Multipath analysis device and program

Abstract

To flexibly set a sampling frequency or a sampling period and to also analyze a multipath of a short delay time.SOLUTION: A multipath analysis device comprises an amplitude frequency characteristic acquisition unit, a delay time acquisition unit, a parameter acquisition unit, a calculation unit, an error detection unit, an extraction unit and an output unit. The amplitude frequency characteristic acquisition unit acquires a first amplitude frequency characteristic. The delay time acquisition unit acquires a first delay time which is a candidate of a delay time of a reflection wave included in a radio wave. The parameter acquisition unit acquires a predetermined parameter. The calculation unit calculates a second amplitude frequency characteristic which is a predicted amplitude frequency characteristic based on the first delay time and the parameter. The error detection unit detects an error of the first amplitude frequency characteristic and the second amplitude frequency characteristic. The extraction unit extracts a second delay time which is the delay time of the reflection wave included in the radio wave based on the detected error. The output unit outputs the extracted second delay time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a multipath analysis device and a program. [Background technology]

[0002] It is known that radio waves transmitted by the Orthogonal Frequency Division Multiplexing (OFDM) method include direct waves and reflected waves. Direct waves are radio waves that arrive directly from a single transmitting antenna. Reflected waves are radio waves that are reflected by buildings, mountains, and the like. In particular, radio waves that include multiple reflected waves that arrive at different times due to different propagation paths are called multipath waves. Conventionally, there has been technology for compensating for distortions in such multipath waves (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-101149 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the above-mentioned technology, the DU ratio of the desired wave and multipath is analyzed using a scattered pilot signal (SP signal). Also, multipath analysis is performed by measuring the delay profile, which is the intensity level of the arriving radio wave. According to such conventional technology, there is a problem that when there is a multipath with a short delay time, it may not be possible to analyze it with the existing delay profile.

[0005] Also, in order to obtain multipath components, it is possible to analyze them using the inverse fast Fourier transform (IFFT). With the inverse fast Fourier transform, it is necessary to widen the frequency band when analyzing short delay times. When using SP signals, the performance limit is the inverse of the IFFT sampling frequency of the transmitter modulator, and when using the amplitude frequency characteristics of OFDM waves, the performance limit is the inverse of the frequency bandwidth of terrestrial digital broadcasting waves. Also, there is a problem in that a large amount of data is required to measure long delay times, and the amount of data must be a power of two.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS The present invention provides a multipath analysis device and program that can flexibly set the sampling frequency and sampling period and can analyze multipaths with short delay times. [Means for solving the problem]

[0007] [1] In order to solve the above problem, a multipath analysis device according to one embodiment of the present invention includes an amplitude frequency characteristic acquisition unit that acquires a first amplitude frequency characteristic, which is an amplitude frequency characteristic representing the strength of a radio wave for each frequency, of a received radio wave; a delay time acquisition unit that acquires a first delay time that is a candidate for the delay time of a reflected wave contained in the radio wave; a parameter acquisition unit that acquires predetermined parameters; a calculation unit that calculates a second amplitude frequency characteristic, which is the predicted amplitude frequency characteristic, based on the acquired first delay time and the acquired parameters; an error detection unit that detects an error between the acquired first amplitude frequency characteristic and the calculated second amplitude frequency characteristic; an extraction unit that extracts a second delay time, which is the delay time of a reflected wave contained in the radio wave, based on the detected error; and an output unit that outputs the extracted second delay time.

[0008] [2] Moreover, one aspect of the present invention is the multipath analysis device described above, further comprising a delay time adding unit that calculates a third delay time by adding or subtracting a predetermined time to the first delay time, wherein the delay time acquiring unit acquires the calculated third delay time, the calculating unit calculates a plurality of the second amplitude frequency characteristics based on the calculated third delay time and the parameter, the error detecting unit detects an error between the acquired first amplitude frequency characteristic and the calculated plurality of the second amplitude frequency characteristics, and the extracting unit extracts the second delay time based on the detected plurality of errors.

[0009] [3] Moreover, in one aspect of the present invention, in the multipath analysis device described above, the extraction unit extracts, as the second delay time, the first delay time or the third delay time that reduces the error.

[0010] [4] In addition, according to one aspect of the present invention, in the above multipath analysis device, the device further includes a correction unit that corrects the parameters so as to reduce the error detected by the error detection unit.

[0011] [5] Moreover, in one aspect of the present invention, in the above-mentioned multipath analysis device, the correction unit further includes a calculation count acquisition unit that acquires the number of times correction is performed by the correction unit, and a judgment unit that judges whether the number acquired by the calculation count acquisition unit has been reached, and the correction unit repeats the correction until the judgment unit judges that the number acquired by the calculation count acquisition unit has been reached.

[0012] [6] Moreover, in one aspect of the present invention, in the multipath analysis device described above, the output section further outputs the first amplitude-frequency characteristic and the second amplitude-frequency characteristic.

[0013] [7] Moreover, according to one aspect of the present invention, in the multipath analysis device described above, the parameters include a terminal voltage of a desired wave contained in the radio wave, a multipath DU ratio, and a high-frequency phase difference.

