JP2021032664A - Radio wave search device and radio wave search method - Google Patents

Abstract

To provide a radio wave search device with which, in a system that performs a signal search while rotating a directional antenna, it is possible to search for the signal to be analyzed, quickly at low cost.SOLUTION: According to an embodiment, a radio wave search device comprises a receiver, azimuth-frequency data generation means, moving average processing means and low-frequency signal extraction means. The receiver receives a wide-band signal while rotating a directional antenna. The azimuth-frequency data generation means generates azimuth-frequency data that indicates a signal level per receive frequency of the wide-band signal having been received in each azimuth of the directional antenna. The moving average processing means generates moving averaged azimuth-frequency data in which the signal level for each set of the azimuth and receive frequency indicated by the azimuth-frequency data is moving-averaged by a time base with respect to preset hours. The low-frequency signal extraction means compares the azimuth-frequency data with the moving averaged azimuth-frequency data, and extracts a signal of low frequency on the basis of a set of azimuth and receive frequency in which there is a difference in signal level exceeding a preset threshold.SELECTED DRAWING: Figure 1

Description

An embodiment of the present invention relates to a radio wave search device and a radio wave search method.

Conventionally, in a device that analyzes a wideband signal received by a receiving antenna, a signal detection threshold value is set to a level slightly higher than the noise level for the wideband spectrum signal, and the level is higher than the threshold value. The signal analysis was performed by synchronizing the signal analysis receiver with the signal. As a result, noise and the like lower than the signal detection threshold value are prevented from being analyzed.

JP-A-2007-037023

In the prior art, in a wide band spectrum signal, signal analysis is performed in synchronization with all signals exceeding the signal detection threshold value. Therefore, a large number of signals having a frequency to be analyzed may be extracted from the broadband spectrum signal. It is also possible to display the spectrum signal and select a specific signal to be analyzed by human judgment, but it is necessary to secure personnel, and the corresponding signal can be selected from the wideband spectrum signal display. The burden of extraction work is heavy.

There are two methods for signal analysis: a method of analyzing signals of different frequencies in parallel, and a method of analyzing signals while switching the frequency to be analyzed at regular intervals.

When using the method of performing signal analysis in parallel, if there are many signals of different frequencies to be analyzed, it is necessary to provide many receivers for receiving the signals to be analyzed, which may increase the cost of the device. is there. Further, when a method of performing signal analysis while switching frequencies at a fixed time is used, if there are many signals of different frequencies to be analyzed, the signal analysis time may become very long.

Furthermore, in a system that searches for signals while rotating a directional antenna, the signal level of the target frequency becomes higher when the directional direction of the antenna matches the target direction, so the reception state changes greatly depending on the directional direction. .. Therefore, it is difficult to search for the signal to be analyzed based only on the signal level for each frequency.

An object to be solved by the present invention is to provide a radio wave search device and a radio wave search method capable of searching for a signal to be analyzed inexpensively and quickly in a system that searches for signals while rotating a directional antenna. Is.

According to the embodiment, the radio wave search device includes a receiver, directional vs. frequency data generation means, moving average processing means, and low frequency signal extraction means. The receiver receives a wideband signal while rotating the directional antenna. The azimuth-to-frequency data generation means generates directional-to-frequency data indicating the signal level of the wideband signal received in each direction of the directional antenna for each reception frequency. The moving average processing means generates moving average azimuth vs. frequency data obtained by moving averaging the signal levels for each of the directional and reception frequency pairs indicated by the directional vs. frequency data on the time axis for a preset time. The low-frequency signal extraction means compares the azimuth-to-frequency data with the moving average azimuth-frequency data, and based on a set of azimuth and reception frequency having a difference in signal level exceeding a preset threshold value. Extract low frequency signals.

The block diagram which shows the structure of the radio wave search apparatus in this embodiment. The flowchart for demonstrating the radio wave search process by the radio wave search device of this embodiment. The figure for demonstrating the moving average processing by the moving average processing part. The figure which shows an example of the direction-to-frequency map corresponding to the moving average direction-to-frequency data. The figure which shows an example of the direction-to-frequency map corresponding to the direction-to-frequency data.

Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a radio wave search device 1 according to the present embodiment. The radio wave search device 1 is provided in, for example, a device for investigating a radio wave environment, and monitors radio waves having a wide band frequency. The radio wave search device 1 of the present embodiment is a radio wave that does not require analysis for a known radio wave that is constantly radiated among the wideband radio waves to be monitored, and therefore is a known radio wave that is constantly radiated. Except for, only newly appearing radio waves with low frequency of appearance are extracted so that analysis can be performed.

Known radio waves that are constantly radiated include, for example, radio waves from broadcasting stations such as television broadcasting and radio broadcasting, radio waves from base stations in wireless communication systems, and radio waves using a predetermined frequency band for which the purpose of use is specified. There are communication radio waves and radio waves for device control. Newly appearing radio waves with low frequency of appearance, excluding known radio waves, include, for example, radio waves from illegal radio waves, radio waves in frequency bands for which the purpose of use is not specified, and radio waves from mobile bodies (sources). ..

The radio wave search device 1 includes a receiving antenna 11, a signal search receiver 12, an azimuth-to-frequency data generation unit 13, a moving average processing unit 14, a low-frequency signal extraction unit 15, a signal analysis receiver 16, and a signal analysis function unit 17. , And a display device 18.

The receiving antenna 11 is a directional antenna and receives radio waves in all directions (360 °) while rotating. The receiving antenna 11 is rotated at a speed that enables processing of receiving a signal having a wide band frequency while being swept by the signal search receiver 12 in each direction in which the radio wave is to be received.

The signal search receiver 12 receives the radio waves of the wide band frequency to be monitored while sweeping through the receiving antenna 11. The signal search receiver 12 receives a reception frequency (hereinafter, simply referred to as a frequency) for a wide band frequency to be monitored for each direction (hereinafter, may be referred to as a reception direction) for receiving radio waves by the reception antenna 11. (May be) Receive while sweeping each radio wave. For example, the signal search receiver 12 receives radio waves while sweeping each frequency in the frequency band to be monitored each time the receiving antenna 11 is rotated by a predetermined angle (for example, 1 °). As a result, it is possible to receive radio waves of each frequency for each direction.

The azimuth-to-frequency data generation unit 13 indicates the azimuth-to-frequency signal level for each reception frequency of the broadband signal received in each direction of the receiving antenna 11 based on the radio wave received by the signal search receiver 12. Generate data. That is, the azimuth-to-frequency data generation unit 13 generates data in which [direction: frequency: signal level] is associated with each pair of all directions to be received by the receiving antenna 11 and all reception frequencies.

Based on the azimuth-to-frequency data generated by the azimuth-to-frequency data generation unit 13, the moving average processing unit 14 presets the signal levels for each of the azimuth-to-frequency data-indicated azimuth and reception frequency pairs. Generate moving average azimuth vs. frequency data that is moved averaged on the time axis for the time. The moving average processing unit 14 targets the average of the integrated (superimposed) signal levels received at a preset time (for example, 6 hours) for each of the azimuth and reception frequency sets over time. Calculate while shifting the time. The time to be the target of the moving average may be fixedly set in advance, or may be set (changed) in advance by user operation (6 hours, 12 hours, 24 hours, 48 hours, etc.).

By adjusting the time for moving average processing, it is possible to adjust the frequency of signal appearance. If the moving average time is lengthened, it becomes possible to detect targets (radio wave transmission sources) that appear infrequently in the long term (for example, on a daily basis). Further, if the moving average time is shortened, it becomes possible to detect a target having a low frequency of appearance in a short period of time (for example, in units of 1 hour).

