JP5875801B2 - Waveform recorder - Google Patents

Description

  The present invention relates to a waveform recording apparatus that samples a signal to be measured and records waveform data indicating the signal waveform.

  As this type of waveform recording apparatus, an analog signal processing apparatus disclosed in Patent Document 1 below is known. The analog signal processing apparatus includes an analog input unit including an analog circuit, a processing unit, a data acquisition memory, and a slave ASIC.

  In this analog signal processing apparatus, an analog circuit A / D converts an input analog signal into digital data at a predetermined sampling period. The processing unit performs an operation on the digital data output from the analog circuit, outputs a digital value for each sampling period, and sequentially stores it in the data collection memory. The processing unit also stores the predetermined value stored in the data acquisition memory when a predetermined number of digital values are stored in the data acquisition memory, that is, when a time corresponding to the product of the sampling period and the predetermined number has elapsed. The digital value of the number is read and transferred to the slave ASIC. The slave ASIC includes a communication interface that controls bus communication between the CPU unit and the analog input unit, and outputs a digital value transferred from the processing unit to the CPU unit.

  Specifically, the processing unit includes a digital value calculation unit, a sampling cycle setting unit, a temperature correction execution unit, a temperature correction command unit, and a storage unit. In this case, the digital value calculation unit performs offset correction and gain correction on the digital data given from the analog circuit, and outputs a digital value for each sampling period. The sampling cycle setting unit sets the sampling cycle in accordance with a command from the CPU unit. The sampling period is set to an appropriate time interval according to the application. In applications where the change in the analog signal from the control target (measurement target) is relatively slow, the sampling cycle can be set longer. Conversely, in an application where the analog signal from the control target changes rapidly, It is necessary to set it short. However, it is not possible to set a sampling period shorter than the sampling unit time required for A / D conversion processing in the analog circuit. The user can specify an appropriate sampling period using a user interface such as a computer connected to the CPU unit.

JP-A-2006-165737 (page 5-7, FIG. 1)

  However, the analog signal processing device as the waveform recording device has the following problems to be solved. That is, in this waveform recording apparatus, since the user designates the sampling period, there is a possibility that the sampling period designated by the user may not be an appropriate sampling period for the analog signal as the measurement target signal. In addition, since the user cannot confirm that such a situation has occurred, this waveform recording apparatus cannot solve the measurement target signal accurately depending on the sampling period specified by the user. Is present.

  The present invention has been made to solve such a problem, and has as its main object to provide a waveform recording apparatus capable of recording a signal to be measured at a more appropriate sampling period.

In order to achieve the above object, the waveform recording apparatus according to claim 1, wherein the A / A outputs the reference waveform data indicating the signal waveform of the measurement target signal by sampling the input measurement target signal at the reference sampling period. A recording sampling period which is a period set by the user via the operation unit from the reference waveform data output from the D conversion unit and the A / D conversion unit and is longer than the reference sampling period And a processing unit that executes a recording process for acquiring the reference waveform data that is input in synchronization with the recording waveform data and recording the recording waveform data in the storage unit, wherein the processing unit includes the recording unit For each comparison period that is defined in advance to a length equal to or longer than the sampling period, a reference wave of the maximum value and the minimum value of the waveform values in the reference waveform data included in the comparison period First difference detection processing for detecting a difference value, and second difference detection for detecting a recording waveform difference value between a maximum value and a minimum value of waveform values in the recording waveform data included in the comparison period for each comparison period For each comparison period, the division value obtained by dividing the reference waveform difference value by the recording waveform difference value is compared with a predetermined threshold value of one or more. When the threshold value is exceeded, a notification process for notifying predetermined information is executed.

  The waveform recording apparatus according to claim 2 is the waveform recording apparatus according to claim 1, wherein the processing unit defines the comparison period to be the same as the recording sampling period, and the first difference detection process, A second difference detection process and the notification process are executed.

  The waveform recording apparatus according to claim 3 is the waveform recording apparatus according to claim 1 or 2, further comprising a display device, wherein the processing unit is configured to output the signal for the measurement target signal represented by the recorded waveform data. A display process for displaying the waveform on the display device is executed, and the content of the information is displayed on the display device for notification in the notification process.