[0014] [8] Also, one aspect of the present invention is a program that causes a computer to execute the following steps: an amplitude frequency characteristic acquisition step of acquiring a first amplitude frequency characteristic, which is an amplitude frequency characteristic of a received radio wave, the first amplitude frequency characteristic being an amplitude frequency characteristic that represents the strength of a radio wave for each frequency; a delay time acquisition step of acquiring a first delay time that is a candidate for the delay time of a reflected wave contained in the radio wave; a parameter acquisition step of acquiring predetermined parameters; a calculation step of calculating a second amplitude frequency characteristic, which is the predicted amplitude frequency characteristic, based on the acquired first delay time and the acquired parameters; an error detection step of detecting an error between the acquired first amplitude frequency characteristic and the calculated second amplitude frequency characteristic; an extraction step of extracting a second delay time, which is the delay time of a reflected wave contained in the radio wave, based on the detected error; and an output step of outputting the extracted second delay time. Effect of the Invention

[0015] According to the present invention, the sampling frequency and sampling period can be flexibly set, and multipaths with short delay times can also be analyzed. [Brief description of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a configuration of a multi-path analysis system according to an embodiment of the present invention and a schematic functional configuration of a multi-path analysis device; [Diagram 2] 4 shows a waveform of a radio wave measured by a spectrum analyzer according to the embodiment. [Diagram 3] 4 shows sampling data measured by the spectrum analyzer according to the embodiment. [Figure 4] 5 is a flowchart showing a procedure for measuring radio waves by the spectrum analyzer according to the embodiment. [Diagram 5] 6 is a flowchart showing a procedure for extracting a delay time by the multipath analysis device according to the embodiment. [Figure 6]5 is a flowchart showing a procedure for analyzing multipath components by the multipath analysis device according to the embodiment. [Figure 7] 4 is a diagram showing an example of an analysis result output by the multipath analysis device according to the embodiment. FIG. [Figure 8] 4A and 4B are diagrams illustrating an example of actual measured values ​​and calculated values ​​output by the multipath analysis device according to the embodiment. [Figure 9] 13 is an example of a case in which values ​​calculated by the multipath analysis device according to the embodiment are displayed for each calculation count. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A multipath analysis system 1 according to this embodiment receives radio waves (hereinafter simply referred to as radio waves) transmitted by OFDM. The multipath analysis system 1 analyzes multipaths contained in the received radio waves and displays the analysis results. Here, analyzing multipaths means, for example, calculating the DU ratio, delay time, and high-frequency phase difference values ​​for multiple reflected waves contained in the radio waves.

[0018] An example of an intended use of the multipath analysis system 1 according to this embodiment is as follows. That is, the multipath analysis system 1 receives radio waves transmitted from a transmission point such as a radio tower at a reception point such as a house. There are usually obstacles such as buildings and mountains between the transmission point and the reception point. The radio waves received at the reception point are multipath waves including a direct wave as well as multiple reflected waves reflected by obstacles. The multipath analysis system 1 analyzes the multipath included in the received radio waves and displays the analysis results. The radio waves transmitted from a transmission point such as a radio tower may be, for example, terrestrial digital broadcasting.

[0019] In order to ensure good reception conditions at a plurality of reception points, an antenna pattern is designed at a transmission point. When designing the antenna pattern, a multipath analysis is performed at a plurality of reception points. The multipath analysis system 1 according to the present embodiment is used at a reception point for designing the antenna pattern at a transmission point.

[0020] [Multipath analysis system configuration] 1 is a block diagram showing a configuration of a multipath analysis system according to an embodiment of the present invention and a schematic functional configuration of a multipath analysis device. As shown in the figure, the multipath analysis system 1 includes a multipath analysis device 10, an antenna 21, a spectrum analyzer 22, a storage unit 30, and a display unit 40.

[0021] The antenna 21 receives radio waves transmitted from a transmission point. Specifically, the antenna 21 receives radio waves for television broadcasting such as terrestrial digital broadcasting. Television broadcasting is broadcasting with content consisting of video and audio. The antenna 21 may be, for example, a UHF (Ultra High Frequency) antenna.

[0022] The spectrum analyzer 22 measures the radio waves received by the antenna 21. The frequency bandwidth, number of sampling data, etc. of the spectrum analyzer 22 are set by the user. The spectrum analyzer 22 displays the measurement results in a two-dimensional graph with the horizontal axis representing frequency and the vertical axis representing power. The spectrum analyzer 22 outputs the measurement results to the multipath analysis device 10. The spectrum analyzer 22 is not limited to an example of a spectrum analyzer as long as it can measure the amplitude-frequency characteristics from the radio waves received by the antenna 21. For example, instead of the spectrum analyzer 22, a level checker (antenna level checker) capable of acquiring the amplitude-frequency characteristics may be used.

[0023] The storage unit 30 is a non-volatile memory such as a magnetic hard disk device or a solid state drive (SSD). The storage unit 30 stores information such as delay times and initial values ​​of parameters, which are used by the multipath analysis device 10 for calculations.

[0024] The display unit 40 displays the results of the analysis performed by the multi-path analysis device 10 in accordance with the control of the multi-path analysis device 10. The display unit 40 may be, for example, a liquid crystal display or an organic EL (Electroluminescence) display.

[0025] The multipath analysis device 10 includes an amplitude frequency characteristic acquisition unit 110, a delay time acquisition unit 121, a parameter acquisition unit 122, a calculation unit 130, an error detection unit 140, a delay time addition unit 150, a correction unit 160, an extraction unit 170, and an output unit 180. Each of these functional units can be realized, for example, by a computer and a program. Each functional unit has a storage means as necessary. The storage means is, for example, a variable in the program or a memory allocated by the execution of the program. A non-volatile storage means such as a magnetic hard disk drive or a solid state drive (SSD) may be used as necessary. At least a part of the functions of each functional unit may be realized as a dedicated electronic circuit rather than a program. The functions of each unit are as follows:

[0026] The amplitude frequency characteristic acquisition unit 110 acquires data measured by the spectrum analyzer 22. The amplitude frequency characteristic acquisition unit 110 may acquire the measurement data by being connected to the spectrum analyzer 22 via a USB (Universal Serial Bus) connection or a predetermined communication network such as a predetermined LAN (Local Area Network). The amplitude frequency characteristic acquisition unit 110 may also acquire the measurement data via a recording medium such as a USB memory. Here, the data measured by the spectrum analyzer 22 includes amplitude frequency characteristics. The amplitude frequency characteristics indicate the strength of radio waves for each frequency. Among the amplitude frequency characteristics, the amplitude frequency characteristics acquired by the spectrum analyzer 22 are also referred to as first amplitude frequency characteristics. In other words, the amplitude frequency characteristic acquisition unit 110 acquires the first amplitude frequency characteristics, which are amplitude frequency characteristics indicating the strength of radio waves for each frequency and are the amplitude frequency characteristics of the received radio waves.

