JP2012229986A - Time interval measurement device and time interval measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement accuracy of a time interval.SOLUTION: A time interval measurement device includes: fine time measurement means (20) for measuring a time interval from a start time to an immediate rise time of each clock signal and a time interval from an immediate rise time of each clock signal to an end time; a first counter (12a) for counting a period from the start time to the end time using a first clock signal; a second counter (12b) for counting a period from the start time to the end time using a second clock signal; a third counter (12c) for counting a period from the start time to the end time using a third clock signal; selection means (31) for selecting fine time and coarse time; and calculation means (32) for calculating a time interval from the start time to the end time on the basis of the coarse time and fine time selected by the selection means.

Description

  The present invention relates to a time interval measuring apparatus and a time interval measuring method for measuring a time interval.

  For measuring the time interval, there is a method using a TDC circuit. The time interval measurement using the TDC circuit is realized by combining a counter that measures the coarse time and a TDC circuit that measures a fine time shorter than the coarse time (see, for example, Patent Document 1).

  The counter and the TDC circuit have different time resolution, and the TDC circuit can measure the time interval with a smaller time resolution than the counter. Therefore, by using the TDC circuit, it is possible to measure the time interval with high accuracy.

JP 2002-014182 A

  As described above, when the time interval is used, the start timing and end timing of the time interval to be measured are determined based on the rising time of the clock signal. In such a case, when the start timing and end timing of the time interval coincide with the rising edge of the clock signal, the reliability of the measured time interval decreases. In the measurement of the time interval using the TDC circuit and the counter, when the start timing or end timing of the time interval to be measured overlaps the rising edge of the clock signal of the counter that measures the coarse time, the counter that measures the coarse time There is a possibility that the time relationship with the TDC circuit for measuring the fine time is shifted by one clock.

  In view of the above problems, an object of the present invention is to provide a time interval measurement device and a time interval measurement method that improve the measurement accuracy of a time interval.

  In order to achieve the above object, the invention described in claim 1 is a time interval measuring device for measuring a time interval from a start time point to an end point specified by an input signal, and a plurality of time interval measuring devices having the same period and different phases. The time interval from the start time to the most recent rise time of each clock signal and the time from the most recent rise time to the end time of each clock signal with a time resolution obtained by subdividing the period of the clock signal using the clock signal A fine time measuring means for measuring an interval; a first counter for counting a period from the start time to the end time using a first clock signal that is a clock signal selected from the plurality of clock signals; The second clock signal is a clock signal selected from a plurality of clock signals and having a phase different from that of the first clock signal. A second counter that counts a period from a start time to the end time, and a third clock signal that is selected from the plurality of clock signals and has a phase different from that of the first clock signal and the second clock signal. A third counter for counting a period from the start time to the end time, and when the start time and the end time are included in a predetermined range including a rising edge of the clock signal, a clock signal other than the clock signal is A time interval measured using the selected time interval is selected as a fine time, and a value counted using a clock signal other than the clock signal in the first counter, the second counter, or the third counter is used as a rough time. From the selection means to select, the rough time selected by the selection means, and the fine time selected by the selection means From serial beginning and a calculating means for calculating a time interval between the end.

  The invention of claim 2 is a time interval measurement method for measuring a time interval from a start time point to an end time point specified by an input signal, and uses a plurality of clock signals having the same period and different phases. Measuring a time interval from the start point to the most recent rising point of each clock signal with a time resolution obtained by subdividing the period of the clock signal, and using the plurality of clock signals having the same period and different phases Measuring a time interval from the most recent rising time point to the ending time point of each clock signal with a time resolution obtained by subdividing the signal cycle; and a first clock signal that is a clock signal selected from the plurality of clock signals. A step of counting a period from the start time to the end time using the plurality of clock signals; A step of counting a period from the start time to the end time using a second clock signal, which is a clock signal having a phase different from that of the first clock signal, and selected from the plurality of clock signals, A step of counting a period from the start time to the end time using a third clock signal which is a clock signal having a phase different from that of the signal and the second clock signal, and within a predetermined range including a rising edge of the clock signal When the start time and the end time are included, a step of selecting a time interval measured using a clock signal other than the clock signal as a fine time, and counting using a clock signal other than the clock signal Selecting a value as the coarse time and the selected coarse time and fine time before the start time And a step of calculating the time interval until the end.

