JPH06281715A - Device for measuring incoming direction of radio wave - Google Patents

Abstract

PURPOSE:To measure the incoming direction of radio wave with high resolution and high accuracy without generating measuring error caused by the phase deviation due to the circuit characteristics by judging the direction of received signal by pattern-matching the intensity data of the received signal which are obtained per every different intensity patterns of the received signal to the intensity pattern data of the received signal which have been obtained in advance, or judging the direction of received signal on the basis of the values which are obtained by normalizing the direction of the received signal, that is obtained per different intensity patterns of the received signal, in a non- directional state. CONSTITUTION:In an antenna unit which is provided with a non-directional feed antenna 5 at the center thereof and a plurality of passive antennas (1a, 1b)-(4a, 4b) in the periphery thereof, by selectively on/off controlling switching elements D1 to D4 provided on the respective passive antennas, the intensity patterns of received signal of the antenna unit are changed over and the incoming direction of radio wave is measured based on the intensity of the received signal in the respective patterns.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave direction measuring device for measuring the arrival direction of radio waves.

[0002]

2. Description of the Related Art As a conventional device of this type, Japanese Patent Publication No.
The devices disclosed in JP-A-15399 and JP-B-54-15400 are known. Japanese Patent Publication 54-
In the invention described in Japanese Patent No. 15399, the directivity of the antenna is rotated substantially periodically, its radio frequency output is detected, and the signal is shaped into a rectangular wave whose phase corresponds to the arrival direction of the radio wave. Of the plurality of light emitting elements to cause the corresponding light emitting element to emit light to display the arrival direction of the radio wave. Further, the invention described in Japanese Patent Publication No. 54-15400 is arranged such that a plurality of parasitic antennas are arranged at equal intervals on a circumference centered on an omnidirectional feeding antenna, and load impedances of the respective parasitic antennas are set. By utilizing the fact that the phase of the scanning frequency component of the detection output of the signal appearing in the omnidirectional power feeding antenna in that state corresponds to the arrival direction of the radio wave by rotating the directional characteristic of the antenna periodically by sequentially switching scanning. Then, the arrival direction of the radio wave is measured by measuring the phase difference between the scanning signal for sequentially switching the load impedance and the scanning frequency component of the detection output.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the inventions described in Japanese Patent Publication No. 399 and Japanese Patent Publication No. 54-15400, since a mechanical rotating mechanism for sequentially rotating the pointing direction of the antenna is not required, the device does not become large and is highly reliable. Since the input circuit of the amplification detector does not require a switching circuit, it is characterized by not being affected by transient distortion and signal loss due to switching.

However, in either method,
The radio wave to be measured is AM-modulated by electronically rotating the directional direction of the antenna, and the phase difference between the modulated wave and the reference signal used to electronically rotate the directional direction of the antenna is compared. Therefore, since the arrival direction of the radio wave is detected, the phase shift generated in the circuit system for sequentially electronically rotating the directional direction of the antenna or the circuit system for phase detection or phase comparison is directly regarded as a measurement error. Therefore, a circuit for correcting a phase shift due to an analog circuit is required, and the characteristics thereof have temperature dependence, which is not suitable for a highly accurate radio wave direction detection apparatus.

An object of the present invention is to solve the above problems and to provide a radio wave arrival direction measuring apparatus which is small in size, has high reliability, and can measure the radio wave arrival direction with high accuracy.

[0006]

A radio wave direction-of-arrival measuring apparatus according to claim 1 of the present invention has an omnidirectional power feeding antenna arranged at the center, and a switching element is loaded in the middle of each antenna to turn on / off the switching element. Depending on the state, an antenna unit formed by arranging a plurality of parasitic antennas with varying reactances at equal intervals on a circle centered on the omnidirectional feeding antenna, and a switching element of each parasitic antenna in the on / off state Switch control means for controlling, and received signal strength measuring means for amplifying the received signal output from the omnidirectional power feeding antenna, converting the strength of the received signal into digital data, and measuring the received signal strength data. And each received signal strength determined by a combination of the on / off states of the switching elements of each antenna unit Received signal strength pattern data storage means for storing a turn in advance as a data group of received signal strength for the direction of the received signal, and controlling the switch control means to change the received signal strength pattern of the antenna unit into a plurality of types. In the state of each received signal strength pattern, a data group consisting of the received signal strength data obtained by the received signal strength measuring means is subjected to pattern matching based on the data group stored in the received signal strength pattern data storage means, and the closest approximation is made. Reception signal direction determining means for determining the direction of the reception signal of the data group.

