JP3661530B2 - Communication jamming method and communications jamming device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus that interferes with frequency hopping communication (hereinafter referred to as FH communication).
[0002]
[Prior art]
The frequency hopping (FH) method is a communication method that improves confidentiality by switching transmission and reception frequencies in time according to a predetermined hopping pattern (spread frequency sequence).
[0003]
FIG. 8 is a conceptual diagram for explaining a hopping pattern. In the figure, f1 to f5 are hopping signals constituting the hopping pattern, p1 is the end time of the hopping signal f1, q1 is the start time of the hopping signal f2, T1 is the period of the hopping pattern, T2 is the duration of the hopping signal, and T3 is This is the time interval between the start time and end time of the hopping signal (hereinafter referred to as the hopping interval).
[0004]
[Problems to be solved by the invention]
In order to interfere with such frequency hopping communication, the hopping signal (hereinafter referred to as FH signal) must be detected and followed from a large number of radio waves existing in the real sky. Moreover, the detection process must be performed in a very short time. That is, the signal must be detected and interrupted immediately after the start of communication.
[0005]
The present invention provides a communication jamming device that detects the FH signal and performs jamming in a very short time after frequency hopping communication is started.
[0006]
[Means for Solving the Problems]
The communication jamming method according to the present invention is a communication jamming device for jamming a frequency hopping communication in which a first frequency signal and a second frequency signal having different transmission frequencies are sequentially transmitted. Radiates interfering radio waves corresponding to the signal, stops emission of the interfering signal before the end of the first frequency signal, and detects an end timing of the first frequency signal and a signal appearing after a predetermined time has elapsed from the end timing. Thus, the second frequency signal is detected, and the jamming radio wave corresponding to the detected second frequency signal is radiated.
[0007]
In the communication interference method according to the present invention, the first frequency signal is detected by determining the arrival direction of the received signal, and the second frequency signal is received without determining the arrival direction of the received signal. Detection is based on the occupied frequency bandwidth of the signal, the modulation scheme, or the signal level.
[0010]
Furthermore, in the communication jamming apparatus according to the present invention, the first and second receiving means arranged with a difference in distance from the hopping signal generation source, and the difference between the distances with the first receiving means. A calculating means for converting a reception time difference generated with the second receiving means, a first extracting means for extracting a radio wave signal arriving from a known direction from an output of the first receiving means, and a first extraction Second extraction means for extracting, as a hopping signal, a radio signal in which the difference between the reception time at the first reception means and the reception time at the second reception means is the reception time difference from the radio signal extracted by the means; , A third extraction means for extracting the hopped signal of the hop destination of the extracted hopping signal from the output of the first or second receiving means based on a known timing between the hopping signals, and the third Detecting means and a disturbance means for radiating jamming based on the frequency of the extracted hopping signal.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
In the first embodiment, the source direction of the FH signal to be disturbed (hereinafter referred to as the target direction), the same frequency duration of the FH signal to be disturbed (that is, the duration of each hopping signal, shown in FIG. 8) Assume that T2) and the hopping interval of the FH signal to be disturbed (that is, T3 shown in FIG. 8) are known in advance. The target direction can be specified by using a radar device or the like. Also, even if the same frequency duration and hopping interval are not known in advance, they can be easily known by the method described later. Hereinafter, the FH signal to be disturbed is referred to as a target signal.
[0012]
The disturbing method according to the first embodiment includes an initial process for detecting a target signal and a tracking process for continuously tracking the detected target signal. In the initial process of the first embodiment, a signal arriving from the same direction as the target direction is detected as a target signal. Thereby, even if the hopping pattern of the target signal is not accurately grasped, the target signal can be detected.
[0013]
However, if such target signal detection based on the arrival direction is performed for each hopping, it takes time to specify the arrival direction, and the interference execution time is shortened. Therefore, in the following process of the first embodiment, the FH signal is continuously followed by a method different from the initial process.
