JP2011149713A - Apd measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an APD (amplitude probability distribution) measuring device, capable of transmitting a large number of sampled signal levels to a software-processing side, without causing transfer capacity of an interface and storage capacity of the software processing side to be insufficient. <P>SOLUTION: A hardware unit 2 includes: a difference calculation unit 21 for calculating time-series difference values of signal levels, in each frequency band component obtained by sampling a signal to be measured at a prescribed sampling rate; a table storage unit 22 for storing a table, where the difference values are correlated with reversible variable-length bits; a code conversion unit 23 for converting the time-series difference values of signal levels to variable-length bit trains based on the table; and buffers 20, 24 for transferring the initial values of signal levels for each frequency band component and the variable-length bit trains converted by the code conversion unit 23 to the software processing unit 3, along with PDF data for creating an APD. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an APD measuring apparatus that measures APD (Amplitude Probability Distribution).

  APD measurement is one method of obtaining statistical data for obtaining the time probability of a received signal whose amplitude exceeds a certain level. By observing the received signal statistically, it is possible to observe signal characteristics that cannot be seen instantaneously. it can.

  As a conventional APD measuring apparatus, a received signal is converted into digital data by an analog-digital converter (hereinafter simply referred to as “A / D converter”), and the output is divided into a plurality of frequency band components by a filter bank. , The amplitude of each frequency band component is individually weighted and synthesized by a desired amount, the weighted APD receives the output and obtains the probability based on the frequency of occurrence of the synthesized amplitude after the synthesis. There is what is displayed on the display unit in a manner (see, for example, Patent Document 1).

  When the band of a signal to be measured by such an APD measuring device is wide, when trying to observe the behavior of a temporal signal in detail, the signal is at a speed twice as fast as the highest frequency in this band. Need to be sampled and observed. For example, when the measurement band is 10 MHz, it is necessary to observe data by sampling at 10M × 10 = 100 M / second, which is 10 times that band.

  When measuring the APD of this enormous amount of data, it becomes necessary to store and accumulate the data by real-time processing. In order to reduce this real-time processing, the conventional APD measuring apparatus quantizes the sampled data with a precision that does not interfere with practical use, and stores the appearance frequency per certain time (for example, 1 second), thereby generating a probability density function. (PDF, Probability Density function) data is created.

  Since this PDF data is generated at regular time intervals (for example, every second), it is not necessary to execute processing for creating APD statistical data, which is a distribution function obtained by cumulatively adding PDF data, in real time. Processing can be performed at regular intervals, and can be executed by software processing that can easily handle processing that cannot be handled by more complicated hardware such as display processing and signal processing.

  Software processing is slower than hardware in terms of processing speed, but it is a very good implementation method in terms of manufacturing cost and future technology inheritance, and more complicated processing such as control including judgment is required. Therefore, coexistence with hardware processing including the usefulness of software processing is an effective means of realization.

  As described above, the conventional APD measurement apparatus realizes APD measurement by two processes of the real time process and the non-real time process. Here, the real-time processing is processed by hardware, and the non-real-time processing is processed by software.

  In hardware, the received signal is separated into an in-phase (In-Phase, hereinafter simply referred to as “I”) component and a quadrature (Quadrature-Phase, hereinafter simply referred to as “Q”) component, and envelope detection is performed. Logarithmically converted.

  Here, when the signal level is counted every 0.1 dB, by preparing 1000 counters, it is possible to accumulate a signal history every 0.1 dB with a dynamic range of 100 dB. Similarly, when the signal level is counted every 0.05 dB, by preparing 2000 counters, it is possible to accumulate a signal history every 0.05 dB with a dynamic range of 100 dB.

  Since these counters need to be prepared for each frequency band component, for example, assuming that the sampling period is 100 M / s and the quantized level of the counter is 1000 levels, a maximum of 100 M × 1000 per second × 1000 The content value of the count is transferred from the hardware to the software processing side. Since an integer value up to 100M can be expressed by 28 bits, in this example, the count value for each frequency band component is transferred at 28 × 1000 = 28 kb / s. On the other hand, in the case of transferring time-series data after envelope detection, a transfer amount of 1.6 Gb / s, which is 100 M / s × 16 bits per second (16 bits per sample) is required.