  According to the present invention, measurement errors in time intervals can be avoided.

It is a block diagram explaining the structure of the time interval measuring device which concerns on embodiment of this invention. It is a timing chart explaining an example of the measurement of the rough time in the time interval measuring device of FIG. It is a timing chart explaining the other example of measurement of the rough time in the time interval measuring device of FIG. It is a timing chart explaining the other example of measurement of the rough time in the time interval measuring device of FIG. It is a timing chart explaining an example of the measurement of the fine time in the time interval measuring device of FIG.

  A time interval measuring device according to each embodiment of the present invention will be described with reference to the drawings. The time interval measuring device according to the present invention is a device that measures a time interval and measures, for example, the time interval from the rising edge of a pulse signal to the rising edge of the next pulse signal. As shown in FIG. 1, the time interval measuring apparatus 1 includes a coarse time measuring means 10 for measuring a rough time, a fine time measuring means 20 for measuring a fine time, and a measurement result of the coarse time measuring means 10 and the fine time measuring means 20. And a processing circuit 30 for obtaining the time interval of the measurement object.

  The time resolution measurable by the coarse time measuring means 10 and the time resolution measurable by the fine time measuring means 20 are different. Specifically, the fine time measuring means 20 measures the time interval with a finer time resolution than that measured by the coarse time measuring means 10. In the time interval measuring apparatus 1, each time (rough time and fine time) measured at different time resolutions by the processing circuit 30 coarse time measuring means 10 and the fine time measuring means 20 is arithmetically processed to measure an accurate time interval. To do.

  The time interval measuring apparatus 1 inputs a pulse signal (PULSE) that specifies the start and end timing of the time interval to be measured. This pulse signal is input to the coarse time measuring means 10 and the fine time measuring means 20.

  The coarse time measuring means 10 includes a plurality of synchronization circuits 11a to 11c, a plurality of counters 12a to 12c, and a plurality of registers 13a to 13c, and measures the coarse time using these. The synchronization circuits 11a to 11c synchronize the counters 12a to 12c and the registers 13a to 13c.

  The first synchronization circuit 11a is a D-flip flop that inputs the first clock signal CLK0 and a pulse signal. The output signal Q (Q0 in FIGS. 2 to 4) from the first synchronization circuit 11a is input to the first counter 12a and the first register 13a. The first counter 12a counts the number of clocks during the period from when the signal input from the first synchronization circuit 11a changes from 0 to 1 to when it changes from 0 to 1, and stores the counter value in the first register. To 13a. The first counter 12a resets the counter value when the input signal from the first synchronization circuit 11a changes from 0 to 1. The first register 13 a outputs the counter value input from the first counter 12 a to the processing circuit 30 when the value input from the first synchronization circuit 11 a changes.

  The second synchronization circuit 11b is a D-flip flop that inputs the second clock signal CLK1 and a pulse signal. The second clock signal CLK1 is a clock signal having the same cycle as the first clock signal CLK0 but having a different phase. 2 to 4 show an example in which the second clock signal CLK1 is shifted from the first clock signal CLK0 by ¼ clock. The output signal Q (Q1 in FIGS. 2 to 4) from the second synchronization circuit 11b is input to the second counter 12b. The second counter 12b counts the number of clocks during the period from when the signal input from the second synchronization circuit 11b changes from 0 to 1, and then changes from 0 to 1, and stores the counter value in the second register. To 13b. The second counter 12b resets the counter value when the signal input from the second synchronization circuit 11b changes from 0 to 1. When the value input from the second synchronization circuit 11b changes, the second register 13b outputs the counter value input from the second counter 12b to the processing circuit 30.