[0027] The delay time acquisition unit 121 acquires a value of a delay time used when the calculation unit 130 performs calculation. Here, the calculation unit 130 performs calculations multiple times. The calculation unit 130 uses an initial value of the delay time stored in the storage unit 30 for the first calculation, and uses the value of the delay time added by the delay time addition unit 150 for the second and subsequent calculations. That is, the delay time acquisition unit 121 acquires the value of the delay time from either the storage unit 30 or the delay time addition unit 150. The initial value of the delay time is also referred to as the first delay time. The first delay time is a candidate for the delay time of the reflected wave included in the radio wave. That is, the delay time acquisition unit 121 acquires the first delay time, which is a candidate for the delay time of the reflected wave included in the radio wave. The initial value of the delay time refers to the delay time stored in the storage unit 30 among the delay times used by the calculation unit 130 in the calculation.

[0028] The parameter acquisition unit 122 acquires predetermined parameters used in the calculations performed by the multipath analysis device 10. Specifically, the predetermined parameters are the terminal voltage of a desired wave included in the radio wave, the multipath DU ratio, and the high-frequency phase difference. In the first calculation, the parameter acquiring unit 122 acquires the initial values ​​of the predetermined parameters from the storage unit 30. In the second and subsequent calculations, the parameter acquiring unit 122 acquires the values ​​of the predetermined parameters corrected by the correcting unit 160, which will be described later. The predetermined parameter may be at least one of the terminal voltage, the multipath DU ratio, and the high-frequency phase difference of the desired wave included in the radio wave. The initial value of the predetermined parameter refers to a predetermined parameter stored in the storage unit 30 among the predetermined parameters used by the calculation unit 130 in the calculation.

[0029] Calculation unit 130 calculates the amplitude frequency characteristic based on the first delay time acquired by delay time acquisition unit 121 and the predetermined parameters acquired by parameter acquisition unit 122. Among the amplitude frequency characteristics, the amplitude frequency characteristic calculated by calculation unit 130 is also referred to as the second amplitude frequency characteristic. That is, calculation unit 130 calculates the second amplitude frequency characteristic based on the first delay time acquired by delay time acquisition unit 121 and the parameters acquired by parameter acquisition unit 122. In other words, the second amplitude frequency characteristic is the amplitude frequency characteristic of a radio wave predicted to be similar to the first amplitude frequency characteristic, which is the amplitude frequency characteristic of an actually measured radio wave.

[0030] The amplitude-frequency characteristics are expressed by the following equation (1), where the terminal voltage of the desired wave is D [μV], the terminal voltage of the multipath is U [μV], the delay time is τ [μsec], the high-frequency phase difference is φ [rad: radian measure], the frequency is f [MHz], the sample point number on the amplitude-frequency characteristics is s, the number of multipaths is n, and the numbers assigned to the multipaths are j and k.

[0031]

number

[0032] The error detection section 140 detects an error between the first amplitude frequency characteristic acquired by the amplitude frequency characteristic acquisition section 110 and the second amplitude frequency characteristic calculated by the calculation section 130. Specifically, the error detection section 140 detects an error function ER m The error is detected based on the error function ER m is the actual measured value of the amplitude frequency characteristic T(f s ), and the calculated value is √(V m (f s )), the number of sample points on the amplitude frequency characteristic is S, and the number of calculations is m, then this is expressed by the following equation (2).

[0033]

number

[0034] Here, V m (f s ) can be expressed by the following equation (3).

[0035]

number

[0036] Error function ER m By differentiating with respect to the parameters of the terminal voltage D of the desired wave, the terminal voltage U of the multipath, and the high-frequency phase difference φ, the following equations (4) to (6) can be derived.

[0037]

number

[0038]

number

[0039]

number

[0040] The parameters of the terminal voltage D of the desired wave, the terminal voltage U of the multipath, and the high-frequency phase difference φ are given by the following equations (7) to (9). Here, ε is a correction coefficient and is a number smaller than 1. m indicates that each parameter is used in the (m+1)th calculation.

[0041]

number

[0042]

number

[0043]

number

[0044] Here, the multipath analysis device 10 calculates the first amplitude-frequency characteristic (actual measurement value) by the steepest descent method. and the second amplitude frequency characteristic (calculated value). In order to find a delay time and parameters that further reduce the error, calculation unit 130 repeatedly calculates the second amplitude frequency characteristic based on a plurality of delay times and parameters. Specifically, when calculation unit 130 calculates the second amplitude frequency characteristic, delay time adding unit 150 and correction unit 160 calculate the delay time and parameters to be used in the next calculation, respectively, based on the amplitude frequency characteristic calculated by calculation unit 130.

