JP6420576B2 - Measuring apparatus, measuring method and program - Google Patents

Description

  The present invention relates to a measurement apparatus, a measurement method, and a program, and more particularly, to a measurement apparatus, a measurement method, and a program for measuring a desired wave to interference ratio.

  Japanese terrestrial digital broadcasting uses UHF (Ultra High Frequency) television band radio waves and adopts the ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) system. . Therefore, the broadcast wave of each channel in terrestrial digital broadcasting is transmitted by a modulation method according to the ISDB-T method (see Non-Patent Document 1, for example). Hereinafter, for convenience of explanation, it is assumed that the transmission parameter of the ISDB-T system is mode 3 (the guard interval is 1/8).

  In the ISDB-T system, there are several thousand OFDM (Orthogonal Frequency-Division Multiplexing) carriers, and the transmission signal in each carrier is QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation). , And 64QAM. In order to obtain a reference phase and a reference level for demodulating the modulated signal, SP (Scattered Pilot), which is a pilot symbol, is inserted in the OFDM frame as shown in FIG.

  In FIG. 16, a black circle 901 is SP and a white circle 903 is data. The SP is inserted once every 12 carriers in the frequency direction (carrier direction) and once every 4 symbols (4536 [μs]) in the time direction (symbol direction). That is, SP can be observed as a periodic signal at intervals of 4 symbols. The SP is not different depending on the broadcast channel or program, but is a known signal having a predetermined amplitude and phase.

  Conventionally, there is a method (hereinafter referred to as SP method) for obtaining a DU ratio (Desired to Undesired signal ratio) between a desired wave and a delayed wave (interference wave) of an OFDM signal using SP. It is known (see, for example, Patent Document 1). First, SPs are accumulated from the four-symbol carriers in the symbol direction, and SPs that are spaced once every three carriers are extracted as shown in FIG. Then, as shown in the upper diagram of FIG. 17, the SP amplitude data is placed at the SP carrier (frequency) position, and the data of amplitude = 0 is substituted (0 complementation) at the data carrier position between the SPs.

  A terrestrial digital broadcast receiving apparatus or the like performs an inverse fast Fourier transform (IFFT) on the SP amplitude data and zero-complemented data to obtain a delay profile as shown in the lower diagram of FIG. The data after IFFT is obtained in the range of Δt (delay profile resolution) × FFT points on the time axis, but data other than SP once per 3 carriers is 0-supplemented. A folded waveform is observed. Accordingly, the data range T of the effective delay profile is 1/3 of Δt × FFT points. A peak (impulse) corresponding to the desired wave appears at time 0, and a peak having a lower intensity (power) than the peak corresponds to a delayed wave. The multipath DU ratio is obtained from the difference between the peak intensity related to the desired wave and the peak intensity related to the delayed wave. In FIG. 17, only the image of amplitude data is shown, but in practice, IFFT can be performed by complex calculation using phase data, and a delay profile can be obtained from the amplitude data and phase data for each Δt. By measuring the DU ratio, it is possible to specify whether or not a delayed wave causing a reception failure has occurred, and measures to improve reception quality such as changing the modulation method and adjusting the antenna are taken.

For example, in the mode 3 ISDB-T system, the carrier interval Δf is 125/126 [kHz], and the time width T of the delay profile is expressed by Equation (1).

  However, in the conventional SP method, if a delayed wave (multipath wave) having a delay time exceeding 336 [μs] (corresponding to 1/3 of the effective symbol length in mode 3) is generated, the delayed wave cannot be specified. . Therefore, the SP method cannot measure the DU ratio.

  Further, as interference waves that cause reception failures, there are not only multipath delay waves (multipath waves) from the same transmission apparatus, but also interference waves from other transmission apparatuses that broadcast different programs. When a plurality of transmitters broadcast different programs on the same channel (same frequency band), DD interference related to the different programs (interference between digital broadcasts) occurs in an area where radio waves reach from these transmitters. When trying to specify an interference wave related to DD interference by the SP method, since the SP has a period of 4 symbols (4536 [μs]) regardless of the program, the interference wave is recognized as a delayed wave within 4536 [μs]. . Since the measurement limit value of the SP method is 336 [μs], the SP method cannot measure the DU ratio related to the interference wave corresponding to the delayed wave whose delay time exceeds 336 [μs]. In order to measure the DU ratio, it is necessary to compare the intensity of the desired wave measured during the broadcast of the desired wave with the intensity of the interference wave measured by stopping the desired wave. It becomes.

  Further, in recent years, a relay station that outputs radio waves in the same frequency band as a transmission device that is a master station that broadcasts digital signals is installed for the purpose of effective use of frequencies, and an SFN (Single Frequency Network) is installed. It is expanding. In SFN, the relay station transmits a signal of the same channel and the same program as the master station. Therefore, DD interference related to the same program occurs in an area where radio waves of both the master station and the relay station reach. When the signal from the relay station reaches the receiving apparatus with a delay time exceeding 336 [μs], it is impossible to measure the DU ratio by the SP method as in the case of DD interference related to a different program. Also in this case, in order to measure the DU ratio, it is necessary to stop broadcasting of the relay station.

  In order to deal with such a problem, Patent Document 2 makes it possible to measure a DU ratio related to an interference wave corresponding to a delayed wave having a delay time exceeding 336 [μs] using a measuring apparatus having the configuration shown in FIG. That is, in FIG. 18, a delay profile is calculated from a synthesized SP synthesized based on the SP extracted from the received wave and the pilot symbol of the analytic wave, and specified from a plurality of delay profiles corresponding to analytic waves of different delay amounts. The DU ratio is measured by obtaining a difference between the representative intensity of the desired wave and the representative intensity of the interference wave.

  However, according to the study by the present inventors, it has been found that the technique disclosed in Patent Document 2 has further points to be improved. That is, even in the measuring device described in Patent Document 2, when the intensity difference between the desired wave and the interference wave is large, the interference wave may not be extracted well as a delayed wave or may be erroneously extracted. In such a case, it becomes difficult to measure the DU ratio by quantifying the intensity of the interference wave.

JP 2000-115087 A JP 2013-198102 A

“Outline of Standards and Outline of Revision ARIB STD-B31 Transmission System for Digital Terrestrial Television Broadcasting”, formulated on May 31, 2001, <URL: http://www.arib.or.jp/tyosakenkyu/kikaku_hoso /hoso_std-b031.html>

  Accordingly, an object of the present invention made to solve the above-described problems is to provide a measuring apparatus, a measuring method, and a program capable of measuring the DU ratio even when the intensity difference between the desired wave and the disturbing wave is large. is there.

In order to solve the above-described problems, the measuring apparatus according to the present invention is:
A measuring device that receives a received wave including a desired wave and an interfering wave that interferes with the desired wave, and measures a ratio of the desired wave to the interfering wave,
An accumulator that performs an averaging process by adding the received waves every four symbols to generate an added pilot symbol;
A pilot symbol that corresponds to a pilot symbol included in the desired wave, and that generates a pilot symbol having a strength greater than that of the received wave; and
A delay unit for determining a plurality of relative delay times between the added pilot symbol and the corresponding pilot symbol;
A delay profile calculator that calculates a delay profile based on a combined signal of the added pilot symbol and the corresponding pilot symbol;
A delay profile analyzer that measures a desired wave to jamming ratio from a plurality of the delay profiles corresponding to a plurality of the relative delay times,
In each of the plurality of delay profiles, obtain the intensity of the delayed wave based on the corresponding pilot symbol or the analytic wave that is the corresponding pilot symbol after the delay processing by the delay unit ,
With respect to the relative delay time, calculate an absolute delay time considering a delay time related to the analytic wave or the received wave,
Among the plurality of absolute delay times, absolute delay times whose differences are integer multiples of the measurement limit value of the delay profile calculation unit are grouped as the same delay time group,
Specify the maximum intensity for each delay time group as a representative intensity,
A delay profile analysis unit that measures a desired signal to jamming signal ratio based on a difference in representative intensity between a delay time group having the largest representative intensity and a delay time group having a representative intensity of the second and subsequent magnitudes; It is characterized by.

