Spectrum analysis program, signal processing device, radar device, communication terminal, fixed communication device, and recording medium

Abstract

This spectrum analysis program causes a computer system to execute: the generation of first frequency spectrum data obtained by taking, from a wireless signal, continuous values of frequency values by means of an AF method; the generation of second frequency spectrum data obtained by taking, from the wireless signal, discrete values of the frequency values by means of a frequency spectrum analysis method in which a reference power value of the wireless signal is output; the association of the nearest frequency values among frequency values of the first frequency spectrum data and frequency values of the second frequency spectrum data; and the generation of frequency spectrum data as an analysis result on the basis of a comparison between a first power value of a first frequency of the first frequency spectrum data and a second power value of a second frequency of the second frequency spectrum data corresponding to the first frequency.

Description

[Technical field]

[0001] The present invention relates to a spectrum analysis program, a signal processing device, a radar device, a communication terminal, and a recording medium. [Background technology]

[0002] As a high-resolution algorithm for estimating the direction of arrival of radio waves, for example, the Multiple Signal Classification (MUSIC) method is known. Patent Document 1 describes a method in which a plurality of incoming waves arriving from each direction are received via a plurality of antennas arranged at different positions, and the number and direction of the incoming waves are estimated from the received signals of each antenna using the MUSIC method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-121716 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method described in Patent Document 1, when the estimated number of waves is greater than the actual number of arriving waves, many spurious waves appear, among which spurious waves may have power levels above a threshold, making it difficult to distinguish between actual arriving waves and spurious waves.

[0005] Therefore, an object of the present invention is to propose an analysis method that can solve such problems and has high resolution and can improve the accuracy of estimating the power value of frequency spectrum data of a radio signal. [Means for solving the problem]

[0006] In order to achieve the above object, a spectrum analysis program according to the present invention causes a computer to execute the following operations: generating first frequency spectrum data from a received radio signal by an annihilating filter method; generating second frequency spectrum data from the radio signal by a frequency spectrum analysis method different from the annihilating filter method; associating closest frequency values ​​among a frequency value of the first frequency spectrum data and a frequency value of the second frequency spectrum data; and generating frequency spectrum data as an analysis result based on a comparison between a first power value of a first frequency in the first frequency spectrum data and a second power value of a second frequency in the second frequency spectrum data corresponding to the first frequency, wherein if the first power value is equal to or less than the second power value, the first power value is adopted as the power value of the first frequency of the frequency spectrum data as the analysis result, and if the second power value is less than the first power value, the second power value is adopted as the power value of the first frequency of the frequency spectrum data as the analysis result. Effect of the Invention

[0007] According to the present invention, it is possible to achieve high resolution and improve the accuracy of estimating the power value of frequency spectrum data of a radio signal. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram illustrating a hardware configuration of a signal processing device according to an embodiment of the present invention. [Diagram 2] 1 is a flowchart showing a process flow of a spectrum analysis method according to an embodiment of the present invention. [Diagram 3] FIG. 2 is an explanatory diagram of a spectrum analysis method according to an embodiment of the present invention. [Figure 4] FIG. 2 is an explanatory diagram of a spectrum analysis method according to an embodiment of the present invention. [Diagram 5] 1 is an explanatory diagram illustrating a configuration of a radar device according to an embodiment of the present invention; [Figure 6] 1 is a graph showing an analysis result of a conventional AF method. [Figure 7] 1 is a graph showing the analysis results of a spectrum analysis method according to an embodiment of the present invention. [Figure 8] FIG. 2 is an explanatory diagram of a communication terminal according to an embodiment of the present invention. [Figure 9] FIG. 2 is an explanatory diagram showing a configuration of a communication terminal according to an embodiment of the present invention. [Figure 10] FIG. 2 is an explanatory diagram of a communication terminal according to an embodiment of the present invention. [Figure 11] FIG. 1 is an explanatory diagram of a fixed communication device according to an embodiment of the present invention. [Figure 12] FIG. 1 is an explanatory diagram showing a configuration of a fixed communication device according to an embodiment of the present invention. [Figure 13] FIG. 2 is an explanatory diagram of a radio signal according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, the same reference numerals denote the same components, and duplicated explanations will be omitted.