  The waveform recording apparatus according to claim 1, wherein the processing unit detects, for each comparison period, a reference waveform difference value between a maximum value and a minimum value of the waveform values in the reference waveform data included in the comparison period. , Second difference detection processing for detecting a recording waveform difference value between the maximum value and the minimum value of the waveform values in the recording waveform data included in the comparison period, and division obtained by dividing the reference waveform difference value by the recording waveform difference value When the value exceeds the threshold value, a notification process is performed to notify information specified in advance.

  Therefore, according to this waveform recording apparatus, when sampling is performed at a recording sampling period set by the user, a part of the signal waveform of the measurement target signal is missed, or aliasing due to this missing occurs. It is possible to surely recognize that there is a high possibility that the user is doing. In addition, this allows the user to be notified so that a period shorter than the current recording sampling period is set as the recording sampling period, so that the signal to be measured is recorded at a recording sampling period with a shorter appropriate length. By sampling, the signal waveform of the signal to be measured can be accurately recorded.

  In addition, according to the waveform recording apparatus of the second aspect, it is possible to determine the appropriateness / inappropriateness of the recording sampling period at every recording sampling period, that is, at a shorter period. It is possible to more quickly recognize that the recording sampling period for sampling the target signal is not appropriate, and to set an appropriate recording sampling period. In addition, it is possible to improve the detection accuracy of the oversight of the signal waveform of the measurement target signal.

  According to the waveform recording apparatus of claim 3, when it is determined that the recording sampling period is inappropriate, the fact is displayed on the display device, so that the user can display the signal waveform for the measurement target signal. While observing, it can be confirmed whether or not the current recording sampling period is inappropriate. For this reason, the user can be surely recognized that the recording sampling period is inappropriate.

1 is a configuration diagram of a waveform recording apparatus 1. FIG. FIG. 6 is a waveform diagram for explaining the operation of the waveform recording apparatus 1. 6 is a waveform diagram for explaining another operation of the waveform recording apparatus 1. FIG.

  Hereinafter, an embodiment of the waveform recording apparatus 1 will be described with reference to the accompanying drawings.

  First, the configuration of the waveform recording apparatus 1 will be described with reference to FIGS.

  As shown in FIG. 1, the waveform recording apparatus 1 includes an A / D conversion unit 2, a processing unit 3, an operation unit 4, a storage unit (recording unit) 5, and an output unit 6, and samples the input measurement target signal S <b> 1. Then, it is A / D converted into waveform data indicating the signal waveform, and recorded (stored) as recorded waveform data Dwm. The measurement target signal S1 may be any of an AC signal, a DC signal, and a signal obtained by superimposing the AC signal on the DC signal.

  The A / D converter 2 includes an A / D converter (not shown), and inputs the measurement target signal S1 to a predetermined reference sampling period Ts (for example, the period of the internal clock Sck (for example, 25 ns). The sampling period is converted into waveform data (reference waveform data) Dws indicating the signal waveform of the measurement target signal S1 and output to the processing unit 3.

  The processing unit 3 includes, as an example, a first processing unit 3a configured with an FPGA (Field Programmable Gate Array) and a second processing unit 3b configured with a CPU. For example, the first processing unit 3a is also referred to as a first maximum value detection unit 11 (hereinafter also referred to as “maximum value detection unit 11”) and a first minimum value detection unit 12 (hereinafter also referred to as “minimum value detection unit 12”). ), First difference detector 13 (hereinafter also referred to as “difference detector 13”), data extraction unit 14, second maximum value detector 15 (hereinafter also referred to as “maximum value detector 15”), second minimum A value detection unit 16 (hereinafter also referred to as “minimum value detection unit 16”), a second difference detection unit 17 (hereinafter also referred to as “difference detection unit 17”), and a division value calculation unit 18 are provided.

  In this case, the maximum value detection unit 11 receives the reference waveform data Dws output from the A / D conversion unit 2 and the comparison clock Sck2 (comparison cycle Tc (see FIG. 2)) output from the second processing unit 3b. The maximum value Dmax1 for the reference waveform data Dws within one cycle of the comparison clock Sck2 (that is, the comparison cycle Tc) is detected. Further, the maximum value detection unit 11 outputs the detected maximum value Dmax1 to the difference detection unit 13 in synchronization with the comparison cycle Tc (for example, in synchronization with the end of the comparison cycle Tc where detection of the maximum value Dmax1 is completed).