JP 2008-275401 A

  Even in APD measurement, there is a need to know each sampled signal level. For example, when an abnormal value is detected during APD measurement, it is possible to know what has occurred by analyzing these signal levels. In this way, if it is possible to know what kind of signal appeared at which time, it becomes useful information for, for example, analysis of current conditions and countermeasures at the time of abnormality.

  Even if the signal level cannot be acquired in real time, it may be analyzed later by offline processing. That is, by analyzing the signal level and the APD statistical data as a pair, it becomes possible to simultaneously grasp the phenomenon that occurred during the APD measurement from the viewpoints of the micro standpoint and the macro standpoint.

  However, when the conventional APD measuring apparatus is to be observed from a micro standpoint, the transfer capacity of the interface for transferring a large amount of time-series data from the hardware to the software processing side and the storage capacity on the software processing side as described above. Due to the shortage, there is a problem that a device having a large storage capacity for storing a large number of time-series signals sampled on the software processing side has been required.

  The present invention has been made to solve the conventional problems, and transfers a large number of sampled time-series signals to the software processing side without causing shortage of the transfer capacity of the interface and the storage capacity of the software processing side. An object of the present invention is to provide an APD measuring apparatus capable of performing the above.

  An APD measuring apparatus of the present invention includes a hardware unit (2) configured by hardware and a software processing unit (3) that executes software processing, and is an APD measuring apparatus that measures APD of a measurement target signal. The hardware unit acquires a signal level of each predetermined frequency band component of the measurement target signal at a predetermined sampling rate to measure the APD, and a signal level acquisition unit (13 to 18); A difference calculation unit (21) that calculates a time-series difference value of the signal level acquired by the signal level acquisition unit for each frequency band component, and a first table in which the difference value is associated with a reversible variable-length bit. A first table storage unit (22) for storing the time series difference values calculated by the difference calculation unit based on the first table A code conversion unit (23) for converting to a variable-length bit string, an initial value of the signal level for each frequency band component acquired by the signal level acquisition unit together with the APD measurement data, and the code conversion unit A transfer unit (20, 24) for transferring the converted variable-length bit string to the software processing unit, wherein the software processing unit stores a second table that is the same as the first table. A table storage unit (33) and a variable-length bit sequence transferred from the transfer unit are converted into the time-series difference value based on the second table, and the initial value and the time-series difference value are converted into the time-series difference value. And a restoration unit (30) for restoring the signal level for each of the frequency band components acquired by the signal level acquisition unit.

  With this configuration, the APD measurement apparatus according to the present invention calculates the time series difference value of the signal level acquired by the signal level acquisition unit for each frequency band component, and thus the appearance distribution of the data to be transmitted to the software processing unit. Since conversion to reversible variable-length bits is performed using bias, the compression rate of the code amount by variable-length bits is improved.

  The APD measuring apparatus according to the present invention transfers the variable-length bit sequence with the improved compression rate to the software processing unit, so that a large amount of sampling can be performed without depleting the transfer capacity of the interface and the storage capacity of the software processing unit. The signal level can be transferred to the software processing unit.

  For example, in the first table, variable length bits with a shorter bit length are associated with a difference value closer to 0.

  The APD measuring apparatus according to the present invention adjusts the first table so that a difference value having a higher appearance frequency is associated with a variable-length bit having a shorter bit length based on a result of the APD prior measurement. (63) may be provided.

  With this configuration, the APD measurement apparatus according to the present invention associates variable length bits with shorter bit lengths in a measurement environment in which the appearance frequency of time-series data varies, so that the difference value has a higher appearance frequency. Since the first and second tables can be adjusted, the compression rate of the code amount using variable length bits can be further improved.