  Moreover, it is preferable to further comprise a noise floor calculation unit that extracts a signal having an intensity exceeding a threshold calculated based on a noise floor level of the delay profile as the delayed wave.

  Moreover, it is preferable to specify the absolute delay time having the representative intensity based on the addition processing of intensity data between the absolute delay time and the absolute delay time shifted from the absolute delay time by the measurement limit value.

  Further, it is preferable that the delay unit changes the relative delay time between the added pilot symbol and the corresponding pilot symbol by delaying the added pilot symbol.

In order to solve the above-described problems, the measurement method according to the present invention includes:
A measuring method by a measuring device that receives a received wave including a desired wave and an interfering wave that interferes with the desired wave, and measures a desired wave to interfering wave ratio,
Performing an averaging process by adding the received waves every 4 symbols to generate an added pilot symbol;
Generating a pilot symbol corresponding to a pilot symbol included in the desired wave, the pilot symbol having a strength greater than that of the received wave;
Determining a plurality of relative delay times between the added pilot symbol and the corresponding pilot symbol;
Calculating a delay profile based on a combined signal of the added pilot symbol and the corresponding pilot symbol;
In each of the plurality of delay profiles, obtaining a strength of a delay wave based on an analysis wave that is the corresponding pilot symbol or the corresponding pilot symbol after delay processing ;
Calculating an absolute delay time in consideration of a delay time related to the analytic wave or the received wave in the relative delay time;
Grouping the absolute delay times of which the difference is an integral multiple of the time width of the delay profile among the plurality of absolute delay times as the same delay time group; and
Specifying the maximum intensity for each delay time group as a representative intensity;
A step of measuring a desired wave-to-jamming wave ratio according to a difference in representative intensity between a delay time group having the largest representative intensity and a delay time group having a second or later representative intensity. To do.

  In order to solve the above-described problems, a program according to the present invention causes a computer to function as the measuring device.

  According to the measuring apparatus, measuring method, and program according to the present invention configured as described above, the DU ratio can be measured even when the intensity difference between the desired wave and the disturbing wave is large.

1 is a schematic broadcasting system configuration diagram according to a first embodiment of the present invention. It is a figure which shows the OFDM frame which concerns on 1st Embodiment of this invention. It is a functional block diagram showing a schematic structure of a measuring device concerning a 1st embodiment of the present invention. It is a figure which shows the addition process which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the delay profile which concerns on 1st Embodiment of this invention. It is a figure (measurement data) which shows the relationship between delay time and intensity | strength which concerns on embodiment of this invention. It is a figure which shows intensity distribution for the noise floor calculation which concerns on embodiment of this invention. It is a figure which shows the DU ratio calculation method which concerns on embodiment of this invention. It is a flowchart which shows the process of the measuring apparatus which concerns on 1st Embodiment of this invention. It is a functional block diagram which shows schematic structure of the measuring apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows operation | movement of the delay part which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process of the measuring apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of the delay profile which concerns on 2nd Embodiment of this invention. It is a functional block diagram which shows schematic structure of the measuring apparatus which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the process of the measuring apparatus which concerns on 3rd Embodiment of this invention. It is explanatory drawing which shows arrangement | positioning and extraction of SP of the current ISDB-T system. It is explanatory drawing which shows calculation of the delay profile in the present SP method. It is a functional block diagram which shows schematic structure of the conventional measuring apparatus.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a broadcasting system according to the first embodiment of the present invention. The broadcasting system 100 includes a broadcasting device 101 (101a and 101b) and a measuring device 103. The broadcasting apparatus 101 performs digital terrestrial television broadcasting, for example, and the broadcasting apparatuses 101a and 101b transmit different programs (programs) in the same frequency band (same channel). In FIG. 1, an area 105a indicates a range (cell) within which radio waves from the broadcasting apparatus 101a can reach. An area 105b indicates a cell of the broadcasting apparatus 101b. The measuring device 103 is located in a region where the regions 105a and 105b overlap. Therefore, radio waves in the same frequency band from both the broadcasting apparatuses 101a and 101b reach the measuring apparatus 103. Therefore, DD interference occurs between the broadcast from the broadcast apparatus 101a and the broadcast from the broadcast apparatus 101b.

  In the present embodiment, the desired wave for the measuring apparatus 103 is a radio wave from the broadcast apparatus 101a (first broadcast apparatus), and the disturbing wave that interferes with the desired wave is from the broadcast apparatus 101b (second broadcast apparatus). It is assumed that the radio wave. In the present embodiment, it is assumed that the intensity of the desired wave (such as the power level and amplitude of the radio wave) is greater than the interference wave. The measuring device 103 receives a radio wave (received wave) in which a desired wave and an interfering wave are mixed, and measures a desired wave to interfering wave ratio (DU ratio). The measuring apparatus 103 is realized as part of a television receiver, for example.

  The broadcasting device 101a performs television broadcasting using an OFDM signal. Hereinafter, in this embodiment, it is assumed that the ISDB-T (mode 3) system is adopted for the broadcasting apparatus 101a. An example of the OFDM frame used by the broadcasting apparatus 101a is shown in FIG. In the ISDB-T (mode 3) system, an OFDM frame is composed of 13 segments, and each segment includes 432 (0 to 431) carriers and 204 symbols. One symbol is 1134 [μs], and is composed of an effective symbol length of 1008 [μs] and a guard interval of 126 [μs]. Hereinafter, a range defined by one carrier and one symbol of the OFDM frame is referred to as a block.

  Broadcast apparatus 101a inserts a periodic pilot symbol in the OFDM frame. In the present embodiment, it is assumed that the pilot symbols are SPs inserted once every 12 carriers in the carrier direction and once every 4 symbols (4536 [μs]) in the symbol direction. SP is a known signal having a predetermined amplitude and phase. The SP is regularly dispersed in the OFDM frame and inserted into the SP block 107 in FIG. The measuring apparatus 103 can acquire SPs at intervals of once every three carriers by receiving a desired wave from the broadcasting apparatus 101a and accumulating SPs for four symbols. Data to be transmitted to the measuring apparatus 103 is inserted into the data block 109 indicated as D in FIG. Note that the present invention is not limited to the SP being a pilot symbol. For example, CP (Continual Pilot) can be used as a pilot symbol. The CP is continuously inserted in the symbol direction in a certain carrier. In FIG. 2, CP is inserted continuously in the symbol direction after 13 segments.

  FIG. 3 is a functional block diagram showing a schematic configuration of the measuring apparatus according to the first embodiment of the present invention. The measurement apparatus 103 includes a reception antenna unit 111, an analytic wave generation unit 113, a synthesis unit 115, a frequency conversion unit 117, a storage unit 118, an A / D conversion unit 119, an FFT unit 121, and an SP extraction unit. 123 (pilot symbol extraction unit), a delay profile calculation unit 125, a noise floor calculation unit 126, a delay profile analysis unit 127, and a misidentification prevention processing unit 128.

  The receiving antenna unit 111 receives a radio signal in which a desired wave from the broadcasting device 101 a and an interference wave from the broadcasting device 101 b are mixed, and sends the radio signal to the frequency converting unit 117.

  The frequency conversion unit 117 down-converts the received wave from the reception antenna unit 111 and outputs it to the storage unit 118.

  The accumulation unit 118 performs an averaging process by adding the signals down-converted by the frequency conversion unit 117 every four symbols as shown in FIG. As shown in FIG. 2, in the desired wave, the same pilot symbol is inserted into the same carrier every four symbols. Therefore, by adding the received wave every four symbols, the signal strength of the pilot symbols increases in proportion to the number of additions. On the other hand, since it is considered that there is no correlation between symbols, the noise component does not increase in proportion to the number of additions. Therefore, the carrier-to-noise ratio is improved by adding and averaging the received waves every four symbols. In the present embodiment, the number of additions can be, for example, 10 times. Hereinafter, the pilot symbol after the averaging process by the addition process is referred to as an addition pilot symbol.

