JP6143545B2 - Radio frequency signal identification apparatus and radio frequency signal identification method - Google Patents

Description

  The present invention relates to a radio frequency signal identification device and a radio frequency signal identification method for identifying a radio frequency signal.

  Many wireless devices are installed in an environment that radiates radio frequency signals. Developed technology to identify received radio frequency signals and identify the radio devices that radiated radio frequency signals among many radio devices. Has been.

  In the conventional radio frequency signal identification device, a radio frequency signal including a rising portion whose amplitude increases from approximately zero to a peak value and a falling portion whose amplitude decreases from the peak value to approximately zero is targeted. A radio frequency signal is identified based on the amplitude versus phase characteristic (see, for example, Patent Document 1).

  Specifically, first, a signal including an amplitude changing portion whose amplitude changes at the rising or falling portion of the radio frequency signal, and an amplitude saturation portion having an amplitude corresponding to the peak value continuously from the amplitude changing portion. A part is extracted.

  Subsequently, based on the amplitude change and the phase change in the signal portion, an amplitude-to-phase characteristic representing a phase change with respect to the amplitude change is output, and this amplitude-to-phase characteristic is recorded in advance as a radio frequency signal feature quantity. The radio frequency signal is identified by collating with the feature amount of the device.

Japanese Patent No. 4675216

Hideki Aso, Koji Tsuda, Noboru Murata, “Statistics of Pattern Recognition and Learning”, Iwanami Shoten, 2003, p. 12-31, 107-115

However, the prior art has the following problems.
The radio frequency signal identification device described in Patent Document 1 has a problem that radio frequency signals cannot be identified only from a region where the signal amplitude is substantially constant, and there are few opportunities for identification. In addition, when noise is superimposed on a radio frequency signal, the amplitude vs. phase characteristic is changed and observed particularly in a region having a small amplitude, leading to a problem that the identification accuracy of the radio frequency signal is deteriorated.

  The present invention has been made to solve the above-described problems, and can identify a radio frequency signal even in a region where the signal amplitude is substantially constant, and can also identify by superimposing noise. An object of the present invention is to obtain a radio frequency signal identification device and a radio frequency signal identification method capable of suppressing deterioration in accuracy.

Identification device of the radio frequency signal according to the present invention is based on a radio frequency signal, the signal characteristic output unit for extracting a cycle difference feature of the radio frequency signals, recording storage unit for recording the verification signal characteristic pattern, and the radio frequency signal An apparatus for identifying a radio frequency signal comprising a collation unit that collates a periodic difference feature with a collation signal feature pattern and identifies a radio frequency signal, wherein the signal feature output unit is a periodic solution in which modulation of the radio frequency signal is repeated. A difference between corresponding complex samples between predetermined different periods of the part , or a sum of a first period including one or more predetermined periods and a period different from the sum of the first periods It has a period difference feature extraction unit that extracts a difference of complex samples between each complex waveform in the sum of the second periods as a period difference feature of the radio frequency signal .

The radio frequency signal identification method according to the present invention includes a signal feature output unit that extracts a period difference feature of a radio frequency signal based on the radio frequency signal , a record storage unit that records a verification signal feature pattern, and a radio frequency signal A radio frequency signal identification method executed by a radio frequency signal identification device including a collation unit that collates a periodic difference feature of a signal with a collation signal feature pattern and identifies a radio frequency signal, the signal feature output unit A difference between corresponding complex samples between predetermined different periods of the periodic solution portion where the modulation of the radio frequency signal is repeated , or a sum of a first period including one or more predetermined periods The difference between the complex samples between the complex waveforms in the second period sum including a period different from the sum period of the first period is defined as the period difference feature of the radio frequency signal. Those having a period difference feature extraction step of extracting.

According to the radio frequency signal identification device and radio frequency signal identification method according to the present invention, the signal feature output unit (step) extracts a period difference feature that extracts a feature amount of a periodic solution portion where the modulation of the radio frequency signal is repeated. It has an extraction unit (step).
Thereby, an individual difference can be extracted from the signal of the area | region where an amplitude is substantially constant, and a radio frequency signal can be identified. Further, identification can be performed in a region where power is large and noise resistance is high.
That is, even in a region where the signal amplitude is substantially constant, identification of the radio frequency signal can be performed, and degradation of identification accuracy due to noise superposition can be suppressed.

