JP2012191343A - System determination device and system determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a modulation system even when a carrier frequency is unknown.SOLUTION: A system determination device 110 has a sampling section 112, a detector 113, a calculation section 114, a determination section 116, and an output section 117. The sampling section 112 samples a received communication wave on a different cycle from a symbol cycle of the communication wave. The detector 113 detects a phase difference between consecutive sampling data sampled by the sampling section 112. The calculation section 114 calculates distribution information indicating a distribution state of the phase difference detected by the detector 113 in a predetermined time period. The determination section 116 determines a modulation system of the communication wave based on the distribution information calculated by the calculation section 114. The output section 117 outputs a determination result by the determination section 116.

Description

  The present invention relates to a method determination apparatus and a method determination method for determining a modulation method.

  For example, in wireless communication, a technique for receiving a communication wave whose modulation method is unknown and determining the modulation method of the received communication wave is known. For example, a technique for determining a modulation method of a communication wave subjected to phase modulation (PSK: Phase Shift Keying) is known (see, for example, Patent Document 1 below). In this technique, a symbol point is detected from a baseband signal obtained by quadrature detection using a local signal having the same frequency as the carrier frequency of the communication wave, and the communication wave is detected based on the frequency distribution of the phase difference between the symbol points. Determine the modulation method.

JP 2008-54186 A

  However, the above-described conventional technique has a problem that the modulation scheme cannot be determined if the carrier frequency of the communication wave to be determined is unknown.

  An object of the present invention is to provide a method determining apparatus and a method determining method capable of determining a modulation method even when the carrier frequency is unknown in order to solve the above-described problems caused by the prior art.

  In order to solve the above-described problems and achieve the object, according to one aspect of the present invention, a received communication wave is sampled at a period different from the symbol period of the communication wave, and a phase difference between consecutive sampled data sampled. A method determining apparatus for calculating distribution information indicating a phase difference distribution state detected within a predetermined period, determining a modulation method of the communication wave based on the calculated distribution information, and outputting a determination result; A method determination method is proposed.

  According to another aspect of the present invention, a plurality of sampling data sequences obtained by sampling received communication waves at a plurality of periods are acquired, and a phase difference between consecutive sampled sampling data is obtained for each of the plurality of sampling data sequences. Distribution information indicating a phase difference distribution state detected and detected within a predetermined period is calculated for each of the plurality of sampling data strings, and the communication is performed based on the distribution information calculated for each of the plurality of sampling data strings. A method determining apparatus and a method determining method for determining a wave modulation method and outputting a determination result are proposed.

  According to one aspect of the present invention, the modulation scheme can be determined even when the carrier frequency is unknown.

FIG. 1 is a diagram illustrating a configuration example of a communication system according to an embodiment. FIG. 2 is a graph showing an example of sampling with an arbitrary period. FIG. 3 is a diagram showing a change in phase on the IQ orthogonal coordinate plane. FIG. 4 is a diagram illustrating an example of sampling with a plurality of periods. FIG. 5A is a reference diagram illustrating ideal symbol points when the modulation method is BPSK. FIG. 5B is a reference diagram illustrating an ideal symbol point when the modulation method is QPSK. FIG. 5C is a reference diagram illustrating ideal symbol points when the modulation method is π / 4 shift QPSK. FIG. 5-4 is a reference diagram illustrating an ideal symbol point when the modulation scheme is 8PSK. FIG. 6A is a diagram illustrating an ideal phase difference distribution state when the modulation method is BPSK. FIG. 6B is a diagram illustrating an ideal phase difference distribution state when the modulation method is QPSK. FIG. 6C is a diagram illustrating an ideal phase difference distribution when the modulation method is π / 4 shift QPSK. FIG. 6-4 is a diagram illustrating an ideal phase difference distribution state when the modulation method is 8PSK. FIG. 7 is a diagram illustrating a configuration example of the method determination device according to the embodiment. FIG. 8 is a flowchart illustrating an example of determination processing by the modulation scheme determination unit.

  Embodiments of a method determination apparatus and method determination method according to the present invention will be described below in detail with reference to the accompanying drawings.

(Embodiment)
(Configuration example of communication system)
FIG. 1 is a diagram illustrating a configuration example of a communication system according to an embodiment. As illustrated in FIG. 1, the communication system 100 according to the embodiment includes a wireless communication device 101 and a method determination device 110. The wireless communication device 101 wirelessly transmits a phase-modulated communication wave 102. The communication wave 102 may be a communication wave destined for the method determination device 110 or a communication wave destined for a communication device different from the method determination device 110. The method determination device 110 determines the modulation method of the communication wave 102 transmitted by the wireless communication device 101.