  The A / D conversion unit 119 performs A / D conversion (analog / digital conversion) on the added signal, and outputs the converted digital signal to the FFT unit 121.

  The FFT unit 121 performs fast Fourier transform on the signal output from the A / D conversion unit 119 and performs demodulation.

  The SP extraction unit 123 extracts the added pilot symbol of the received wave from the demodulated information. The SP extraction unit 123 extracts information of one SP for each carrier in which an addition pilot symbol is inserted, and as a result, an addition pilot symbol is extracted for every three carriers. In addition, the SP extraction unit 123 substitutes 0 (0 complementation) for the data of the carrier in which no SP exists.

  The synthesizing unit 115 synthesizes the SP extracted from the received wave by the SP extracting unit 123 and a pilot symbol from the analysis wave generating unit 113 described later to obtain a synthesized SP. The synthesized SP is used by the delay profile calculation unit 125 to obtain a delay profile.

  The analytic wave generating unit 113 generates an analytic wave, and includes a pilot symbol generating unit 141 and a delay processing unit 133.

  The pilot symbol generator 141 generates a pilot symbol (SP or the like) corresponding to the added pilot symbol (SP in this embodiment) included in the desired wave. The pilot symbol corresponding to the SP included in the desired wave is a digital signal in which the pilot symbol is inserted in the SP arrangement obtained when the SP is extracted from the desired wave. That is, in the present embodiment, pilot symbols arranged at intervals of once every three carriers are generated. The pilot symbols inserted in the SP arrangement extracted from the desired wave are not limited to the pilot symbols inserted in the same carrier as all the SPs extracted from the desired wave. For example, the pilot symbol generation unit 141 can generate a pilot symbol that shares a carrier with some of the SPs extracted from the desired wave. In this case, the DU ratio in a part of the frequency bands of all carriers is obtained by the measuring apparatus 103. That is, the pilot symbol generation unit 141 can generate pilot symbols according to a frequency band in which analysis is desired.

  In addition, pilot symbol generation section 141 generates pilot symbols so that the strength of pilot symbols is greater than the strength of received waves. High intensity means that the amplitude of the signal is large. For example, the pilot symbol is generated so as to have a peak larger than the value of the maximum peak of the delay profile related to the received wave. The pilot symbol generation unit 141 can also generate a pilot symbol larger than the strength of the received wave based on the received signal strength indication (RSSI) of the received wave.

  Delay processing section 133 delays the signal generated by pilot symbol generation section 141 for a predetermined time and sends the delayed signal to combining section 115. The predetermined time is a value corresponding to the SP symbol cycle range of the desired wave (in this embodiment, 0 to 4500 [μs]). The delay processing unit 133 can determine a delay time by changing a predetermined time under the control of a delay profile analysis unit 127 described later, and can output a plurality of delayed signals in order. For example, the delay processing unit 133 can change the predetermined time by 100 [μs] which is equal to or shorter than the guard interval (126 [μs]). In the present embodiment, the delay processing unit 133 outputs 46 signals using 46 delay times of 0, 100, 200,..., 4500 [μs].

  The delay profile calculation unit 125 performs a fast inverse Fourier transform on the extracted synthesized SP to calculate a delay profile. The measurement limit value (time width of the delay profile) of the delay profile calculation unit 125 is 1/3 of Δt × FFT points as shown in the above formula (1). In this embodiment, 336 [ μs].

  Assume that the delay profile as shown in FIG. 5 is calculated when the predetermined time by the delay processing unit 133 is 100 [μs]. Since the intensity of the analytic wave is set larger than that of the received wave, the maximum peak on 0 [μs] corresponds to the analytic wave. That is, the delay profile calculated by the delay profile calculation unit 125 is centered on the analysis wave. Therefore, the desired wave and the interference wave are specified as a delayed wave based on the analysis wave. In FIG. 5, the peak on 49 [μs] corresponds to the desired wave or the disturbing wave. Note that the delay profile in FIG. 5 is set so that the peak related to the analysis wave is 0 [dB].

  The noise floor calculation unit 126 performs noise floor calculation from the delay profile. FIG. 6 is an example of a time-axis waveform of a delay profile after fast inverse Fourier transform corresponding to a delay time of 0 to 4536 [μs]. In addition, the horizontal line which shows the threshold value and a noise floor in FIG. 6 is not related to this embodiment. In this waveform, the delay profile analysis unit 127 wants to process a signal having an intensity [dB] of a certain level or higher as a desired wave or an interference wave. It may not be extracted well because it is not enough.

  Therefore, the noise floor calculation unit 126 generates a power intensity distribution as shown in FIG. 7 from the delay profile data shown in FIG. 5, and the intensity data of 70% excluding the upper 20% and the lower 10% of the distribution. The addition average value is calculated as a noise floor. Then, the noise floor calculation unit 126 sets a value higher than the calculated noise floor by a predetermined level as a threshold value, and extracts a signal having an intensity exceeding the threshold value when extracting an interference wave or the like from the delay profile. Extract. By extracting the interference wave etc. in consideration of the noise floor in this way, even if the received wave level fluctuates for various reasons, the interference wave of a small level is accurately extracted and the delay profile analysis described later is performed. The unit 127 can perform processing.

  It should be noted that how many dB the threshold value is set higher than the calculated noise floor may be arbitrarily determined. For example, the threshold value may be set relatively low when it is desired to extract more disturbing waves, and the threshold value may be set relatively high when it is desired to prevent erroneous detection as much as possible.

  The delay profile analysis unit 127 obtains the peak intensity and time corresponding to the delay wave from the delay profile calculated by the delay profile calculation unit 125. The threshold value calculated by the noise floor calculation unit 126 is used for extracting the delayed wave. That is, the delay profile analysis unit 127 uses, for example, a threshold higher by +15 [dB] than the noise floor calculated by the noise floor calculation unit 126, and extracts a signal having an intensity exceeding the threshold as a delayed wave. Since the time of the delay wave in FIG. 5 is a delay time when the analysis wave is used as a reference, the time is hereinafter referred to as a relative delay time. A specific example of signal extraction will be described later.

  Since the analytic wave itself is accompanied by a delay of a predetermined time (100 [μs] in the example of FIG. 5), the absolute delay time of the delayed wave (hereinafter referred to as the absolute delay time) is the relative delay time. 49 [μs] and a predetermined time are added. In the example of FIG. 5, the absolute delay time is 149 [μs]. The delay profile analysis unit 127 obtains an absolute delay time (149 [μs]) by adding the relative delay time and the predetermined time, and stores the absolute delay time in association with the intensity (−5.1 [dB]). Note that the delay profile analysis unit 127 can also obtain a difference (0 − (− 5.1) = 5.1) from the analysis wave as the intensity, and store the difference in the memory.

  When there is no delayed wave peak, the delay profile analysis unit 127 stores nothing in the memory. In FIG. 5, only one delay wave peak is shown, but when there are a plurality of delay wave peaks in the delay profile, the delay profile analysis unit 127 performs absolute delay for each of the plurality of peaks. Time and intensity can be determined and stored in memory. Furthermore, the delay profile analysis unit 127 can store information on a peak whose difference from the analytic wave intensity is less than a predetermined threshold, for example, in addition to the threshold calculated by the noise floor calculation unit 126.

  When the delay profile analysis unit 127 obtains information related to the delay wave of one delay profile, the delay profile analysis unit 127 changes the predetermined time of the delay processing unit 133 so that the generated pilot symbol generates a new analysis wave delayed by the predetermined time. The analytic wave generation unit 113 is controlled. Then, a delay profile relating to a new analysis wave is calculated, and the delay profile analysis unit 127 similarly stores information on the delay wave (intensity and absolute delay time) in the new delay profile in the memory. In the present embodiment, it is assumed that 46 delay profiles related to 46 delay times from 0 to 4500 [μs] are calculated, and the information shown in Table 1 below is stored in the memory.