The low-frequency signal extraction unit 15 includes azimuth-to-frequency data (representing the current reception status of radio waves) generated by the signal search receiver 12 and moving average azimuth-to-frequency data (representing the current reception status of radio waves) generated by the moving averaging processing unit 14. Compared with the reception status of radio waves for the time targeted for mobile averaging up to now), the frequency is low based on the set of azimuth and reception frequency with a difference in signal level exceeding a preset threshold value. Extract the signal. The low frequency signal extraction unit 15 compares the signal levels for each of the directional and received frequency pairs indicated by the directional vs. frequency data and the moving average directional vs. frequency data. The signal level corresponding to the known radio wave constantly emitted does not make a big difference between the signal level indicated by the azimuth-to-frequency data and the signal level indicated by the moving average azimuth-to-frequency data obtained by the moving average. On the other hand, the signal level corresponding to the radio wave having a low appearance frequency becomes lower by moving averaging, so that the difference in signal level between the azimuth-to-frequency data and the moving average azimuth-to-frequency data becomes large. In particular, for radio waves from mobile objects, even if they continue to output radio waves of the same frequency, they are processed as data of different azimuth and reception frequency sets by moving the position, so a signal is obtained by moving average. The level goes down. Therefore, similarly, the difference in signal level between the azimuth-to-frequency data and the moving average azimuth-to-frequency data becomes large.

The threshold value for determining the difference in signal levels is a predetermined value capable of specifying a signal level that is clearly determined to be low in comparison with the signal level corresponding to a known radio wave that is constantly radiated. Is set to. The threshold value may be fixedly set in advance, or may be set in advance by a user operation.

The signal analysis receiver 16 performs tuning processing on the signal received by the receiving antenna 11 according to only the frequency corresponding to the low frequency signal extracted by the low frequency signal extraction unit 15. Further, the signal analysis receiver 16 instructs the receiving antenna 11 of the direction in which the low-frequency signal specified from the direction-to-frequency data generated by the direction-to-frequency data generation unit 13 is received. It captures the target target (the source of the signal) and receives the radio waves transmitted from the target target.

The signal analysis function unit 17 executes a predetermined analysis on the signal received by the tuning process by the signal analysis receiver 16.

The display device 18 is an azimuth-to-frequency map (specific examples will be described later) showing signal levels in each of the azimuth-to-receive frequency sets based on the directional-to-frequency data generated by the azimuth-to-frequency data generation unit 13. Is displayed. In the azimuth-to-frequency map, for example, the areas corresponding to each of the azimuth and reception frequency pairs of the two-axis matrix of reception frequency and azimuth are displayed by display attributes according to the signal level. That is, in the azimuth-to-frequency map, a set of azimuth and reception frequency corresponding to a known radio wave constantly radiated, and an azimuth and reception corresponding to a low frequency radio wave excluding the known radio wave constantly radiated. It is displayed in a display form that can distinguish the frequency set.

Display attributes according to the signal level include display using density. For example, the density when the signal level is the maximum value is 100, the density when the signal level is the minimum value is 0, and the corresponding area in the map is displayed according to the density according to the frequency. Further, in the case of a signal level equal to or lower than a preset threshold value for determining noise or the like, the signal level may be excluded from the display target in the directional vs. frequency map. In addition, a unique display form corresponding to each of a known radio wave that is constantly radiated and a low-frequency radio wave may be determined. In addition to displaying by changing the density, it is also possible to display using other display attributes such as display color and brightness.

Further, the display device 18 displays not only the directional-to-frequency map based on the directional-to-frequency data but also the directional-to-frequency map based on the moving average directional-to-frequency data generated by the moving average processing unit 14. You may. Further, the directional vs. frequency map (only the display corresponding to the low frequency radio wave) may be displayed excluding the display corresponding to the known radio wave constantly radiated. Further, the above-mentioned different forms of the directional vs. frequency map may be switched and displayed according to the user operation, or a plurality of directional vs. frequency maps may be displayed at the same time to facilitate comparison.

Next, the operation of the radio wave search device 1 in this embodiment will be described.

FIG. 2 is a flowchart for explaining a radio wave search process by the radio wave search device 1 of the present embodiment.

The signal search receiver 12 receives the radio waves of the wide band to be monitored while sweeping through the receiving antenna 11 that receives the radio waves while rotating (step S1). That is, the signal search receiver 12 receives the radio waves while sweeping the radio waves for each reception frequency to be monitored for each direction in which the radio waves to be received by the receiving antenna 11 are to be received.

The azimuth-to-frequency data generation unit 13 generates azimuth-to-frequency data indicating the signal level for each reception frequency received in each direction of the reception antenna 11 based on the radio waves received by the signal search receiver 12. (Step S2).