[0045] The delay time adding unit 150 adds or subtracts a predetermined delay time to the delay time used in the calculation by the calculation unit 130. The delay time to which the predetermined delay time is added or subtracted by the delay time adding unit 150 is also referred to as a third delay time. In other words, the delay time adding unit 150 calculates the third delay time by adding or subtracting a predetermined time to the first delay time. In this case, the delay time acquisition unit 121 acquires the third delay time calculated by the delay time addition unit 150, and the calculation unit 130 calculates the second amplitude frequency based on the third delay time added by the delay time addition unit 150 and the parameter. The addition or subtraction of the delay time by the delay time addition unit 150 and the calculation by the calculation unit 130 based on the calculated delay time are repeated a predetermined number of times. That is, the calculation unit 130 calculates a plurality of second amplitude frequency characteristics by performing the calculation multiple times.

[0046] The correction section 160 corrects the parameters used by the calculation section 130 to calculate the amplitude-frequency characteristic, based on the error detected by the error detection section 140. The calculation section 130 finds highly accurate parameters by calculating a plurality of amplitude-frequency characteristics based on a plurality of parameters. That is, the correction section 160 corrects the parameters so that the error detected by the error detection section 140 is reduced.

[0047] The extraction unit 170 extracts the second delay time based on the error detected by the error detection unit 140. The second delay time is the delay time of the reflected wave included in the radio wave, and is the delay time calculated by the multipath analysis device 10. When there are multiple detected errors, the extraction unit 170 extracts the second delay time based on the multiple errors. Specifically, the extraction unit 170 extracts, as the second delay time, the delay time that minimizes the error from the multiple detected errors. That is, the extraction unit 170 extracts, as the second delay time, the first delay time or the third delay time that minimizes the error between the actual measurement value and the calculated value of the amplitude frequency characteristic.

[0048] The output unit 180 outputs the second delay time extracted by the extraction unit 170. In addition to the second delay time, or instead of the second delay time, the output unit 180 may output parameters used in calculating the second delay time. The parameters output by the output unit 180 may be the terminal voltage D, DU ratio, and amplitude of the desired wave, and are expressed by, for example, the following equations (10) to (12).

[0049]

number

[0050]

number

[0051]

number

[0052] [Measuring radio waves using a spectrum analyzer] The spectrum analyzer 22 measures the radio waves received by the antenna 21 based on the frequency band and the number of sampling data sets set by the user. Measurement of radio waves by the spectrum analyzer 22 will be described with reference to Figs. 2 to 4.

[0053] 2 shows the waveform of a radio wave measured by a spectrum analyzer according to the embodiment. An example of a radio wave measured by a spectrum analyzer will be described with reference to the figure. The figure shows the amplitude-frequency characteristics of the measured radio wave, with the frequency (MHz) of the measured radio wave on the horizontal axis and the amplitude (dBμV) on the vertical axis. In the example shown in the figure, the number of sampling data S is 19.

[0054] Fig. 3 shows sampling data measured by the spectrum analyzer according to the embodiment. This figure shows discrete data of the waveform shown in Fig. 2. Specifically, an example is shown in which the number of sampling data S=19. The amplitude frequency characteristic acquisition unit 110 acquires the discrete data shown in Fig. 3 as the first amplitude frequency characteristic. In the amplitude frequency characteristic, frequency and amplitude are associated with each other.

[0055] 4 is a flow chart showing a procedure for measuring radio waves using a spectrum analyzer according to the embodiment, which will be described with reference to the drawing.

[0056] First, in steps S110 to S130, measurement conditions are set in the spectrum analyzer 22 by the user. Specifically, in step S110, the measurement channel is set in the spectrum analyzer 22 by a user operation. Next, in step S120, the frequency bandwidth of the spectrum analyzer 22 is set by the user's operation. Next, in step S130, the number S of sampling data is set in the spectrum analyzer 22.

[0057] Next, in step S140, the spectrum analyzer 22 acquires sampling data of the amplitude-frequency characteristics of the radio wave received by the antenna 21. Next, in step S150, the spectrum analyzer 22 determines whether or not the number of acquired sampling data is greater than the number of sampling data S set in step S130. If the number of acquired sampling data is greater (i.e., step S150; YES), the spectrum analyzer 22 proceeds to step S160. If the number of acquired sampling data is not greater (i.e., step S150; NO), the spectrum analyzer 22 proceeds to step S140.

[0058] Next, in step S160, the spectrum analyzer 22 outputs the measured S sets of sampling data. When the spectrum analyzer 22 and the multipath analysis device 10 are connected via USB, the spectrum analyzer 22 outputs the measured S sets of sampling data to the amplitude frequency characteristic acquisition unit 110 as the first amplitude frequency characteristic. The spectrum analyzer 22 may also output the measured S sets of sampling data to the amplitude frequency characteristic acquisition unit 110 via a storage medium such as a USB memory. The spectrum analyzer 22 may also output the measured S sets of sampling data to the amplitude frequency characteristic acquisition unit 110 via a predetermined communication network or the like.

[0059] [Extraction of delay time using multipath analysis device] 5 is a flowchart showing a procedure for extracting delay times by the multipath analysis device according to the embodiment, and the procedure for extracting delay times by the multipath analysis device 10 will be described with reference to the drawing.

[0060] First, in step S310, the number of calculations LC1 is set by a user operation. Here, the number of calculations LC1 is the number of times the parameters are corrected by the correction unit 160. The larger the number of calculations LC1 is, the better the accuracy of the calculations is. However, when the number of calculations LC1 is increased, the calculation time becomes longer. Therefore, the number of calculations LC1 is set in consideration of the trade-off between the accuracy of the calculations and the calculation time. In this case, the multipath analysis device 10 is provided with a calculation count acquisition unit (not shown) to acquire the calculation count LC1.