  The APD measurement method of the present invention uses an APD measurement apparatus (1) including a hardware unit (2) configured by hardware and a software processing unit (3) that executes software processing. In the APD measurement method for measuring the APD of the measurement target signal, the hardware unit acquires the signal level of each predetermined frequency band component of the measurement target signal at a predetermined sampling rate in order to measure the APD. Signal level acquisition step, the hardware unit calculates a difference value of the time series of the signal level acquired in the signal level acquisition step for each frequency band component, and the hardware unit, Based on the first table in which the difference value is associated with a reversible variable length bit, the time system calculated in the difference calculating step A code conversion step for converting the difference value into the variable-length bit sequence, and the hardware unit, together with the APD measurement data, the signal level for each frequency band component acquired in the signal level acquisition step. A transfer step of transferring an initial value and a variable length bit sequence converted in the code conversion step to the software processing unit, and the software processing unit based on a second table identical to the first table, The frequency band component acquired in the signal level acquisition step based on the initial value and the time-series difference value, by converting the variable-length bit sequence transferred from the wear unit into the time-series difference value A restoration step of restoring each signal level.

  Therefore, the APD measurement method of the present invention calculates the time series difference value of the signal level acquired in the signal level acquisition step for each frequency band component, thereby correcting the appearance distribution bias of the data transmitted to the software processing unit. Since it is converted to reversible variable-length bits by using it, the compression rate of the code amount by variable-length bits is improved.

  Since the APD measurement method of the present invention transfers the variable-length bit string with the improved compression ratio to the software processing unit, a large amount of sampling is performed without causing shortage of the interface transfer capacity and the storage capacity of the software processing unit. The signal level can be transferred to the software processing unit.

  For example, in the first table, variable length bits with a shorter bit length are associated with a difference value closer to 0.

  In the APD measurement method of the present invention, the hardware unit associates the variable length bits with shorter bit lengths as the difference value having a higher appearance frequency based on the result of the prior measurement of the APD. There may be provided a table adjustment step for adjusting.

  Therefore, the APD measurement method of the present invention can adjust the first and second tables in accordance with the measurement environment by associating variable length bits with shorter bit lengths as the difference frequency has a higher appearance frequency. The compression rate of the code amount by long bits can be further improved.

  The present invention can provide an APD measuring apparatus capable of transferring a large amount of sampled signal levels to the software processing side without causing the transfer capacity of the interface and the storage capacity of the software processing side to be insufficient.

It is a block diagram of the APD measuring device of a 1st embodiment of the present invention, and is a block diagram which shows a hardware part in detail especially. It is a conceptual diagram which shows an example of the table stored in the table storage part which comprises the hardware part of the APD measuring apparatus of the 1st Embodiment of this invention. It is a block diagram of the APD measuring device of a 1st embodiment of the present invention, and is a block diagram showing a software processing part in detail. It is a conceptual diagram which shows the example of a display of the display apparatus which comprises the software processing part of the APD measuring apparatus of the 1st Embodiment of this invention. It is a sequence diagram which shows the operation example of the APD measuring apparatus of the 1st Embodiment of this invention. It is a block diagram of the APD measuring apparatus of the 2nd Embodiment of this invention, and is a block diagram which shows especially a hardware part in detail.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiment, an example in which APD is measured using a signal obtained from an external radio wave received outdoors as a measurement target signal will be described.

(First embodiment)
As shown in FIG. 1, an APD measuring apparatus 1 according to the first embodiment of the present invention includes a hardware unit 2 configured by hardware, a software processing unit 3 that executes software processing, and a hardware unit 2. And an interface 4 for transferring data to the software processing unit 3.

  The hardware unit 2 includes an RF receiver 11 that receives an RF (Radio Frequency) signal via an antenna 10 and a down converter (hereinafter simply referred to as “D / C”) 12 that down-converts the RF signal into a baseband signal. An A / D converter 13 that converts the baseband signal into a digital signal, a band limiting filter 14 that limits the band of the digital signal in the band to be measured, and the band-limited signal as an I component and a Q component. An I / Q separator 15 for separating the frequency band components, a filter bank 16 for extracting each frequency band component predetermined as a measurement target, an envelope detector 17 for detecting an envelope for each frequency band component, and envelope detection And a logarithmic conversion unit 18 for logarithmically converting the result of the above.