  The third synchronization circuit 11c is a D-flip flop that inputs the third clock signal CLK2 and the pulse signal. The third clock signal CLK2 is a clock signal having the same cycle but a different phase from the first clock signal CLK0 and the second clock signal CLK1. 2 to 4 show an example in which the third clock signal CLK2 is shifted from the first clock signal CLK0 by ½ clock. The output signal Q (Q2 in FIGS. 2 to 4) from the third synchronization circuit 11c is input to the third counter 12c. The third counter 12c counts the number of clocks during the period from when the signal input from the third synchronization circuit 11c changes from 0 to 1 to when it changes from 0 to 1, and stores the counter value in the third register. To 13c. The third counter 12c resets the counter value when the signal input from the third synchronization circuit 11c changes from 0 to 1. The third register 13c outputs the counter value input from the third counter 12c to the processing circuit 30 when the value input from the third synchronization circuit 11c changes.

  The processing in the processing circuit 30 will be described in detail later. In the processing circuit 30, an appropriate value is selected as the coarse time from the values input from the registers 13a to 13c of the coarse time measuring means 10, and the selected value is selected. Used to calculate the target time interval. As described above, the time resolution in the coarse time measuring means 10 using the first clock signal CLK0, the second clock signal CLK1, and the third clock signal CLK2, respectively, is a time corresponding to one clock of the clock signal used in the coarse time measuring means 10. It becomes.

  The fine time measuring means 20 measures the fine time using a plurality of clock signals having the same period but different phases. Here, the rising intervals of the plurality of clock signals are set to be equally divided. FIG. 5 shows an example in which eight clock signals CLK00 to CLK07 whose phases are shifted by 1/8 clock by the fine time measuring means 20 are used.

  The plurality of clock signals used in the coarse time measuring means 10 are clock signals selected from the plurality of clock signals used in the fine time measuring means 20. For example, in the time interval measuring apparatus 1, the clock signal CLK00 is the first clock signal CLK0 of the coarse time measuring means 10, the clock signal CLK02 is the second clock signal CLK1 of the coarse time measuring means 10, and the clock signal CLK04 is the coarse time measuring means 10. The third clock signal CLK3 is selected and used.

  The fine time measuring means 20 uses a larger number of clock signals than the coarse time measuring means 10 and can measure the time interval on the basis of the section from the rising edge to the rising edge of each clock signal, so that it is finer than the coarse time measuring means 10. Time can be measured with time resolution. That is, since the time resolution in the coarse time measuring means 10 is one clock time, the coarse time measuring means 10 cannot measure the time from the rise of the pulse signal to the rise of the clock signal. On the other hand, since the time resolution in the fine time measuring means 20 is a time finer than one clock (in the example of FIG. 5, 1/8 of one clock), the fine time measuring means 20 uses a preset section. Thus, the time from the rise of the pulse signal to the rise of the clock signal can also be measured.

  Specifically, when the input pulse signal changes from 0 to 1, the fine time measuring means 20 measures the time from the change point to the rising point of each of the clock signals CLK00 to CLK07 closest to the change. In other words, the fine time measuring means 20 measures how many of the sections equally divided with reference to the rising edges of the plurality of clock signals CLK00 to CLK07, so that each clock signal CLK00 to CLK00 from the rising edge of the pulse signal. The time until the rising edge of CLK07 can be measured. If the number of clock signals to be used is increased, the time resolution measurable by the fine time measuring means 20 can be made fine.

  The fine time measuring means 20 measures the time from the rising edge of the pulse signal to the rising edge of each of the clock signals CLK00 to CLK07, and outputs the measured time to the processing circuit 30.