[0061] Next, in step S320, the maximum DU ratio DU of the detected multipath is set by the user. max is set. Maximum DU ratioDU max If is increased, the calculation time becomes longer and the accuracy of delay time extraction also decreases. max It is desirable that the DU ratio is 25 dB or less. If the DU ratio is 25 dB or more, no reception interference occurs, so even if there are delayed waves with a DU ratio of 25 dB or more, there is no practical problem. max If the DU ratio is not set, the delay times of delayed waves that are not included in the actual multipath waves will be extracted endlessly, which will reduce the unevenness of the amplitude-frequency characteristics and reduce the accuracy of the delay time extraction. Therefore, by setting an appropriate DU ratio, the accuracy of the delay time extraction can be maintained.

[0062] Next, in step S330, the extraction range and extraction interval of the delay time are set by the user. Specifically, the minimum delay time τ min and the maximum delay time τ max is set, and the extraction interval τ step is set, where the minimum delay time τ min If is set to 0, the minimum delay time τ min The sampling interval is τ stepis set. If the extraction range of the delay time is widened, it becomes possible to measure more reflected waves, but the calculation time becomes longer. Also, if the extraction interval is shortened, the calculation accuracy becomes higher, but the calculation time becomes longer. Therefore, the minimum delay time τ min , maximum delay time τ max and sampling interval τ step is set taking into consideration the trade-off between calculation accuracy and calculation time.

[0063] Next, in step S340, the initial value of the delay time is set to the minimum delay time τ min Specifically, the delay time acquisition unit 121 sets the minimum delay time τ min is obtained.

[0064] Next, in step S350, the calculation unit 130 calculates the set minimum delay time τ min and calculates the amplitude-frequency characteristic based on predetermined parameters.

[0065] Next, in step S360, the error detection section 140 detects the error between the actual value of the amplitude frequency characteristic measured by the spectrum analyzer 22 and the calculated value of the amplitude frequency characteristic calculated by the calculation section .

[0066] Next, in step S370, it is determined whether the number of times that the calculation unit 130 has calculated the amplitude frequency characteristic is greater than the calculation number of times LC1. If the number of times that the calculation has been performed is greater than the calculation number of times LC1 (i.e., step S370; YES), the process proceeds to step S390. If the number of times that the calculation has been performed is not greater than the calculation number of times LC1 (i.e., step S370; NO), the process proceeds to step S380. In this case, the multipath analysis device 10 includes a determination unit (not shown) to determine whether the number of calculations is greater than the number of calculations LC1. That is, the determination unit determines whether the number of calculations by the calculation unit 130 has reached the number acquired by the calculation number acquisition unit. The correction unit 160 repeats correction until the determination unit determines that the number of calculations has reached the number acquired by the calculation number acquisition unit. Furthermore, the calculation unit 130 repeats calculation based on the corrected parameters until the determination unit determines that the number of calculations has reached the number acquired by the calculation number acquisition unit. Furthermore, the error detection unit 140 repeats error detection until the determination unit determines that the number of calculations has reached the number acquired by the calculation number acquisition unit. That is, the error detection unit 140 detects an error between the first amplitude frequency characteristic acquired by the spectrum analyzer 22 and the multiple second amplitude frequency characteristics calculated by the calculation unit 130.

[0067] Next, in step S380, the correction unit 160 corrects the parameters based on the error detected by the error detection unit 140. Specifically, the parameters corrected by the correction unit 160 are the terminal voltage D of the desired wave, the terminal voltage U of the multipath, and the high-frequency phase difference φ.

[0068] Next, in step S390, the delay time adding unit 150 judges whether the value of the error detected by the error detecting unit 140 is the smallest value among the errors detected multiple times. If the error is the smallest (i.e., step S390; YES), the process proceeds to step S400. If the error is not the smallest (i.e., step S390; NO), the process proceeds to step S410.

[0069] Next, in step S400, the calculation unit 130 calculates the delay time used in calculating the amplitude-frequency characteristic as the extraction candidate τ t Set to.

[0070] Next, in step S410, the delay time adding unit 150 adds the extraction interval τ step Add.

[0071] Next, in step S420, the delay time adding unit 150 calculates the extraction interval τ step The delay time adding unit 150 judges whether the delay time obtained by adding the extraction interval τ step If the delay time to which the delay time is added is not included in the extracted delay time (i.e., step S420; YES), the process proceeds to step S430. If the delay time to which the delay time is added is included in the extracted delay time (i.e., step S420; NO), the process proceeds to step S410.

[0072] Next, in step S430, the extraction unit 170 extracts the extraction interval τ step The delay time added to this is the maximum delay time τ max The extraction unit 170 determines whether the extraction interval τ step The delay time added to this is the maximum delay time τ max If it is greater (i.e., step S430; YES), the process proceeds to step S440. max If it is not greater than τ (i.e., step S430; NO), the process proceeds to step S350. Here, when the process of step S350 is performed for the second or subsequent times, that is, in the extraction of the second or subsequent multipath waves, the already extracted delay time τ c If there is a delay time τ c The calculation is performed by determining the multipath having the following:

[0073] Next, in step S440, the extraction unit 170 extracts the extraction candidate τ t , the delay time τ c Let us assume that.

[0074] Next, in step S450, the extraction unit 170 extracts the delay time τ c The DU ratio is the maximum DU ratio max Determine whether the delay time τ is greater than c The DU ratio is the maximum DU ratio max If it is greater (i.e., step S450; YES), the process proceeds to step S460. maxIf it is not greater (ie, step S450; NO), the process proceeds to step S340.

[0075] Next, in step S460, the extraction unit 170 extracts the last extracted delay time τ c Delete.

