JPH07140269A - Time difference measuring method - Google Patents

Abstract

PURPOSE:To count the pulse numbers of two different systems of cycle signals respectively so as to simultaneously measure the cycle of clock signals and the generating cycle of the clock signals. CONSTITUTION:A first oscillation part 1 generates short cycle signals sufficiently shorter in the cycle than clock signals. A second oscillation part 2 generates long cycle signals longer in the cycle than the short cycle signals. A first counting part 5 counts and outputs the pulse number of the first oscillation part 1 from the fall to fall of the clock signals. A second counting part 6 counts and outputs the pulse number of the second oscillation part 2 during the time of no clock signals being outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time difference measuring method for simultaneously measuring a clock signal period and a clock signal generation period.

[0002]

2. Description of the Related Art Normally, when measuring the frequency of a continuous clock signal, a single frequency oscillator is used. On the other hand, some clock signals are intermittent. When the clock signal is intermittent, if the difference between the clock signal period and the clock signal intermittent period is too large, the counter for the clock signal generation period is overflowed only by using a single frequency oscillator. -However, it may not be possible to detect both cycles at the same time. Therefore, when measuring the frequency of a clock signal that is periodically generated, a bandpass filter is used to extract and measure only a specific frequency component.

[0003]

However, when a bandpass filter is used, it is necessary to have as many bandpass filters as the number of frequency components to be detected. Therefore, the size of the whole detector is large and the cost is high. It was a thing.

Further, when the frequency bands of the frequency components to be detected are close to each other, the accuracy of detection has deteriorated.

The present invention has been made in order to eliminate such disadvantages, and the number of pulses of two different periodic signals is respectively counted, and the period of the input clock signal and the generation period of the clock signal are simultaneously measured. The purpose is to

[0006]

A time difference measuring method according to the present invention is a time difference measuring method for simultaneously measuring a period of a clock signal and a generation period of the clock signal, and the period is sufficiently shorter than the period of the clock signal. Generate a periodic signal and a long period signal with a period greater than the period of the short period signal,
The number of pulses of the short-period signal and the long-period signal between the falling and the falling of the clock signal that is the measured signal is counted, and the counted number of pulses of the short-period signal is smaller than the number of pulses of the short-period signal counted last time. When it is larger than a certain ratio, the number of pulses of the long-period signal is output, and in other cases, the number of pulses of the short-period signal is output.

Further, the count value of the short cycle signal and the count value of the long cycle signal are sequentially stored.

Further, the frequency of the short period signal and the frequency of the long period signal are changed in accordance with the clock signal.

[0009]

According to the present invention, a short period signal having a period sufficiently smaller than that of the clock signal and a long period signal having a period larger than that of the short period signal are generated. The number of pulses of the short-period signal and the long-period signal between the falling edge and the falling edge of the clock signal that is the signal under measurement is counted, and different periods are counted simultaneously.

When the number of counted short-period signals is larger than the number of counted short-period signals by a certain ratio or more, the number of long-period signals is output. In other cases, the number of short-period signals is counted. Is output, and whether the period of the clock signal or the generation period of the clock signal is determined by the number of pulses of the short period signal, and any one of the numbers of pulses is output.

Further, the count value of the short cycle signal and the count value of the long cycle signal are sequentially stored, and the cycle is stored in time series.

Further, the frequency of the short-period signal and the frequency of the long-period signal are changed in accordance with the clock signal, and the frequencies of the short-period signal and the long-period signal approach a multiple of the frequency of the clock signal and the generation frequency of the clock signal. To adjust.

[0013]

1 is a block diagram showing an embodiment of the present invention. As shown in the figure, a time difference measuring device adopting the time difference measuring method according to the present invention is a device for simultaneously measuring the period of a clock signal generated intermittently and the generation period of the clock signal, the first oscillating unit 1, a second oscillating unit 2, an input buffer unit 3, a control unit 4, a first counting unit 5, a second counting unit 6,
A first storage unit 7, a second storage unit 8, a first input port unit 9 and a second input port unit 10 are provided.