  Specifically, the method determination apparatus 110 includes a reception unit 111, a sampling unit 112, a detection unit 113, a calculation unit 114, an acquisition unit 115, a determination unit 116, and an output unit 117. . The receiving unit 111 receives the communication wave 102 transmitted wirelessly. For example, the reception unit 111 performs quadrature detection of the communication wave 102 using a local signal having an arbitrary frequency. The frequency of the local signal may be different from the carrier frequency of the communication wave 102. The receiving unit 111 outputs the received communication wave 102 to the sampling unit 112.

  The sampling unit 112 samples (samples) the signal output from the receiving unit 111 at an arbitrary period. Therefore, the sampling period of the sampling unit 112 may be different from the symbol period of the communication wave 102 output from the receiving unit 111. A symbol period is a period in which a symbol changes. The sampling unit 112 outputs sampling data obtained by sampling to the detection unit 113.

  The detection unit 113 detects a phase difference between continuous sampling data output from the sampling unit 112. For example, every time sampling data is output from the sampling unit 112, the detection unit 113 detects a phase difference from the previous sampling data output from the sampling unit 112. The detection unit 113 notifies the calculation unit 114 of the detected phase difference.

  The calculation unit 114 calculates distribution information indicating the phase difference distribution state notified from the detection unit 113. The distribution information is information indicating the number of different phase differences notified (detected) within a predetermined period, for example. Alternatively, the distribution information may be a frequency distribution indicating the number of times the phase difference is notified (detected) within a predetermined period for each phase difference. The calculation unit 114 outputs the calculated distribution information to the determination unit 116.

  The acquisition unit 115 acquires correspondence information that associates the distribution information calculated by the calculation unit 114 with the modulation scheme of the communication wave 102 received by the reception unit 111. For example, the correspondence information is stored in the memory of the method determination device 110, and the acquisition unit 115 acquires the correspondence information stored in the memory of the method determination device 110. The acquisition unit 115 may acquire correspondence information from an external device. The correspondence information is, for example, a table that associates distribution information with modulation schemes. Alternatively, the correspondence information may be a program configured to output a modulation method corresponding to the input distribution information. The acquisition unit 115 outputs the acquired correspondence information to the determination unit 116.

  The determination unit 116 determines the modulation scheme of the communication wave 102 received by the reception unit 111 based on the distribution information output from the calculation unit 114. When the modulation method of the communication wave 102 is any phase modulation method, the distribution information is different information depending on the type of the phase modulation method of the communication wave 102. Therefore, the determination unit 116 can determine the type of modulation scheme of the communication wave 102 based on the distribution information.

  Specifically, the determination unit 116 determines the modulation scheme based on the distribution information output from the calculation unit 114 and the correspondence information output from the acquisition unit 115. The determination unit 116 notifies the output unit 117 of the determination result of the modulation scheme. The output unit 117 outputs information indicating the determination result from the determination unit 116. Thereby, even if the carrier frequency and symbol period of the communication wave 102 are unknown, the modulation system of the communication wave 102 can be determined.

  The sampling unit 112 may output a plurality of sampling data strings obtained by sampling the communication wave 102 at a plurality of different periods. The plurality of periods may be arbitrary periods, and may be different from the symbol period of the communication wave 102.

  The detection unit 113 detects a phase difference between successive sampling data for each of the plurality of sampling data strings output from the sampling unit 112. The detection unit 113 notifies the calculation unit 114 of the phase difference detected for each of the plurality of sampling data strings. The calculation unit 114 calculates distribution information indicating the distribution state of the phase difference output from each of the plurality of sampling data strings from the detection unit 113 for each of the plurality of sampling data strings. The calculation unit 114 outputs distribution information calculated for each of the plurality of sampling data strings to the determination unit 116.

  The determination unit 116 determines the modulation method of the communication wave 102 based on the plurality of distribution information output from the calculation unit 114. The plurality of distribution information is distribution information based on different sampling periods. Therefore, the probability that at least one of the plurality of distribution information becomes different information depending on the modulation method of the communication wave 102 is higher than the probability that the single distribution information becomes different information depending on the modulation method of the communication wave 102. For this reason, the modulation system of the communication wave 102 can be determined with higher accuracy by using a plurality of distribution information.

  For example, the determination unit 116 determines distribution information that can determine a modulation scheme based on correspondence information among a plurality of pieces of distribution information, and determines a modulation scheme based on the determined distribution information and correspondence information. Alternatively, the correspondence information may associate a combination of a plurality of distribution information with a modulation method. In this case, the determination unit 116 determines the modulation scheme based on a combination of a plurality of distribution information and correspondence information.