[0076] [Analysis of multipath components using a multipath analyzer] 6 is a flowchart showing a procedure for analyzing multipath components by the multipath analysis device according to the embodiment. The procedure for analyzing multipath components based on the extracted delay time by the multipath analysis device 10 will be described with reference to the drawing.

[0077] First, in step S510, the number of calculations LC2 is set by a user operation. Here, the number of calculations LC2 is the number of times that parameters are corrected in the analysis procedure of the multipath components, and is different from the number of calculations LC1. The larger the number of calculations LC2, the better the analysis accuracy. However, increasing the number of calculations LC2 increases the analysis time. Therefore, the number of calculations LC2 is set in consideration of the trade-off between the analysis accuracy and the analysis time. The number of calculations LC1 and the number of calculations LC2 may be the same value.

[0078] Next, in step S520, multipath setting is performed. Specifically, the delay time τ extracted in the delay time extraction process described with reference to FIG. c and the number of multipaths are set.

[0079] Next, in step S530, the calculation unit 130 calculates the set delay time τ c and the predetermined parameters, the amplitude frequency characteristic is calculated.

[0080] Next, in step S540, the error detection section 140 detects the error between the actual value of the amplitude frequency characteristic measured by the spectrum analyzer 22 and the calculated value of the amplitude frequency characteristic calculated by the calculation section .

[0081] Next, in step S550, it is determined whether the number of times that the calculation unit 130 has calculated the amplitude frequency characteristic is greater than the number of calculations LC2. If the number of calculations is greater than the number of calculations LC2 (i.e., step S550; YES), the process proceeds to step S570. If the number of calculations is not greater than the number of calculations LC2 (i.e., step S550; NO), the process proceeds to step S560.

[0082] Next, in step S560, the correction unit 160 corrects the parameters based on the error detected by the error detection unit 140. Specifically, the parameters corrected by the correction unit 160 are the terminal voltage D of the desired wave, the terminal voltage U of the multipath, and the high-frequency phase difference φ.

[0083] Next, in step S570, the output unit 180 outputs the actual measured value and the calculated value of the amplitude frequency characteristic to the display unit 40. Specifically, the output unit 180 outputs information to the display unit 40 so that the actual measured value and the calculated value of the amplitude frequency characteristic are displayed superimposed on each other on a graph.

[0084] Next, in step S580, the output unit 180 outputs the numerical information used to calculate the amplitude-frequency characteristic. Specifically, the output unit 180 outputs the terminal voltage D of the desired wave, the multipath DU ratio, and the delay time τ c and the high-frequency phase difference φ are displayed on the display unit 40.

[0085] [Example of display by multipath analyzer] The display unit 40 displays a display screen based on the information output by the multi-path analysis device 10. An example of a display screen displayed by the display unit 40 will be described with reference to Figs.

[0086] 7 is a diagram showing an example of an analysis result output by the multi-path analysis device according to the embodiment. A display screen D10 is an example of a display screen when the analysis result analyzed by the multi-path analysis device 10 is displayed as numerical data. The display screen D10 includes reference characters D110 to D180 as components of the display screen.

[0087] Reference symbol D110 is a radio button having the options of "actual measurement data" and "simulation." The user switches the numerical data displayed on the display screen D10 by selecting either "actual measurement data" or "simulation." Each of the components D120 to D180 displays either "actual measurement data" or "simulation" based on the information selected in reference symbol D110.

[0088] Reference D120 indicates the terminal voltage D [dBμV] of the desired wave and the delay wave number, which is the number of delayed waves analyzed by the multipath analysis device 10. In the example shown in Fig. 7, the terminal voltage D of the desired wave is "74.9 [dBμV]" and the delay wave number is "7".

[0089] Reference D130 displays the numerical information of the multipath calculated in the extraction of the delay time. Specifically, it displays the DU ratio [dB], delay time τ [μs], high frequency phase difference φ [degrees], and path length difference [m] of each delayed wave analyzed by the multipath analysis device 10. In the example shown in FIG. 7, since the number of delayed waves is "7", numerical information is displayed for each of the seven delayed waves shown as U1 to U7. In the example shown in FIG. 7, for example, the DU ratio of the delayed wave U1 is "13.823 [dB]", the delay time τ is "0.15 [μs]", the high frequency phase difference φ is "355.96 [degrees]", and the path length difference is "45 [m]".

[0090] Reference symbol D140 indicates a correction coefficient ε and the number of sampling data S. The correction coefficient ε is the correction coefficient ε used in the calculation by the error detection unit 140. The number of sampling data S is the number of samples of the amplitude frequency characteristic measured by the spectrum analyzer 22. In the example shown in Fig. 7, the correction coefficient ε is "0.1" and the number of sampling data S is "111".

[0091] The reference symbol D150 indicates the number of calculations LC1 and the minimum delay time τ min [μs], maximum delay time τ max [μs] 、 and sampling interval τ step In the example shown in FIG. 7, the number of calculations LC1 is “50”, and the minimum delay time τ min is “0[μs]”, and the maximum delay time τ max is “2[μs]”, and the sampling interval τ step [μs] is “0.01[μs]”.

[0092] Reference D160 indicates numerical information of the multipath calculated in the analysis of the multipath components. Specifically, it indicates the delay time τ [μs] and DU ratio [dB] of each delayed wave analyzed by the multipath analysis device 10. In the example shown in FIG. 7, the delay time τ of the delayed wave U1 is "0.15 [μs]" and the DU ratio is "14.7 [dB]". In the analysis of the multipath components, the delay time τ calculated in the extraction of the delay time is used, so the same value as the delay time τ indicated by reference D130 is indicated. The DU ratio calculated in the analysis of the multipath components is more accurate than the DU ratio calculated in the extraction of the delay time.