[0010] FIG. 1 is an explanatory diagram showing a hardware configuration of a signal processing device 100 according to an embodiment of the present invention. The signal processing device 100 is a computer including a processor 101 for executing DSP (Digital Signal Processing) processing, a memory 102, an input / output interface 103, and a storage device 104. A spectrum analysis program 200 according to an embodiment of the present invention is stored in the storage device 104. The spectrum analysis program 200 is a program for causing the processor 101 to execute a spectrum analysis method according to an embodiment of the present invention. The spectrum analysis program 200 is read from the storage device 104 to the memory 102 and executed by the processor 101. An A / D converted radio signal (a radio signal received by an antenna not shown in FIG. 1 and further A / D converted) is input to the input / output interface 103. The processor 101 inputs the A / D converted radio signal through the input / output interface 103, executes the spectrum analysis method according to an embodiment of the present invention, generates frequency spectrum data as an analysis result, and outputs the generated frequency spectrum data through the input / output interface 103. It should be noted that the frequency spectrum includes an amplitude spectrum and a phase spectrum.

[0011] FIG. 2 is a flowchart showing the process flow of the spectrum analysis method according to the embodiment of the present invention.

[0012] In step 201, the processor 101 generates first frequency spectrum data, in which the frequency values ​​take continuous values, from a radio signal by an AF (Annihilating Filter) method.

[0013] In step 202, the processor 101 generates second frequency spectrum data in which the frequency values ​​are discrete values ​​from the wireless signal by a frequency spectrum analysis method (a frequency spectrum analysis method different from the AF method) that outputs a reference power value of the wireless signal. The frequency spectrum analysis method that outputs a reference power value of the wireless signal is a frequency spectrum analysis method with high estimation accuracy of the power value (for example, a discrete Fourier transform such as a fast Fourier transform, the Beamformer method, or the Capon method).

[0014] In step 203, the processor 101 associates the closest frequency values ​​among the frequency values ​​of the first frequency spectrum data and the second frequency spectrum data (frequency pairing). "Associating the closest frequency values" means, for example, when a specific frequency of the first frequency spectrum data is the first frequency and a frequency of the second frequency spectrum data that is the closest to the first frequency is the second frequency, linking (or associating) the first frequency of the first frequency spectrum data with the second frequency of the second frequency spectrum data. Such linking (or association) is referred to as pairing in this specification.

[0015] In step 204, the processor 101 generates frequency spectrum data as an analysis result based on a comparison between a first power value of a first frequency of the first frequency spectrum data and a second power value of a second frequency of the second frequency spectrum data corresponding to the first frequency. For example, if the first power value is equal to or less than the second power value, the processor 101 sets the first power value as the power value of the first frequency of the frequency spectrum data as the analysis result. Also, for example, if the second power value is less than the first power value, the processor 101 sets the second power value as the power value of the first frequency of the frequency spectrum data as the analysis result.

[0016] Here, the details of the process of step 204 will be described with reference to Figs. 3 and 4. Reference D1 indicates first frequency spectrum data at a first frequency f1. Reference D2 indicates second frequency spectrum data at a second frequency f2. The first frequency f1 and the second frequency f2 are associated with each other through the process of step 203. The first frequency f1 and the second frequency f2 may be the same frequency or may be different frequencies. When the first frequency f1 and the second frequency f2 have the same frequency value, the same specific frequency value is paired.

[0017] 3, when the first power value P1 of the first frequency spectrum data D1 at the first frequency f1 is less than the second power value P2 of the second frequency spectrum data D2 at the second frequency f2, the first power value P1 is set as the power value of the first frequency f1 of the frequency spectrum data as the analysis result, i.e., the first frequency spectrum data D1 at the first frequency f1 is set as the frequency spectrum data as the analysis result at the first frequency f1.

[0018] 4, when the second power value P2 of the second frequency spectrum data D2 at the second frequency f2 is equal to or smaller than the first power value P1 of the first frequency spectrum data D1 at the first frequency f1, the second power value P2 is set as the power value of the first frequency f1 of the frequency spectrum data as the analysis result. That is, data obtained by correcting the power value of the first frequency spectrum data D1 at the first frequency f1 (data obtained by correcting the first power value P1 to the second power value P2) is set as the frequency spectrum data as the analysis result at the first frequency f1.

[0019] In this manner, the frequency spectrum data as the analysis result is generated by executing, for each frequency of the first frequency spectrum data, a correction process for the power value of the first frequency spectrum data based on a comparison between the power value of the first frequency spectrum data and the reference power value of the second frequency spectrum data.