In the radio wave direction-of-arrival measuring apparatus according to the second aspect of the present invention, the omnidirectional power feeding antenna is arranged at the center, the switching elements are loaded in the middle, and the reactance changes depending on the on / off state of the switching elements. An antenna unit having a plurality of parasitic antennas arranged at equal intervals on a circumference centered on the omnidirectional feeding antenna, and a switch control means for controlling ON / OFF states of switching elements of the parasitic antennas. A received signal strength measuring means for amplifying a received signal output from the omnidirectional power feeding antenna, converting the strength of the received signal into digital data, and measuring the received signal strength data; and the switch control means. To make the received signal strength pattern of the antenna unit substantially omnidirectional, and Reference received signal strength extraction means for extracting the received signal strength obtained by the received signal strength measuring means as reference received signal strength, and the switch control means to control the received signal strength pattern of the antenna unit to have directivity. Direction detection received signal strength extraction means for normalizing the received signal strength obtained by the received signal strength measurement means as a ratio to the reference received signal strength for different received signal strength patterns and extracting as direction detection received signal strength And reception signal strength pattern data storage means for pre-storing each reception signal strength pattern determined by a combination of ON / OFF states of the switching elements of the parasitic antennas as a data group of the reception signal strength with respect to the direction of the reception signal, and the reception Different reception by referring to the data of the signal strength pattern data storage means Received signal direction determination means for determining an assumed direction of the received signal from the received signal strength for direction detection for each signal strength pattern and determining the most accurate direction from the plurality of assumed directions of the received signal as the direction of the received signal. ,, and.

[0008]

In the radio wave direction-of-arrival measuring apparatus according to claim 1 of the present invention, the antenna unit has the omnidirectional power feeding antenna arranged at the center thereof, and the switching element is loaded in the middle of the antenna unit. A plurality of parasitic antennas whose reactance changes depending on the ON / OFF state are arranged at equal intervals on a circumference centered on the omnidirectional feeding antenna.

Here, an example of the configuration of the antenna unit is shown in FIG.
Shown in. In the antenna unit according to the present invention in FIG. 2, an omnidirectional power feeding antenna 5 is arranged at the center, and a plurality of parasitic antennas 1, 2, 3 and 4 are arranged on a circle around the omnidirectional power feeding antenna position. They are evenly spaced. In the example shown in the figure, the parasitic antennas 1, 2, 3, 4 are (1a, 1b), (2a, 2b), (3a, 3), respectively.
b) and (4a, 4b), a switching element is provided in the parasitic antenna support portions 6, 7, 8, and 9, and the parasitic antennas 1, 2, 3, 3 depend on the ON / OFF state of the switching element. The reactance of 4 changes.

The switch control means controls the ON / OFF states of the switching elements of the parasitic antennas. The parasitic antennas are used as reflectors and directors depending on the ON / OFF states of the switching elements of the parasitic antennas. Or equivalently, it acts as a nonexistent state, and the directional characteristic of the antenna unit changes. FIG. 3 is a diagram showing only the main part of the top view of the antenna unit shown in FIG. 2. For example, the parasitic antennas 1, 2, 3 and 4 are north (N), east (E), and south (S), respectively. , Shall be placed in the west (W) direction,
If the parasitic antennas 2, 3 and 4 are reflectors, respectively, and the parasitic antenna 1 is equivalently absent,
At, the directional characteristic of the received signal strength pattern as shown by A1 is obtained. If all parasitic antennas are in the state of reflectors or equivalently none,
When the parasitic antennas 3 and 4 are reflectors and the parasitic antennas 1 and 2 are not equivalently present, for example, B1 in FIG. The directional characteristics of the received signal strength pattern as shown are obtained.

The received signal strength measuring means amplifies the received signal output from the omnidirectional power feeding antenna and converts the received signal strength into digital data to obtain the received signal strength. The received signal strength pattern data storage means stores in advance a received signal strength pattern determined by a combination of ON / OFF states of the switching elements of the parasitic antennas as a data group with a correspondence relationship between the direction of the received signal and the received signal strength. To do. The received signal direction detecting means controls the switch control means to change the received signal strength pattern of the antenna unit into a plurality of types, and the received signal strength measuring means determines the received signal strength in each received signal strength pattern state. Pattern matching is performed on a data group consisting of intensity data based on the data group stored in the received signal strength pattern data storage means, and the direction of the received signal of the most approximate data group is obtained.