[0093] Reference D170 indicates the number of calculations LC2 used in the analysis of the multipath components. In the example shown in FIG.

[0094] Reference D180 denotes the value of the error function used in the analysis of the multipath components. In the example shown in Figure 7, the error is "0.20063323".

[0095] FIG. 8 is a diagram showing an example of actual measurement values ​​and calculated values ​​output by the multipath analysis device according to the embodiment. The display screen D210 is an example of a display screen when the calculated values ​​analyzed by the multipath analysis device 10 are displayed in a graph superimposed on the actual measurement values. In the figure, the amplitude frequency characteristics of the actual measurement values ​​and the calculated values ​​are displayed with the frequency (MHz) on the horizontal axis and the terminal voltage (dBμV) on the vertical axis. The amplitude frequency characteristics of the actual measurement values ​​are shown by a waveform W1, and the amplitude frequency characteristics of the calculated values ​​are shown by a waveform W2. In this example, the actual measurement values ​​are the first amplitude frequency characteristics measured by the spectrum analyzer 22, and the calculated values ​​are the second amplitude frequency characteristics calculated by the multipath analysis device 10. That is, the output unit 180 further outputs the first amplitude frequency characteristics and the second amplitude frequency characteristics.

[0096] Reference symbol D220 indicates the setting value of the spectrum analyzer 22 when the actual measurement value was measured. In the example shown in Fig. 8, the bandwidth is "5.57 [MHz]" and the RBW (Resolution Band Width) is "10 [kHz]".

[0097] Fig. 9 shows an example of a case where the calculation value calculated by the multipath analysis device according to the embodiment is displayed for each number of calculations. With reference to Fig. 9(A) to Fig. 9(D), a change in the analysis result according to a change in the number of calculations LC1 in the extraction of the delay time will be described. Fig. 9(A) shows an example of a case where the number of calculations LC1 is set to 5, Fig. 9(B) shows an example of a case where the number of calculations LC1 is set to 100, Fig. 9(C) shows an example of a case where the number of calculations LC1 is set to 300, and Fig. 9(D) shows an example of a case where the number of calculations LC1 is set to 500.

[0098] In Fig. 9(A), the amplitude frequency characteristics of the actual measured values ​​are shown by waveform W1A, and the amplitude frequency characteristics of the calculated values ​​are shown by waveform W2A. In Fig. 9(B), the amplitude frequency characteristics of the actual measured values ​​are shown by waveform W1B, and the amplitude frequency characteristics of the calculated values ​​are shown by waveform W2B. In Fig. 9(C), the amplitude frequency characteristics of the actual measured values ​​are shown by waveform W1C, and the amplitude frequency characteristics of the calculated values ​​are shown by waveform W2C. In Fig. 9(D), the amplitude frequency characteristics of the actual measured values ​​are shown by waveform W1D, and the amplitude frequency characteristics of the calculated values ​​are shown by waveform W2D.

[0099] Referring to FIG. 9A, where the number of calculations LC2 is 5, the waveforms W1A and W2A differ from each other by about 10 to 20 dB. In other words, the error between the actual measurement value and the calculated value is large. On the other hand, referring to FIG. 9D, where the number of calculations LC2 is 500, the waveforms W1D and W2D are almost the same and there is no difference between them. In other words, the error between the actual measurement value and the calculated value is small. Therefore, it can be seen from these figures that the error between the actual measurement value and the calculated value decreases as the value of the number of calculations LC2 increases.

[0100] [Summary of the embodiment] According to the embodiment described above, the multipath analysis device 10 includes the amplitude frequency characteristic acquisition unit 110 and acquires the first amplitude frequency characteristic measured by the spectrum analyzer 22. The multipath analysis device 10 also includes the delay time acquisition unit 121 and acquires the first delay time, which is a candidate for the delay time, and the parameter acquisition unit 122 and acquires a predetermined parameter. The multipath analysis device 10 also includes the calculation unit 130 and calculates the second amplitude frequency characteristic based on the acquired first delay time and the parameter. The multipath analysis device 10 also includes the error detection unit 140 and detects the error between the acquired first amplitude frequency characteristic and the second amplitude frequency characteristic. The multipath analysis device 10 also includes the extraction unit 170 and extracts the second delay time, which is the delay time, based on the detected error. The multipath analysis device 10 also includes the output unit 180 and outputs the extracted second delay time.

[0101] That is, the multipath analysis device 10 calculates the delay time by repeatedly comparing the first amplitude frequency characteristic measured by the spectrum analyzer 22 with the calculated second amplitude frequency characteristic. Therefore, according to this embodiment, there is no limit to the sampling frequency or sampling period in the setting of the spectrum analyzer 22. Also, according to this embodiment, unlike the method using an existing delay profile such as the conventional analysis method using an SP signal, it is possible to measure multipaths with short delay times. Therefore, according to this embodiment, it is possible to flexibly set the sampling frequency and sampling period and analyze multipaths with short delay times.

[0102] According to the above-described embodiment, the multipath analysis device 10 calculates the second amplitude-frequency characteristic based on a so-called provisionally determined delay time stored in the storage unit 30 in the first calculation, and based on a delay time obtained by calculation in the second and subsequent calculations. The multipath analysis device 10 extracts the delay time based on the error between the calculated second amplitude-frequency characteristic and the measured first frequency characteristic. Specifically, the multipath analysis device 10 extracts the delay time that minimizes the error between the calculated second amplitude-frequency characteristic and the measured first frequency characteristic. That is, according to the present embodiment, the delay time can be extracted by the steepest descent method.