  The minimum value detection unit 12 receives the reference waveform data Dws and is synchronized with the comparison clock Sck2 (for each comparison cycle Tc), and the reference waveform data within one cycle of the comparison clock Sck2 (that is, the comparison cycle Tc). The minimum value Dmin1 for Dws is detected. Further, the minimum value detection unit 12 is synchronized with the comparison cycle Tc (for example, synchronized with the end of the comparison cycle Tc in which the detection of the minimum value Dmin1 is completed), that is, the output timing of the maximum value Dmax1 by the maximum value detection unit 11. The detected minimum value Dmin1 is output to the difference detection unit 13 at the same timing.

  The difference detection unit 13 is synchronized with the comparison clock Sck2 (for each comparison cycle Tc), and the difference value between the maximum value Dmax1 output from the maximum value detection unit 11 and the minimum value Dmin1 output from the minimum value detection unit 12 A reference waveform difference value Ddif1 that is (= Dmax1-Dmin1) is detected and output to the division value calculation unit 18 (first difference detection process).

  The data extraction unit 14 receives the reference waveform data Dws output from the A / D conversion unit 2 and, from the reference waveform data Dws, one cycle of the sampling clock Sck1 output from the second processing unit 3b ( The reference waveform data Dws input in synchronization with the recording sampling period Tm (see FIG. 2) is extracted (acquired) and output as the recording waveform data Dwm. That is, the data extraction unit 14 thins out the reference waveform data Dws of the reference sampling period Ts and outputs it as the recording waveform data Dwm of the recording sampling period Tm.

  The maximum value detection unit 15 receives the recording waveform data Dwm output from the data extraction unit 14 and records the recording waveform within one cycle of the comparison clock Sck2 (that is, the comparison cycle Tc) in synchronization with the comparison clock Sck2. The maximum value Dmax2 for the data Dwm is detected. The maximum value detection unit 15 outputs the detected maximum value Dmax2 to the difference detection unit 17 in synchronization with the comparison cycle Tc (for example, in synchronization with the end of the comparison cycle Tc where detection of the maximum value Dmax2 is completed).

  The minimum value detection unit 16 receives the recording waveform data Dwm and synchronizes with the comparison clock Sck2 (for each comparison cycle Tc), and records the waveform data Dwm within one cycle (comparison cycle Tc) of the comparison clock Sck2. The minimum value Dmin2 is detected. Further, the minimum value detection unit 16 is synchronized with the comparison cycle Tc (for example, synchronized with the end of the comparison cycle Tc when the detection of the minimum value Dmin2 is completed), that is, the output timing of the maximum value Dmax2 by the maximum value detection unit 15. The detected minimum value Dmin2 is output to the difference detection unit 17 at the same timing (which is also the output timing of the maximum value Dmax1 by the maximum value detection unit 11).

  The difference detection unit 17 is a difference value between the maximum value Dmax2 output from the maximum value detection unit 15 and the minimum value Dmin2 output from the minimum value detection unit 16 in synchronization with the comparison clock Sck2 (for each comparison cycle Tc). The recording waveform difference value Ddif2 (= Dmax2−Dmin2) is detected and output to the division value calculation unit 18 (second difference detection process).

  The division value calculation unit 18 synchronizes the reference waveform difference value Ddif1 output from the difference detection unit 13 and the recording waveform difference value Ddif2 output from the difference detection unit 17 in synchronization with the comparison clock Sck2 (for each comparison cycle Tc). In addition to the input, a division value Ddiv obtained by dividing the reference waveform difference value Ddif1 by the recording waveform difference value Ddif2 is calculated and output to the second processing unit 3b.

  The second processing unit 3b performs a clock generation process, a recording process, a display process, and a notification process. In the clock generation process, the second processing unit 3b divides the internal clock Sck to generate and output a sampling clock Sck1 having a recording sampling period Tm indicated by the sampling setting data Dcyc input from the operation unit 4. Further, in this clock generation process, the second processing unit 3b divides the internal clock Sck to generate a comparison clock Sck2 having a period (comparison period) that is n (an integer greater than or equal to 1) times the sampling clock Sck1. Output. In this example, since the numerical value n is defined in advance as 1, for example, the second processing unit 3b generates and outputs the comparison clock Sck2 having the same period as that of the sampling clock Sck1.