Based on the azimuth-to-frequency data generated by the azimuth-to-frequency data generation unit 13, the moving average processing unit 14 presets the signal levels for each of the azimuth-to-frequency data-indicated azimuth and reception frequency pairs. The moving average azimuth vs. frequency data that is moved and averaged on the time axis is generated for the time (step S3).

FIG. 3 is a diagram for explaining the moving average processing by the moving average processing unit 14. In FIG. 3, the horizontal axis represents time and the vertical axis represents signal level (amplitude), and shows the change in signal level corresponding to a certain direction and reception frequency set.

The moving average processing unit 14 sets the signal level of the radio wave of a certain reception frequency received in the target direction as the target of the moving average over time R1, R2, R3, R4. While updating ，… sequentially, the signal levels for the corresponding time are integrated and averaged. As a result, it is possible to obtain a moving average signal level corresponding to a certain direction and reception frequency set.

The signal level PS corresponding to the known radio wave constantly radiated is continuously integrated even if the time R1, ..., Which is the target of the moving average, is updated. Therefore, the moving average signal level corresponding to the corresponding direction and reception frequency is a high signal level.

On the other hand, the signal level TS corresponding to the new radio wave that is not constantly emitted is integrated in a part of the time targeted for the moving average. In particular, when the source of the radio wave is a moving body, the moving body causes the radio wave to be received in a different direction, so that it is not subject to the moving average. Therefore, the signal level corresponding to the reception frequency in the corresponding direction is lower than the average value obtained by integrating the signal level PS corresponding to the constantly radiated radio wave.

On the other hand, the low-frequency signal extraction unit 15 sets the azimuth-to-frequency data generated by the signal search receiver 12 and the moving average azimuth-to-frequency data generated by the moving average processing unit 14 into a set of azimuth and reception frequency. Compare each time (step S4). That is, the low-frequency signal extraction unit 15 compares the signal level of the current radio wave indicated by the azimuth-to-frequency data with the signal level of the moving averaged radio wave indicated by the moving average azimuth-frequency data up to the present, and sets in advance. It is determined for each of all azimuth and reception frequency pairs whether there is a difference in signal levels that exceeds the threshold.

FIG. 4 shows an example of the directional-to-frequency map corresponding to the moving average directional-to-frequency data generated by the moving average processing unit 14, and FIG. 5 shows the directional-to-frequency data generated by the directional-to-frequency data generation unit 13. An example of the directional vs. frequency map according to is shown.

In the orientation-to-frequency map shown in FIGS. 4 and 5, the horizontal axis represents the orientation and the vertical axis represents the reception frequency. In the examples shown in FIGS. 4 and 5, all directions (0 ° to 360 °) are divided into, for example, 30 directions, and all frequency bands (F0 Hz to 50 Hz) to be monitored are divided into 50 steps of frequencies. Represents. The number of divisions of the direction and the number of divisions of the reception frequency can be arbitrarily changed.

In FIGS. 4 and 5, the darkly displayed areas A and B correspond to the radio waves constantly radiated. For radio waves constantly radiated from broadcasting stations, etc., the signal level is high even if the moving average is calculated, so the difference is smaller than the threshold value even when compared with the signal level indicated by the orientation-to-frequency data. .. Therefore, it can be determined that the radio wave is constantly radiated.

On the other hand, in FIG. 5, the lightly displayed areas C and D correspond to radio waves from a target whose appearance frequency is low, such as a moving body. In the current reception status of radio waves indicated by the azimuth-to-frequency data, it is shown that radio waves are being received not only in areas A and B but also in areas C and D. When the source (target) of the radio wave corresponding to the areas C and D is a moving body, the signal level corresponding to the areas C and D becomes low when the moving average is calculated as shown in FIG. Therefore, when compared with the signal level indicated by the directional vs. frequency data, the difference in signal level or the threshold value is exceeded. Therefore, it can be determined that there is a radio wave that appears infrequently from a moving body or the like.
The low-frequency signal extraction unit 15 corresponds to the case where there is a set of a direction and a reception frequency in which the difference in signal levels exceeds the threshold value as in areas C and D shown in FIGS. 4 and 5 (steps S5, Yes). The signal analysis receiver 16 is instructed to set the direction and the reception frequency to be tuned.