As described above, the received signal obtained for each different received signal strength pattern is not detected while the phase of the scanning frequency component of the received signal is detected while the directional direction of the antenna unit is sequentially and cyclically rotated. Since the received signal direction is determined by pattern matching from the received signal strength pattern data in which the strength data is obtained in advance,
There is no measurement error due to the phase shift caused by the circuit characteristics, and if the correspondence relationship between the received signal direction and the received signal strength of each received signal strength pattern is accurately obtained in advance, it is possible to obtain radio waves with high resolution and high accuracy. It becomes possible to measure the direction of arrival.

In the radio wave arrival direction measuring apparatus according to the second aspect of the present invention, the respective operations of the antenna unit, the switch control means, the received signal strength measuring means and the received signal strength pattern data storage means are the same as those described above.
The reference reception signal strength extraction means extracts the reception signal strength in a state where the reception signal strength pattern of the antenna unit is substantially omnidirectional under the control of the switch control means as the reference reception signal strength.

In the example shown in FIG. 4, the value of Lr becomes the reference received signal strength. Direction detection received signal strength extraction means,
The received signal strength pattern of the antenna unit is given directivity under the control of the switch control means, and the received signal strength obtained for different received signal strength patterns is normalized as a ratio to the reference received signal strength, and this is received for direction detection. Extract as signal strength. In the example shown in FIG. 4, the direction detection reception signal strength for each of the reception signal strength patterns A1, B1, A2, B2 is La1 / L.
r, Lb1 / Lr, La2 / Lr, Lb2 / Lr. The received signal direction determination means obtains the assumed direction of the received signal from the received signal strength for direction detection for each different received signal strength pattern, and determines the direction with the highest accuracy from the plurality of assumed directions of the received signal. Is determined as. In the example shown in FIG. 4, if the arrival azimuth angle of the radio wave based on the north is θ, the received signal strength pattern A1 is line-symmetrical with the north direction as the center.
In the received signal strength for direction detection of this received signal strength pattern A1, it can be assumed that the arrival direction of the radio wave is θ or −θ. Further, since the received signal strength pattern B1 is line-symmetric with respect to the northeast direction, it is assumed that the arrival direction of the radio wave is θ or (90 ° −θ) in the direction detection received signal strength for this received signal strength pattern B1. can do.

Similarly, since the received signal strength pattern A2 is line-symmetrical with the east direction as the center, the direction detection received signal strength according to the received signal strength pattern A2 has a radio wave arrival direction of θ or (180 ° −). θ) can be assumed. Similarly, for the other received signal strength patterns, two directions can be assumed to be the arrival direction of the radio wave from the direction detection received signal strength for each received signal strength pattern. However, since all the received signal strength patterns have different directions of the center of symmetry, the direction (θ direction) in which the assumed directions obtained from the direction detection received signal strength for each received signal strength pattern overlap is the true radio wave. It can be determined as the direction of arrival.

As described above, the received signal obtained for each different received signal strength pattern is not detected by sequentially rotating the pointing direction of the antenna unit periodically and detecting the phase of the scanning frequency component of the received signal. Since the received signal direction is determined based on the value obtained by normalizing the intensity with the received signal intensity in the non-directional state, there is no measurement error due to the phase shift caused by the circuit characteristics, and each received signal intensity If the correspondence relationship between the received signal direction and the received signal strength of the pattern is accurately obtained in advance, the radio wave arrival direction can be measured with high resolution and high accuracy.

[0017]

【Example】

<First Embodiment> First, FIG. 2 shows the structure of an antenna unit used in a radio wave arrival direction measuring apparatus according to an embodiment of the present invention.
It will be explained based on. In FIG. 2, 14 is a pole, 10,1
Paragraphs 1, 12 and 13 are parasitic antenna support bars for attaching the parasitic antennas to their tips. An omnidirectional feed antenna 5 is erected at the tip of the pole 14, and the parasitic antenna support bars 10, 11, 12, and 13 are used as ground conductor wires to form a grounded antenna. Parasitic antenna support bars 6, 11, 8 and 9 are provided at the tips of the parasitic antenna support bars 10, 11, 12 and 13 so that no power is fed from the parasitic antenna support bars 10, 11, 12 and 13 in an insulated state. Antennas (1a, 1b), (2a,
2b), (3a, 3b) and (4a, 4b) are attached. Inside the parasitic antenna support portions 6, 7, 8 and 9, parasitic antennas extending in the vertical direction in the figure are connected via diodes. The element length of the omnidirectional power feeding antenna 1 is λ / 4 (1/4) of the radio wave to be received.
Wavelength), and the parasitic antennas 1a, 1b, 2a,
The element lengths of 2b, 3a, 3b, 4a, 4b and the lengths of the parasitic antenna support bars 10, 11, 12, 13 are also λ.
/ 4, the equivalent element length of the parasitic antenna is λ / 2 when the diode is in the conductive state, has a positive reactance, and acts as a reflector.