  In the recording process, the second processing unit 3b acquires the recording waveform data Dwm output from the data extraction unit 14 for each cycle of the sampling clock Sck1 (recording sampling cycle Tm), and records it in the storage unit 5. In the display process, the second processing unit 3b displays the waveform of the measurement target signal S1 based on the recorded waveform data Dwm recorded in the storage unit 5 on the output unit 6 configured by a display device as an example as will be described later. Let

  In the notification process, the second processing unit 3b synchronizes with the comparison clock Sck2 (for each comparison cycle Tc) and the division value Ddiv output from the division value calculation unit 18 and a predetermined threshold value (a number of 1 or more. For example, And the numerical value “1.2”), when the division value Ddiv exceeds the threshold value, it is determined that the recording sampling period Tm is inappropriate, and the recording sampling period Tm is inappropriate. Is notified as information prescribed in advance. In this example, when the second processing unit 3b determines that the recording sampling period Tm is inappropriate in the notification process, the second processing unit 3b indicates that in the display process (for example, the recording sampling period Tm is inappropriate). A notification mark M (for example, a character “recording sampling period is NG”) is displayed on the output unit 6 together with the signal waveform W of the measurement target signal S1.

  The operation unit 4 includes a plurality of operation keys (not shown), for example, and outputs sampling setting data Dcyc indicating the recording sampling period Tm designated by the operated operation key to the second processing unit 3b. The storage unit 5 is composed of a semiconductor memory such as a RAM or an HDD (Hard disk drive), and records recording waveform data Dwm and the like.

  For example, the output unit 6 is configured by a display device such as a liquid crystal display, and displays the signal waveform W of the measurement target signal S1 and the notification mark M on the screen. Note that, instead of the display device, the output unit 6 is configured by an interface circuit with an external device (including an external storage device such as an external storage medium), and the signal waveform W of the measurement target signal S1 and notification are provided to this external device. The mark M can also be output.

  Next, the operation of the waveform recording apparatus 1 will be described with reference to the drawings. Note that sampling setting data Dcyc indicating that the recording sampling period Tm of the sampling clock Sck1 is set to four times the period of the internal clock Sck is input in advance to the second processing unit 3b via the operation unit 4. And In addition, the measurement target signal S1 is, for example, a sine wave signal.

  In this state, in the waveform recording apparatus 1, the second processing unit 3 b executes the clock generation process, so that the sampling clock Sck <b> 1 (recording sampling period) at the period set by the sampling setting data Dcyc based on the internal clock Sck. Tm) and comparison clock Sck2 (comparison cycle Tc) are generated and output.

  As shown in FIG. 2, the A / D converter 2 samples the input measurement target signal S1 in synchronization with the internal clock Sck (reference sampling period Ts), and as shown in FIG. Convert to data Dws and output.

  In the first processing unit 3a, the data extraction unit 14 inputs the reference waveform data Dws (data attached with symbols ◯ and □ in FIG. 2), and 1 of the sampling clock Sck1 is selected from the reference waveform data Dws. Reference waveform data Dws (data with a symbol □ in FIG. 2) input in synchronization with the period (recording sampling period Tm) is extracted (acquired) and output as recording waveform data Dwm. As a result, the reference waveform data Dws at the points P0, P4, P8, P12,... Shown in FIG. 2 are extracted and output as the recording waveform data Dwm by the data extraction unit 14.

  Further, the maximum value detection unit 11 inputs the reference waveform data Dws, and the reference waveform data Dws in one cycle (comparison cycle Tc) of the comparison clock Sck2 in synchronization with the comparison clock Sck2 (comparison cycle Tc). Is detected and output to the difference detector 13. Further, the minimum value detection unit 12 receives the reference waveform data Dws, and in synchronization with the comparison clock Sck2, the minimum value detection unit 12 obtains the minimum value Dmin1 for the reference waveform data Dws within one period (comparison period Tc) of the comparison clock Sck2. Detect and output to the difference detector 13.

  The difference detection unit 13 detects and divides a reference waveform difference value Ddif1 that is a difference value (= Dmax1−Dmin1) between the maximum value Dmax1 and the minimum value Dmin1 in synchronization with the comparison clock Sck2 (for each comparison cycle Tc). The value is output to the value calculation unit 18.

