Frequency counters and timers can be used for measuring many signals like
- Digital logic signals
- RF (radio frequencies)
- Microwaves.
Counter technology has evolved so that these frequency counters and timers are able to measure time intervals as well as frequency. Time interval is an inverse function of frequency that allows digital processing technology to measure.
How frequency counters work?
The number of events occurring within a specific period of time is counted. The preset (specific) period is called the gate time and after every accumulation is transferred to a display the counter is reset to zero.A clock oscillator is used that allows the resolution of the measurement. This can be improved if the number of cycles is counted over a set period of time rather than counting the cycles for a set time. The internal oscillator is referred to as the time base and this needs calibration. The stability of time base is directly proportional to the accuracy of the frequency counter.
When using a frequency counter, it is necessary to select the time base interval. Generally options of 0.1s, 1s, 10s are the most common. These refer to the length of time over which the frequency counter gate is open and incoming pulses are counted. Thus, for a gate time of 1 second, 1 000 000 pulses will be counted for a 1 MHz (mega hertz) signal or if five pulses are counted, with a gate time of a second, then the frequency is 5Hz (hertz). Hertz is the frequency unit in the International system of units. It is named after Heinrich Rudolf Hertz (1857 - 1894) the German scientist who proved the theory of electromagnetic waves.
The Tektronix FCA3000 and FCA3100 Frequency Counter Series are most commonly used as these instruments combine many features and several functions.