[0020] According to the spectrum analysis method of the embodiment of the present invention, it is possible to generate frequency spectrum data having both the high frequency resolution of the AF method and the high estimation accuracy of the power value. In particular, even if the actual number of incoming waves changes, it is possible to generate frequency spectrum data with high resolution and high reliability of the power value. Moreover, even in a situation where the phase of the radio wave changes for each measurement, such as in mobile communications, it is possible to accurately distinguish between true waves and false waves.

[0021] The spectrum analysis program 200 includes instructions for causing the signal processing device 100 to execute each of steps 201 to 204. The signal processing device 100 functions as a means for executing each of steps 201 to 204. Functions similar to those of each of these means may be realized using dedicated hardware resources (for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.) or firmware.

[0022] 5 is an explanatory diagram showing a configuration of a radar device 300 according to an embodiment of the present invention. The radar device 300 is a frequency modulated continuous wave radar (FM-CW radar), which is a type of continuous wave radar that employs a frequency modulation method. The radar device 300 can measure, for example, a relative position of a target 400 with respect to the radar device 300 (for example, an angle θ of the target 400 with respect to the radar device 300 and a distance R between the radar device 300 and the target 400). The radar device 300 includes an oscillator 301, an amplifier 302, a plurality of distributors 303, a transmitting antenna 304, a receiving antenna 305, a plurality of amplifiers 307, a plurality of mixers 308, a plurality of filters 309, a plurality of A / D converters 310, and a signal processing device 100.

[0023] The oscillator 301 generates and outputs a transmission signal St. The oscillator 301 is, for example, a voltage controlled oscillator. The amplifier 302 amplifies the power of the transmission signal St output from the oscillator 301. Each distributor 303 distributes the power-amplified transmission signal St output from the amplifier 302 to a transmission antenna 304 and a mixer 308. The power-amplified transmission signal St from the amplifier 302 and distributed to the mixer 308 is also called a local signal. The transmission antenna 304 transmits the transmission signal St as a radar wave.

[0024] The receiving antenna 305 is a linear array antenna in which a plurality of antenna elements 306 are arranged at equal intervals. The receiving antenna 305 receives a reflected wave of the transmission signal St reflected by the target 400 as a reception signal Sr. Each amplifier 307 amplifies the reception signal Sr output from the antenna element 306. Each mixer 308 mixes the amplified reception signal Sr output from the amplifier 307 with the transmission signal St distributed by the distributor 303 to generate and output an intermediate frequency signal. The intermediate frequency signal is a beat signal indicating the frequency difference between the transmission signal St and the reception signal Sr. Each filter 309 is a low-pass filter that removes unnecessary signal components of the intermediate frequency signal output from the mixer 308. Each A / D converter 310 A / D converts the intermediate frequency signal output from each filter 309.

[0025] The signal processing device 100 estimates any one of the distance R, angle θ, and speed (change in distance R per unit time) of the target 400 by processing the intermediate frequency signals converted into digital signals by each A / D converter 310 according to a spectrum analysis method according to an embodiment of the present invention. For example, the signal processing device 100 performs signal processing on the "intermediate frequency signals converted into digital signals by each A / D converter 310" as the "wireless signals" in steps 201 to 204 of Fig. 2, and estimates any one of the distance R, angle θ, and speed (change in distance R per unit time) of the target 400 from the frequency spectrum data as the analysis result.

[0026] The number of each of the distributors 303 , the amplifiers 307 , the mixers 308 , the filters 309 , and the A / D converters 310 is equal to the number of the antenna elements 306 .

[0027] As an algorithm executed by the signal processing device 100, the first frequency spectrum data was generated using the AF method, and the second frequency spectrum data was generated using the discrete Fourier transform method. FIG. 6 is a graph showing an analysis result when the generated first frequency spectrum data and the generated second frequency spectrum data are superimposed. As shown in the figure, a false wave 602 with a high power value is generated in addition to the incoming wave 601 from the target 400 as a target. FIG. 7 is a graph showing an analysis result when the spectrum analysis method according to the embodiment of the present invention is used as an algorithm executed by the signal processing device 100. As shown in the figure, no false wave with a high power value is generated in addition to the incoming wave 603 from the target 400 as a target, and it can be seen that the power of the false wave can be effectively reduced.

