JPS5858032B2 - Pulse width measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse width measurement method, and more particularly to a measurement method when noise is superimposed on an input signal or when there are pulse cracks caused during quantization.

Conventional methods for measuring pulse width count the time between the rise and fall of a signal pulse, so if there is noise superimposed on the input signal or cracks in the pulse during quantization, these are ignored. This method has the disadvantage that it is incorrectly determined as the rising or falling edge of a signal pulse, and the width of one pulse is measured as the pulse width of divided pulses.

FIG. 1 is a block diagram showing an example of a conventional method.

In FIG. 1, 1 is a slicer, and the slicer 1 quantizes an input signal, such as an input video signal.

2 is a rising differentiation circuit that differentiates the rising point of the output pulse of slicer 1, and uses this pulse as the starting pulse 1 for pulse width measurement.
Set to 0.

3 is a falling differentiation circuit that differentiates the falling point of the output pulse of slicer 1, and uses this pulse as the end pulse 1 for pulse width measurement.
Set to 1.

4 is a clock generation circuit that generates a clock pulse 9 with a stable frequency, and 5 is a pulse counter that generates a measurement start pulse 10.
The period clock 9 of the gate defined by the measurement end pulse 11 is counted.

Therefore, the total i value of the counter 5 represents the pulse width.

The counter 5 is also provided with a suitable reset circuit, although not shown in FIG.

In the circuit shown in Figure 1, noise superimposed on the input signal and cracks in pulses during quantization are detected by the rising differentiation circuit 2 and the falling differentiation circuit 3, and the width of one pulse is measured as the pulse width of the divided pulses. There are cases.

This is a drawback of the conventional device shown in FIG.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pulse width measurement method that eliminates the above-mentioned drawbacks of conventional devices and that does not cause erroneous measurements even when there is noise superimposed on the signal or cracks in the pulse during quantization. It is.

FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, 1-5.9 to 11 indicate the same or equivalent parts as the same reference numerals shown in FIG. 1.

6 and 8 are each 6 with one shot multi-buy break
8 is a non-retriggerable circuit, 8 is a retriggerable circuit, and 7 is a delay circuit.

An input signal, for example a video signal, is quantized in a slicer 1.

This quantized signal drives a one-shot multi-pipe brake circuit 6 that cannot be retriggered.

The output of this one-shot multi-by-break 6 is standing, 1
It is differentiated by the differential (2) path 2, inputted into the delay circuit 7, and is delayed by a time equal to the metastable time id of the retriggerable one-shot multi-by-break 8 to become the start pulse 10.

On the other hand, the quantized signal sequentially triggers the retriggerable one-shot multi-by-break 8, and its output is differentiated by the falling differentiation circuit 3 to become the end pulse 11.

FIG. 3 is an example of an operation time chart of the embodiment shown in FIG.

a is an example of an input pulse signal, such as a video pulse signal;
b is the output of slicer 1, C is the output of one-shot multi-by break 6 that cannot be retriggered, d, e, f are the trigger status of one-shot multi-by break 8 that can be retriggered, TD Hawan Shot Maruna By Break 8 , g is the output of the retriggerable one-shot multi-by-break 8, h is the start pulse 10, i is the end pulse 11. J indicates a gate signal for counting clocks 9 by counter 5.

As in the example in Figure 3, even if the quantized video signal is divided, if the interval between the divided video signals is less than the one-shot multi-by-break metastable time tcl, the correct pulse width will be reproduced in the signal j. Therefore, the correct pulse width can be measured without any hassle.

Note that although the above description has been made regarding the case of pulse width measurement, the present invention is not limited to this, and may be used to measure the input time of a pulse train.

In this case, the metastable time td of the one-shot multi-by-break may be selected to a value greater than or equal to the pulse interval of the pulse train.

As described above, according to the present invention, the division of the quantized pulse signal can be ignored, so there is an advantage that the pulse width can be measured even if the amplitude of the input pulse is at the limit of quantization.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of a conventional pulse width measuring device, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is an operation time chart in the embodiment of Fig. 2. . In the figure, 1 is a slicer, 2 is a rising differentiation circuit, 3 is a falling differentiation circuit, 4 is a clock generation circuit, 5 is a counter, and 6
is a re-triggerable one-shot multi-bye break,
7 is a delay circuit, 8 is a retriggerable one-shot multi-by-break, 9 is a clock signal, 10 is a start pulse signal, and 11 is an end pulse signal. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A stage of triggering a one-shot multi-bye break that cannot be retriggered at the rising edge of a quantized pulse signal, a stage of performing I-IJ on a one-shot multi-bye break that can be retriggered at the falling edge of the pulse signal, and a stage of one-shot multi-bye break that cannot be retriggered. A step in which a measurement start pulse is generated by delaying the break trigger point by a time equal to the metastable time of the retriggerable one-shot multi-bye break, and a measurement end pulse is generated at the stable state return point of the retriggerable one-shot multi-bye break. A pulse width measuring method comprising: a step of generating a pulse width; and a step of measuring a time from the measurement start pulse to the measurement end pulse.