Next, FIG. 1 is a block diagram showing the configuration of a radio wave arrival direction measuring apparatus according to an embodiment of the present invention. Figure 1
In, the diodes D1, D2, D3 and D4 are diodes as switching elements connected in the middle of each parasitic antenna described above. The drive circuit 10 controls the energization of the diodes D1, D2, D3, D4. CPU22
Supplies a control signal to the drive circuit 20 via the parallel I / O port 21. The receiving circuit 23 detects the strength of the signal induced in the omnidirectional power feeding antenna 5. The A / D converter 24 converts the signal into digital data. CP
U22 reads the received signal strength digital data,
It is stored in a predetermined area in the memory 25.

Next, the diodes D1 to D4 shown in FIG.
FIG. 5 shows the correspondence between the ON / OFF state of each and the received signal strength patterns shown in FIG. In FIG. 5, the blank part is shown in FIG.
The received signal strength patterns A1 to A4 and B1 are not shown in FIG.
~ Received signal strength patterns different from B4 and R are obtained. Eventually, 16 types of received signal strength patterns can be obtained by combining the on / off states of the four diodes.
6 and 7 show examples of all received signal strength patterns. Note that FIG. 7 is a diagram in which the horizontal axis is the angle θ and the vertical axis is the gain. As described above, the 16 types of received signal strength patterns obtained by the combination of the ON / OFF states of the four diodes are constant, and the received signal strength with respect to the direction of the received signal is created in advance as a table as shown in FIG. Can be set. Then, as shown in the measurement data of the same figure, 16 types of data are measured by changing the combinations of the on / off states of the four diodes.
6 pieces of data are pattern-matched from table data. As a result, the angle with the best matching pattern is
It is the angle to be sought.

<Second Embodiment> If the antenna unit is an accurate rotationally symmetric body centered on the omnidirectional power feeding antenna, the received signal strength patterns A1 to A4 and B1 to B will be described.
The patterns 4 have the same pattern shape except that the directions of the directional centers are different. Therefore, for example, for the received signal strength patterns A1 to A4, one received signal strength pattern can be used as shown in FIG.
Moreover, since the pattern is line-symmetrical, the relationship between the received signal intensity La and the angle θ for only the solid line portion in FIG. 9A may be stored as a table as shown in FIG. 10A. Similarly, for the received signal strength patterns B1 to B4, FIG. 10 is a table showing the relationship between the received signal strength Lb and the angle θ for only the solid line portion in FIG. 9B.
It may be stored as shown in (B). Then, 16 types of data are measured by changing the combinations of the on / off states of the four diodes, and 15 types of measurement data having directivity characteristics out of these 16 data are compared with the measurement data in the non-directional state. Then, the corresponding angle is obtained from each table data, and the common angle data among the obtained corresponding angles is used as the measurement result.

In the above embodiment, the switching element loaded on the parasitic antenna is selectively acted as a reflector by switching the ON / OFF state. However, the element length may be changed or the state of the switching element may be changed. The loading impedance may be selectively changed so as to have a negative reactance, and it may be configured to act as a director. Further, in the embodiment, the received signal strength pattern is replaced with all possible patterns, and an example of determining the received signal direction based on all the received signal strength data obtained is shown, but a plurality of received signal strengths are shown. You may make it use only some typical patterns among the patterns.
Furthermore, although four parasitic antennas are used in the embodiment,
For example, three parasitic antennas may be arranged, for example, five or more parasitic antennas may be arranged.