(An example of sampling at an arbitrary period)
FIG. 2 is a graph showing an example of sampling with an arbitrary period. FIG. 3 is a diagram showing a change in phase on the IQ orthogonal coordinate plane. The horizontal axis in FIG. 2 indicates time. The communication wave 102 is a phase modulation communication wave received by the receiving unit 111. The phase change point 211 is a phase change point (symbol change point) of the communication wave 102. In the example shown in FIG. 2, the phase of the communication wave 102 changes by π at the phase change point 211. Thus, in the phase modulation type communication wave 102, the phase of the carrier (carrier wave) changes every symbol period.

  The upward arrows (..., Tn, tn + 1, tn + 2, tn + 3, tn + 4,...) On the horizontal axis in FIG. The phase change of the communication wave 102 at tn, tn + 1, tn + 2, tn + 3, and tn + 4 is as shown in the IQ orthogonal coordinate plane 300 shown in FIG.

  In the example illustrated in FIGS. 2 and 3, the sampling unit 112 performs sampling at a period shorter than the symbol period of the communication wave 102. Phase differences 221 to 224 indicate phase differences detected by the detection unit 113 at tn + 1, tn + 2, tn + 3, and tn + 4, respectively. For example, the phase of the communication wave 102 does not change in the interval from tn to tn + 1, the interval from tn + 1 to tn + 2, and the interval from tn + 3 to tn + 4. For this reason, the phase differences 221, 222, and 224 are constant phase differences (referred to as φ).

  On the other hand, in the interval from tn + 2 to tn + 3, the phase of the communication wave 102 changes by π, so the phase difference 223 becomes φ + π. The calculation unit 114 acquires the phase differences 221 to 224, and calculates distribution information indicating the distribution state of each acquired phase difference.

(An example of sampling with multiple periods)
FIG. 4 is a diagram illustrating an example of sampling with a plurality of periods. In FIG. 4, the same parts as those shown in FIG. The symbol period T indicates the symbol period of the communication wave 102. Stages 1 to 4 show sampling of the communication wave 102 by a plurality of periods. An upward arrow in each stage indicates the sampling timing in each stage. The circles at each stage indicate the timing at which the phase difference detection result changes from the previous sampling among the sampling timings at each stage.

  Stage 1 shows sampling of the communication wave 102 with a period Ts shorter than the symbol period T of the communication wave 102. Stage 2 shows sampling of the communication wave 102 with a period 2Ts that is twice the period Ts. Stage 3 shows sampling of the communication wave 102 with a period 4Ts that is twice the period 2Ts. Stage 4 shows sampling of the communication wave 102 with a period 8Ts that is twice the period 4Ts.

  In the example shown in FIG. 4, the periods Ts and 2Ts of the stages 1 and 2 are shorter than the symbol period T of the communication wave 102. The periods 4Ts and 8Ts of the stages 3 and 4 are longer than the symbol period T of the communication wave 102. As shown in FIG. 4, the timing at which the phase difference detection result changes in each stage from the previous sampling is the timing immediately after the phase change point 211 of the communication wave 102 in the sampling timing in each stage. Although the sampling with four periods (stages) has been described here, the number of periods (the number of stages) for sampling may be one or more.

(Ideal symbol point for each modulation method)
FIG. 5A is a reference diagram illustrating ideal symbol points when the modulation method is BPSK. It is assumed that the communication wave 102 is modulated by BPSK and the baseband signal can be accurately detected from the communication wave 102. In this case, the phase of the communication wave 102 takes two values, 0 and π, as indicated by symbol points 511 and 512 on the IQ orthogonal coordinate plane 510 in FIG.

  FIG. 5B is a reference diagram illustrating an ideal symbol point when the modulation method is QPSK. It is assumed that the communication wave 102 is modulated by QPSK and the baseband signal can be accurately detected from the communication wave 102. In this case, the phase of the communication wave 102 is 4 of 0, π / 2, π, 3π / 2 (−π / 2π) as indicated by the symbol points 521 to 524 of the IQ orthogonal coordinate plane 520 in FIG. Take street value.

  FIG. 5C is a reference diagram illustrating ideal symbol points when the modulation method is π / 4 shift QPSK. It is assumed that the communication wave 102 is modulated by π / 4 shift QPSK and the baseband signal can be accurately detected from the communication wave 102. In this case, the phase of the communication wave 102 is 0, π / 4, 3π / 4, 5π / 4 (−3π / 4) as indicated by symbol points 531 to 535 of the IQ orthogonal coordinate plane 530 in FIG. , 5 values of 7π / 4 (−π / 4).

