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Subject: Re: Using Frequency Counter to measure short pulses
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Date: Mon, 4 Nov 2002 15:09:30 -0800
NNTP-Posting-Date: Mon, 04 Nov 2002 15:09:39 MET
Organization: @Home Network
"Nick Funk" wrote in message
> Is it possible to utilize a frequency counter to measure short pulses.
> I would guess that if it is possible one must design a oscillator to be
> used as a time base and then a trigger circuit to start and stop the
> pulse train for measurement.
> With proper selection of oscillator frequency one can measure RPMs or
> distance measurements with proper display in revolutions per minute or
> feet (meters).
The timebase oscillator output is divided down to a gate time (1 second for
example).The gate signal is used to reset the counter (which is incremented
by the input) and to latch the present value into the display. The timebase
is usually a high frequency crystal oscillator for stability and accuracy
You can measure frequency by counting a number of pulses per timeperiod, or
by measuring the time between pulses (there are some other methods too).
The gatetime could be adjusted to change the displayed unit. If you have a
signal of 100Hz and a gate time of 1 second, 100 will be display. Halve the
gatetime and 50 is displayed. Double the gatetime to 2 seconds and 200 is
displayed. For RPM you could set the gatetime to 0.6 seconds. You'll get an
display in 100 rpm units then. It's better to convert the measured frequency
to some other unit.
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