  In the example of FIG. 5, when the rising edge of the pulse signal exists between the rising edge of the clock signal CLK00 and the rising edge of the clock signal CLK02, the time measured using the clock signal CLK01 is not used, and the clock signal CLK01. When the rise of the pulse signal exists between the rise of the clock signal CLK03 and the rise of the clock signal CLK03, the time measured using the clock signal CLK02 is not used, and the rise of the clock signal CLK02 to the rise of the clock signal CLK04. When the rising edge of the pulse signal exists between the two, the time measured using the clock signal CLK03 is not used, and the rising edge of the pulse signal exists between the rising edge of the clock signal CLK03 and the rising edge of the clock signal CLK05. You Time measured using the clock signal CLK04 is defined as such is not used in the case.

  The processing circuit 30 selects an appropriate value from a plurality of values input from the coarse time measuring means 10 and a selecting means 31 for selecting an appropriate time from a plurality of times input from the fine time measuring means 20; Computation means 32 for computing the target time interval from the value selected at 31.

  Specifically, the selection unit 31 grasps which of the clock signals CLK00 to CLK07 used by the fine time measurement unit 20 corresponds to each of the clock signals CLK0 to CLK2 used by the coarse time measurement unit 10. Yes. Further, the selection means 31 grasps the relationship between the change position of the pulse signal and the clock signal not suitable for use. Therefore, the selection means 31 selects a rough time suitable for use from the rough times input from the registers 13a to 13c using the rising position of the pulse signal input from the fine time measuring means 20. Further, the selection unit 31 selects the first fine time and the second fine time measured using the clock signal used for the measurement of the selected coarse time as appropriate fine times.

  For example, in the example shown in FIG. 2, the rising edge of the pulse signal coincides with the rising edge of the first clock signal CLK0 and does not coincide with the rising edges of the second clock signal CLK1 and the third clock signal CLK2. In this case, the counter value obtained using the first clock signal CLK0 may not be appropriate. Therefore, in the time interval measuring apparatus 1, the counter value obtained by using the first clock signal CLK0 output from the first register 13a is not reliable and is not used. It is necessary to select and use the counter value obtained by using CLK1 or the third clock signal CLK2 as the coarse time. Moreover, the selection means 31 selects the time measured by the fine time measurement means 20 as a fine time using the clock signal used for the measurement of the selected rough time. That is, in the example of FIG. 2, the selection unit 31 selects the time measured by the fine time measurement unit using the clock signal corresponding to the second clock signal CLK1 or the second clock signal CLK2.

  In the example shown in FIG. 3, the rising edge of the pulse signal does not coincide with the rising edge of each of the clock signals CLK0 to CLK2, but the falling edge of the pulse signal coincides with the falling edge of the first clock signal CLK0. . In this case, the counter value obtained using the first clock signal CLK0 may not be appropriate. Therefore, in the time interval measuring apparatus 1, the counter value obtained by using the first clock signal CLK0 output from the first register 13a is not reliable and is not used, and the second clock signal CLK1 or the third clock is not used. It is necessary to select and use the counter value obtained using the signal CLK2. Moreover, the selection means 31 selects the time measured by the fine time measurement means 20 as a fine time using the clock signal used for the measurement of the selected rough time.

  Further, in the example shown in FIG. 4, the rising edge of the pulse coincides with the rising edge of the first clock signal CLK0, and the falling edge of the pulse signal coincides with the rising edge of the second clock signal CLK1. In this case, the counter value obtained using the first clock signal CLK0 and the counter value obtained using the second clock signal CLK1 may not be appropriate. Therefore, in the time interval measuring apparatus 1, the counter value obtained by using the first clock signal CLK0 or the second clock signal CLK1 is not reliable and is not used, and the third clock output from the third register 13c is not used. It is necessary to select and use the counter value obtained using the signal CLK2. Moreover, the selection means 31 selects the time measured by the fine time measurement means 20 as a fine time using the clock signal used for the measurement of the selected rough time.

  If there are a plurality of clock signals that can be used, the time measured using a predetermined clock signal may be selected. For example, when the first clock signal CLK0 and the second clock signal CLK1, or the first clock signal CLK0 and the third clock signal CLK2 are usable, the first clock signal CLK0 is selected, and the second clock signal CLK1 and When the third clock signal CLK2 is usable, it can be determined to select the second clock signal.