It is a block block diagram which shows the identification device of the radio frequency signal which concerns on Embodiment 1 of this invention. In the radio frequency signal identification device according to the first embodiment of the present invention, it is an explanatory view illustrating a periodic solution portion (periodic region) in the signal extracted by the amplitude versus phase characteristic extraction unit. 3 is a graph showing in-phase components and quadrature components (complex number components) of a difference between a waveform of periods 2 to 6 and a waveform of periods 1 to 5 in the periodic solution portion shown in FIG. 2.

  Hereinafter, preferred embodiments of a radio frequency signal identification device and a radio frequency signal identification method according to the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals. To explain.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a radio frequency signal identification apparatus according to Embodiment 1 of the present invention. In FIG. 1, the radio frequency signal identification apparatus includes an A / D converter 10, a signal feature output unit 20, a record storage unit 30, and a verification unit 40.

  The signal feature output unit 20, the record storage unit 30, and the collation unit 40 are configured by a computer, for example. The signal feature output unit 20 and the collation unit 40 are functional blocks executed by the CPU of the computer. Further, the recording storage unit 30 is constituted by, for example, a memory built in or attached to the computer, a hard disk, and the like.

  The A / D converter 10 digitizes both the in-phase component and the quadrature component of the received unknown radio frequency signal SR and outputs a radio frequency signal P.

  The signal feature output unit 20 receives the digitized radio frequency signal P and outputs a radio frequency signal feature pattern CP1. The signal feature output unit 20 that outputs the radio frequency signal feature pattern CP1 of the digitized radio frequency signal P has an amplitude-to-phase characteristic extraction unit 21, and the amplitude-to-phase characteristic extraction unit 21 is a period difference feature extraction unit. 22 is included.

  The amplitude-to-phase characteristic extracting unit 21 outputs one or more combinations of the amplitude-to-phase characteristic extracted by the period difference feature extracting unit 22 described later and the amplitude-to-phase characteristic described in Patent Document 1 described above.

  The periodic difference feature extraction unit 22 identifies a periodic solution portion (periodic region) in which modulation is repeated from the signal extracted by the amplitude versus phase characteristic extraction unit 21, and extracts a periodic difference feature (feature amount). Here, FIG. 2 illustrates a periodic solution portion (periodic region) in the signal extracted by the amplitude versus phase characteristic extraction unit 21. In FIG. 2, the modulation frequency of the received signal is plotted against time.

  The period difference feature extraction unit 22 calculates a difference z (k + (m−1) T) −z (k + () of a corresponding complex sample in a predetermined period m and period n (m and n are different period numbers). n-1) T) (k = 1, 2,..., T represents a subscript of the sample, and T represents the number of samples included in one period) and is output.

  In addition, the period difference feature extraction unit 22 includes a predetermined period sum M and a period sum N (the period sum M includes one or more periods, and the period sum N is an integer h other than 0). On the other hand, the difference between each complex waveform in each cycle m included in the sum M of cycles (including the m + h-th cycle) is obtained and used as a feature of the waveform.

  Here, as an example, FIG. 3 shows a graph of the in-phase component and quadrature component (complex number component) of the difference between the waveform of periods 2 to 6 and the waveform of periods 1 to 5 in the periodic solution portion shown in FIG. .

  In FIG. 3, if the periodic solution portion in the signal extracted by the amplitude vs. phase characteristic extraction unit 21 is strictly a periodic solution, the above-described periodic difference is 0 for all the subscripts, and the origin of FIG. It becomes the point. This case is clearly not suitable for identifying individual differences, but FIG. 3 shows a characteristic deviation from an ideal periodic solution.

  Such characteristic divergence is caused by individual variations that occur because individual parts constituting each transmitter cannot be manufactured in exactly the same way. That is, it is considered that the periodic solution that should be reproduced accurately is expressed as the individuality of each part. These individual differences often have a smaller energy than the main period component, but by taking the period difference, the main period component is canceled and can be observed.