  On the other hand, the maximum value detection unit 15 inputs the recording waveform data Dwm and, in synchronization with the comparison clock Sck2, outputs the maximum value Dmax2 for the recording waveform data Dwm within one period (comparison period Tc) of the comparison clock Sck2. Detect and output to the difference detector 17. Further, the minimum value detection unit 16 inputs the recording waveform data Dwm, and in synchronization with the comparison clock Sck2 (for each comparison period Tc), the recording waveform data within one period (comparison period Tc) of the comparison clock Sck2. The minimum value Dmin2 for Dwm is detected and output to the difference detector 17. The difference detection unit 17 detects and divides the recording waveform difference value Ddif2 that is the difference value (= Dmax2−Dmin2) between the maximum value Dmax2 and the minimum value Dmin2 in synchronization with the comparison clock Sck2 (for each comparison cycle Tc). The value is output to the value calculation unit 18.

  The division value calculation unit 18 synchronizes the reference waveform difference value Ddif1 output from the difference detection unit 13 and the recording waveform difference value Ddif2 output from the difference detection unit 17 in synchronization with the comparison clock Sck2 (for each comparison cycle Tc). In addition to the input, a division value Ddiv obtained by dividing the reference waveform difference value Ddif1 by the recording waveform difference value Ddif2 is calculated and output to the second processing unit 3b.

  Next, the division value Ddiv output from the division value calculation unit 18 to the second processing unit 3b will be described.

  First, as in this example, when the recording sampling period Tm is equal to the comparison period Tc (same length and synchronized), the recording waveform data Dwm is compared with the comparison period Tc as shown in FIG. Are present only at two points of the beginning (for example, point P0 in the comparison cycle Tc (1)) and the end (for example, point P4 in the comparison cycle Tc (1)). For this reason, one of the recording waveform data Dwm at these two points is always the maximum value Dmax2 within the comparison period Tc, and the other is always the minimum value Dmin2.

  On the other hand, since the length of the reference sampling period Ts is shorter than the comparison period Tc, the reference waveform data Dws is not only between the two points at the beginning and the end of the comparison period Tc, but between these two points. There is also a state that exists. For this reason, the position where each point having the maximum value Dmax1 and the minimum value Dmin1 with respect to the reference waveform data Dws varies depending on the waveform shape of the signal waveform of the measurement target signal S1 within the comparison period Tc.

  Specifically, the first, sixth, and seventh comparison periods Tc (1), Tc (6), and Tc (7) of each comparison period Tc shown in FIG. When the signal waveform gradually decreases or rises (when there is no local maximum or local minimum in the comparison cycle Tc), the reference at the start of the comparison cycle Tc (for example, point P0 in the comparison cycle Tc (1)). The waveform data Dws and the recorded waveform data Dwm are one of the maximum values Dmax1, Dmax2 and the minimum values Dmin1, Dmin2 within the comparison cycle Tc, and the end of the comparison cycle Tc (for example, at the comparison cycle Tc (1), the point P4 The reference waveform data Dws and the recording waveform data Dwm in (1) are the other of the maximum values Dmax1, Dmax2 and the minimum values Dmin1, Dmin2 within the comparison period Tc. That. For this reason, in such a comparison cycle Tc, both the maximum values Dmax1, Dmax2 are equal and both the minimum values Dmin1, Dmin2 are equal, so that the reference waveform difference value Ddif1 and the recording waveform difference value Ddif2 are also equal. The division value Ddiv is a numerical value “1”.

  On the other hand, the second, third, fourth, and fifth comparison periods Tc (2), Tc (3), Tc (4), and Tc (5) in each comparison period Tc shown in FIG. When one or more local maximum points or local minimum points exist in the comparison cycle Tc, the reference waveform data Dws is the reference waveform data at a point located at or near the local maximum point. The maximum value of Dws becomes the maximum value Dmax1, and the minimum value of the reference waveform data Dws at the point located at or near the minimum point becomes the minimum value Dmin1. For this reason, the reference waveform difference value Ddif1 for the reference waveform data Dws has a maximum value Dmax2 at one of the two points positioned at the start and end of the comparison cycle Tc, and the other has a minimum value Dmin2. This is a value different from the recording waveform difference value Ddif2 for the recording waveform data Dwm. Therefore, the division value Ddiv is a value exceeding the numerical value “1”.