  Then, the delay profile analysis unit 127 groups absolute delay times stored in the memory. Specifically, the delay profile analysis unit 127 classifies the absolute delay times whose absolute delay time difference is an integral multiple of the measurement limit value of the delay profile calculation unit 125 into the same delay time group. The delayed wave exceeding the measurement limit value is folded back and appears on the delay profile as a pseudo wave. Therefore, absolute delay times that are separated by an integer multiple of the measurement limit value are related to the same radio wave. Therefore, in Table 1, the absolute delay times of 149 and 485 [μs] are classified into the same delay time group. The absolute delay times of 1653, 1989, 2325, 2661 and 2997 [μs] are also classified into the same delay time group. Also, the absolute delay times of 3677, 4013, and 4349 [μs] are also classified into the same delay time group. The integral multiple of the measurement limit value is not strictly limited to the fact that the difference between absolute delay times can be divided by the measurement limit value. For example, if the error range is determined in advance and the difference between the absolute delay times is divided by the measurement limit value and the fractional part is within the error range, the difference between the absolute delay times is an integral multiple of the measurement limit value Can be considered.

  The difference between the absolute delay times is not only the difference between the two absolute delay times stored in the memory, but also the value obtained by adding the SP symbol period (4536 [μs]) to one absolute delay time and the other. It can also mean the difference from the absolute delay time. From the periodicity of SP, it can be considered that 0 [μs] and 4536 [μs] indicate the same time. Therefore, for example, the delayed wave of 149 [μs] in Table 1 can be regarded as a delayed wave of 4585 [μs]. Then, since the difference between 4665 [μs] and 4349 [μs] is 336 [μs], they are classified into the same delay time group. As a result, the delay profile analysis unit 127 assigns absolute delay times of 149, 485, 3677, 4013, and 4349 [μs] to a certain delay time group (hereinafter referred to as delay time group 1), and 1653, 1989, 2325, The absolute delay times of 2661 and 2997 [μs] are classified into another delay time group (hereinafter referred to as delay time group 2). Note that the delay time group is not limited to two, and there may be three or more delay time groups depending on the amount of information stored in the memory. The group of three or more delay times means that a plurality of interfering waves due to multipath are received by the receiving antenna unit 111 and radio waves from three or more broadcasting stations are interfering.

  The misidentification prevention processing unit 128 generates intensity data in which the influence of the aliasing component for each ± 336 [μs] is corrected from the absolute delay time and intensity data in Table 1 calculated by the delay profile analysis unit 127. As described above, the delayed wave exceeding the measurement limit value of 336 [μs] is folded and appears on the delay profile as a pseudo wave. Therefore, in Table 1, the intensity at the absolute delay time of 2325 [μs] is −21.1 [dB], but the intensity at the absolute delay time of 1989 [μs] and 2661 [μs] adjacent thereto is also It is considered that the intensity in the absolute delay time of 2325 [μs] is expressed to some extent.

  Therefore, the misidentification prevention processing unit 128 calculates the corrected intensity data by adding half the value of the adjacent intensity data (value reduced by −3 dB) to the intensity data at each absolute delay time.

  The intensity data shown in Table 2 is corrected intensity data obtained by adding half of the adjacent data (value reduced by −3 dB) to the intensity data in Table 1. As described above, by using the intensity data corrected by the misidentification prevention processing unit 128, for example, even if the intensity data in any absolute delay time is detected to be abnormally large due to the influence of noise, correction is performed with the adjacent intensity data. By doing so, the possibility that the abnormal data is processed as the maximum intensity data can be reduced.

  Subsequently, the misidentification prevention processing unit 128 specifies the maximum intensity (hereinafter referred to as representative intensity) among the intensity corresponding to the absolute delay time constituting each delay time group. When the difference with the intensity related to the analytic wave is stored in the memory, the misidentification prevention processing unit 128 uses the smallest difference with the analytic wave for each delay time group (hereinafter referred to as a representative difference). Identify. In the present embodiment, the representative intensity of the delay time group 1 is the intensity (−1.4 [dB]) in the absolute delay time of 4349 [μs], which is the same as the absolute delay time indicating the representative intensity before the misidentification prevention processing. It is. The representative strength of the delay time group 2 is the strength at the absolute delay time of 2325 [μs] (−18.7 [dB]), which is also the absolute delay time indicating the representative strength before the misidentification prevention processing. Are the same. Therefore, in the example of Table 1, it can be seen that data other than the desired wave or the interference wave is not erroneously extracted due to the influence of noise or the like.

  If the absolute delay time indicating the representative strength before the correction is different from the absolute delay time indicating the representative strength after the correction, the misperception prevention processing unit 128 uses the absolute delay time indicating the representative strength after the correction. The intensity before correction is newly adopted as the representative intensity.

  The misidentification prevention processing unit 128 is such that the delay time group having the largest representative strength (smallest representative difference) is related to the desired wave, and the delay time groups having the second and subsequent representative strengths are related to the interference wave. Judge that there is. In this embodiment, the delay time group 1 is related to the desired wave, and the delay time group 2 is related to the disturbing wave.

  FIG. 8 is a diagram showing a DU ratio calculation method according to the present embodiment. FIG. 8 is a graph showing the intensity of the delayed wave for each absolute delay time in Table 1. In addition, the horizontal line which shows a threshold value and a noise floor in FIG. 8 is not related to this embodiment.

  The data indicated by the solid line (desired wave) or the broken line (jamming wave) in FIG. 8 is an extracted delayed wave having an intensity exceeding the threshold calculated by the noise floor calculating unit 126 for each delay profile.

  The misidentification prevention processing unit 128 measures the DU ratio by obtaining a difference between the largest representative strength (smallest representative difference) and the second largest representative strength (second smallest representative difference). In this embodiment, as shown in FIG. 8, the DU ratio is 17.6 (−3.5 − (− 21.1) = 21.1−3.5 = 17.6). When the measuring apparatus 103 has a display unit (monitor), the measuring apparatus 103 can display the resulting DU ratio value on the display unit.

  In the present embodiment, the misperception prevention processing unit 128 is configured to calculate the DU ratio using the intensity data of the delay time group having the second largest representative intensity as an interference wave. It is not limited to an aspect. The misidentification prevention processing unit 128 may calculate the DU ratio using the intensity data of the delay time group having the third and subsequent magnitudes.

  Next, a method for measuring a desired wave-to-interference wave ratio between a desired wave from the broadcasting device 101a and an interference wave from the broadcasting device 101b will be described with reference to FIG. FIG. 9 is a flowchart showing processing of the measuring apparatus 103 according to the first embodiment of the present invention.

  The receiving antenna unit 111 of the measuring apparatus 103 receives a radio wave (received wave) in which a desired wave from the broadcasting apparatus 101a and an interference wave from the broadcasting apparatus 101b are mixed (step S101). The received radio wave is subjected to addition processing every four symbols in the storage unit 118 after processing by the frequency conversion unit 117 (step S102). The received wave after the addition processing is subjected to processing by the A / D conversion unit 119 and the FFT unit 121, and an addition pilot symbol is extracted by the SP extraction unit 123 (step S103). The extracted added pilot symbols are sent to combining section 115.

  On the other hand, in analysis wave generation section 113, pilot symbols of analysis waves are generated in pilot symbol generation section 141, and delay processing is performed in delay processing section 133 for a predetermined time. The pilot symbol of the analytic wave subjected to the delay process is combined with the added pilot symbol extracted from the received wave (step S104). Thereafter, the delay profile calculation unit 125 calculates a delay profile from the combined pilot symbols (step S105).

  Next, the noise floor calculation unit 126 calculates the noise floor from the delay profile sample data (step S106). And the noise floor calculation part 126 sets a threshold value using this calculated noise floor, and extracts a desired wave or an interference wave from a delay profile as a delay wave (step S107).

  The delay profile analysis unit 127 obtains information (absolute delay time and intensity) of the delayed wave extracted from the delay profile, and stores the information in the memory (step S108).