[0014]
In the following process of the first embodiment, the FH signal is continuously followed based on a known timing (here, a hopping interval) between the hopping signals. More specifically, the FH signal is continuously followed by monitoring the reception start time and reception end time of each reception signal obtained by sweeping reception in the real space. In general FH communication, the time difference (that is, the hopping interval) between the signal end time of the Nth hop and the signal start time of the (N + 1) th hop is constant. Therefore, here, after the end of the FH signal detected in the initial process (hereinafter referred to as the first hop signal), a signal that newly appears when a predetermined hopping interval that has been known in advance has passed is the next hop destination signal. (Ie, 2nd hop signal) to detect and interfere. Thereafter, similarly, a signal appearing at the same hopping interval is followed and interfered as a target signal. Such detection processing based on the hopping interval can be performed in a very short time compared to detection processing based on the direction of arrival, so that it is possible to reduce the time for which interference must be stopped for detection, and as a result, time that can be spent on interference. Will increase.
[0015]
FIG. 1 is an explanatory diagram for explaining a disturbing method of the disturbing device according to the first embodiment. In the figure, the horizontal axis represents time and the vertical axis represents frequency. Further, fp1 is a first hop signal detected in the initial process, fp2 is a second hop signal detected in the following process, fp3 and fp4 are FH signals continuously detected in the following tracking process, and chain lines fx1 to fx4 are target values. It is a signal other than a signal.
[0016]
Periods Tp1 to Tp4 are transmission periods of jamming radio waves. The time widths of these transmission periods Tp1 to Tp4 are determined based on the same frequency duration of the target signal that is known in advance. More specifically, after the target signal is detected, a jamming radio wave is transmitted to the detected target signal. Then, transmission of the jamming radio wave is stopped before the target radio wave hops to the next frequency. That is, during transmission of the jamming radio wave, the target signal cannot be detected due to the interference radio wave, so the jamming is temporarily stopped to prepare for the detection of the target signal of the next hop destination. Thereafter, the same processing is repeated, and the follow-up and interference are terminated when there is no signal appearing at the hopping interval.
[0017]
This will be described in more detail. FIG. 2 is a configuration diagram illustrating the communication jamming device according to the first embodiment. In the figure, 4 is a receiving means for receiving a radio wave signal coming from a radio wave generation source with an antenna, 1 is an initial processing means for performing the above-described initial process, and 2 is a tracking means for following the signal detected by the initial processing means 1. Reference numeral 3 denotes a disturbing unit that emits jamming radio waves to the signal detected by the initial processing unit 1 and the signal tracked by the following unit 2. The initial processing means 1 is composed of azimuth determining means for measuring the arrival azimuth of each input signal and extracting a signal coming from the same azimuth as the target azimuth.
[0018]
The operation will be described. The initial processing means 1 shown in FIG. 2 extracts from the output signal of the receiving means 4 a signal arriving from the same direction as the previously known target azimuth, and notifies the disturbing means 3 of the frequency of the signal. There are various methods for determining the direction of arrival of radio waves. For example, a large number of omnidirectional antennas are arranged on the circumference, and these are sequentially scanned and received to utilize the Doppler effect. The direction of arrival can be specified accurately.
[0019]
The jamming means 3 radiates a jamming radio wave having a frequency notified from the initial processing means 1. That is, a jamming radio wave is radiated for the first hop signal. This interference continues until just before the target radio wave hops to the next frequency. The timing at which the target radio wave hops to the next frequency can be predicted from the same frequency duration that is known in advance.
[0020]
Following the end of the disturbance of the first hop signal, the follower 2 monitors the end time of the first hop signal. Then, after the end of the first hop signal, a newly appearing signal is detected as the next second hop signal when a previously known hopping interval elapses, and the frequency of the signal is notified to the disturbing means 3. Similar to the first hop signal, the disturbing means 3 radiates an interfering radio wave having the frequency until just before the second hop signal hops to the next frequency. After the third hop, the following unit 2 and the blocking unit 3 repeat the same processing as the second hop to detect and block the target signal.
