Figure 3-6.
Electronic counter period measurement, block diagram
(1) A periodic measurement gives a more accurate measurement of an unknown
low frequency signal because of increased resolution.
A frequency measurement of
100 hertz on a counter with a 10-second gate time will be displayed as 0000.1000
kilohertz (kHz).
(2) When using the same counter, a single period measurement of 100 Hz with
10 megahertz (MHz) as the counter frequency would be displayed as 0010000.0
microseconds on the counter. The resolution is increased by a factor of 100.
e. The ratio of two frequencies is obtained by using the lower frequency
signal for gate control and having the higher frequency signal counted (fig 3-7).
If you use the proper transducers, ratio measurements may be applied to any
phenomena, providing the phenomena can be represented by sine waves or pulses.
Measurements that can be made with the ratio method are clutch slippage, gear
ratios, and frequency divider operations.
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