  FIG. 5-4 is a reference diagram illustrating an ideal symbol point when the modulation scheme is 8PSK. It is assumed that the communication wave 102 is modulated by 8PSK, and the baseband signal can be accurately detected from the communication wave 102. In this case, the phase of the communication wave 102 is 0, π / 4, π / 2, 3π / 4, π, 5π / as shown by symbol points 541 to 548 of the IQ orthogonal coordinate plane 540 in FIG. Eight values of 4, 3π / 2 and 7π / 4 are taken.

(Phase difference distribution in each modulation system)
FIG. 6A is a diagram illustrating an ideal phase difference distribution state when the modulation method is BPSK. Histograms 611 to 614 shown in FIG. 6A indicate the number of detections for each ideal phase difference in stages 1 to 4 when the modulation method of the communication wave 102 is BPSK. When the modulation method of the communication wave 102 is BPSK, two phase differences φ and φ + π are detected in each of the stages 1 to 4.

  FIG. 6B is a diagram illustrating an ideal phase difference distribution state when the modulation method is QPSK. Histograms 621 to 624 shown in FIG. 6B indicate the number of detections for each ideal phase difference in stages 1 to 4 when the modulation method of the communication wave 102 is QPSK. When the modulation method of the communication wave 102 is QPSK, four phase differences of the phase differences φ, φ + π / 2, φ + π, and φ + 3π / 2 are detected in each of the stages 1 to 4.

  FIG. 6C is a diagram illustrating an ideal phase difference distribution when the modulation method is π / 4 shift QPSK. Histograms 631 to 634 shown in FIG. 6C indicate the number of detections for each ideal phase difference in stages 1 to 4 when the modulation method of the communication wave 102 is π / 4 shift QPSK. When the modulation method of the communication wave 102 is π / 4 shift QPSK, the phase difference φ, φ + π / 4, φ + 3π / 4, φ + 5π / 4, and φ + 7π / 4 are provided in stages 1 and 2. Detected. This is because in the π / 4 QPSK system, there is no phase change of 0 at the time of phase change, and the transition is made to any one of four symbol points of π / 4, 3π / 4, 5π / 4, and 7π / 4.

  In the stages 3 and 4, eight kinds of phase differences of phase differences φ, φ + π / 4, φ + π / 2, φ + 3π / 4, φ + π, φ + 5π / 4, φ + 3π / 2, and φ + 7π / 4 are detected. This is because stages 3 and 4 have a long sampling period, so a phase difference is detected across multiple phase changes, and as a result, for example, a phase difference of π / 2 is detected when π / 4 is added twice. It is to be done.

  FIG. 6-4 is a diagram illustrating an ideal phase difference distribution state when the modulation method is 8PSK. Histograms 641 to 644 shown in FIG. 6-4 indicate the number of detections for each ideal phase difference in stages 1 to 4 when the modulation method of the communication wave 102 is 8PSK. When the modulation method of the communication wave 102 is 8PSK, the phase differences φ, φ + π / 4, φ + π / 2, φ + 3π / 4, φ + π, φ + 5π / 4, φ + 3π / 2, and φ + 7π / 4 in each of the stages 1 to 4 are used. Eight phase differences are detected.

  As illustrated in FIGS. 6-1 to 6-4, the distribution of the phase difference detected by the detection unit 113 differs for each modulation scheme of the communication wave 102. Thereby, it is possible to determine the modulation method of the communication wave 102 based on the distribution of the phase difference detected by the detection unit 113. In each modulation method, the number of detections of the phase difference φ increases at a stage with a short sampling period such as stage 1. This is because the sampling period is shorter than the symbol period of the communication wave 102.

(Configuration example of method judgment device)
FIG. 7 is a diagram illustrating a configuration example of the method determination device according to the embodiment. A method determination apparatus 700 illustrated in FIG. 7 is a configuration example of the method determination apparatus 110 illustrated in FIG. As illustrated in FIG. 7, the method determination apparatus 700 includes a reception antenna 711, a local signal generator 712, a quadrature detection unit 713, an A / D converter 714, and a digital processing unit 720. The receiving antenna 711 receives the communication wave 102 from the air. The reception antenna 711 outputs the received communication wave 102 (RF signal) to the quadrature detection unit 713.

  The local signal generator 712 outputs two-phase local signals (local signals) having phases different from each other by 90 [°]. The frequency of the local signal is, for example, an arbitrary frequency at which the carrier of the communication wave 102 can be sufficiently detected. For example, when the carrier of the communication wave 102 is estimated to be in the 2 to 3 [GHz] band, the frequency of the local signal is set to a frequency close to the estimated band of the carrier such as 2 [GHz]. However, the frequency of the local signal and the carrier frequency of the communication wave 102 do not need to match. Therefore, the carrier frequency of the communication wave 102 may be unknown.