[0021]
FIG. 3 is a conceptual diagram illustrating target detection and jamming radio waves. In the figure, 11 is a communication jamming device, w1 is a target signal source existence range, w2 is a target azimuth spread, and w3 is a range in which jamming radio waves are radiated (that is, directivity of jamming radio waves).
[0022]
As described above, the target signal is detected based on the arrival direction of the received signal, and then the target signal is detected based on the hopping interval, so that the FH signal can be detected in a very short time after the communication starts. For this reason, the time for which the interruption must be stopped can be made extremely short.
[0023]
In addition, the method of performing arrival direction analysis every time can interfere with a target signal having a very short duration of the same frequency, which cannot be disturbed due to a delay in processing time.
[0024]
Here, the following process based on the hopping interval is exemplified as the following process based on the “known timing between the hopping signals”, but is not limited to this, for example, the appearance periodicity of the hopping signal (that is, the hopping signal) The hopping signal may be followed based on the signal duration T2 + the hopping interval T3).
[0025]
Embodiment 2. FIG.
In the initial process of the first embodiment, the target signal is detected by analyzing the arrival direction of the received signal. However, when there are a plurality of signal transmission sources in the same direction, the target signal cannot be identified / separated only by analyzing the arrival direction. Therefore, in the initial process of the second embodiment, the target signal is detected by using the analysis of the occupied frequency bandwidth of the received signal together. In the second embodiment, it is assumed that the target orientation and the occupied frequency bandwidth of the target signal (hereinafter referred to as the target signal bandwidth) are known in advance.
[0026]
FIG. 4 is a configuration diagram illustrating the communication jamming device according to the second embodiment. In the figure, the same or corresponding parts as in FIG. Here, the initial processing means 1 includes an azimuth determining means 5 and a bandwidth determining means 6. The azimuth determining means 5 measures the arrival azimuth of each input signal and extracts a signal coming from the same azimuth as the target azimuth. The bandwidth determination means 6 measures the occupied frequency bandwidth of each input signal, and extracts the target signal by comparing the measured value with the target signal bandwidth.
[0027]
The operation of the initial process will be described. The direction determining unit 5 extracts a signal coming from the same direction as the target direction from the output signal of the receiving unit 4 and inputs the extraction result to the bandwidth determining unit 6. The bandwidth determination unit 6 extracts the target signal by comparing the occupied frequency bandwidth of the input signal with the target signal bandwidth, and notifies the interference unit 3 of the frequency of the extracted signal. The jamming means 3 radiates a jamming radio wave having a frequency notified from the bandwidth judgment means 6. Thereafter, the operation of the following process is the same as that in FIG.
[0028]
As described above, by detecting the target signal based on the arrival direction of the received signal and the occupied frequency bandwidth of the received signal, the target signal can be detected accurately even when there are a plurality of signal transmission sources in the same direction. Can do. Even in the following process, the detection accuracy can be improved by using both the analysis of the hopping interval and the analysis of the occupied frequency bandwidth.
[0029]
Embodiment 3 FIG.
In the initial process of the second embodiment, the target signal is identified and separated based on the arrival direction of the received signal and the occupied frequency bandwidth of the received signal. In the third embodiment, the target signal is identified and separated based on the arrival direction of the received signal and the modulation method of the received signal. In the third embodiment, it is assumed that the target direction and the modulation method of the target signal are known in advance. Here, the modulation scheme means a modulation scheme such as AM, FM, or PSK.
[0030]
FIG. 5 is a configuration diagram illustrating the communication jamming device according to the third embodiment. In the figure, the same or corresponding parts as in FIG. Here, the initial processing unit 1 includes an azimuth determining unit 5 and a modulation method determining unit 7. The modulation scheme determination means 7 analyzes the modulation scheme of each input signal and extracts a signal that is modulated by the same modulation scheme as the target signal.