  Next, the delay profile analysis unit 127 changes the predetermined time used by the analysis wave generation unit 113 from 0 [μs], which is the symbol period range, to 4500 [μs] at 100 [μs] intervals. That is, 46 predetermined times are sequentially set in the delay processing unit 133. The delay profile analysis unit 127 determines whether or not the predetermined time can be changed based on the predetermined time currently set in the analytic wave generation unit 113 (step S109).

  When the predetermined time can be changed (Yes in step S109), the delay profile analysis unit 127 shifts the predetermined time set in the analytic wave generation unit 113 by 100 [μs] and changes the predetermined time (step S110). Thereby, a new relative delay time is determined. Then, the processes in steps S104 to S110 are repeated, and information on delayed waves based on the 46 delay profiles is stored in the memory.

  When 4500 [μs] is set as the predetermined time of the delay processing unit 133, the delay profile analysis unit 127 cannot change the predetermined time any longer (No in step S109). In this case, the delay profile analysis unit 127 groups the absolute delay time and intensity data information stored in the memory based on the delay time group (step S111).

  Next, the misidentification prevention processing unit 128 generates intensity data in which the influence of the aliasing component is corrected from the absolute delay time and intensity data grouped in step S111 (step S112). The misidentification prevention processing unit 128 determines whether or not the absolute delay time having the representative intensity in the corrected intensity data matches the absolute delay time having the representative intensity in the intensity data before correction in step S111. (Step S113). When the absolute delay time having the representative intensity before correction and the absolute delay time having the representative intensity after correction in a certain delay time group match with the absolute delay time having the representative intensity after correction in a certain delay time group, Judge that there is no detection. Then, the DU ratio is measured by obtaining the difference between the representative intensity of the delay time group related to the desired wave before correction and the representative intensity of the delay time group related to the disturbing wave (step S115).

  On the other hand, if the absolute delay time having the representative intensity before correction in a certain delay time group does not match the absolute delay time having the representative intensity after correction in the certain delay time group, the misidentification prevention processing unit 128 It is determined that a false detection has occurred. Then, the value of the representative intensity before correction in the absolute delay time having the corrected representative intensity is regarded as the representative intensity in the delay time group (step S114), and the DU ratio is measured (step S115).

  The misidentification prevention processing unit 128 can also obtain the DU ratio from information stored in the memory before the predetermined time cannot be changed by the delay profile analysis unit 127. As the predetermined time is changed, a new delay profile for the changed predetermined time is calculated, and the representative intensity value of the delay time group changes. Since the DU ratio may change with the change in the representative intensity value, the misidentification prevention processing unit 128 can measure the DU ratio before all the changes in the predetermined time within the symbol period are completed. .

  The delay profile analysis unit 127 changes the predetermined time from 0 [μs] to 4500 [μs], and then changes the predetermined time from 0 [μs] to 4500 [μs] again, and stores the information in the memory. Can also be updated. This makes it possible to measure the DU ratio that reflects the communication environment that changes from moment to moment.

  The measurement apparatus 103 includes a CPU (Central Processing Unit), a volatile storage medium such as a RAM (Random Access Memory), a nonvolatile storage medium such as a ROM (Read Only Memory), and an interface. It is comprised by the computer provided with etc. Each function of the measuring apparatus 103 is realized by storing a program in which these functions are described in a storage medium, and causing the CPU to read and execute the program.

  As described above, in the present embodiment, the analytic wave generation unit 113 generates pilot symbols corresponding to the pilot symbols included in the desired wave and having a strength greater than that of the received wave, and the pilot symbols are predetermined. Generate an analysis wave with a time delay. Then, the delay profile calculation unit 125 combines the added pilot symbol extracted from the received wave and the pilot symbol of the analysis wave to calculate a delay profile. By synthesizing the analytic wave having a higher intensity than the received wave, a delay profile based on the analytic wave is obtained. Therefore, the desired wave and the interference wave are specified as a delayed wave based on the analysis wave. The reference of the analysis wave shifts as the pilot symbol delay time (predetermined time) changes. Therefore, even if the interference wave is delayed from the measurement limit value (336 [μs]) with respect to the desired wave, the delay profile analysis unit 127 and the intensity relationship between the analysis wave and the desired wave and the analysis wave and the interference wave Strength relationship can be specified. Since the DU ratio is the difference in intensity between the desired wave and the disturbing wave, the difference in intensity between the analyzed wave and the desired wave and the difference in intensity between the analyzed wave and the disturbing wave are specified. By determining the further difference, the DU ratio is determined. Therefore, the measuring apparatus 103 can measure the DU ratio without stopping the broadcast of the disturbing wave (during the broadcast of the disturbing wave) even if the disturbing wave with a delay exceeding the measurement limit value occurs.

  In the present embodiment, the SP extraction unit 123 extracts the SP from the received wave, and the combining unit 115 combines the SP extracted from the received wave and the pilot symbol of the analysis wave. That is, the analytic wave generation unit 113 may generate a pilot symbol that is a digital signal as an analytic wave. For this reason, in the present embodiment, since the processing from the generation of the analytic wave to the acquisition of the synthesized SP can be realized by software processing, the measuring apparatus 103 can be downsized.

  Further, in the present embodiment, since the accumulation unit 118 performs symbol addition processing at intervals of 4 symbols, the carrier-to-noise ratio of pilot symbols from the received wave can be improved, and the measurement accuracy can be improved.

  Further, in the present embodiment, the noise floor in the delay profile is calculated, and the threshold value for extracting the delayed wave is determined based on the result, so that it is possible to accurately extract a small level delayed wave. Measurement accuracy can be improved.

  In the present embodiment, representative strengths in each delay time group are recognized in consideration of adjacent strength data, so that false detection of the representative strength can be prevented due to the influence of noise and the like, and measurement accuracy is improved. Can be made.

  In this embodiment, the delay profile analysis unit 127 can measure a desired wave to jamming ratio when a new delay profile is calculated by the delay profile calculation unit 125 and the value of the representative intensity changes. That is, when the representative strength value changes due to a change in the communication environment, the DU ratio value is updated. This makes it possible to measure the DU ratio reflecting the communication environment that changes from moment to moment.

  In the present embodiment, the desired wave is a radio wave from the first broadcasting apparatus 101a, and the interference wave is a radio wave from the second broadcasting apparatus 101b that transmits a program different from that of the first broadcasting apparatus. . That is, the measuring apparatus 103 can measure the DU ratio even when different programs broadcast in the same frequency band (same channel) interfere with each other.

(Second Embodiment)

  FIG. 10 is a functional block diagram showing a schematic configuration of a measuring apparatus according to the second embodiment of the present invention. The measurement apparatus 203 includes a reception antenna unit 111, an analytic wave generation unit 113, a synthesis unit 115, a frequency conversion unit 117, a storage unit 118, an A / D conversion unit 119, a delay unit 120, and an FFT unit 121. An SP extraction unit 123 (pilot symbol extraction unit), a delay profile calculation unit 125, a noise floor calculation unit 126, a delay profile analysis unit 227, and a misidentification prevention processing unit 128.

  Note that, in the above configuration, the configurations and functions of elements other than the delay unit 120, the analysis wave generation unit 113, and the delay profile analysis unit 227 are the same as those in the first embodiment, and thus further description thereof is omitted here. .

  The delay unit 120 performs delay processing for a predetermined delay time on the time-symbol data for four symbols subjected to addition processing a plurality of times in the storage unit 118, and transmits a signal to the subsequent FFT unit 121. FIGS. 11A and 11B show OFDM data for four symbols delayed by different delay times. In FIGS. 11A and 11B, the delay time is from the beginning of the OFDM data to the start of the first symbol.

  That is, in the present embodiment, the delay unit 120 gives a delay to the received wave, so that even when the received wave is delayed more than the measurement limit value (336 [μs]) with respect to the analytic wave, the measurement is performed. Is possible. In this embodiment, the delay of the received wave with respect to the analytic wave is increased by operating the delay unit 120. However, as described in the first embodiment, 0 [μs] and 4536 [4536 [ μs] can be regarded as indicating the same delay time. Therefore, by making the delay amount of the reception wave in the delay unit 120 variable in the range of 0 to 4536 [μs], the delay time of the reception wave with respect to the analysis wave is substantially measured as the measurement limit value (as in the first embodiment). 336 [μs]).