The first oscillating unit 1 continuously generates a short cycle signal having a cycle sufficiently smaller than that of the clock signal. The second oscillating unit 2 continuously outputs a long period signal having a period smaller than the generation period of the clock signal and larger than the short period signal generated by the first oscillating unit 1. The input buffer unit 3 inputs a clock signal which is a signal under measurement and shapes the waveform into a digital signal. The control unit 4 includes a first counting unit 5 and a second counting unit 6.
Is a part for controlling the output and reset of the count value of. When the control unit 4 detects the falling edge of the clock signal,
The count value of the first counting unit 5 is read, the count value read this time and the count value read last time are compared, and the first count unit 5 or the second count unit 6 is instructed to output the count value according to the comparison result. Further, when the first counting unit 5 or the second counting unit 6 outputs the count value, the control unit 4 instructs the first counting unit 5 and the second counting unit 6 to reset the count value. The first counting unit 5 counts the number of pulses of the periodic signal generated by the first oscillating unit 1, and the control unit 4
Output the count value or reset the count value. The second counting unit 6 counts the number of periodic signal field pulses generated by the second oscillating unit 2 and outputs the count value or resets the count value according to an instruction from the control unit 4. The first storage unit 7 stores the count value output from the first counting unit 5. Second
The storage unit 8 outputs the count value output by the second counting unit 6.
The first input port unit 9 inputs the change information of the cycle of the output signal of the first oscillating unit 1. The second input port unit 10 inputs the change information of the cycle of the output signal of the second oscillator 2.

Referring to the flow chart of FIG. 2 and the timing chart of FIG. 3, the operation in the case of measuring the period of the clock signal and the generation period of the clock signal by using the time difference measuring device having the above-mentioned configuration. explain.

When the time difference measuring device starts the measurement, first the first oscillating unit 1 and the second oscillating unit 2 start to generate a short period signal and a long period signal, respectively (step S1). The input buffer unit 3 inputs the clock signal and shapes the waveform into a digital signal. The first counting unit 5 and the second counting unit 6 independently start counting the number of pulses of the short cycle signal and the long cycle signal. When the control unit 4 detects the falling edge of the clock signal input via the input buffer unit 3 (step S2), the count value of the first counting unit 5 is read and stored in the control unit 4.

When the control unit 4 stores the count value of the first counting unit 5, it outputs a signal for resetting the count value to the first counting unit 5 and the second counting unit 6, and the first counting unit 5 and the second counting unit. The unit 6 restarts counting the number of pulses of the first oscillator 2 and the second oscillator 2 (step S3). When the control unit 4 detects the next falling edge of the clock signal (step S4), the count value of the first counting unit 5 is read, the count value read this time is compared with the count value read last time, and the count value read this time is read. Memorize the numerical value. In this way, since the count value read this time and the count value read last time are compared, even if the cycle of the first oscillator 1 or the frequency of the second oscillator 2 is changed, other set values are changed, etc. Clock signals of various frequencies can be measured without any adjustment.

When the count value read this time is not larger than the count value read last time by a certain ratio or more, the control section 4 counts the first count section 5 because the detected cycle is the cycle of the clock signal in FIG. The output of a numerical value is instructed (step S5). The first counting unit 5 outputs the count value of the first oscillating unit 1 according to an instruction from the control unit 4. The first storage unit 7 stores the count value output by the first counting unit 5 (step S6).
As a result, the first storage unit 7 sets the cycle of the clock signal to the first
It can be stored in the form of a multiple of the period of the oscillator 1.

When the count value read this time is larger than the count value read last time by a certain ratio or more, the control section 4 indicates the detected cycle to the clock signal generation cycle in FIG. To output (step S5). The second counting unit 6 outputs the count value of the second oscillating unit 2 according to an instruction from the control unit 4. The second storage unit 8 is the second counting unit 6
The count value output by is stored (step S7). As a result, the second storage unit 8 can store the generation cycle of the clock signal in the form of a multiple of the cycle of the second oscillation unit 2.