[0028] 8 is an explanatory diagram of a communication terminal 500 according to an embodiment of the present invention. A part of radio waves from a base station 600 may be received by the communication terminal 500 after being reflected by an obstacle 900 such as a building, and a part of radio waves from the base station 600 may be received by the communication terminal 500 without being reflected by an obstacle 900 such as a building. The communication terminal 500 estimates the direction of arrival of the radio waves from the base station 600, and directs the peak of the directivity of the antenna in the estimated direction. The server device 700 will be described later.

[0029] 9 is an explanatory diagram showing the configuration of a communication terminal 500 according to an embodiment of the present invention. The communication terminal 500 includes a modulation circuit 501, a mixer 502, a plurality of phase shifters 503, a plurality of amplifiers 504, a transmission antenna 505, a reception antenna 507, a plurality of amplifiers 509, a mixer 510, an A / D converter 511, a signal processing device 100, and a demodulation circuit 512. The transmission antenna 505 and the reception antenna 507 may be shared by using a circulator or a switch.

[0030] Transmission data is modulated by a modulation circuit 501, and a signal carrying information of the transmission data is up-converted by a mixer 502. The transmission antenna 505 is a linear array antenna in which a plurality of antenna elements 506 are arranged at equal intervals. Each phase shifter 503 controls the phase of the high-frequency signal fed to each antenna element 506 so that the directivity peak of the transmission antenna 505 faces the direction of the base station 600. The transmission antenna 505 transmits a radio signal carrying information of the transmission data.

[0031] The receiving antenna 507 is a linear array antenna in which a plurality of antenna elements 508 are arranged at equal intervals. The radio signals received by each antenna element 508 are power amplified by an amplifier 509, down-converted by a mixer 510, and A / D converted by an A / D converter 511.

[0032] The signal processing device 100 estimates the arrival direction of the radio signal by processing the radio signal converted into a digital signal by the A / D converter 511 according to the spectrum analysis method of the embodiment of the present invention. For example, the signal processing device 100 performs signal processing on the "radio signal converted into a digital signal by the A / D converter 511" as the "radio signal" in steps 201 to 204 of Fig. 2, and estimates the arrival direction of the radio signal (the azimuth and elevation angles of the base station 600 relative to the communication terminal 500) from frequency spectrum data as the analysis result. The signal processing device 100 calculates the amount of phase shift of each phase shifter 503 so that the directivity peak of the transmitting antenna 505 faces the direction of the base station 600, and outputs the calculation result to each phase shifter 503.

[0033] The signal processing device 100 performs beam synthesis by executing DBF (Digital Beam Forming) processing on the radio signals converted into digital signals by each A / D converter 511. From the result of the beam synthesis, the demodulation circuit 512 demodulates the received data.

[0034] Returning now to the description of Fig. 8. In the above description, an example has been shown in which the communication terminal 500 performs signal processing on the wireless signal received from the base station 600 according to the spectrum analysis method of the embodiment of the present invention, and estimates the arrival direction of the wireless signal from frequency spectrum data as the analysis result, but the present invention is not limited to such an example. For example, the communication terminal 500 may transfer the wireless signal received from the base station 600 to the server device 700 and request the server device 700 to estimate the arrival direction of the wireless signal.

[0035] The server device 700 is, for example, a general-purpose computer system such as a cloud server. The server device 700 includes a processor 701, a memory 702, a communication interface 703, and a storage device 704. The storage device 704 stores a spectrum analysis program 200 according to an embodiment of the present invention. The spectrum analysis program 200 is loaded from the storage device 704 to the memory 702 and executed by the processor 701.

[0036] In response to a request from the communication terminal 500, the server device 700 estimates the arrival direction of the wireless signal by processing the wireless signal received from the communication terminal 500 according to a spectrum analysis method according to an embodiment of the present invention. The server device 700 transmits the estimation result of the arrival direction of the wireless signal to the communication terminal 500. The communication terminal 500, which has received the estimation result of the arrival direction of the wireless signal, directs the peak of the directivity of the antenna based on the estimation result.

[0037] In the above description, an example has been shown in which the communication terminal 500 estimates the arrival direction of radio waves from the base station 600 and points the directivity peak of the antenna in the estimated direction, but the present invention is not limited to such an example. For example, as shown in Fig. 10, any one of the communication terminals 500 may estimate the arrival direction of radio waves from the other communication terminals 500 and point the directivity peak of the antenna in the estimated direction. The hardware configuration in which one communication terminal 500 estimates the arrival direction of radio waves from the other communication terminals 500 is the same as the hardware configuration shown in Fig. 9, and therefore detailed description thereof will be omitted.