  In the present embodiment, the A / D converter 13, the band limiting filter 14, the I / Q separation unit 15, the filter bank 16, the envelope detection unit 17, and the logarithmic conversion unit 18 are the signal level acquisition unit in the present invention. Configure.

  The filter bank 16 is composed of a plurality of bandpass filters respectively corresponding to the I component and Q component of each frequency band component to be measured. The envelope detection unit 17 is configured by a plurality of envelope detection circuits respectively corresponding to each frequency band component to be measured, and each envelope detection circuit is based on the I component and Q component of the corresponding frequency band component. The signal level of each frequency band component is calculated by square detection.

  The logarithmic conversion unit 18 is configured by a plurality of logarithmic conversion circuits corresponding to each envelope detection circuit, and performs logarithmic conversion of the signal level of each frequency band component in dB units.

  The hardware unit 2 includes a counter unit 19 that accumulates the frequency of occurrence of the logarithmically converted signal level for each frequency band component, and a buffer 20 for transferring the count value of the counter unit 19 to the software processing unit 3. In addition.

  The counter unit 19 includes a plurality of counters corresponding to the frequency band component to be measured and the resolution when the signal level is quantized. For example, the counter unit 19 is configured by 1000 × N counters when the number of frequency band components to be measured is N, the dynamic range is 100 dB, and signal history is accumulated every 0.1 dB.

  The buffer 20 is configured to transfer the value of each counter constituting the counter unit 19 to the software processing unit 3 via the interface 4 at a constant time interval T (for example, one second interval). Each counter constituting the counter unit 19 transfers a count value to the buffer 20 at a time interval T, and resets the count value to zero.

  In addition, the hardware unit 2 includes a difference calculation unit 21 that calculates a time-series difference value of the signal level for each frequency band component, and a first that associates these difference values with reversible variable-length bits such as a Huffman code. Table storage unit 22 for storing the table and code for converting the time-series difference value calculated by the difference calculation unit 21 into a variable length bit string (hereinafter simply referred to as “variable length bit string”) based on the first table. A conversion unit 23 and a buffer 24 for transferring the initial value of the signal level and the variable length bit string converted by the code conversion unit 23 to the software processing unit 3 are further provided.

  The difference calculation unit 21 holds a signal level for each frequency band component, and calculates a difference value from the signal level acquired in the next sampling period for each frequency band component. Here, the band-limited signal has a gradual fluctuation of the signal level in inverse proportion to the bandwidth. This can be understood from the fact that the relationship between the time resolution (Δt) and the frequency resolution (Δf) of Fourier transform / inverse transform is constant.

  That is, since the signal levels of narrow bands adjacent in time series are highly correlated and concentrate in a portion where the difference value is small, in the present invention, the code conversion unit 23 is applied by applying the time series difference value of the signal level. The compression rate of the code amount by the variable-length bits converted by is improved.

  In the present embodiment, the difference calculation unit 21 is described as calculating a difference value between two signal levels that are continuous in time series. However, a difference value between three or more signal levels that are continuous in time series is described. May be calculated.

  The table storage unit 22 is configured by a non-volatile storage medium such as a ROM (Read Only Memory), for example, and constitutes a first table storage unit in the present invention. Here, for example, as shown in FIG. 2, the first table is associated with variable-length bits having a shorter bit length as the difference value is closer to zero.

  In FIG. 1, the code conversion unit 23 converts, for each frequency band component, a time-series difference value calculated by the difference calculation unit 21 into a variable length bit string based on the first table, and converts the converted variable length bit string. Is transferred to the buffer 24 for transfer to the software processing unit 3. The buffer 20 and the buffer 24 constitute a transfer unit in the present invention.