  The quadrature detection unit 713 performs quadrature detection by mixing the communication wave 102 output from the reception antenna 711 with each local signal output from the local signal generator 712. For example, the quadrature detection unit 713 branches the communication wave 102, mixes each local signal different by 90 [°] into each branched communication wave, and adds the mixed signals. The quadrature detection unit 713 outputs the signals i and q obtained by the quadrature detection to the A / D converter 714.

  The A / D converter 714 converts the analog signals i and q output from the quadrature detection unit 713 into digital signals by digital sampling. The A / D converter 714 outputs each sampling data converted into a digital signal to the digital processing unit 720. Sampling data output from the A / D converter 714 to the digital processing unit 720 are I (t) and Q (t), respectively. t indicates the sampling time.

  The sampling rate of A / D converter 714 is, for example, a sampling rate faster than the estimated symbol rate of communication wave 102. For example, when the symbol rate is estimated to be 2 [MHz], the sampling rate of the A / D converter 714 is set to a rate higher than 2 [MHz] such as 10 [MHz]. When the symbol rate is unknown, the sampling rate in the A / D converter 714 may be a high rate such as several hundreds [MHz].

  The digital processing unit 720 includes a branching unit 721, a thinning-out processing unit 722, a phase difference detection unit 723, a phase difference distribution creation unit 724, and a modulation scheme determination unit 725. The digital processing unit 720 can be implemented by, for example, an FPGA (Field Programmable Gate Array).

  The branching unit 721 performs n-branching (duplication) on I (t) and Q (t) output from the A / D converter 714. n is the number of stages described above (for example, 4). The branching unit 721 outputs the branched n-stage I (t) and Q (t) to the thinning processing unit 722.

  The thinning processing unit 722 thins out the n stages I (t) and Q (t) output from the branching unit 721 at different periods for each stage. For example, the thinning-out processing unit 722 does not thin out I (t) and Q (t) of stage 1 and keeps the sampling time t. The thinning processing unit 722 outputs I (t) and Q (t) whose sampling time is t to the phase difference detection unit 723.

  Further, the thinning processing unit 722 thins out I (t) and Q (t) of the stage 2 to ½. The thinning processing unit 722 outputs I (2t) and Q (2t) obtained by thinning I (t) and Q (t) to ½ to the phase difference detection unit 723. Further, the thinning processing unit 722 thins out I (t) and Q (t) of the stage 3 to ¼. The thinning processing unit 722 outputs I (4t) and Q (4t) obtained by thinning I (t) and Q (t) to ¼ to the phase difference detection unit 723.

Similarly, the thinning processing unit 722 thins out I (t) and Q (t) of stage n to 1/2 ⁿ⁻¹ . The thinning processing unit 722 supplies I (2 ⁿ⁻¹ t) and Q (2 ⁿ⁻¹ t) obtained by thinning I (t) and Q (t) to 1/2 ⁿ⁻¹ to the phase difference detection unit 723. Output. Thus, if the sampling period of stage 1 is Ts, the sampling period of stage 2 can be 2 Ts, the sampling period of stage 3 can be 4 Ts, and the sampling period of stage n can be 2 ^n-1 Ts.

  The phase difference detection unit 723 detects a phase difference between consecutive sampling data for each stage with respect to I (t) and Q (t) of each stage output from the thinning processing unit 722. Here, the phase θ (T) at time T of the sampling data indicated by I (t) and Q (t) can be expressed by the following equation (1).

θ (T) = tan ⁻¹ [Q (T) / I (T)] (1)

  Therefore, the phase difference detection unit 723 can calculate the phase difference Δθ (T) between the time T-1 and the time T of the sampling data indicated by I (t) and Q (t) by the following equation (2). .

Δθ (T) = θ (T) −θ (T−1)
= Tan ⁻¹ [Q (T) / I (T)]
-Tan ^-1 [Q (T-1) / I (T-1)] (2)

  The phase difference detection unit 723 can detect the phase difference between consecutive sampling data by calculating the phase difference Δθ (T). Moreover, the phase difference detection unit 723 can detect the phase difference for each stage continuously by calculating the phase difference Δθ (T) for each sampling data for each stage. The phase difference detection unit 723 outputs the detected phase difference in each sampling data for each stage to the phase difference distribution creation unit 724.

