In this note, we are going to know about Digital Frequency Meter Block Diagram and Operation. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.
Author Name: Arun Paul.
What is Digital Frequency Meter?
A Digital Frequency Meter (DFM) is a powerful electronic equipment used to precisely measure the frequency of a periodic electrical signal. It counts the number of oscillations or cycles of a waveform that occur within a specific time period and displays the results in a digital format, usually in Hertz (Hz), kilohertz (kHz), megahertz (MHz), or gigahertz (GHz).
This tool is commonly used in electrical, electronics, and communication engineering to investigate signal frequencies in circuits, communication systems, and industrial applications. Unlike analog frequency meters, which use mechanical or moving coil systems, digital frequency meters display the measured frequency directly on a digital screen, resulting in higher precision, faster response times, and better readability.
Key features of Digital Frequency Meter
- This device measures frequency in Hz, kHz, MHz, or GHz.
- It has high accuracy and fast response time as well.
- It can measure various waveforms (sine, square, triangular).
- It often includes additional features like period measurement, time interval measurement, and totalizing mode.
Digital Frequency Meter Working Principle
The signal waveform is converted into trigger pulses and continuously applied to an AND gate, as shown in the figure. A pulse of 1 second is applied to the other terminal, and the number of pulses counted during this period indicates the frequency.
The signal whose frequency is to be measured is first converted into a train of pulses, with one pulse corresponding to each cycle of the signal. The number of pulses occurring within a fixed time interval is then counted by an electronic counter. Since each pulse represents one cycle of the unknown signal, the total count directly indicates the frequency of the signal.
Because electronic counters operate at high speeds, they can accurately measure high-frequency signals.
Digital Frequency Meter Block Diagram and Operation
The block diagram of a basic Circuit of a digital frequency meter is shown in fig below.
The signal may be amplified before being applied to the Schmitt trigger. The Schmitt trigger converts the input signal into a square wave with fast rise and fall times, which is then differentiated and clipped. As a result, the output from the Schmitt trigger is a train of pulses, with one pulse corresponding to each signal cycle.
The output pulses from the Schmitt trigger are then fed to a START/STOP gate. When this gate is enabled, the input pulses pass through and are fed directly to the electronic counter, which counts the number of pulses.
When the gate is disabled, the counter stops counting the incoming pulses. The counter then displays the total number of pulses that have passed through it during the time interval between start and stop. If this time interval is known, the unknown frequency can be accurately measured using the formula:
Advantages of Digital Frequency Meter
Here we have listed some digital frequency meter advantages –
- The electronic counting mechanism of digital frequency meters allows for exact frequency readings with minimum mistakes.
- Because they involve high-speed electronic counters, they can swiftly measure and show frequency values.
- The frequency is presented on a digital screen, which reduces the possibility of misinterpretation as compared to analog meters.
- Unlike analog meters, which need manual reading from a scale, digital meters remove parallax problems and increase reliability.
- These meters can detect and correctly measure signals with very low amplitudes.
- Many digital frequency meters are designed to consume less power, making them more suitable for long-term use.
- Some models have additional functionalities such as period measurement, time interval measurement, and totalizing mode, making them useful for a variety of applications.
Digital Frequency Meter Applications
Here are the applications of digital frequency meter –
- Used in communication systems like in radio, TV, and telecommunications for signal analysis.
- Used in labs for testing and calibration of electronic circuits.
- Used to monitor frequency variations in machines and electrical networks.