At this time, the cumulant component defined below can be calculated from the above-described period difference. First, random variables x ₁ , x ₂ ,. . . , X _M is defined by the following equation (1).

In formula (1), ξ ₁ , ξ ₂ , ξ _M represent real numbers, and m ₁ , m ₂ ,. . . , _{M M} represents a non-negative integer, the symbol <A> represents the sample mean of the random variable A, and the symbol! Indicates the factorial operation, and Σ indicates the sum of possible terms.

Here, from the logarithm of the moment generating function expressed by the following equation (2), for any non-negative integer pair (m ₁ , m ₂ ,..., _{M M} ), Define cumulants with coefficients.

Cumulant of the formula (3), the condition Σ _k m _k ≧ 3 nonnegative integer pairs that satisfy the _{(m 1, m 2, ...} , m M) with respect to, the thermal noise is superimposed Since it has the property that the value does not change in principle, identification that is strong against noise is possible.

  In addition to the technique described in Patent Document 1, the amplitude versus phase characteristic extraction unit 21 outputs a combination of zero or more predetermined period difference waveforms and cumulants output from the period difference feature extraction unit 22. May be. Further, the signal feature output unit 20 may output these in addition to the technique described in Patent Document 1.

  Returning to FIG. 1, the record storage unit 30 records a large number of collation signal feature patterns CP1ref that are collated with the unknown radio frequency signal feature pattern CP1 output from the signal feature output unit 20. This verification signal feature pattern CP1ref is obtained by extracting each radio frequency signal feature pattern CP1 in advance for a number of known wireless devices such as pulse radar devices and wireless communication devices.

  Specifically, the record storage unit 30 actually receives the radio frequency signal SR from each known radio device, extracts each radio frequency signal feature pattern CP1 by the signal feature output unit 20, and extracts these known radio frequency signals. The radio frequency signal feature pattern CP1 is recorded in advance as a verification signal feature pattern CP1ref.

  The matching signal feature pattern CP1ref is obtained in advance for each known wireless device by using the same means as the signal feature output unit 20 regardless of the signal feature output unit 20, and this is obtained. May be recorded in the recording storage unit 30 as the verification signal feature pattern CP1ref.

  At this time, each matching signal feature pattern CP1ref is recorded with the corresponding wireless device name or a unique identification number representing the wireless device name. Further, the recording storage unit 30 may record zero or more combinations of a predetermined cyclic difference waveform and cumulant output from the cyclic difference feature extraction unit 22.

  The collation unit 40 collates the unknown radio frequency signal feature pattern CP1 output from the signal feature output unit 20 with the known collation signal feature pattern CP1ref recorded in the record storage unit 30. This collation is performed by a general method, that is, a numerical comparison between the radio frequency signal feature pattern CP1 based on the threshold value and the collation signal feature pattern CP1ref.

  For example, when the correlation coefficient between the radio frequency signal feature pattern CP1 and the matching signal feature pattern CP1ref exceeds a threshold, it is determined that these signal feature patterns match each other. Alternatively, when the sum of squares of the difference between the radio frequency signal feature pattern CP1 and the verification signal feature pattern CP1ref is equal to or less than a threshold value, it is determined that these signal feature patterns match each other.

  In addition, when an unknown radio frequency signal feature pattern CP1 is input from the signal feature output unit 20, the collation unit 40 reads a number of known collation signal feature patterns CP1ref recorded in the recording storage unit 30, and performs radio frequency It is sequentially determined whether or not the signal feature pattern CP1 and the matching signal feature pattern CP1ref match each other.

  When the matching unit 40 finds a matching known matching signal feature pattern CP1ref, the input unknown radio frequency signal feature pattern CP1 is determined to be the same as the matching known matching signal feature pattern CP1ref. Then, the wireless device that has emitted the radio frequency signal feature pattern CP1 is identified from the wireless device name added to the known verification signal feature pattern CP1ref or its identification number.