  The phase difference distribution creating unit 724 takes the statistics of the phase difference for each stage output from the phase difference detecting unit 723 and calculates the frequency of detection of each phase difference for each stage. The frequency of detection is, for example, the number of detections. The detection frequency may be a ratio of the number of detections to a predetermined number. The phase difference distribution creation unit 724 outputs distribution information indicating the frequency of detection of each phase difference calculated for each stage to the modulation scheme determination unit 725.

  The modulation method determination unit 725 determines the modulation method of the communication wave received by the reception antenna 711 based on the distribution information output from the phase difference distribution creation unit 724. The modulation scheme determination unit 725 outputs information indicating the determination result. An example of a modulation method by the modulation method determination unit 725 will be described with reference to FIG.

  The receiving unit 111 illustrated in FIG. 1 can be realized by, for example, the receiving antenna 711, the local signal generator 712, and the quadrature detection unit 713. The sampling unit 112 illustrated in FIG. 1 can be realized by an A / D converter 714, a branching unit 721, and a thinning processing unit 722, for example. The detection unit 113 illustrated in FIG. 1 can be realized by the phase difference detection unit 723, for example. The calculation unit 114 illustrated in FIG. 1 can be realized by the phase difference distribution generation unit 724, for example. The acquisition unit 115, the determination unit 116, and the output unit 117 illustrated in FIG. 1 can be realized by the modulation scheme determination unit 725, for example.

(An example of determination processing by the modulation method determination unit)
FIG. 8 is a flowchart illustrating an example of determination processing by the modulation scheme determination unit. Here, the phase difference distribution creation unit 724 calculates the number of different phase differences (referred to as the number of distributions) detected by the phase difference detection unit 723 for each of the n stages as distribution information, and sends it to the modulation scheme determination unit 725. A case of outputting will be described. The modulation method determination unit 725 determines the modulation method of the communication wave 102 by executing, for example, each step shown in FIG. 8 using the number of distributions for each stage output from the phase difference distribution generation unit 724.

  In FIG. 8, stage is a variable indicating stages 1 to n. First, the modulation scheme determination unit 725 sets n indicating the highest stage to stage (step S801). Next, the modulation scheme determination unit 725 determines whether or not the number of phase difference distributions on the stage indicated by the stage is eight (step S802).

  In step S802, when the number of phase difference distributions on the stage indicated by stage is 8 (step S802: Yes), the modulation scheme determination unit 725 reduces stage by 1 (step S803). Next, the modulation scheme determination unit 725 determines whether stage is 0 (step S804). As a result, it is possible to determine whether or not all stages have been determined.

  In step S804, when stage is not 0 (step S804: No), the modulation scheme determination unit 725 returns to step S802. When the stage is 0 (step S804: Yes), the modulation scheme determination unit 725 determines that the modulation scheme of the communication wave 102 is 8PSK (step S805), and ends the series of processes.

  In step S802, when the number of distributions of phase differences in the stage indicated by stage is not eight (step S802: No), the modulation scheme determination unit 725 determines whether the number of distributions of phase differences in the stage indicated by stage is five. Is determined (step S806). When the number of phase difference distributions in the stage indicated by stage is 5 (step S806: Yes), the modulation scheme determination unit 725 determines the modulation scheme of the communication wave 102 to be π / 4 shift QPSK (step S807). A series of processing ends.

  In step S806, when the number of distributions of phase differences in the stage indicated by the stage is not 5 (step S806: No), the modulation scheme determination unit 725 determines whether the number of distributions of phase differences in the stage indicated by the stage is 4. Is determined (step S808). When the number of phase difference distributions at the stage indicated by the stage is 4 (step S808: Yes), the modulation method determination unit 725 determines that the modulation method of the communication wave 102 is QPSK (step S809), and performs a series of processing. finish.

  In step S808, when the number of distributions of phase differences in the stage indicated by the stage is not 4 (step S808: No), the modulation scheme determination unit 725 determines whether the number of distributions of phase differences in the stage indicated by the stage is two. Is determined (step S810). When the number of phase difference distributions at the stage indicated by the stage is 2 (step S810: Yes), the modulation scheme determination unit 725 determines that the modulation scheme of the communication wave 102 is BPSK (step S811), and performs a series of processes. finish.

  In step S810, when the number of phase difference distributions on the stage indicated by stage is not 2 (step S810: No), the modulation scheme determination unit 725 reduces stage by 1 (step S812). Next, the modulation scheme determination unit 725 determines whether stage is 0 (step S813). As a result, it is possible to determine whether or not all stages have been determined.

  In step S813, when stage is not 0 (step S813: No), the modulation scheme determination unit 725 returns to step S802. When the stage is 0 (step S813: Yes), the modulation scheme determination unit 725 determines that the modulation scheme of the communication wave 102 cannot be determined (step S814), and ends the series of processes.