  In the present embodiment, the buffer 24 sends the interface 4 to the software processing unit 3 with the count value transferred by the buffer 20, that is, the initial value of the signal level of each frequency band component at the same period T as the APD measurement data. It shall be transferred via

  In addition, the buffer 24 transmits the initial value of the signal level of each frequency band component in time series until the initial value of the signal level of each frequency band component of the next sampling period is transmitted. The variable length bit string of the component is transferred to the software processing unit 3 through the interface 4.

  As shown in FIG. 3, the software processing unit 3 includes a CPU (Central Processing Unit) 30, a RAM (Random Access Memory) 31, a ROM 32, and a hard disk device 33 that are connected to the buses that constitute the interface 4. And an input device 34 including a keyboard device and a pointing device, and a display device 35 including a liquid crystal display.

  The ROM 32 and the hard disk device 33 store a program for causing the software processing unit 3 to function. That is, the CPU 30 executes the program stored in the ROM 32 and the hard disk device 33 using the RAM 31 as a work area, so that the software processing unit 3 functions.

  The hard disk device 33 constitutes a second table storage unit in the present invention, and the hard disk device 33 stores a second table identical to the first table. The CPU 30 also counts each counter transferred from the buffer 20, the initial value of the signal level of each frequency band component transferred from the buffer 24, and a variable-length bit string of each frequency band component transferred from the buffer 24. Are stored in the hard disk device 33. The hard disk device 33 may be a storage device having a function of a nonvolatile memory.

  Further, the CPU 30 constitutes a restoration unit in the present invention, converts the variable-length bit string stored in the hard disk device 33 into a time-series difference value of the signal level based on the second table, and the signal level of each frequency band component The signal level of each frequency band component is restored based on the initial value and the time-series difference value.

  Further, the CPU 30 calculates an APD based on the count value of each counter transferred from the buffer 20. For example, as illustrated in FIG. 4, the CPU 30 displays the calculated APD and the restored signal level of each frequency band component on the display device 35.

  In FIG. 4, the APD measurement result of the frequency band component designated via the input device 34 is shown in the upper stage, and this APD measurement result corresponds to the marker 50 operated via the input device 34. Each signal level in the time zone is shown in the lower part.

  The results of the APD measurement in FIG. 4 are displayed in the APD probability band such as APD ≦ 10%, 10% <APD ≦ 50%, 50% <APD ≦ 70%, and 70% <APD ≦ 100% from the top. Yes.

  The operation of the APD measuring apparatus 1 configured as described above will be described with reference to FIG. Note that the operation of the APD measuring apparatus 1 described below is started in response to a measurement start instruction input by the input device 34 of the software processing unit 3.

  First, the signal level for each frequency band component of the measurement target signal is acquired by the A / D converter 13, the band limiting filter 14, the I / Q separation unit 15, the filter bank 16, the envelope detection unit 17, and the logarithmic conversion unit 18. The

  The initial value of the signal level for each frequency band component of the measurement target signal acquired in this way is transferred from the hardware unit 2 to the software processing unit 3 (step S1), and the frequency band is transferred to the hard disk device 33 of the software processing unit 3 Stored for each component (step S2).

  Here, a variable-length bit string for each frequency band component converted by the code conversion unit 23 from the difference value of the signal level for each frequency band component of the measurement target signal calculated by the difference calculation unit 21 is predetermined in the buffer 24. When the maximum capacity is stored, that is, when the transmission timing comes (step S3: YES), the variable length bit string for each frequency band component stored in the buffer 24 is transferred from the hardware unit 2 to the software processing unit 3. Transferred (step S4).

  On the other hand, when the transmission timing is not reached (step S3: NO), the operation of the APD measuring apparatus 1 waits until the transmission timing is reached. Thus, the variable-length bit string for each frequency band component received by the software processing unit 3 is stored for each frequency band component in the hard disk device 33 of the software processing unit 3 (step S5).

  Here, when the transmission of the variable length bit string for each frequency band component within the APD measurement cycle is not completed (step S6: NO), the operation of the APD measurement apparatus 1 waits until the transmission timing is reached (step S3). ).

  On the other hand, when transmission of the variable-length bit string for each frequency band component in the APD measurement cycle is completed (step S6: YES), the APD measurement data is transferred from the hardware unit 2 to the software processing unit 3 ( Step S7).

