Time frequency counter , As the name implies, it is used for Measuring time interval, frequency, frequency ratio, accumulating count, cycle time and so on, the basic working principle is that it has a variety of measuring functions with proper logic circuits, mainly including frequency, cycle and time interval measurement, and usually includes frequency ratio, pulse count in any time interval and cumulative count.

Accumulating the number of oscillations of the input signal in the predetermined standard time, or accumulating the number of standard time base signals in the time interval to be measured, and measuring the frequency, period and time interval; the basic circuit is composed of an input channel, a time base generation and transformation unit, a main gate, a control unit, a counting and display unit, etc. 。

Inspection of appearance and working normality

Visual inspection General counter Appearance, touch the switch and input socket. Correct electrifying and operating according to the instructions shall conform to the requirements of the regulations. That is, the general counter should not be affected by normal mechanical damage. The control knob and key should be able to act normally. The input socket should be solid and reliable. The front or rear panel should have the name of the instrument, the name of the manufacturer, the trademark, the type of the instrument, the serial number of the instrument or the serial number, and the power requirement.

After switching on the power supply, it will operate normally according to the instruction manual, and the self checking and self diagnosis function of the general counter and all kinds of measuring functions should be checked.

Built in time base oscillator

Time interval counter The calibration of the built-in time-based oscillator is based on the type and accuracy of the internal oscillator, and the boot characteristics, the daily frequency fluctuation and the daily aging rate of the universal counter. 1s frequency stability, frequency reproducibility and frequency accuracy were checked. A general counter with a built-in time base oscillator frequency output, usually referred to JJG180 "quartz crystal oscillator in electronic measuring instruments" or JJG181 "quartz crystal frequency standard" or JJG292 "rubidium atomic frequency standard" for verification.

Frequency measurement range, input sensitivity and measurement error verification

It should be noted that the output impedance of the synthesized signal generator matches the input impedance of the universal counter. If the input terminal has an attenuator, the decrement is transferred to the minimum position.Input signal frequency exceeds At 1 GHz, the output level error of the synthesized signal generator is less than 0.5 dB, and the insertion loss of the connection line is less than O. 5 dB. Otherwise, the output level is measured by the power meter. The general counter is selected to select frequency measurement function, and the gate time is selected to be 1 s.

The output signal frequency of the synthesized signal generator is adjusted to each frequency point, and the output level of each point is from 10mV gradually increases, knowing that the checked universal counter works normally and the readings are stable and accurate. At this time, the output level of the synthesized signal generator is the input sensitivity of the verification point; when the power meter is used to measure the output power, its display value is the input sensitivity of the verification point. At the same time, the effective resolution of the display frequency of the general counter is recorded.

General counter Other applications include the computer field, where high-performance clock is used in data communication, microprocessor and display. The application areas with low performance requirements include measuring mechanical and electrical products. One of the early applications of the frequency counter is as part of the signal generator. Before the output of the signal generator, the signal is measured by the frequency counter component. The measured result is converted to analog signal, which is used to feedback the frequency of the control signal generator until the desired value is reached, so that a stable signal output can be obtained. Many signal generators are integrated with a simple function of frequency counters.

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