  When an appropriate coarse time and fine time are selected by the selection means 31, the calculation means 32 calculates a target time interval using the coarse time and the fine time selected by the selection means 31. Specifically, the calculating means 32 adds the rough time and the first fine time, and subtracts the second fine time to obtain the fine time.

  As described above, in the time interval measuring apparatus 1 according to the embodiment of the present invention, the coarse time measuring means 10 also uses a plurality of clock signals, and selects an optimum value from a plurality of values obtained from each clock signal. And measure the time interval. Thereby, in the time interval measuring device 1, even when the change in the pulse coincides with the rising edge of the clock signal, a value obtained by using another clock signal can be used. An error occurring in the interval can be prevented.

  As mentioned above, although this invention was demonstrated in detail using each embodiment, this invention is not limited to embodiment described in this specification. The scope of the present invention is determined by the description of the claims and the scope equivalent to the description of the claims.

DESCRIPTION OF SYMBOLS 1 ... Time interval measuring device 10 ... Coarse time measuring means 11a ... 1st synchronizing circuit 11b ... 2nd synchronizing circuit 11c ... 3rd synchronizing circuit 12a ... 1st counter 12b ... 2nd counter 12c ... 3rd counter 13a ... First register 13b ... Second register 13c ... Third register 20 ... Fine time measuring means 21 ... Selecting means 30 ... Processing circuit 31 ... Selecting means 32 ... Calculating means

Claims (2)

A time interval measuring device that measures a time interval from a start time point to an end time point specified by an input signal,
The time interval from the start time to the most recent rise time of each clock signal and the most recent rise of each clock signal with a time resolution obtained by subdividing the period of the clock signal using a plurality of clock signals having the same cycle and different phases A fine time measuring means for measuring a time interval from a time point to the end time point;
A first counter that counts a period from the start time to the end time using a first clock signal that is a clock signal selected from the plurality of clock signals;
A second counter that counts a period from the start time to the end time using a second clock signal that is selected from the plurality of clock signals and is a clock signal having a phase different from that of the first clock signal;
A third counter that counts a period from the start time to the end time using a third clock signal that is selected from the plurality of clock signals and that is a clock signal having a phase different from that of the first clock signal and the second clock signal. When,
When the start time and the end time are included in a predetermined range including a rising edge of a clock signal, a time interval measured using a clock signal other than the clock signal is selected as a fine time, and the first time is selected. Selecting means for selecting, as a rough time, a value counted using a clock signal other than the clock signal in the counter, the second counter or the third counter;
A calculation means for calculating a time interval from the start time to the end time from the coarse time selected by the selection means and the fine time selected by the selection means;
A time interval measuring device comprising: A time interval measurement method for measuring a time interval from a start point to an end point specified by an input signal,
Measuring a time interval from the start time to the most recent rising time of each clock signal with a time resolution obtained by subdividing the clock signal period using a plurality of clock signals having the same period and different phases;
Measuring the time interval from the most recent rising point of each clock signal to the end point with a time resolution obtained by subdividing the period of the clock signal using the plurality of clock signals having the same period and different phases;
Counting a period from the start time to the end time using a first clock signal that is a clock signal selected from the plurality of clock signals;
Counting a period from the start time to the end time using a second clock signal selected from the plurality of clock signals and having a phase different from that of the first clock signal;
Counting a period from the start time to the end time using a third clock signal selected from the plurality of clock signals and having a phase different from that of the first clock signal and the second clock signal;
When the start time and the end time are included in a predetermined range including a rising edge of a clock signal, selecting a time interval measured using a clock signal other than the clock signal as a fine time; and
Selecting a value counted using a clock signal other than the clock signal as a coarse time;
Calculating a time interval from the start time to the end time from the selected coarse time and fine time;
A time interval measurement method comprising:

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