[0038] Also, for example, one communication terminal 500 may transfer a wireless signal received from another communication terminal 500 to the server device 700 and request the server device 700 to estimate the arrival direction of the wireless signal. In response to the request from the communication terminal 500, the server device 700 estimates the arrival direction of the wireless signal by performing signal processing on the wireless signal received from the communication terminal 500 according to the spectrum analysis method related to the embodiment of the present invention. The server device 700 transmits the estimation result of the arrival direction of the wireless signal to the communication terminal 500. The communication terminal 500 that has received the estimation result of the arrival direction of the wireless signal orients the directivity peak of the antenna based on the estimation result.

[0039] FIG. 11 is an explanatory diagram of a fixed communication device 800 according to an embodiment of the present invention. The fixed communication device 800 is a base station that functions as an access point that connects to the communication terminal 500 by short-distance wireless communication. The communication terminal 500 and each fixed communication device 800 are time-synchronized in advance, for example, through a GPS (Global Positioning System) system. The communication terminal 500 transmits a wireless signal at a constant period. The fixed communication device 800 estimates the time when the wireless signal transmitted from the communication terminal 500 was received, and estimates the distance between the communication terminal 500 and the fixed communication device 800 from the difference between the time when the wireless signal was transmitted from the communication terminal 500 and the time when the fixed communication device 800 received the wireless signal. By each fixed communication device 800 performing such an estimation process, the position of the communication terminal 500 can be obtained by trigonometry.

[0040] FIG. 12 is an explanatory diagram showing a configuration of a fixed communication device 800 according to an embodiment of the present invention. The fixed communication device 800 includes a receiving antenna 801, an A / D converter 802, and a signal processing device 100. The receiving antenna 801 receives a radio signal from the communication terminal 500. The A / D converter 802 A / D converts the radio signal received by the receiving antenna 801. The signal processing device 100 estimates the time when the radio signal transmitted from the communication terminal 500 was received by signal processing the A / D converted radio signal according to the spectrum analysis method according to the embodiment of the present invention. For example, the signal processing device 100 performs signal processing on the "radio signal converted into a digital signal by the A / D converter 802" as the "radio signal" in steps 201 to 204 in FIG. 2, regenerates the original time signal from the phase decomposition data (spectrum), and estimates the time when the radio signal transmitted from the communication terminal 500 was received.

[0041] FIG. 13(a) shows a radio signal 131 transmitted from the communication terminal 500 at time t1. FIG. 13(b) shows a radio signal 132 received by the fixed communication device 800 and regenerated by fast Fourier transform, and radio signals 133 and 134 regenerated by the AF method. Since the power of the radio signal 134 regenerated by the AF method is higher than the power of the radio signal 132 regenerated by fast Fourier transform, the radio signal 134 regenerated by the AF method is a false wave. The signal processing device 100 estimates the time t2 at which the radio signal transmitted from the communication terminal 500 was received based on the radio signal 133 regenerated by the AF method. The signal processing device 100 estimates the distance between the communication terminal 500 and the fixed communication device 800 from the difference between the time t1 at which the radio signal was transmitted from the communication terminal 500 and the time t2 at which the fixed communication device 800 received the radio signal.

[0042] Here, we return to the description of FIG. 11. In the above description, an example has been shown in which the fixed communication device 800 estimates the time when the wireless signal transmitted from the communication terminal 500 was received, and estimates the distance between the communication terminal 500 and the fixed communication device 800 from the difference between the time when the wireless signal was transmitted from the communication terminal 500 and the time when the fixed communication device 800 received the wireless signal. However, the present invention is not limited to such an example. For example, the fixed communication device 800 may transfer the wireless signal transmitted from the communication terminal 500 to the server device 700 and request the server device 700 to estimate the time when the fixed communication device 800 received the wireless signal transmitted from the communication terminal 500. In response to the request from the fixed communication device 800, the server device 700 estimates the time when the fixed communication device 800 received the wireless signal transmitted from the communication terminal 500 by performing signal processing on the wireless signal received by the fixed communication device 800 from the communication terminal 500 according to the spectrum analysis method related to the embodiment of the present invention. The server device 700 transmits the estimated result of the reception time to the fixed communication device 800. The fixed communication device 800, which has received the estimated result of the reception time, estimates the distance between the communication terminal 500 and the fixed communication device 800 based on the estimated result.