The control unit 4 includes a first counting unit 5 or a second counting unit 6.
Outputs the count value, the first counting unit 5 and the second counting unit 6
A signal for resetting the count value is output to. First counting unit 5
And when continuing the measurement, the second counting unit 6 starts counting again (step S8). Thereby, the first counting unit 5
The second counting unit 6 can accurately count the number of pulses of the first oscillating unit 1 and the second oscillating unit 2 from the falling edge of the clock signal to the next falling edge.

It should be noted that the first oscillating unit 1 is added together with the clock signal.
By adjusting the frequency of the second oscillating unit 2, more accurate measured value can be obtained. In that case, the change information of the frequency of the output signal of the first oscillating unit 1 is input to the first input port unit 9 and the frequency of the output signal of the second oscillating unit 2 is input to the second input port unit 10. Enter the change information. The first input port unit 9 and the second input port unit 10 change the setting of the oscillation frequencies of the first oscillator 1 and the second oscillator 2 based on the input values. In this case, the frequency change information is input by an external signal or manually.

Further, in the above embodiment, the control unit 4 stores the previously read count value. However, the reference value may be stored in advance, or the reference value may be stored in the idling state first. May be fixedly set. As a result, the processing becomes faster, and a gradual change can be detected.

It is also possible to increase the number of oscillating units and counting units so that a plurality of periods of the combined signal can be measured separately.

[0024]

As described above, the present invention generates a short period signal having a period sufficiently smaller than that of a clock signal and a long period signal having a period larger than that of the short period signal.
The number of pulses of the short-period signal and the long-period signal between the falling edge and the falling edge of the clock signal, which is the signal under measurement, is counted, and different periods are counted simultaneously, so that the clock signal periodically occurs. Even in this case, the period of the clock signal and the generation period of the clock signal can be counted at the same time. In addition, since they are counted independently of each other, the generation cycle can be counted simultaneously even if the frequency bands are close.

When the number of counted short-period signals is larger than the number of counted short-period signals by a certain percentage or more, the number of long-period signals is output. In other cases, the number of short-period signals is counted. Is output and the number of pulses is output by determining whether the period of the clock signal or the generation period of the clock signal is detected according to the detected time. Therefore, it is possible to determine the period of the clock signal without separating the clock signal for each period component. The generation period of the clock signal can be measured.

Further, since the count value of the short cycle signal and the count value of the long cycle signal are sequentially stored and the cycle is stored in time series,
Cycles can be detected continuously and replayed to check for changes.

Further, the frequency of the short-period signal and the frequency of the long-period signal are changed in accordance with the clock signal, and the frequencies of the short-period signal and the long-period signal approach a multiple of the frequency of the clock signal and the generation frequency of the clock signal. Therefore, the cycle can be measured more accurately.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 3 is a timing chart of each signal.

[Explanation of symbols]

 1 1st oscillation part 2 2nd oscillation part 3 Input buffer part 4 Control part 5 1st counting part 6 2nd counting part 7 1st memory part 8 2nd memory part 9 1st input port part 10 2nd input port -Ground part

Claims (3)

[Claims] 1. A time difference measuring method for simultaneously measuring the period of a clock signal and the generation period of the clock signal, the short-period signal having a period sufficiently smaller than the period of the clock signal,
A long period signal having a period larger than that of the short period signal is generated, and the number of pulses of the short period signal and the long period signal between the falling edge and the falling edge of the clock signal as the signal under measurement is counted and counted. When the number of pulses of the short-cycle signal is larger than the number of pulses of the short-cycle signal previously counted by a certain ratio or more, the number of pulses of the long-cycle signal is output, and in other cases, the number of pulses of the short-cycle signal is output. How to measure the time difference. 2. The time difference measuring method according to claim 1, wherein the count value of the short cycle signal and the count value of the long cycle signal are sequentially stored. 3. The time difference measuring method according to claim 1, wherein the frequency of the short-period signal and the frequency of the long-period signal are changed together with the clock signal.