  For example, a program for executing the above steps is stored in the memory of the method determination apparatus 700 as correspondence information between the distribution information and the modulation method. Then, the modulation scheme determination unit 725 executes each step by executing a program stored in the memory, and determines the modulation scheme of the communication wave 102.

  Through the above steps, the modulation scheme determination unit 725 determines distribution information that can determine the modulation scheme among the distribution information (number of distributions) for each stage, and the communication wave 102 based on the determined distribution information and correspondence information. Can be determined.

  Here, an example in which the modulation scheme of the communication wave 102 is determined to be BPSK, QPSK, π / 4 shift QPSK, or 8PSK has been described, but the type of phase modulation scheme that can be determined is not limited thereto. For example, by adding distribution information corresponding to another phase modulation scheme such as DQPSK (Differential Quadrature PSK) to the correspondence information, it is possible to determine another phase modulation scheme such as DQPSK.

  In addition, here, a case has been described in which the number of detected different phase differences (number of distributions) is used as the distribution information, but the distribution information is not limited thereto. For example, the detection frequency for each detected phase difference (for example, each frequency distribution shown in FIGS. 6-1 to 6-4), the distribution ratio for each phase difference, or the like may be used as the distribution information.

  As described above, the method determining apparatus 110 according to the embodiment samples the received communication wave 102 at an arbitrary period. Therefore, the sampling period may be different from the symbol period of the communication wave 102. Then, the method determination device 110 detects the phase difference between the sampling data obtained by sampling, and uses the distribution of the detected phase difference, so that the modulation method can be selected even if the carrier frequency of the communication wave 102 is unknown. Can be determined.

  For this reason, for example, the modulation scheme can be determined in a shorter time (smaller processing amount) than when the modulation scheme is determined by analyzing the carrier frequency of the communication wave 102 in advance. In addition, since there is no need for a facility for analyzing the carrier frequency of the communication wave 102 in advance, the apparatus can be made small.

  As described above, according to the method determining apparatus and method determining method, the modulation method can be determined even if the carrier frequency is unknown. However, the method determination apparatus and the method determination method are applicable even when the carrier is known.

  The method determining apparatus and method determining method according to the present invention can also be applied to optical communication. Specifically, the reception unit 111 of the method determination apparatus 110 may receive a phase-modulated optical signal (communication wave) by quadrature detection, photoelectrically convert the received optical signal, and output the photoelectric signal to the sampling unit 112. . Thereby, the modulation method of the optical signal can be determined.

  The following additional notes are disclosed with respect to the embodiment described above.

(Supplementary Note 1) A sampling unit that samples a received communication wave at a period different from the symbol period of the communication wave;
A detection unit for detecting a phase difference between consecutive sampling data sampled by the sampling unit;
A calculation unit that calculates distribution information indicating a distribution state of phase differences detected within a predetermined period by the detection unit;
A determination unit that determines a modulation method of the communication wave based on the distribution information calculated by the calculation unit;
An output unit for outputting a determination result by the determination unit;
A method determining apparatus comprising:

(Additional remark 2) It is provided with the acquisition part which acquires the correspondence information which matches the said distribution information and a modulation system,
The method according to claim 1, wherein the determination unit determines a modulation method of the communication wave based on the distribution information calculated by the calculation unit and the correspondence information acquired by the acquisition unit. Judgment device.

(Supplementary Note 3) A detection unit that orthogonally detects the communication wave using a local signal having a frequency different from the carrier frequency of the communication wave is provided.
The system determination apparatus according to appendix 1 or 2, wherein the sampling unit samples a signal obtained by quadrature detection of the detection unit.

(Additional remark 4) The said determination part determines the kind of phase modulation system of the said communication wave, The system determination apparatus as described in any one of Additional remarks 1-3 characterized by the above-mentioned.

(Additional remark 5) The said calculation part calculates the said distribution information which shows the number of mutually different phase differences detected by the said detection part, The system determination apparatus as described in any one of Additional remark 1-4 characterized by the above-mentioned .

(Additional remark 6) The said calculation part calculates the said distribution information which shows the frequency detected by the said detection part for every phase difference, The system determination apparatus as described in any one of Additional remark 1-4 characterized by the above-mentioned.