  In the software processing unit 3 that has received the PDF data for APD creation, the CPU 30 calculates the APD (step S9), the display on the display device 35 is updated (step S10), and the APD calculation result is transferred to the hard disk device 33 in the frequency band. Stored for each component (step S11). Here, step S10 may be executed after step S11 is executed.

  On the other hand, in the hardware unit 2 that has transmitted the APD measurement data, it is determined whether or not the measurement is completed (step S8), and if it is determined that the measurement is completed, the operation of the APD measurement apparatus 1 is performed. Is completed, but if it is determined that the measurement is not completed, the operation of the APD measuring apparatus 1 returns to step S3.

  The determination as to whether or not the measurement is completed may be made based on the measurement end instruction transmitted from the software processing unit 3, and the measurement start time and the measurement time transmitted from the software processing unit 3 may be determined. You may make it perform based on this instruction | indication.

  As described above, the APD measuring apparatus 1 according to the first embodiment of the present invention uses the hardware unit 2 to calculate the time-series difference value of the signal level for each frequency band component, thereby performing software processing. Since it is converted to reversible variable length bits using the bias of the appearance distribution of data transmitted to the unit 3, the compression rate of the code amount by the variable length bits is improved.

  The APD measuring apparatus 1 transfers the variable length bit string with the entire data amount reduced from the hardware unit 2 to the software processing unit 3, and therefore transfers data from the hardware unit 2 to the software processing unit 3. A large amount of sampled signal levels can be transferred to the software processing unit 3 without causing the transfer capacity of the interface 4 and the storage capacity of the hard disk device 33 to be insufficient.

(Second Embodiment)
An APD measuring apparatus according to the second embodiment of the present invention is shown in FIG. In the present embodiment, the same components as those of the APD measuring apparatus 1 in the first embodiment of the present invention are denoted by the same reference numerals and description thereof is omitted.

  As illustrated in FIG. 6, the APD measurement apparatus 61 according to the second embodiment of the present invention includes a hardware unit 62 configured by hardware, a software processing unit 3, and an interface 4.

  The hardware unit 62 is a table adjustment unit that adjusts the first table stored in the table storage unit 22 in addition to the configuration of the hardware unit 2 that configures the APD measurement apparatus 1 according to the first embodiment of the present invention. 63.

  The APD measuring device 61 takes either a mode for executing APD pre-measurement or a mode for executing APD measurement. The APD pre-measurement is performed before the APD measurement is performed. Note that whether or not to perform APD pre-measurement before executing APD measurement may be selected via the input device 34.

  The table adjustment unit 63 adjusts the first table so that a difference value having a higher appearance frequency is associated with a reversible variable-length bit having a shorter bit length based on the result of APD prior measurement. In the present embodiment, the table storage unit 22 is configured by an electrically rewritable storage medium such as a flash memory.

  The table adjustment unit 63 transfers the adjusted first table to the software processing unit 3 via the interface 4 and stores the first table in the hard disk device 33 of the software processing unit 3 as the second table.

  That is, in the present embodiment, the CPU 30 of the software processing unit 3 stores the table transferred from the hardware unit 2 through the interface 4 in the hard disk device 33 when the APD pre-measurement is completed. ing.

  At the time of APD pre-measurement, the hardware unit 62 executes the APD measurement for a predetermined time, but the APD measurement result, the initial value of the signal level of each frequency band component, and the variable of each frequency band component The long bit string may not be transferred to the software processing unit 3. That is, the hardware unit 62 may stop the counter unit 19, the buffer 20, and the code conversion unit 23 during the prior measurement of the APD.

  In the present embodiment, the table storage unit 22 may store the first table corresponding to each frequency band component to be measured. In this case, the table adjustment unit 63 is configured to adjust the first table corresponding to each frequency band component. The hard disk device 33 of the software processing unit 3 stores a second table corresponding to each frequency band component.