  The configuration and function of the analytic wave generation unit 113 is also the same as that of the first embodiment in that it includes the pilot symbol generation unit 141. However, as described above, in the present embodiment, the generated pilot symbols are supplied to the synthesis unit 115 without being delayed by the delay processing unit 133.

  The configuration and function of the delay profile analysis unit 227 are generally the same as those of the delay profile analysis unit 127 in the first embodiment, but different operations are performed in the process of calculating the absolute delay time based on the relative delay time obtained from the delay profile. Accompany. That is, the delay profile analysis unit 227 calculates the absolute delay time in consideration of the delay of the received wave (delay given by the delay unit 120). For example, when the delay time of the received wave in the delay unit 120 is 100 [μs] and the relative delay time of the delay wave with respect to the analysis wave is 249 [μs] in the delay profile, the delay profile analysis unit 227 calculates the absolute delay time. Calculated as 249-100 = 149 [μs].

  In the present embodiment, the generated pilot symbols are configured to be sent to the combining unit 115 without being delayed in time, but the present invention is not limited to this mode. Depending on the delay of the added pilot symbol included in the received wave, a certain delay may be given when generating the pilot symbol of the analytic wave. In this case, the delay profile analysis unit 227 further calculates the absolute delay time in consideration of the fixed delay time of the analysis wave.

  Next, a method for measuring a desired wave to jamming wave ratio between the desired wave from the broadcasting apparatus 101a and the jamming wave from the broadcasting apparatus 101b will be described with reference to FIG. FIG. 12 is a flowchart showing processing of the measuring apparatus 203 according to the second embodiment of the present invention.

  The receiving antenna unit 111 of the measuring apparatus 203 receives a radio wave (received wave) in which the desired wave from the broadcasting apparatus 101a and the interference wave from the broadcasting apparatus 101b are mixed (step S201). The received radio wave is subjected to addition processing every four symbols in the storage unit 118 after processing by the frequency conversion unit 117 (step S202). The received wave after the addition processing is converted into a digital signal by the A / D conversion unit 119 and then sent to the delay unit 120.

  The delay unit 120 delays the received wave converted into the digital signal in the range of 0 to 4536 [μs] (step S203). The delay time at this time is determined based on an instruction from the delay profile analysis unit 227 (change of a predetermined time).

  After the predetermined delay processing is performed, the received wave undergoes processing by the FFT unit 121, and the added pilot symbol is extracted by the SP extraction unit 123 (step S204). The extracted added pilot symbols are sent to combining section 115.

  On the other hand, in analysis wave generation section 113, pilot symbols of analysis waves are generated in pilot symbol generation section 141. Then, the generated pilot symbol of the analytic wave is combined with the added pilot symbol extracted from the received wave (step S205). Thereafter, the delay profile calculation unit 125 calculates a delay profile from the combined pilot symbols (step S206). As described above, a certain delay may be given to the pilot symbol of the generated analysis wave based on the delay amount of the reception wave or the like.

  Next, the noise floor calculation unit 126 calculates a noise floor from the delay profile sample data (step S207). And the noise floor calculation part 126 sets a threshold value using this calculated noise floor, and extracts a desired wave or an interference wave from a delay profile as a delay wave (step S208).

  Subsequently, the delay profile analysis unit 227 obtains information (absolute delay time and intensity) of the delayed wave extracted from the delay profile, and stores the information in the memory (step S209).

  When calculating the absolute delay time, the delay profile analysis unit 227 considers both the delay of the analysis wave (no delay or a fixed delay) and the delay of the reception wave (the delay given by the delay unit 120). It can be performed. As an example, when the fixed delay of the analytic wave is 100 [μs] and the delay of the predetermined time in the delay unit 120 is 200 [μs], a delay profile having a relative delay time of 149 [μs] shown in FIG. 13 is obtained. To do. The delay profile analysis unit 227 calculates 149 + 100−200 = 49 [μs] to calculate the absolute delay time of the received wave.

  Next, the delay profile analysis unit 227 changes the predetermined time to be sent to the delay unit 120 from 0 [μs], which is the symbol period range, to 4500 [μs] at 100 [μs] intervals. That is, 46 predetermined times are sequentially set in the delay unit 120. The delay profile analysis unit 227 determines whether or not the predetermined time can be changed based on the predetermined time currently set in the delay unit 120 (step S210).

  When the predetermined time can be changed (Yes in step S210), the delay profile analysis unit 227 shifts the predetermined time set in the delay unit 120 by 100 [μs] and changes the predetermined time (step S211). Then, the processing of steps S203 to S211 is repeated, and information on delayed waves based on 46 delay profiles is stored in the memory.

  When 4500 [μs] is set to the predetermined time of the delay unit 120, the delay profile analysis unit 227 cannot change the predetermined time any more (No in step S210). In this case, the delay profile analysis unit 227 groups the absolute delay time and intensity data information stored in the memory based on the delay time group (step S212).

  Next, the misidentification prevention processing unit 128 generates intensity data in which the influence of the aliasing component is corrected from the absolute delay time and intensity data grouped in step S212 (step S213). Then, the misidentification prevention processing unit 128 determines whether or not the absolute delay time having the representative intensity in the corrected intensity data matches the absolute delay time having the representative intensity in the intensity data before correction in step S212. (Step S214). When the absolute delay time having the representative intensity before correction and the absolute delay time having the representative intensity after correction in a certain delay time group match with the absolute delay time having the representative intensity after correction in a certain delay time group, Judge that there is no detection. Then, the DU ratio is measured by obtaining the difference between the representative intensity of the delay time group related to the desired wave before correction and the representative intensity of the delay time group related to the disturbing wave (step S216).

  On the other hand, if the absolute delay time having the representative intensity before correction in a certain delay time group does not match the absolute delay time having the representative intensity after correction in the certain delay time group, the misidentification prevention processing unit 128 It is determined that a false detection has occurred. Then, the value of the representative intensity before correction in the absolute delay time having the corrected representative intensity is regarded as the representative intensity in the delay time group (step S215), and the DU ratio is measured (step S216).

  Note that the misidentification prevention processing unit 128 can also obtain the DU ratio from information stored in the memory before the predetermined time cannot be changed by the delay profile analysis unit 227. As the predetermined time is changed, a new delay profile for the changed predetermined time is calculated, and the representative intensity value of the delay time group changes. Since the DU ratio may change with the change in the representative intensity value, the misidentification prevention processing unit 128 can measure the DU ratio before all the changes in the predetermined time within the symbol period are completed. .

  The delay profile analysis unit 227 changes the predetermined time from 0 [μs] to 4500 [μs], and then changes the predetermined time from 0 [μs] to 4500 [μs] again, and stores the information in the memory. Can also be updated. This makes it possible to measure the DU ratio that reflects the communication environment that changes from moment to moment.

  The measurement device 203 includes a CPU (Central Processing Unit), a volatile storage medium such as a RAM (Random Access Memory), a nonvolatile storage medium such as a ROM (Read Only Memory), and an interface. It is comprised by the computer provided with etc. Each function of the measuring device 203 is realized by storing a program in which these functions are described in a storage medium, and causing the CPU to read and execute the program.

  As described above, in this embodiment, a time delay is generated with respect to the received wave, not the analytic wave that is the reference signal for DU ratio measurement. At this time, since the reference signal uses only one symbol SP signal that is already supplemented every three carriers using four symbols, a common reference signal can be used even if the measured wave is delayed. Therefore, power fluctuation does not occur in the reference signal. Therefore, it is possible to suppress the occurrence of measurement errors due to power fluctuations that have conventionally occurred in the reference signal.