  For example, as shown in the second comparison cycle Tc (2), the minimum point of the reference waveform data Dws at the point 5 located near the minimum point is present although the minimum point of the measurement target signal S1 exists. The difference between the value Dmin1 and the minimum value Dmin2 for the recording waveform data Dwm at the beginning of the comparison period Tc adjacent to the point 5 (point 4) is slightly different, but these minimum values Dmin1, When the difference between Dmin2 and the maximum values Dmax1 and Dmax2 of the reference waveform data Dws and the recording waveform data Dwm at the end of the comparison period Tc (point 8) is large (for example, when the difference is close to the amplitude of the measurement target signal S1) ), Although the reference waveform difference value Ddif1 and the recording waveform difference value Ddif2 are different, both difference values Ddif1, Difference recording waveform difference value divided by the value in Ddif2 of dif2 (i.e., greater than a numerical value "1" in the division value Ddiv value (Ddiv-1)) has more likely to become smaller. That is, although the division value Ddiv exceeds the numerical value “1”, there is a high possibility that the division value Ddiv will be a value equal to or less than the threshold value. In this case, in this comparison cycle Tc (2), the division value Ddiv is a value exceeding the numerical value “1”, but is a value equal to or less than the threshold value. The third comparison cycle Tc (3) is the same as the second comparison cycle Tc (2) except that the polarity is reversed, and thus the description thereof is omitted, but the division value Ddiv is a numerical value “1”. Although the value exceeds the threshold value, the value is not more than the threshold value.

  On the other hand, as shown in the fifth comparison cycle Tc (5), there is a local maximum point or local minimum point (in this case, local minimum point) of the measurement target signal S1, and the reference waveform difference with respect to the reference waveform data Dws. When the recording waveform difference value Ddif2 for both the value Ddif1 and the recording waveform data Dwm is small, even if the difference between the difference values Ddif1 and Ddif2 is small, a value obtained by dividing the difference by the recording waveform difference value Ddif2 ( That is, the possibility that the value (Ddiv-1) exceeding the numerical value “1” in the division value Ddiv increases will increase. In other words, the division value Ddiv is more likely to exceed the threshold value. In this case, in this comparison cycle Tc (5), the division value Ddiv greatly exceeds the numerical value “1” and exceeds the threshold value.

  Further, as in the fourth comparison cycle Tc (4), the local maximum point resulting from the superimposition of noise (in FIG. 2, exaggerated for easy understanding of the invention) on the measurement target signal S1. Alternatively, when there is a minimum point (in this case, a maximum point), a division value Ddiv obtained by dividing the reference waveform difference value Ddif1 for the reference waveform data Dws by the recording waveform difference value Ddif2 for the recording waveform data Dwm is There is a high possibility that the value greatly exceeds the numerical value “1” and exceeds the threshold value. In this case, in the comparison cycle Tc (4), the noise level is large, and the reference waveform difference value Ddif1 is also increased accordingly, so that the division value Ddiv exceeds the numerical value “1” and exceeds the threshold value. Further, as in this example, when the noise is superimposed on the intermediate portion of the comparison period Tc in the measurement target signal S1, the reference waveform data Dws in the noise portion is missing from the recorded waveform data Dwm. .

  The second processing unit 3b executes the recording process, acquires the recording waveform data Dwm output from the data extraction unit 14 for each cycle of the sampling clock Sck1 (recording sampling cycle Tm), and stores it in the storage unit 5. Let me record. As a result, the reference waveform data Dws sampled at the recording sampling period Tm set via the operation unit 4, that is, the recording waveform data Dwm is recorded in the storage unit 5. In addition, the second processing unit 3b performs a display process in parallel with the recording process, reads out the recording waveform data Dwm recorded in the storage unit 5, and performs measurement on the basis of the read recording waveform data Dwm. The signal waveform W of the signal S1 is displayed on the output unit 6 configured by a display device.

  Moreover, the 2nd process part 3b performs an alerting | reporting process in parallel with a recording process and a display process. In this notification process, the second processing unit 3b synchronizes with the comparison clock Sck2 (for each comparison cycle Tc) and the division value Ddiv output from the division value calculation unit 18 and a predetermined threshold (in this example, as an example) , Numerical value “1.2”), and when the division value Ddiv exceeds the threshold value, it is determined that the recording sampling period Tm is inappropriate, and this is displayed as predetermined information as a display device. The information is displayed on the output unit 6 configured as follows.

