Frequency counter is a commonly used instrument for measuring time and frequency. It is widely used in time measurement and frequency measurement in scientific research metrology, industrial production, aerospace, weapons, missiles, and other fields of research and metrology, such as crystal oscillator and electronic components. This article will explain the function characteristics of the frequency counter.

Before the invention of the counter, the frequency measurement was completed by the frequency meter, and the frequency meter is a coordination device with low accuracy. The frequency counter can be called the first batch.

One of the first instruments to accurately measure signal parameters in digital form.

Time and frequency counters can measure frequency, period, time interval, frequency ratio, accumulating count, timing, etc., with corresponding plug-ins, and can also measure phase, voltage and so on. Its basic working principle is to accumulate the standard time (Shi Ji) signal of the input signal to be measured in the predetermined standard time (gate time) with appropriate logic circuit, or in the time interval to be measured. The number, frequency, cycle and time interval measurement.

The basic circuit of the counter consists of an input channel, a time base generation and conversion unit, a main gate, a control unit, a counting and display unit, etc. it has many measuring functions, including frequency, cycle and time interval measurement, and usually includes frequency ratio, pulse number in any time interval and accumulating count.

The time base circuit is used to generate a standard time signal. The standard time signal is the counting standard time of the counter, and its accuracy determines the accuracy of the frequency meter to a large extent.

The gate circuit is used to control the counting time, consisting of a NAND gate. One end of the NAND gate is supplied by the time base pulse of the time base circuit, and the other end is input from the measured signal after being reshaped. The working principle of the circuit is that the time pulse provided by the time base circuit is used as the gating signal. When the gating signal is high, the gate is opened, and the pulse signal after shaping is passed through the gate to the frequency divider circuit. When the gating signal is low, the gate is closed, and the pulse signal is forbidden.

The recommended model of the domestic time frequency counter is the SYN5636 high precision general counter. It is a time-frequency tester with high performance price ratio developed according to the verification regulation of JJG 349-2014 general counter. The universal counter can be used as a time base for a constant temperature crystal oscillator or a rubidium clock. The standard product is a temperature compensated crystal oscillator base. At the same time, it has two functions of measurement and statistics. Measure frequency, cycle, frequency ratio, input voltage maximum / minimum / peak value, time interval, pulse width, rise time / fall time, duty cycle, phase and so on. Statistics (mean, standard deviation, maximum, minimum, peak value, count, Allen variance).

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