[0031]
The operation of the initial process will be described. The direction determining means 5 extracts a signal coming from the same direction as the target direction from the output signal of the receiving means 4 and inputs the extraction result to the modulation method determining means 7. The modulation method determination unit 7 extracts a signal modulated by the same modulation method as the target signal from the signal input from the direction determination unit 5 and notifies the interference unit 3 of the frequency. The jamming means 3 radiates a jamming radio wave having a frequency notified from the modulation method judgment means 7. Thereafter, the operation of the following process is the same as that in FIG.
[0032]
As described above, by detecting the target signal based on the arrival direction of the received signal and the modulation method of the received signal, the target signal can be detected accurately even when there are a plurality of signal transmission sources in the same direction. . Even in the following process, the detection accuracy can be improved by using the analysis of the hopping interval and the analysis of the modulation method in combination.
[0033]
Embodiment 4 FIG.
In the fourth embodiment, the target signal is identified and separated based on the arrival direction of the received signal and the signal level of the received signal. In the fourth embodiment, it is assumed that the target direction and the signal level at the time of receiving the target signal (hereinafter referred to as the target signal reception level) are known in advance.
[0034]
FIG. 6 is a configuration diagram illustrating the communication jamming device according to the fourth embodiment. In the figure, the same or corresponding parts as in FIG. Here, the initial processing unit 1 includes an azimuth determining unit 5 and a reception level determining unit 8. The reception level determination means 8 extracts a signal having the same reception level as the target signal reception level from the input signals.
[0035]
The operation of the initial process will be described. The direction determination means 5 extracts a signal coming from the same direction as the target direction from the output signal of the reception means 4 and inputs the extraction result to the reception level determination means 8. The reception level determination unit 8 extracts a signal having a target signal reception level from the signal input from the direction determination unit 5 and notifies the interference unit 3 of the frequency. The jamming means 3 radiates a jamming radio wave having a frequency notified from the reception level judgment means 8. Thereafter, the operation of the following process is the same as that in FIG. Even in the following process, the detection accuracy can be improved by combining the analysis of the hopping interval and the analysis of the reception level.
[0036]
As described above, by detecting the target signal based on the arrival direction and the reception level of the received signal, the target signal can be detected accurately even when there are a plurality of signal transmission sources in the same direction. Even in the following process, the detection accuracy can be improved by combining the analysis of the hopping interval and the analysis of the reception level.
[0037]
Embodiment 5 FIG.
The communication jamming apparatus according to Embodiment 5 has first and second receiving means at two different points, respectively. In the fifth embodiment, the target orientation viewed from the first receiving means, the distance from the target signal generating source to the first receiving means, and the distance from the target signal generating source to the second receiving means are known in advance. It shall be.
[0038]
FIG. 7 is a configuration diagram illustrating a communication jamming device according to the fifth embodiment. In the figure, the same or corresponding parts as in FIG. Here, 4 is a first receiving means, and the initial processing means 1 is composed of a direction determining means 5, a correlation determining means 9, and a second receiving means 10. It is assumed that the second receiving unit 10 is installed at a location different from the first receiving unit 4.
[0039]
The operation of the initial process will be described. The direction determining means 5 extracts a signal coming from the same direction as the target direction viewed from the first receiving means 4 from the output signal of the first receiving means 4, and outputs the extraction result to the correlation determining means 9 together with the reception time. . On the other hand, the second receiving means 10 outputs each signal received at that point to the correlation determining means 9 together with the reception time. The correlation determination unit 9 extracts a target signal based on the temporal correlation of signals from the direction determination unit 5 and the reception unit 10. That is, even if the signals are simultaneously emitted from the same signal generation source, a certain time difference occurs in the reception time in each receiving means. The correlation determination unit 9 extracts a signal received by the second reception unit 10 with a certain time difference from the signals input from the direction determination unit 5 as a target signal. Here, the constant time difference means that the distance from the target signal generating source to the first receiving means 4 is X, the distance from the target signal generating source to the second receiving means 10 is Y, and the radio wave transmission speed is V. Then, | X−Y | / V.