[0043] The server device 700 may download the spectrum analysis program 200 through a network and store it in the storage device 704. Alternatively, the server device 700 may install the spectrum analysis program 200 recorded in a computer-readable recording medium into the storage device 704. The computer-readable recording medium may be any recording medium, such as a magneto-optical recording medium, a magnetic recording medium, or a semiconductor memory.

[0044] The above-described embodiments are provided to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention may be modified / improved without departing from the spirit of the present invention, and equivalents are also included in the present invention. In other words, even if a person skilled in the art appropriately modifies the design of the embodiments, the present invention will be included in the scope of the present invention as long as the features of the present invention are included. In addition, the elements of the embodiments can be combined to the extent technically possible, and the combination of these elements will be included in the scope of the present invention as long as the features of the present invention are included. [Explanation of symbols]

[0045] 100: signal processing device 101: processor 102: memory 103: input / output interface 104: storage device 200: spectrum analysis program 300: radar device 400: target object 500: communication terminal 600: base station 700: server device 800: fixed communication device 900: obstacle

Claims

1. On the computer, generating first frequency spectrum data from the received wireless signal by an annihilating filter method; generating second frequency spectrum data from the wireless signal by a frequency spectrum analysis method different from the annihilating filter method; Corresponding the closest frequency values ​​between the frequency value of the first frequency spectrum data and the frequency value of the second frequency spectrum data; generating frequency spectrum data as an analysis result based on a comparison between a first power value of a first frequency in the first frequency spectrum data and a second power value of a second frequency in the second frequency spectrum data corresponding to the first frequency, wherein if the first power value is equal to or less than the second power value, the first power value is adopted as the power value of the first frequency of the frequency spectrum data as the analysis result, and if the second power value is less than the first power value, the second power value is adopted as the power value of the first frequency of the frequency spectrum data as the analysis result; A spectrum analysis program that runs

2. 2. The spectrum analysis program according to claim 1, A spectrum analysis program, wherein the frequency values ​​of the second frequency spectrum data are discrete values.

3. 3. The spectrum analysis program according to claim 1, A spectrum analysis program, wherein the frequency spectrum analysis method different from the annihilating filter method is discrete Fourier transform.

4. 1. A signal processing device, comprising: means for generating first frequency spectrum data from a received wireless signal by an annihilating filter method; means for generating second frequency spectrum data from the wireless signal by a frequency spectrum analysis method different from the annihilating filter method; a means for associating the closest frequency values ​​between the frequency values ​​of the first frequency spectrum data and the frequency values ​​of the second frequency spectrum data; a means for generating frequency spectrum data as an analysis result based on a comparison between a first power value of a first frequency in the first frequency spectrum data and a second power value of a second frequency in the second frequency spectrum data corresponding to the first frequency, the means being configured to adopt the first power value as the power value of the first frequency of the frequency spectrum data as the analysis result when the first power value is equal to or less than the second power value, and to adopt the second power value as the power value of the first frequency of the frequency spectrum data as the analysis result when the second power value is less than the first power value; A signal processing device comprising:

5. a transmitting antenna for transmitting a transmission signal to a target; a receiving antenna for receiving a reflected wave of the transmission signal reflected by the target as a received signal; a mixer that mixes the transmit signal and the receive signal to output an intermediate frequency signal indicative of a frequency difference between the transmit signal and the receive signal; 5. A signal processing device according to claim 4, which generates frequency spectrum data as the analysis result using the intermediate frequency signal as the radio signal, and estimates any one of a speed, a distance, and an angle of the target based on the frequency spectrum data as the analysis result; A radar device comprising:

6. a receiving antenna for receiving a radio signal from a base station or another communication terminal; 5. A signal processing device according to claim 4, comprising: a signal processing device that estimates an arrival direction of the wireless signal from frequency spectrum data as a result of the analysis; A communication terminal comprising:

7. A receiving antenna for receiving a wireless signal from a communication terminal; A signal processing device according to claim 4; A fixed communication device comprising: The signal processing device is equipped with a means for estimating the time when the receiving antenna received the radio signal from the frequency spectrum data as the analysis result, and estimating the distance between the communication terminal and the fixed communication device from the difference between the time when the radio signal was transmitted from the communication terminal and the time when the receiving antenna received the radio signal.

8. 2. A computer-readable recording medium having the spectrum analysis program according to claim 1 recorded thereon.

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