  As described above, the APD measuring apparatus 61 according to the second embodiment of the present invention associates a reversible variable-length bit with a shorter bit length as a difference value having a higher appearance frequency, according to the measurement environment. Since the first and second tables can be adjusted, the compression rate of the code amount by variable length bits can be further improved, the data transmission amount can be reduced, and the micro display corresponding to the APD macro display is possible. It becomes.

DESCRIPTION OF SYMBOLS 1, 61 APD measuring apparatus 2, 62 Hardware part 3 Software processing part 4 Interface 10 Antenna 11 RF receiver 13 A / D converter 14 Band-limited filter 15 I / Q separation part 16 Filter bank 17 Envelope detection part 18 Logarithm Conversion unit 19 Counter unit 20, 24 Buffer 21 Difference calculation unit 22 Table storage unit 23 Code conversion unit 30 CPU
31 RAM
32 ROM
33 Hard Disk Device 34 Input Device 35 Display Device 63 Table Adjustment Unit

Claims (6)

In an APD measurement apparatus that includes a hardware unit (2) configured by hardware and a software processing unit (3) that executes software processing, and measures the APD of a measurement target signal,
The hardware part is
In order to measure the APD, a signal level acquisition unit (13 to 18) that acquires a signal level of each predetermined frequency band component of the measurement target signal at a predetermined sampling rate;
A difference calculation unit (21) that calculates a time-series difference value of the signal level acquired by the signal level acquisition unit for each frequency band component;
A first table storage unit (22) for storing a first table in which the difference value is associated with a reversible variable length bit;
A code conversion unit (23) for converting the time-series difference value calculated by the difference calculation unit into the variable-length bit sequence based on the first table;
Along with the APD measurement data, the initial value of the signal level for each frequency band component acquired by the signal level acquisition unit and the variable length bit string converted by the code conversion unit are transferred to the software processing unit. A transfer unit (20, 24),
The software processing unit
A second table storage unit (33) for storing a second table identical to the first table;
The variable length bit sequence transferred from the transfer unit is converted into the time-series difference value based on the second table, and the signal level acquisition unit is based on the initial value and the time-series difference value. A restoration unit (30) for restoring the signal level for each frequency band component acquired by the APD measurement apparatus.   The APD measurement apparatus according to claim 1, wherein the first table is associated with variable-length bits having a shorter bit length as the difference value is closer to zero.   A table adjustment unit (63) is provided that adjusts the first table so that a difference value with a higher appearance frequency is associated with a variable-length bit having a shorter bit length based on a result of the prior measurement of the APD. The APD measuring apparatus according to claim 1. APD measurement for measuring APD of a signal to be measured using an APD measuring device (1) including a hardware unit (2) configured by hardware and a software processing unit (3) that executes software processing In the method
A signal level acquisition step in which the hardware unit acquires a signal level of each predetermined frequency band component of the measurement target signal at a predetermined sampling rate in order to measure the APD;
A difference calculating step in which the hardware unit calculates a time-series difference value of the signal level acquired in the signal level acquiring step for each frequency band component;
The hardware unit converts the time-series difference value calculated in the difference calculation step into the variable-length bit string based on a first table in which the difference value is associated with a reversible variable-length bit. A conversion step;
The hardware unit includes the APD measurement data, the initial value of the signal level for each frequency band component acquired in the signal level acquisition step, and the variable length bit sequence converted in the code conversion step. A transfer step for transferring to the software processing unit;
The software processing unit converts a variable-length bit sequence transferred from the hardware unit into the time-series difference value based on a second table that is the same as the first table, and converts the initial value and the time An APD measurement method comprising: a restoration step of restoring a signal level for each frequency band component acquired in the signal level acquisition step based on a sequence difference value.   The APD measurement method according to claim 4, wherein the first table is associated with variable-length bits having a shorter bit length as the difference value is closer to zero.   The hardware unit has a table adjustment step of adjusting the first table so that a difference value having a higher appearance frequency is associated with a variable-length bit having a shorter bit length based on a result of the prior measurement of the APD. The APD measuring method according to claim 4, wherein

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