  In the example shown in FIG. 2, as described above, each divided value Ddiv in the comparison cycle Tc (4) and the comparison cycle Tc (5) among the comparison cycles Tc (1) to Tc (7) exceeds the threshold value. It becomes a state. For this reason, the second processing unit 3b inputs the respective division values Ddiv in the comparison cycle Tc (4) and the comparison cycle Tc (5), and completes the comparison with the threshold value. Is displayed in the output unit 6 together with the signal waveform W of the measurement target signal S1 in the display process (for example, a notification mark M indicating that the recording sampling period Tm is inappropriate). Let them know.

  At this time, the second processing unit 3b, as an example, informs the output unit 6 of the notification mark for at least several seconds to several tens of seconds so that the user of the waveform recording apparatus 1 can reliably recognize the display of the notification mark M. M is displayed continuously.

  Next, the operation in which the waveform recording apparatus 1 records the recording waveform data Dwm for the measurement target signal S1 of the signal waveform shown in FIG. 3 will be described. In this example, unlike the case of FIG. 2, no noise is superimposed on the measurement target signal S1, but the cycle of the measurement target signal S1 is shorter than the recording sampling cycle Tm.

  In this state, in the recording waveform data Dwm recorded in the storage unit 5 by the second processing unit 3b, aliasing (recording waveform data Dwm includes data indicating a signal with a late cycle that does not exist as indicated by a broken line in FIG. Equivalent phenomenon). However, in this case, the difference between the reference waveform difference value Ddif1 for the reference waveform data Dws and the recording waveform difference value Ddif2 for the recording waveform data Dwm is large, so the division value Ddiv exceeds the numerical value “1”. And the value exceeds the threshold. For this reason, the second processing unit 3b detects the occurrence of aliasing and notifies the fact (notification mark M indicating that the recording sampling period Tm is inappropriate) as described above.

  As described above, in the waveform recording apparatus 1, the first processing unit 3a performs the comparison period Tc (the same period as the recording sampling period Tm in the above example) defined in advance to a length equal to or longer than the recording sampling period Tm. The reference waveform difference value Ddif1 between the maximum value Dmax1 and the minimum value Dmin1 of the waveform value in the reference waveform data Dws included in the comparison period Tc is detected, and the maximum value Dmax2 and the minimum value Dmin2 of the waveform value in the recording waveform data Dwm are detected. The recording waveform difference value Ddif2 is detected, and the second processing unit 3b calculates a division value Ddiv obtained by dividing the reference waveform difference value Ddif1 by the recording waveform difference value Ddif2 for each comparison period Tc, and compares it with a threshold value. When the value Ddiv exceeds the threshold value, it is determined that the recording sampling period Tm is inappropriate, and a notification mark M indicating that fact is set in advance. It is displayed as a constant information.

  Therefore, according to the waveform recording apparatus 1, when sampling is performed at the recording sampling period Tm set by the user, like the signal waveform of the measurement target signal S1 at the comparison period Tc (4) in FIG. In this case, a part of the signal waveform of the measurement target signal S1 is missed (the reference waveform data Dws sampled in the noise portion is missing from the recorded waveform data Dwm), or the signal waveform of the measurement target signal S1 shown in FIG. Thus, it is possible to reliably recognize that there is a high possibility that aliasing due to missing of the signal waveform of the measurement target signal S1 has occurred. This also gives the user a period shorter than the current recording sampling period Tm (in this example, the reference sampling period Ts is 25 ns, which is four times that of 100 ns) (for example, a period such as 75 ns or 50 ns). ) Can be set to be set as the recording sampling period Tm, so that the measurement target signal S1 is sampled at a recording sampling period Tm having a shorter appropriate length, and the signal waveform of the measurement target signal S1 is accurately recorded. Can be made.

  In the waveform recording apparatus 1, the first processing unit 3a defines the comparison period Tc to be the same as the recording sampling period Tm, and detects the reference waveform difference value Ddif1, and the recording waveform difference value Ddif2 The second difference detection process for detecting the notification and the notification process for displaying the notification mark M are executed. In this case, the comparison period Tc can be defined as a multiple (2 times, 3 times,...) Of the recording sampling period Tm. However, by defining the comparison period Tc to be the same as the recording sampling period Tm, The second processing unit 3b can determine whether the recording sampling period Tm is appropriate or inappropriate for each recording sampling period Tm, that is, with a shorter period. As a result, the measurement target signal S1 is sampled for the user. It is possible to recognize that the recording sampling period Tm to be performed is not appropriate and to set the recording sampling period Tm to an appropriate recording sampling period Tm.