(Third embodiment)
FIG. 14 is a functional block diagram showing a schematic configuration of a measuring apparatus according to the third embodiment of the present invention. The measurement device 303 includes a reception antenna unit 111, an analytic wave generation unit 113, a synthesis unit 115, a frequency conversion unit 117, a storage unit 118, an A / D conversion unit 119, a delay unit 120, and an FFT unit 121. An SP extraction unit 123 (pilot symbol extraction unit), a delay profile calculation unit 325, a noise floor calculation unit 326, a delay profile analysis unit 327, and a misperception prevention processing unit 128.

  Note that, among the above configurations, the configurations and functions of elements other than the delay profile calculation unit 325, the noise floor calculation unit 326, and the delay profile analysis unit 327 are the same as those in the second embodiment. Is omitted.

  The configuration and function of the delay profile calculation unit 325 are generally the same as those of the delay profile calculation unit 125 in the first and second embodiments. The delay profile calculation unit 325 saves the calculated delay profile, changes the predetermined time of the delay unit 120, and delays the received wave converted into the digital signal by a new predetermined time.

  The noise floor calculation unit 326 calculates a noise floor based on all delay profile data between 0 and 4536 [μs] stored by the delay profile calculation unit 325. That is, the noise floor calculation unit 326 uses the delay profile all sample data corresponding to 46 delay times of 0, 100, 200,..., 4500 [μs] shown in FIG. A strong power intensity distribution. Then, an average value of 70% intensity data excluding the upper 20% and the lower 10% of the distribution is calculated as the noise floor. Then, the noise floor calculation unit 326 increases a value (for example, −30 [dB] in the example of FIG. 6) higher by +15 [dB] than the calculated noise floor (−45 [dB] in the example of FIG. 6). When a threshold is set and an interference wave or the like is extracted from the delay profile, a signal having an intensity exceeding the threshold is extracted. By extracting the interference wave etc. in consideration of the noise floor in this way, even if the received wave level fluctuates for various reasons, the interference wave of a small level is accurately extracted and the delay profile analysis described later is performed. It can be processed by the unit 327.

  The delay profile analysis unit 327 obtains the peak intensity and time corresponding to the delay wave from all the delay profile data calculated by the delay profile calculation unit 325. The threshold value calculated by the noise floor calculation unit 326 is used for extracting the delayed wave. That is, the delay profile analysis unit 327 extracts a signal having an intensity exceeding the threshold calculated by the noise floor calculation unit 326 as a delay wave, and acquires the relationship data between the absolute delay time and the intensity as shown in Table 1.

  Next, a method for measuring a desired wave-to-interference wave ratio between a desired wave from the broadcasting device 101a and an interference wave from the broadcasting device 101b will be described with reference to FIG. FIG. 15 is a flowchart showing processing of the measuring apparatus 303 according to the third embodiment of the present invention.

  The receiving antenna unit 111 of the measuring device 303 receives a radio wave (received wave) in which a desired wave from the broadcasting device 101a and an interference wave from the broadcasting device 101b are mixed (step S301). The received radio wave is subjected to addition processing every four symbols in the storage unit 118 after processing by the frequency conversion unit 117 (step S302). The received wave after the addition processing is converted into a digital signal by the A / D conversion unit 119 and then sent to the delay unit 120.

  The delay unit 120 delays the received wave converted into the digital signal within a range of 0 to 4536 [μs] (step S303). The delay time at this time is determined based on an instruction from the delay profile calculation unit 325 (change of a predetermined time).

  After predetermined delay processing is performed, the received wave undergoes processing by the FFT unit 121, and an added pilot symbol is extracted by the SP extraction unit 123 (step S304). The extracted added pilot symbols are sent to combining section 115.

  On the other hand, in analysis wave generation section 113, pilot symbols of analysis waves are generated in pilot symbol generation section 141. The generated pilot symbol of the analytic wave is combined with the added pilot symbol extracted from the received wave (step S305). Thereafter, the delay profile calculation unit 325 calculates a delay profile from the synthesized pilot symbols (step S306). As described above, a certain delay may be given to the pilot symbol of the generated analysis wave based on the delay amount of the reception wave or the like.

  Subsequently, the delay profile calculation unit 325 stores the delay profile information (absolute delay time and intensity) in the memory (step S307).

  When calculating the absolute delay time, the delay profile calculation unit 325 considers both the delay of the analysis wave (no delay or a fixed delay) and the delay of the reception wave (the delay given by the delay unit 120). It can be performed. As an example, when the fixed delay of the analytic wave is 100 [μs] and the delay of the predetermined time in the delay unit 120 is 200 [μs], a delay profile having a relative delay time of 149 [μs] shown in FIG. 13 is obtained. To do. The delay profile calculation unit 325 calculates 149 + 100−200 = 49 [μs], and calculates the absolute delay time of the received wave.

  Next, the delay profile calculation unit 325 changes the predetermined time to be sent to the delay unit 120 from 0 [μs], which is the symbol period range, to 4500 [μs] at 100 [μs] intervals. That is, 46 predetermined times are sequentially set in the delay unit 120. The delay profile calculation unit 325 determines whether the predetermined time can be changed based on the predetermined time currently set in the delay unit 120 (step S308).

  When the predetermined time can be changed (Yes in step S308), the delay profile calculation unit 325 shifts the predetermined time set in the delay unit 120 by 100 [μs] and changes the predetermined time (step S309). Then, the processing of steps S303 to S309 is repeated, and information on delayed waves based on 46 delay profiles is stored in the memory.

  When 4500 [μs] is set to the predetermined time of the delay unit 120, the delay profile calculation unit 325 cannot change the predetermined time any longer (No in step S308).

  If it is determined in step S308 that the predetermined time cannot be changed, the noise floor calculation unit 326 reads all the delay profiles stored by the delay profile calculation unit 325 (step S310), and the desired wave as shown in FIG. All delay profile data in the symbol period range (0 to 4536 [μs]) of the SP starting from is generated. And the noise floor calculation part 326 produces | generates distribution of electric power intensity | strength like FIG. 7 from all delay profile data. Then, an average value of 70% intensity data excluding the upper 20% and the lower 10% of the distribution is calculated as a noise floor (step S311). Then, the noise floor calculation unit 326 increases a value (for example, −30 [dB] in the example of FIG. 6) higher by +15 [dB] than the calculated noise floor (−45 [dB] in the example of FIG. 6). Set to threshold.

The delay profile analysis unit 327 extracts the absolute delay time and intensity of the delay wave based on the threshold value determined by the noise floor calculation unit 326 from the total delay profile data (step S312). The delayed wave data extracted in this way is, for example, the data shown in Table 1.
Then, the delay profile analysis unit 327 groups absolute delay time and intensity data information based on the delay time group (step S313).

  Next, the misidentification prevention processing unit 128 generates intensity data in which the influence of the aliasing component is corrected from the absolute delay time and intensity data grouped in step S313 (step S314). The delayed wave data corrected in this way is, for example, the data shown in Table 2. Then, the misidentification prevention processing unit 128 determines whether or not the absolute delay time having the representative intensity in the corrected intensity data matches the absolute delay time having the representative intensity in the intensity data before correction in step S313. (Step S315). When the absolute delay time having the representative intensity before correction and the absolute delay time having the representative intensity after correction in a certain delay time group match with the absolute delay time having the representative intensity after correction in a certain delay time group, Judge that there is no detection. Then, the DU ratio is measured by obtaining the difference between the representative intensity of the delay time group related to the desired wave before correction and the representative intensity of the delay time group related to the disturbing wave (step S317).

  The method for calculating the DU ratio according to the present embodiment is as shown in FIG. FIG. 8 is a graph showing the intensity of the delayed wave for each absolute delay time in Table 1. Note that the noise floor and threshold indicated by horizontal lines in FIG. 8 are the noise floor and threshold calculated by the noise floor calculation unit 326 from all delay profile data in step S311.

  Data indicated by a solid line (desired wave) or a broken line (interfering wave) in FIG. 8 is an extracted delayed wave having an intensity exceeding the threshold (−30 [dB]) calculated by the noise floor calculation unit 326.