(Supplementary Note 7) A sampling unit that acquires a plurality of sampling data strings obtained by sampling received communication waves at a plurality of periods;
A detection unit for detecting a phase difference between successive sampling data sampled by the sampling unit for each of the plurality of sampling data strings;
A calculation unit that calculates distribution information indicating a distribution state of phase differences detected within a predetermined period by the detection unit for each of the plurality of sampling data strings;
A determination unit that determines a modulation method of the communication wave based on distribution information calculated for each of the plurality of sampling data strings by the calculation unit;
An output unit for outputting a determination result by the determination unit;
A method determining apparatus comprising:

(Additional remark 8) The said determination part determines the distribution information which can determine the modulation system of the said communication wave among the distribution information calculated about each of the said some sampling data sequence, Based on the determined distribution information The system determining apparatus according to appendix 7, wherein the system determines a communication wave modulation system.

(Supplementary note 9) The received communication wave is sampled at a period different from the symbol period of the communication wave,
Detect the phase difference between the sampled continuous sampling data,
Calculate distribution information indicating the distribution state of the phase difference detected within a predetermined period,
Determine the modulation method of the communication wave based on the calculated distribution information,
Output the judgment result,
A method determination method characterized by the above.

(Appendix 10) Obtaining a plurality of sampling data strings obtained by sampling the received communication wave at a plurality of cycles,
Detecting a phase difference between consecutive sampled data sampled for each of the plurality of sampling data strings;
Calculating distribution information indicating a phase difference distribution state detected within a predetermined period for each of the plurality of sampling data strings;
Determining a modulation method of the communication wave based on distribution information calculated for each of the plurality of sampling data strings;
Output the judgment result,
A method determination method characterized by the above.

DESCRIPTION OF SYMBOLS 100 Communication system 102 Communication wave 110,700 System determination apparatus 111 Reception part 112 Sampling part 113 Detection part 114 Calculation part 115 Acquisition part 116 Determination part 117 Output part 211 Phase change point 221-224 Phase difference 300,510,520,530, 540 IQ Cartesian coordinate plane 511, 512, 521-524, 531-535, 541-548 Symbol points 611-614, 621-624, 631-634, 641-644 Histogram 711 Reception antenna 712 Local signal generator 713 Quadrature detection unit 714 A / D converter 720 Digital processing unit 721 Branching unit 722 Thinning processing unit 723 Phase difference detection unit 724 Phase difference distribution creation unit 725 Modulation method determination unit

Claims (7)

A sampling unit that samples the received communication wave at a period different from the symbol period of the communication wave;
A detection unit for detecting a phase difference between consecutive sampling data sampled by the sampling unit;
A calculation unit that calculates distribution information indicating a distribution state of phase differences detected within a predetermined period by the detection unit;
A determination unit that determines a modulation method of the communication wave based on the distribution information calculated by the calculation unit;
An output unit for outputting a determination result by the determination unit;
A method determining apparatus comprising: An acquisition unit that acquires correspondence information that associates the distribution information with a modulation method;
The said determination part determines the modulation system of the said communication wave based on the distribution information calculated by the said calculation part, and the corresponding information acquired by the said acquisition part. Method determination device. A detector for orthogonally detecting the communication wave by a local signal having a frequency different from the carrier frequency of the communication wave;
The method determination apparatus according to claim 1, wherein the sampling unit samples a signal obtained by quadrature detection of the detection unit. A sampling unit for acquiring a plurality of sampling data sequences obtained by sampling the received communication wave at a plurality of periods;
A detection unit for detecting a phase difference between successive sampling data sampled by the sampling unit for each of the plurality of sampling data strings;
A calculation unit that calculates distribution information indicating a distribution state of phase differences detected within a predetermined period by the detection unit for each of the plurality of sampling data strings;
A determination unit that determines a modulation method of the communication wave based on distribution information calculated for each of the plurality of sampling data strings by the calculation unit;
An output unit for outputting a determination result by the determination unit;
A method determining apparatus comprising:   The determination unit determines distribution information capable of determining a modulation method of the communication wave among distribution information calculated for each of the plurality of sampling data strings, and modulates the communication wave based on the determined distribution information The method determining apparatus according to claim 4, wherein the method is determined. The received communication wave is sampled at a period different from the symbol period of the communication wave,
Detect the phase difference between the sampled continuous sampling data,
Calculate distribution information indicating the distribution state of the phase difference detected within a predetermined period,
Determine the modulation method of the communication wave based on the calculated distribution information,
Output the judgment result,
A method determination method characterized by the above. Obtain multiple sampling data strings that sample received communication waves at multiple cycles,
Detecting a phase difference between consecutive sampled data sampled for each of the plurality of sampling data strings;
Calculating distribution information indicating a phase difference distribution state detected within a predetermined period for each of the plurality of sampling data strings;
Determining a modulation method of the communication wave based on distribution information calculated for each of the plurality of sampling data strings;
Output the judgment result,
A method determination method characterized by the above.

Images