  Further, if the comparison period Tc is made too long with respect to the recording sampling period Tm, the number of recording waveform data Dwm included in the period of the comparison period Tc increases. Therefore, the measurement target signal of the signal waveform as shown in FIG. Regarding S1, even if a part of the signal waveform is missing, the difference between the reference waveform difference value Ddif1 and the recording waveform difference value Ddif2 becomes small, and the signal waveform of the measurement target signal S1 is missing ( Furthermore, there may be a case where the occurrence of aliasing due to this cannot be detected. For this reason, it is preferable that the comparison period Tc is defined to be the same as the recording sampling period Tm from the viewpoint of increasing the detection accuracy of the signal waveform of the measurement target signal S1.

  In addition, the waveform recording apparatus 1 includes an output unit 6 including a display device, and the second processing unit 3b displays the signal waveform of the measurement target signal S1 represented by the recorded waveform data Dwm on the display device. In addition to executing the process, when it is determined that the recording sampling period Tm is inappropriate, a notification process for displaying the notification (notification mark M) on the output unit 6 (display device) is performed. Therefore, according to the waveform recording apparatus 1, the user confirms whether or not the notification mark M is displayed (whether or not the current recording sampling period is inappropriate) while observing the signal waveform of the measurement target signal S1. Therefore, the user can be surely recognized that the recording sampling period Tm is inappropriate.

  In the waveform recording apparatus 1 described above, the processing unit 3 is configured by the first processing unit 3a and the second processing unit 3b, but the first processing unit 3a configured by hardware (FPGA in this example). Can also be realized by software. In this case, the processing unit 3 can be configured only by the second processing unit 3b having the software. Further, in the waveform recording apparatus 1 described above, the threshold value is fixed, but the threshold value is input to the second processing unit 3b via the operation unit 4 and can be changed to any numerical value greater than or equal to the numerical value “1”. Can also be adopted.

1 Waveform recording device
2 A / D converter
3 processing section
4 Operation Unit Ddif1 Reference Waveform Difference Value Ddif2 Recording Waveform Difference Value Ddiv Divided Value Dmax1, Dmax2 Maximum Value Dmin1, Dmin2 Minimum Value Dws Reference Waveform Data Dwm Recorded Waveform Data S1 Measurement Target Signal Tc Comparison Period Tm Recording Sampling Period Ts Reference Sampling Period S5 Second synchronization signal Sck1 Sampling clock Sck2 Comparison clock V1 AC voltage V2 Detection output voltage

Claims (3)

An operation unit;
An A / D converter that samples the input measurement target signal at a reference sampling period and outputs reference waveform data indicating the signal waveform of the measurement target signal;
Of the reference waveform data output from the A / D converter, input in synchronization with a recording sampling period which is set by the user via the operation unit and is longer than the reference sampling period A waveform recording apparatus including a processing unit that executes a recording process of acquiring the reference waveform data as recording waveform data and recording the reference waveform data in a storage unit,
The processor is
First difference detection for detecting a reference waveform difference value between the maximum value and the minimum value of the waveform values in the reference waveform data included in the comparison period for each comparison period previously defined to be longer than the recording sampling period Processing,
A second difference detection process for detecting a recording waveform difference value between a maximum value and a minimum value of a waveform value in the recording waveform data included in the comparison period for each comparison period;
For each comparison period, a division value obtained by dividing the reference waveform difference value by the recording waveform difference value is compared with a threshold value of one or more values defined in advance, and the division value exceeds the threshold value. A waveform recording apparatus that executes notification processing for notifying information that is prescribed in advance.   The waveform recording apparatus according to claim 1, wherein the processing unit executes the first difference detection process, the second difference detection process, and the notification process by setting the comparison period to be the same as the recording sampling period. A display device,
The processing unit executes a display process for causing the display device to display the signal waveform for the measurement target signal represented by the recorded waveform data, and displays the content of the information on the display device in the notification process. The waveform recording apparatus according to claim 1, wherein the waveform recording apparatus is notified.

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