Similarly, the low-frequency signal extraction unit 15 is generated by the azimuth-to-frequency data generated by the signal search receiver 12 and the mobile averaging processing unit 14 based on the radio waves received by the receiving antenna 11. When the pair of the azimuth and the reception frequency whose signal level difference exceeds the threshold value is determined by the comparison with the moving average azimuth vs. frequency data, the signal analysis receiver 16 is instructed.

The signal analysis receiver 16 executes tuning processing on the radio waves received by the receiving antenna 11 according to the tuning frequency and direction instructed by the low frequency signal extraction unit 15 for signal analysis by the signal analysis function unit 17. To do. The signal analysis function unit 17 executes analysis on the signal received by the tuning process by the signal analysis receiver 16. The signal analysis function unit 17 analyzes characteristics such as the waveform and period of the received signal to identify illegal radio waves and the like.

In this way, the radio wave search device 1 in the present embodiment generates azimuth-to-frequency data indicating the signal level for each reception frequency of the wideband signal received in each azimuth of the receiving antenna 11, and also azimuth-to-frequency data. Based on the above, mobile average azimuth-to-frequency data is generated by moving and averaging the signal levels for each of the azimuth and reception frequency pairs indicated by the azimuth-to-frequency data, and radio waves with a large level difference are regarded as radio waves with a low appearance frequency. Can be extracted. Therefore, in a system that searches for radio waves while rotating the receiving antenna 11, which is a directional antenna, radio waves emitted from a moving body or the like other than the constantly radiated radio waves of a broadcasting station or the like can be identified, inexpensively and quickly. It is possible to automatically search and analyze low-frequency signals.

In the radio wave search device 1 of the present embodiment, not only the reception frequency but also the direction of the radio wave emitted from the mobile body or the like is specified. Therefore, for example, even if there are two mobile bodies that output radio waves of the same frequency, they are individually used. Can be determined. In addition, it is possible to estimate the direction in which one moving body has moved (change in direction) based on the history of changes in the direction in which radio waves of the same frequency are received with the passage of time.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

11 ... Reception antenna, 12 ... Signal search receiver, 13 ... Direction vs. frequency data generation unit, 14 ... Moving average processing unit, 15 ... Low frequency signal extraction unit, 16 ... Signal analysis receiver, 17 ... Signal analysis function Department, 18 ... Display device.

Claims (5)

A receiver that receives a wideband signal while rotating the directional antenna,
A directional-to-frequency data generating means for generating directional-to-frequency data indicating the signal level for each reception frequency of the wideband signal received in each direction of the directional antenna, and a directional-to-frequency data generating means.
A moving average processing means for generating moving average directional vs. frequency data obtained by moving averaging the signal levels for each of the directional vs. frequency pairs indicated by the directional vs. frequency data on the time axis for a preset time.
The azimuth vs. frequency data is compared with the moving average azimuth vs. frequency data, and a low frequency signal is extracted based on a pair of azimuth and reception frequency having a difference in signal level exceeding a preset threshold value. A radio wave search device having a low frequency signal extraction means. A signal analysis receiver that tunes the signal received by the directional antenna according to only the frequency of the signal extracted by the low-frequency signal extraction means.
The radio wave search device according to claim 1, further comprising a signal analysis means for performing a predetermined analysis on a signal received by tuning processing by the signal analysis receiver. The radio wave search device according to claim 1 or 2, further comprising a display means for displaying a directional vs. frequency map representing a signal level in each of the directional vs. frequency pairs based on the directional vs. frequency data. The radio wave search device according to claim 1, wherein the moving average processing means can change the target time of the moving average. While rotating the directional antenna, it receives a wideband signal and
Direction-to-frequency data indicating the signal level for each reception frequency of the wideband signal received in each direction of the directional antenna is generated.
A moving average directional vs. frequency data is generated by moving and averaging the signal levels for each of the directional and received frequency pairs indicated by the directional vs. frequency data on the time axis for a preset time.
The azimuth vs. frequency data is compared with the moving average azimuth vs. frequency data, and a low frequency signal is extracted based on a pair of azimuth and reception frequency having a difference in signal level exceeding a preset threshold value. Radio wave search method to do.