[0040]
The jamming means 3 radiates jamming waves having the same frequency as the signal extracted by the correlation judging means 9 as the target signal. Thereafter, the operation of the following process is the same as that in FIG.
[0041]
As described above, by extracting the target signal based on the difference between the signal reception times at two different points, the target signal can be accurately detected even when a plurality of signal transmission sources exist in the same direction. In particular, by moving the second receiving means 10 having a small apparatus scale to a position where the target can be identified, it is not necessary to move the main body of the disturbing apparatus having a large apparatus scale.
[0042]
Embodiment 6 FIG.
In the first embodiment, the first hop signal detected in the initial process is disturbed. In the sixth embodiment, the first hop signal detected in the initial process is not disturbed, but only the signals after the second hop signal detected in the following process are disturbed.
[0043]
Explain why. As described above, in the initial process, the target signal is detected based on the arrival direction of the received signal. In addition, the processing takes a lot of time. Therefore, the time during which the detected signal, that is, the first hop signal can be disturbed is extremely short, and the disturbing effect is small. Furthermore, when determining the disturbance continuation time for the first hop signal, it is necessary to specify the start time of the first hop signal, and the control is complicated.
[0044]
On the other hand, in the following process, the target signal is detected based on the hopping interval, and the time required for this detection process is extremely short. Therefore, the time during which the detected signal, that is, the signal after the second hop signal can be disturbed is long, and the disturbing effect is large. Furthermore, since the time required for the detection process after the second hop is approximately the same every time (for each hop), the interference time for each hop can be made constant.
[0045]
Therefore, in the sixth embodiment, the control is complicated, the first hop signal with little interference effect is not disturbed, the control is simple, and only the signals after the second hop signal with a large interference effect are obtained. Interfering with communication. Thereby, the structure of the jamming device can be simplified, and an inexpensive communication jamming device can be obtained.
[0046]
Embodiment 7 FIG.
The first embodiment has been described on the assumption that the hopping interval of the target signal and the same frequency duration are known in advance. In the seventh embodiment, a method for obtaining these when they are unknown will be described. Note that the target orientation is known in advance as in the first embodiment.
[0047]
In the seventh embodiment, from the signals received from the real space, a signal sequence coming from the target direction and having the same time interval between the reception end time and the reception start time of the next signal is extracted as the target signal. . Thereby, the hopping interval and the same frequency duration of the target signal can be obtained.
[0048]
Such an analysis of the hopping interval and the same frequency duration can be performed in a shorter time than an analysis of a hopping pattern (that is, a change in hopping frequency for one period). For example, in order to know the frequency configuration of the hopping pattern, it is necessary to analyze the change in the hopping frequency over one period. On the other hand, as for the hopping interval and the same frequency duration, if three or more continuous hopping signals can be observed, it can be predicted that it is a hopping signal, and the hopping interval and frequency duration can be known.
[0049]
For example, assume that three signals A, B, and C are received sequentially. At this time, when (the reception start time of signal B−the reception end time of signal A) and (the reception start time of signal C−the reception end time of signal B) are equal, these can be predicted as hopping signals.
[0050]
Thus, by extracting a signal sequence having the same time interval between the reception end time and the reception start time of the next signal from the signals received from the real space as a target signal, the hopping interval and the same frequency can be shortened in a short time. You can get the duration.
[0051]
Therefore, even if the target signal hopping interval and the same frequency duration time are not known in advance, they can be analyzed in a short time, so that the interference method shown in the first embodiment can be quickly started.
[0052]
【The invention's effect】
The communication jamming method according to the present invention is a communication jamming device for jamming a frequency hopping communication in which a first frequency signal and a second frequency signal having different transmission frequencies are sequentially transmitted. Radiates interfering radio waves corresponding to the signal, stops emission of the interfering signal before the end of the first frequency signal, and detects an end timing of the first frequency signal and a signal appearing after a predetermined time has elapsed from the end timing. As a result, the second frequency signal is detected and the jamming radio wave corresponding to the detected second frequency signal is radiated, so that the second frequency signal can be detected and the disturbance can be started in a short time.
