JPH06174816A - Direction finding system - Google Patents

Abstract

PURPOSE:To reduce direction finding errors resulting from the different polarization planes of coming waves. CONSTITUTION:The polarization plane of a coming wave is judged by a polarization plane judging equipment 15 from a difference between a receiving power value 13B at a circular polarization antenna 11 and a receiving power value 14A at a linear polarization antenna 12. Correction data 17A adequate to the polarization plane of the coming wave out of direction finding error correction data for every polarization plane previously stored in a memory 16 is selected by a correction data selector 17 in accordance with judgement information 15A of this polarization plane. The direction finding error correction data 17A is used for a direction finding error corrector 18 to correct direction output 13A from a receiver 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direction finding error correction of a direction finding system using a circularly polarized antenna,
It is useful when applied to an M (Electric Support Measure) system.

[0002]

2. Description of the Related Art In a direction finding system such as a direction finding device or a wireless direction measuring device, a direction finding error is corrected. With reference to FIG. 3, a conventional direction finding system using a circularly polarized antenna will be described.

In FIG. 3, this direction finding system includes a 4-arm spiral antenna 31 as a circularly polarized wave antenna,
It is composed of a mode forming circuit 32, a receiver 33, a direction error correction device 34, and a direction error correction data memory 35. The mode forming circuit 32 creates a Σ signal 32A and a Δ signal 32B by adding the high frequency signals received by the 4-arm spiral antenna 31 with a phase difference, and sends them to the receiver 33. The Σ signal 32A is a signal having the highest beam pattern in front of the antenna, and the Δ signal 32B is a signal having a minimum beam pattern in front of the antenna. The receiver 33 receives the Σ signal 32A and the Δ signal 32
B is detected to determine the arrival direction of the radio wave, and the azimuth output 33A representing this is sent to the direction error correction unit 34. Memory 3
In FIG. 5, what kind of azimuth output 33A is obtained from the receiver 33 for the true arrival direction of the radio wave is measured and acquired in advance, and this is stored as the search error correction data 35A. Therefore, the direction error correction device 34 uses the direction error correction data 35 corresponding to the azimuth output 33A from the receiver 33.
A is read from the memory 35 and is output as the corrected azimuth output 34A.

[0004]

Generally, when a circularly polarized wave antenna 31 receives a linearly polarized radio wave, the beam pattern (reception characteristic) varies depending on whether the plane of polarization is vertical polarization or horizontal polarization. different. However, since the circular polarization antenna 31 itself cannot measure the plane of polarization, the conventional direction finding system uses the same direction finding error correction data regardless of the difference in the plane of polarization, so that the direction finding is different due to the difference in the plane of polarization. There was an error.

An object of the present invention is to provide a direction finding system capable of reducing the direction finding error due to the plane of polarization generated in the above-mentioned prior art.

[0006]

In order to achieve the above object, a direction finding system of the present invention is a direction finding system using a circularly polarized wave antenna, wherein a polarization plane detecting antenna and an incoming radio wave from an antenna output are polarized. Polarization plane determination means for determining the wavefront, memory for storing direction error correction data corresponding to the polarization plane, and correction data selection for selecting the direction error correction data to be used from the memory based on the polarization plane determination information. And a direction error correction unit for correcting the azimuth output using the selected direction error correction data. In this case, the polarization plane detection antenna is
It may be a combination of a circular polarization antenna of the direction finding system and another antenna, or may be a completely separate antenna from this circular polarization antenna.

[0007]

[Operation] When the radio wave is received by the direction finding system, the polarization plane of the radio wave is determined from the output of the polarization plane detection antenna, and the polarization plane of the received radio wave is suitable based on the determination information of the polarization plane. The search error correction data is selected, and the search error correction data is used to correct the search error. Therefore, since the direction finding error correction suitable for the plane of polarization is performed, the direction finding error due to the plane of polarization, which has occurred conventionally, is reduced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a direction finding system according to an embodiment of the present invention. The direction finding system includes a circular polarization antenna 11, a linear polarization antenna 12, and a circular polarization antenna receiver 13.
And the linear polarization antenna receiver 14 and the polarization plane determination device 1
5, a memory 16, a correction data selector 17, and a direction error correction unit 18. In this embodiment, four 2-arm spiral antennas 11-1 to 11-4 are used as the circular polarization antenna 11, and a horn antenna is used as the linear polarization antenna 12, and four 2-arm spiral antennas are used. 11-1 to 1-11-4 and one horn antenna 12 constitute a polarization plane detecting antenna. The circular polarization antenna receiver 13 detects the high-frequency signals received by the two-arm spiral antennas 11-1 to 11-4 and sends an azimuth output 13A representing the arrival direction of the radio wave to the direction error correction unit 18. At the same time, the received power is measured and the measured value 13B is sent to the polarization plane determiner 15. The linearly polarized antenna receiver 14 measures the received power of only the high frequency signal received by the horn antenna 12, and the measured value 1
4A is sent to the polarization measuring device 15.

The polarization plane determiner 15 determines the polarization plane of the received radio wave from the difference between the received power value 13B at the circular polarization antenna receiver 13 and the received power value 14A at the linear polarization antenna receiver 14. It is determined and this determination information 15A is sent to the correction data selector 17. In addition, in the polarization plane determination,
The difference in reception level between the circular polarization antenna 11 and the linear polarization antenna 12 is acquired in advance as data corresponding to the polarization plane, and the polarization plane is determined based on this data.