[0103] Moreover, according to the above-described embodiment, the multipath analysis device 10 further includes the correction unit 160, thereby correcting the values ​​of the parameters used in the calculation by the calculation unit 130. Specifically, the correction unit 160 corrects the parameters so that the error between the calculated second amplitude frequency characteristic and the acquired first amplitude frequency characteristic is reduced. Therefore, according to the present embodiment, the delay time can be extracted with high accuracy. In other words, the multipath analysis can be performed with high accuracy.

[0104] Also, according to the above-described embodiment, the multipath analysis device 10 further includes a calculation count acquisition unit and a determination unit, so that the number of times the correction unit performs correction can be set arbitrarily. Here, there is a trade-off relationship between accuracy and calculation time. Therefore, according to the present embodiment, the number of calculations, i.e., the number of times correction is performed by the correction unit 160, can be set arbitrarily, so that it is possible to set which of accuracy and calculation time is to be prioritized.

[0105] Furthermore, according to the above-described embodiment, the first amplitude-frequency characteristic, which is an actual measurement value, and the second amplitude-frequency characteristic, which is a calculated value, are displayed on the same graph in an overlapping manner. Therefore, according to the present embodiment, the accuracy of the calculation can be easily presented.

[0106] According to the above-described embodiment, at least the terminal voltage, the multipath DU ratio, and the high-frequency phase difference are used as parameters, so that the present embodiment can perform multipath analysis with high accuracy.

[0107] Note that all or part of the functions of each unit of the multi-path analysis system 1 in the above-mentioned embodiment may be realized by recording a program for realizing these functions on a computer-readable recording medium, and reading and executing the program recorded on the recording medium into a computer system. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0108] In addition, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage units such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include those that dynamically hold a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, and those that hold a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client in such cases. Furthermore, the above program may be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

[0109] In addition, the effects described in this specification are merely explanatory or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to a person skilled in the art from the description of this specification, in addition to or in place of the above effects. In addition, the present invention is not limited to these embodiments, and various modifications and substitutions can be made within the scope of the present invention. [Explanation of symbols]

[0110] 1. Multipath analysis system 10 Multipath analysis device 21 Antenna 22 Spectrum Analyzer 30 Storage section 40 Display section 110 Amplitude frequency characteristic acquisition unit 121 Delay time acquisition unit 122 Parameter Acquisition Unit 130 Calculation section 140 Error detection unit 150 Delay time adder 160 Correction section 170 Extraction part 180 Output section

Claims

1. an amplitude frequency characteristic acquisition unit that acquires a first amplitude frequency characteristic which is an amplitude frequency characteristic representing the strength of a radio wave for each frequency of the received radio wave; a delay time acquisition unit that acquires a first delay time that is a candidate for a delay time of a reflected wave included in the radio wave; A parameter acquisition unit that acquires a predetermined parameter; A calculation unit that calculates a second amplitude-frequency characteristic, which is the predicted amplitude-frequency characteristic, based on the acquired first delay time and the acquired parameters; an error detection unit that detects an error between the acquired first amplitude-frequency characteristic and the calculated second amplitude-frequency characteristic; an extraction unit that extracts a second delay time that is a delay time of a reflected wave included in the radio wave based on the detected error; an output section for outputting the extracted second delay time; A multipath analysis device comprising:

2. A delay time adding unit calculates a third delay time by adding or subtracting a predetermined time to the first delay time, The delay time acquisition unit acquires the calculated third delay time, The calculation unit calculates a plurality of the second amplitude-frequency characteristics based on the calculated third delay time and the parameters, the error detection unit detects an error between the acquired first amplitude-frequency characteristic and a plurality of calculated second amplitude-frequency characteristics; The extraction unit extracts the second delay time based on the detected errors.

2. The multipath analysis device according to claim 1.

3. The extraction unit extracts, as the second delay time, the first delay time or the third delay time that reduces the error.

3. The multipath analysis device according to claim 2.

4. The parameter correction unit corrects the parameter so that the error detected by the error detection unit is reduced. The multipath analysis device according to any one of claims 1 to 3.

5. a calculation count acquisition unit that acquires the number of times correction is performed by the correction unit; a determination unit that determines whether the number of calculations acquired by the calculation number acquisition unit has been reached, The correction unit repeats the correction until the determination unit determines that the number of calculations has reached the number acquired by the calculation number acquisition unit.

5. The multipath analysis device according to claim 4.

6. The output unit further outputs the first amplitude frequency characteristic and the second amplitude frequency characteristic. The multipath analysis device according to any one of claims 1 to 5.

7. The parameters include a terminal voltage, a multipath DU ratio, and a high-frequency phase difference of a desired wave included in the radio wave. The multipath analysis device according to any one of claims 1 to 6.

8. On the computer, an amplitude frequency characteristic acquisition step of acquiring a first amplitude frequency characteristic which is an amplitude frequency characteristic representing the strength of a radio wave for each frequency of the received radio wave; a delay time acquisition step of acquiring a first delay time which is a candidate for a delay time of a reflected wave included in the radio wave; A parameter acquisition step of acquiring a predetermined parameter; A calculation step of calculating a second amplitude-frequency characteristic, which is the predicted amplitude-frequency characteristic, based on the acquired first delay time and the acquired parameters; an error detection step of detecting an error between the acquired first amplitude-frequency characteristic and the calculated second amplitude-frequency characteristic; an extraction step of extracting a second delay time, which is a delay time of a reflected wave included in the radio wave, based on the detected error; an output step of outputting the extracted second delay time; A program that executes the following.

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