[0022]

According to the present invention, the phase of the scanning frequency component of the received signal is not detected while the directional direction of the antenna unit is sequentially and cyclically rotated, but the reception is obtained for each different received signal strength pattern. Since the received signal direction is determined by pattern matching from the received signal strength pattern data obtained in advance for the signal strength data,
In addition, since the received signal strength obtained for each different received signal strength pattern is determined based on the value obtained by normalizing the received signal strength in the omnidirectional state, the phase generated by the circuit characteristics is determined. If the correspondence between the received signal direction and the received signal strength of each received signal strength pattern is obtained in advance without causing a measurement error due to the shift, it is possible to measure the incoming direction of the radio wave with high resolution and high accuracy. become.

[0023]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a radio wave arrival direction measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the structure of the antenna unit according to the embodiment of the present invention.

FIG. 3 is a schematic plan view showing an example of an arrangement direction of an antenna unit.

FIG. 4 is a diagram showing an example of various received signal strength patterns.

FIG. 5 is a diagram showing a relationship between an on / off state of a switching element (diode) and a received signal strength pattern obtained thereby.

FIG. 6 is a diagram showing an example of all received signal strength patterns that can be taken depending on the on / off states of four switching elements.

FIG. 7 is a diagram in which the received signal strength pattern of FIG. 6 is expanded to rectangular coordinates.

FIG. 8 is a diagram showing an example of a table of received signal strength pattern data and measurement data according to the first embodiment.

9 is a diagram showing common received signal strength patterns of received signal strength patterns A1 to A4 and B1 to B4 shown in FIG. 4, respectively.

FIG. 10 is a diagram showing an example of a table of common received signal strength pattern data according to the second embodiment shown in FIG.

[Explanation of symbols]

 1 to 4-parasitic antenna 5-omnidirectional antenna 6 to 9-parasitic antenna support portion 10 to 13-parasitic antenna support bar 14-pole D1 to D4-diode (switching element)

Claims (2)

[Claims] 1. An omnidirectional feed antenna, wherein an omnidirectional feed antenna is arranged at the center, a switching element is loaded in the middle of each antenna, and a plurality of parasitic antennas whose reactance changes depending on the on / off state of the switching element are provided. Antenna units arranged at equal intervals on a circle centering around, switch control means for controlling the on / off state of the switching elements of each parasitic antenna, and the reception of the output of the omnidirectional antenna. Received signal strength measuring means for measuring the received signal strength data by amplifying the signal and converting the strength of the received signal into digital data, and each received signal determined by the on / off state of the switching element of each antenna unit. Intensity pattern as a data group of received signal strength for the direction of the received signal For storing the received signal strength pattern data to store the received signal strength pattern data storage means for controlling the switch control means to change the received signal strength pattern of the antenna unit into a plurality of types, and the received signal strength measuring means in the state of each received signal strength pattern. The received signal direction determination for determining the direction of the received signal of the most approximated data group by performing pattern matching on the data group consisting of the received signal strength data determined by the above-mentioned data group stored in the received signal strength pattern data storage means A radio wave arrival direction measuring device comprising: 2. An omnidirectional feed antenna comprising a omnidirectional feed antenna arranged at the center, a switching element loaded in the middle of the omnidirectional feed antenna, and a plurality of parasitic antennas whose reactance changes depending on the on / off states of the switching elements. Antenna units arranged at equal intervals on a circle centering around, switch control means for controlling the on / off state of the switching elements of each parasitic antenna, and the reception of the output of the omnidirectional antenna. Received signal strength measuring means for amplifying the signal, converting the strength of the received signal into digital data, and measuring the received signal strength data, and the switch control means for controlling the received signal strength pattern of the antenna unit. In addition to making it almost omnidirectional,
In that state, a reference received signal strength extracting means for extracting the received signal strength obtained by the received signal strength measuring means as a reference received signal strength, and a directivity in the received signal strength pattern of the antenna unit by controlling the switch control means. For different received signal strength patterns, the received signal strength obtained by the received signal strength measuring means is normalized as a ratio to the reference received signal strength, and the received signal strength for direction detection is extracted as the received signal strength for direction detection. Strength extraction means, and a reception signal strength pattern data storage means for pre-storing each reception signal strength pattern determined by a combination of the ON / OFF states of the switching elements of each parasitic antenna as a data group of reception signal strength with respect to the direction of the reception signal. , With reference to the data of the received signal strength pattern data storage means, From the received signal strength for direction detection for each received signal strength pattern, the assumed direction of the received signal is obtained, and the direction with the highest accuracy is determined from the plurality of assumed directions of the received signal as the received signal direction. A device for measuring the direction of arrival of radio waves, which comprises: