, adjust the receiving polarization angle, and switch the receiving polarization method. In this embodiment, the received signal of the antenna 1 is sent to the tuner 1 through the coaxial cable 3, the signal is transmitted bidirectionally through the coaxial cable 3, and power is supplied from the tuner 2 to the LNB 4. Further, the tuner 2 can perform channel switching and the like using a remote control device 16.

FIG. 2 shows the circuit on the tuner 2 side, which includes a receiving system that receives signals received by the antenna 1 through the coaxial cable 3, and an LNB 4 provided on the antenna 1 side.
The oscillator circuit 5 includes a power supply system that supplies power to the oscillator circuit, and a plurality of oscillation circuits 5 that generate signals of various frequencies corresponding to the various control signals described above. Here, the frequency for the control signal is an audio band frequency in order to improve transmission efficiency and facilitate identification.

FIG. 3 shows the circuit on the antenna 1 side.
LNB lowers the frequency of the signal received by antenna 1
4, a power supply circuit 6 that creates power for each circuit on the antenna 1 side from the voltage supplied from the tuner 2 side via the coaxial cable 3, and the output of an amplifier 8 that amplifies the signal supplied via the coaxial cable 3. It is composed of a plurality of detection circuits 7 for detecting various control signals from. Here, the detection circuit 7 includes a filter 7a that extracts a frequency component corresponding to each control signal, and a Schmitt circuit 7b that amplifies the signal extracted by the filter 7a, shapes the rectified and smoothed output, and outputs the waveform. There is.

FIG. 4 shows a specific configuration in which the planar antenna 1 has the function of switching the polarization method. In this case, the output when horizontally polarized waves are received by the planar antenna 1 and the output when vertically polarized waves are received can be inputted to the LNB 4 selectively, and the above switching is performed using the relay Ry1. . For this antenna system,
When a control signal for polarization switching is sent from the tuner 2 to the antenna 1 side, the detection circuit 7 detects the control signal and switches the polarization method by driving the relay Ry1 with this detection output. .

FIG. 5 shows a specific configuration of the detection circuit 7, in which the filter 7a is configured as a twin T type active filter using an operational amplifier, and the amplifier 8 and Schmitt circuit 7b are configured using operational amplifiers. . FIG. 6 shows the main structure of an antenna system capable of receiving radio waves from a plurality of satellites X, in which the direction of the antenna 1 is switched by a motor 9. In the case of this antenna system, when a control signal from the tuner 2 side is detected by the detection circuit 7, the relays Ry2 and Ry3 are selectively driven according to the output of the detection circuit 7. In this case, one relay Ry2 controls the supply of power to the motor 9, and the relay Ry3 switches the motor 9 to rotate in forward and reverse directions. Here, depending on the driving time of relay Ry2 that switches the power supply state, antenna 1
control the rotation angle of

Incidentally, in the above case, the oscillation circuit 5 was provided on the tuner 2 side for sending out the control signal, and the detection circuit 7 was provided on the antenna 1 side for detecting the control signal. As shown, the oscillation circuit 5 and the detection circuit 7 may each be constructed using ICs. Here, FIG. 7 shows a case where an IC used in a DTMF touch-tone telephone system is used. The IC 10 receives input from the matrix key 11 and outputs signals with frequencies corresponding to various control signals, such as Sharp's LR.
4087 is used. In addition, for inputting the switching signal of this LR 4087, a control circuit 12 consisting of a microcomputer that outputs a switching signal as appropriate according to input data from the tuner 2 may be used as shown in FIG. 7(b). As the IC 13 that detects multiple control signals transmitted through the coaxial cable 3, an MT887 manufactured by Mitel is used.
0CE is used, and the 4-bit output data of this IC 13 is decoded by a decoder 14. When configured using such an IC, a maximum of 16 control signals can be transmitted through the coaxial cable 3.

[0016] In the future, it is being considered that a single geostationary satellite will provide satellite broadcasting services in a wide frequency band. In this case, the NF of the LNB inevitably deteriorates. Therefore, using the method of this embodiment, it is expected that the NF will be improved by switching the input impedance and amplifier in accordance with the receiving channel.

[0017]

Effects of the Invention As described above, the present invention connects a tuner and an antenna equipped with a down converter that lowers the received frequency with a coaxial cable, sends a received signal from the antenna to the tuner through the coaxial cable, and sends a received signal from the tuner side to the tuner. It supplies power for the down converter and sends control signals from the tuner to control the operation of the antenna side using frequency multiplexed transmission, so signals are transmitted bidirectionally and multiplexed on the coaxial cable, and power is supplied. Since the control signal can be transmitted using only a coaxial cable and the control signal is a frequency signal, power loss due to the control signal does not occur in the down converter, and deterioration of NF due to heat generation in the down converter can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of main parts on the tuner side.

FIG. 3 is a circuit diagram showing the configuration on the antenna side.

FIG. 4 is a circuit diagram on the antenna side when switching the polarization method.

FIG. 5 is a specific circuit diagram of the detection circuit same as above.

FIG. 6 is an explanatory diagram of the antenna driving section when adjusting the reception direction.

FIG. 7(a) is a circuit diagram when a control signal transmitting/receiving section is integrated into an IC. (b) is a circuit diagram showing another configuration example of the transmitting side same as above.

FIG. 8 is a system configuration diagram of a conventional antenna system.

FIG. 9(a) is a system configuration diagram of another conventional antenna system. (b) is an explanatory diagram of control signals used in the above.

[Explanation of symbols]

1 Antenna 2 Tuner 3 Coaxial cable 4 LNB

Claims (1)

[Claims] Claim 1: An antenna equipped with a down converter that lowers the reception frequency and a tuner are connected by a coaxial cable, and a received signal is sent from the antenna to the tuner through the coaxial cable, and power for the down converter is supplied from the tuner side. , an antenna system characterized in that a control signal for controlling operation on the antenna side is sent from a tuner by frequency multiplexing transmission.