  On the other hand, if all of the verification signal feature patterns CP1ref recorded in the recording storage unit 30 do not match the input unknown radio frequency signal feature pattern CP1 in the verification unit 40, this unknown radio frequency signal feature pattern. CP1 is identified as a radio frequency signal feature pattern of a new radio frequency signal SR that is not recorded in the recording storage unit 30. At this time, the radio frequency signal feature pattern CP1 is recorded in the recording storage unit 30 as a new matching signal feature pattern CP1ref.

  The collation unit 40 may collate zero or more combinations of a predetermined cyclic difference waveform and cumulant output from the cyclic difference feature extraction unit 22. Here, in addition to the technique described in Patent Document 1, the template matching method described in Non-Patent Document 1, k-recently is used for collating zero or more combinations of a predetermined period difference waveform and cumulant. Any of a side identification method, a subspace method, a neural network, and a support vector machine may be used.

As described above, according to the first embodiment, the signal feature output unit includes the periodic difference feature extraction unit that extracts the feature amount of the periodic solution portion where the modulation of the radio frequency signal is repeated.
Thereby, an individual difference can be extracted from the signal of the area | region where an amplitude is substantially constant, and a radio frequency signal can be identified.
Further, identification can be performed in a region where power is large and noise resistance is high.
That is, even in a region where the signal amplitude is substantially constant, identification of the radio frequency signal can be performed, and degradation of identification accuracy due to noise superposition can be suppressed.

The period difference feature extraction unit analyzes a signal difference between the period regions of the radio frequency signal.
As a result, the modulation component common between the periods is canceled, and even if the modulation component is very small, the individual difference can be extracted and the identification can be executed.

The period difference feature extraction unit outputs a cumulant of a difference waveform of the signal between the period regions of the radio frequency signal.
As a result, even if thermal noise is superimposed, the influence can be eliminated in principle, and identification with high noise tolerance can be executed.

  10 A / D converter, 20 signal feature output unit, 21 amplitude-to-phase characteristic extraction unit, 22 period difference feature extraction unit, 30 record storage unit, 40 verification unit.

Claims (6)

Based on the radio-frequency signal, the signal feature output unit that extracts a periodic difference feature of the radio frequency signals, recording storage unit for recording the verification signal feature pattern, and with the period difference feature of the radio-frequency signal and the comparison signal, wherein the pattern And a radio frequency signal identification device including a collation unit for identifying a radio frequency signal,
The signal feature output unit includes a difference between corresponding complex samples between predetermined different periods of a periodic solution portion where the modulation of the radio frequency signal is repeated , or a first period including one or more predetermined periods And the difference of complex samples between the complex waveforms in the sum of the second period including a period different from the period of the sum of the first period is extracted as the period difference feature of the radio frequency signal. A radio frequency signal identification device having a period difference feature extraction unit. The radio frequency signal identification device according to claim 1, wherein the periodic difference feature extraction unit uses a deviation from an origin in a coordinate system of the in-phase component and the quadrature component of the difference of the complex sample as the periodic difference feature . The radio frequency signal identification apparatus according to claim 2, wherein the period difference feature extraction unit uses a cumulant of a difference waveform of a complex sample as the period difference feature . Based on the radio-frequency signal, the signal feature output unit that extracts a periodic difference feature of the radio frequency signals, recording storage unit for recording the verification signal feature pattern, and with the period difference feature of the radio-frequency signal and the comparison signal, wherein the pattern And a radio frequency signal identification method executed by a radio frequency signal identification device including a collation unit that identifies a radio frequency signal,
A difference of corresponding complex samples between predetermined different periods of the periodic solution portion where the modulation of the radio frequency signal is repeated, which is executed in the signal feature output unit , or a first including one or more predetermined periods The difference of complex samples between the complex waveforms in the sum of one period and the sum of a second period including a period different from the period of the first period is the period difference feature of the radio frequency signal. A method for identifying a radio frequency signal, comprising: extracting a periodic difference feature as a step. The radio frequency signal identification method according to claim 4, wherein the periodic difference feature extraction step uses a deviation from the origin in the coordinate system of the in-phase component and the quadrature component of the difference of the complex sample as the periodic difference feature . The radio frequency signal identification method according to claim 5, wherein the period difference feature extraction step uses a cumulant of a difference waveform of a complex sample as the period difference feature .

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