  The misidentification prevention processing unit 128 measures the DU ratio by obtaining a difference between the largest representative strength (smallest representative difference) and the second largest representative strength (second smallest representative difference). In this embodiment, as shown in FIG. 8, the DU ratio is 17.6 (−3.5 − (− 21.1) = 21.1−3.5 = 17.6). In addition, when the measuring apparatus 303 has a display unit (monitor), the measuring apparatus 303 can display the resulting DU ratio value on the display unit.

  On the other hand, if the absolute delay time having the representative intensity before correction in a certain delay time group does not match the absolute delay time having the representative intensity after correction in the certain delay time group, the misidentification prevention processing unit 128 It is determined that a false detection has occurred. Then, the value of the representative intensity before correction in the absolute delay time having the corrected representative intensity is regarded as the representative intensity in the delay time group (step S316), and the DU ratio is measured (step S317).

  The misidentification prevention processing unit 128 can also obtain the DU ratio from the information stored in the memory before the predetermined time cannot be changed by the delay profile analysis unit 327. As the predetermined time is changed, a new delay profile for the changed predetermined time is calculated, and the representative intensity value of the delay time group changes. Since the DU ratio may change with the change in the representative intensity value, the misidentification prevention processing unit 128 can measure the DU ratio before all the changes in the predetermined time within the symbol period are completed. .

  The delay profile analysis unit 327 also changes the predetermined time from 0 [μs] to 4500 [μs] after changing the predetermined time from 0 [μs] to 4500 [μs], and stores information in the memory. Can also be updated. This makes it possible to measure the DU ratio that reflects the communication environment that changes from moment to moment.

  The measurement device 303 includes a CPU (Central Processing Unit), a volatile storage medium such as a RAM (Random Access Memory), a nonvolatile storage medium such as a ROM (Read Only Memory), and an interface. It is comprised by the computer provided with etc. Each function of the measuring device 303 is realized by storing a program in which these functions are described in a storage medium and causing the CPU to read and execute the program.

  Thus, in this embodiment, since the noise floor is calculated based on all delay profile data between 0 and 4536 [μs], the noise floor can be accurately calculated regardless of the level of the delayed wave. It becomes possible. With this configuration, it is possible to extract a delayed wave based on a more appropriate threshold.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention.

  For example, the functions included in each component, each step, etc. can be rearranged so that there is no logical contradiction, and multiple components, steps, etc. can be combined or divided into one It is.

  In the description of the embodiment of the present invention described above, the interference when the first broadcasting device and the second broadcasting device broadcast different programs of the same channel has been taken up. However, the present invention is limited to this aspect. is not. For example, when the second broadcasting device is a relay station of the first broadcasting device (parent station) and the same program on the same channel (desired wave from the parent station and disturbing wave from the relay station) interferes. The delay profile analysis unit can measure the DU ratio in the same manner as described above.

  In the above description of the embodiment of the present invention, the interference in the case where there are a plurality of broadcasting apparatuses has been described. However, the present invention is not limited to this aspect. For example, even when a multipath wave (jamming wave) exceeding the measurement limit of the SP method (delay profile calculation unit) is generated by multipath of broadcasting from one broadcasting device, the DU is similar to the above. It is possible to measure the ratio.

  In the description of the embodiment of the present invention described above, for example, the meaning of the technical idea of the expression such as the threshold “more than” or the threshold “less than” is not necessarily a strict meaning, and depends on the specification of the measuring device. In addition, the meaning when the reference value is included or not included is included. For example, the threshold “above” may imply not only the case where the value to be compared with the threshold reaches the threshold but also the case where the threshold is exceeded. Further, for example, “less than the threshold value” can imply not only when the value to be compared with the threshold value is below the threshold value but also when the threshold value is reached, that is, when the threshold value is below the threshold value.

  According to the present invention, when the DU ratio is measured using the SP method, it is possible to measure with high accuracy even when the level difference between the desired wave and the interference wave is large. Therefore, it is useful for the purpose of measuring the DU ratio particularly when there is interference between a desired wave relating to a certain program and a minute radio wave relating to a different program, or a minute radio wave relating to the same program in SFN.

100 broadcasting system 101a, 101b broadcasting device 103, 203, 303 measuring device 105a, 105b area (cell)
107 SP block 109 Data block 111 Receiving antenna unit 113 Analytical wave generation unit 115 Synthesis unit 117 Frequency conversion unit 118 Storage unit 119 A / D conversion unit 120 Delay unit 121 FFT unit 123 SP extraction unit (pilot symbol extraction unit)
125, 325 Delay profile calculation unit 126, 326 Noise floor calculation unit 127, 227, 327 Delay profile analysis unit 128 Misidentification prevention processing unit 133 Delay processing unit (delay unit)
141 Pilot symbol generator 901 SP
903 data

Claims (6)

A measuring device that receives a received wave including a desired wave and an interfering wave that interferes with the desired wave, and measures a ratio of the desired wave to the interfering wave,
An accumulator that performs an averaging process by adding the received waves every four symbols to generate an added pilot symbol;
A pilot symbol that corresponds to a pilot symbol included in the desired wave, and that generates a pilot symbol having a strength greater than that of the received wave; and
A delay unit for determining a plurality of relative delay times between the added pilot symbol and the corresponding pilot symbol;
A delay profile calculator that calculates a delay profile based on a combined signal of the added pilot symbol and the corresponding pilot symbol;
A delay profile analyzer that measures a desired wave to jamming ratio from a plurality of the delay profiles corresponding to a plurality of the relative delay times,
In each of the plurality of delay profiles, obtain the intensity of the delayed wave based on the corresponding pilot symbol or the analytic wave that is the corresponding pilot symbol after the delay processing by the delay unit ,
With respect to the relative delay time, calculate an absolute delay time considering a delay time related to the analytic wave or the received wave,
Among the plurality of absolute delay times, absolute delay times whose differences are integer multiples of the measurement limit value of the delay profile calculation unit are grouped as the same delay time group,
Specify the maximum intensity for each delay time group as a representative intensity,
A delay profile analysis unit that measures a desired signal to jamming signal ratio based on a difference in representative intensity between a delay time group having the largest representative intensity and a delay time group having a representative intensity of the second and subsequent magnitudes; Measuring device characterized by.   The measurement apparatus according to claim 1, further comprising a noise floor calculation unit that extracts a signal having an intensity exceeding a threshold calculated based on a noise floor level of the delay profile as the delayed wave.   The absolute delay time having the representative intensity is specified based on an addition process of intensity data between the absolute delay time and an absolute delay time shifted from the absolute delay time by a measurement limit value. 2. The measuring apparatus according to 2.   The measurement according to any one of claims 1 to 3, wherein the delay unit changes the relative delay time between the added pilot symbol and the corresponding pilot symbol by delaying the added pilot symbol. apparatus. A measuring method by a measuring device that receives a received wave including a desired wave and an interfering wave that interferes with the desired wave, and measures a desired wave to interfering wave ratio,
Performing an averaging process by adding the received waves every 4 symbols to generate an added pilot symbol;
Generating a pilot symbol corresponding to a pilot symbol included in the desired wave, the pilot symbol having a strength greater than that of the received wave;
Determining a plurality of relative delay times between the added pilot symbol and the corresponding pilot symbol;
Calculating a delay profile based on a combined signal of the added pilot symbol and the corresponding pilot symbol;
In each of the plurality of delay profiles, obtaining a strength of a delay wave based on an analysis wave that is the corresponding pilot symbol or the corresponding pilot symbol after delay processing ;
Calculating an absolute delay time in consideration of a delay time related to the analytic wave or the received wave in the relative delay time;
Grouping the absolute delay times of which the difference is an integral multiple of the time width of the delay profile among the plurality of absolute delay times as the same delay time group; and
Specifying the maximum intensity for each delay time group as a representative intensity;
A step of measuring a desired wave-to-jamming wave ratio according to a difference in representative intensity between a delay time group having the largest representative intensity and a delay time group having a second or later representative intensity. Measuring method to do.   The program for functioning a computer as a measuring apparatus as described in any one of Claim 1 to 4.