Digital Frequency Meter 20, the basic principle of a digital frequency meter

There are many ways to measure frequency, which are divided into passive measurement method, comparative method, oscilloscope method and counting method according to their working principle. Counting is essentially a comparative method, the most commonly used method of which is the electronic counter method. An electronic counter is one of the most common and basic digital measuring instruments.

A digital counter frequency meter directly counts the number of pulses of the signal being measured per unit of time and then displays the frequency value in digital form. This method has high measurement accuracy and speed, and is suitable for frequency measurement at different frequencies and with different accuracy. There are two ways to measure the frequency with an electronic counter:

The first is the direct frequency measurement method, that is, the number of pulses of the measured signal is measured within a certain gate time; The second is indirect frequency measurement method, such as periodic frequency measurement method.

Due to the rapid development of digital circuits and the popularization of integrated circuits, counters are widely used. The use of electronic counters to measure the frequency has a series of outstanding advantages such as high accuracy, eye-catching and intuitive display, rapid measurement, and convenient automation of the measurement process, so this method is currently the best.

I don't have to do so many components, I made a chip with ICM7216D as the core (special chip for frequency meter) to change the crystal oscillator on the drawing to 10MHz in the rubidium clock, which is very accurate, simple, accurate, and already in use.

What did you do in the end, can you send it to me? Thank you so much.

The frequency meter is mainly composed of four parts: a time base (T) circuit, an input circuit, a counting display circuit, and a control circuit. In the process right of a measurement cycle, the measured periodic signal is amplified, shaped, and differentiated in the input circuit to form a narrow pulse of a specific period, which is sent to an input terminal of the main gate.

The other input of the main gate is the gate pulse generated by the circuit generated by the time-based circuit. During the opening of the main gate by the gate pulse, the narrow pulse of a specific period can pass through the main gate and enter the counter for counting, the display circuit of the counter is used to display the frequency value of the measured signal, and the internal control circuit is used to complete the switching between various measurement functions and realize the measurement setting. Frequency Meter Application Range:

In traditional electronic measuring instruments, oscilloscopes have low measurement accuracy and large errors when performing frequency measurements. The spectrum analyzer can accurately measure the frequency and display the spectrum of the measured signal, but the measurement speed is slow, and it cannot quickly track and capture the change of the frequency of the measured signal in real time. It is precisely because the frequency meter can quickly and accurately capture the change in the frequency of the measured signal that the frequency meter has a very wide range of applications.