In the memory 16, the search error correction data is previously acquired and stored for each polarization plane. The method for acquiring the direction finding error correction data on each polarization plane is the same as the conventional method, and the azimuth output 13A obtained from the receiver 13 with respect to the true arrival direction of the radio wave is measured.

When the correction data selector 17 receives the polarization plane determination information 15A, the memory 1 is based on this determination information 15A.
The most appropriate data 1 for the polarization plane of the received radio wave from the search error correction data for each polarization plane stored in 6
7A is selected and sent to the direction error correction unit 18.

The direction error correction unit 18 corrects the azimuth output 13A from the circular polarization antenna receiver 13 using the direction error correction data 17A selected by the correction data selector 17, and the corrected direction output 13A is corrected. The azimuth output 18A is transmitted.

FIG. 2 shows a direction finding system according to another embodiment of the present invention, which is a circularly polarized antenna 19 and 2
Two linear polarization antennas 20 and 21 and a mode forming circuit 2
2, a receiver 23, front ends 24 and 25 for each linearly polarized wave antenna, a polarization plane determiner 26, and a memory 27.
And a correction data selector 28 and a direction error correction unit 29. In this embodiment, the circular polarization antenna 19
A four-arm spiral antenna is used, and horn antennas are used as the two linear polarization antennas 20 and 21, respectively, and the polarization planes of the horn antennas 20 and 21 are made orthogonal to each other to form a polarization plane detection antenna.

The mode forming circuit 22 creates a Σ signal 22A and a Δ signal 22B by adding the high frequency signals received by the four-arm spiral antenna 19 with a phase difference and adds them to the receiver 23 through the switches SW ₁ and SW _2. Send out. The Σ signal 22A is a signal having the highest beam pattern in front of the antenna, and the Δ signal 22B is a signal having a minimum beam pattern in front of the antenna. The receiver 23 detects the Σ signal 22A and the Δ signal 22B from the mode forming circuit 22 to obtain the arrival direction of the radio wave, sends an azimuth output 23A indicating this to the direction error compensator 29 and a 4-arm spiral antenna. The received power of 19 is measured, and the measured value 23B is sent to the polarization plane determiner 26.

The front ends 24 and 25 adjust the amplitudes and frequencies of the high frequency signals received by the horn antennas 20 and 21 to be approximately the same as the amplitudes and frequencies of the Σ signal 22A and the Δ signal 22B, respectively. Switch S
It is sent to the receiver 23 through W ₁ and SW ₂ . Receiver 2
3 is each signal 24A, 2 from the front end 24, 25
When 5 A is input, the received power is measured for these signals and the measured values 23C and 23D are sent to the polarization plane determiner 26.

The polarization plane determiner 26 determines the polarization plane of the received radio wave from the difference between the received power values 23B to 23D output from the receiver 23, and sends this determination information 26A to the correction data selector 28. . In the polarization plane determination, the linear polarization antenna 20,
The difference of the reception level between 21 is acquired as data,
The polarization plane is determined based on this data.

In the memory 27, the search error correction data is acquired and stored in advance for each polarization plane. The method of acquiring the direction finding error correction data on each polarization plane is the same as the conventional method, and the azimuth output 23A obtained from the receiver 23 with respect to the true arrival direction of the radio wave is measured.

When the correction data selector 28 receives the polarization plane determination information 26A, the memory 2 is based on this determination information 26A.
The most appropriate data 2 for the polarization plane of the received radio wave from the search error correction data for each polarization plane stored in 7.
8A is selected and sent to the direction error correction device 29.

The direction error correction unit 29 corrects the azimuth output 23A from the receiver 23 using the direction error correction data 28A selected by the correction data selector 28 and sends it as a corrected direction output 29A. To do.

In the embodiment shown in FIG. 2, the circularly polarized antenna 1
By partially sharing the receiver 23 with the 9 and the linearly polarized antennas 20 and 21, it is possible to reduce the number of parts, volume and mass of the direction finding system.

[0021]

According to the direction finding system of the present invention, the plane of polarization of the incoming radio wave is detected and the correction is performed using the direction finding error correction data suitable for the plane of polarization. The error is reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a direction finding system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a direction finding system according to another embodiment of the present invention.

FIG. 3 is a diagram showing a conventional direction finding system.

[Explanation of symbols]

 11, 19 Circular polarization antenna 12, 20, 21 Linear polarization antenna 13 Circular polarization antenna receiver 14 Linear polarization antenna receiver 15, 26 Polarization plane determiner 16, 27 Memory 17, 28 Correction data selector 18, 29 Direction error correction device 23 Receiver 24, 25 Front end

Claims (1)

[Claims] 1. A direction finding system using a circular polarization antenna, a polarization direction detecting antenna, a polarization direction determining means for determining a polarization plane of an incoming radio wave from an antenna output, and a direction finding error correction corresponding to the polarization plane. A memory that stores data, a correction data selection unit that selects the direction error correction data to be used from the memory based on the polarization plane determination information, and the direction output correction using the selected direction error correction data A direction finding system comprising a direction finding error correcting means.