[0053]
In the communication interference method according to the present invention, detection is performed by determining the arrival direction of the received signal before the first frequency signal, and the second frequency signal is received without determining the arrival direction of the received signal. Since detection is performed based on the occupied frequency bandwidth of the signal, the modulation method, or the signal level, and the elapsed time from the end timing of the first frequency signal, the frequency hopping signal whose hopping pattern is unknown is set as the arrival direction of the received signal. Detection can be performed based on the second frequency signal and can be detected and disturbed quickly.
[0056]
Furthermore, in the communication jamming apparatus according to the present invention, the first and second receiving means arranged with a difference in distance from the hopping signal generation source, and the difference between the distances with the first receiving means. A calculating means for converting to a reception time difference generated with the second receiving means, a first extracting means for extracting a radio signal arriving from a known direction from an output of the first receiving means, and a first extraction Second extraction means for extracting, as a hopping signal, a radio signal in which the difference between the reception time at the first reception means and the reception time at the second reception means is the reception time difference from the radio signal extracted by the means; , A third extraction means for extracting the hopped signal of the hop destination of the extracted hopping signal from the output of the first or second receiving means based on a known timing between the hopping signals, and the third Since detection means has a disturbing means for radiating jamming based on the frequency of the extracted hopping signals, hopping signal is interference target can be detected accurately.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining a jamming method of a communication jamming device according to a first embodiment.
FIG. 2 is a configuration diagram illustrating a communication jamming device according to the first embodiment;
FIG. 3 is a conceptual diagram illustrating a target detection and obstruction method.
FIG. 4 is a configuration diagram illustrating a communication jamming device according to a second embodiment;
FIG. 5 is a configuration diagram illustrating a communication jamming device according to a third embodiment;
FIG. 6 is a configuration diagram illustrating a communication jamming device according to a fourth embodiment;
FIG. 7 is a configuration diagram illustrating a communication jamming device according to a fifth embodiment;
FIG. 8 is an explanatory diagram illustrating communication of a general frequency hopping method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Initial processing means 2 Following means 3 Interference means 4 (First) receiving means 5 Direction determining means 6 Bandwidth determining means 7 Modulation method determining means 8 Reception level determining means 9 Correlation determining means 10 Second receiving means

Claims (3)

A communication interference method for interfering with frequency hopping communication in which a first frequency signal and a second frequency signal having different transmission frequencies are sequentially transmitted,
Radiates jamming radio waves corresponding to the first frequency signal, stops radiating the jamming signal before the end of the first frequency signal, and finishes the end timing of the first frequency signal and a predetermined time from the end timing. A communication jamming method, comprising: detecting an appearing signal to detect the second frequency signal and radiating a jamming radio wave corresponding to the detected second frequency signal. Detecting the first frequency signal by determining the arrival direction of the received signal;
The second frequency signal is detected based on the occupied frequency bandwidth, modulation method, or signal level of the received signal and the elapsed time from the end timing of the first frequency signal without determining the arrival direction of the received signal. The communication jamming method according to claim 1, wherein: First and second receiving means arranged with a difference in distance from the hopping signal source;
Arithmetic means for converting the difference in distance into a reception time difference generated between the first receiving means and the second receiving means;
First extraction means for extracting a radio signal arriving from a known direction from the output of the first reception means;
A second radio signal is extracted as a hopping signal from the radio signal extracted by the first extraction means, the radio signal having a difference between the reception time at the first reception means and the reception time at the second reception means is the reception time difference. Extraction means,
Third extraction means for extracting a hopping signal hop ahead of the extracted hopping signal from the output of the first or second receiving means based on a known timing between the hopping signals;
An interference device for frequency hopping communication, comprising: interference means for emitting interference radio waves based on the frequency of the hopping signal extracted by the third extraction means.

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