Image Credit: Allied Electronics, Inc.

Frequency counters are digital devices for accurate measurement and display of square wave and pulse input signal frequencies.

 
A frequency counter is an electronic instrument used to measure frequency and time. Frequency counters are used for a wide range of frequency and time measurements and display many digits of accuracy.
  

Frequency counters are designed to work on a wide range of radio frequencies. If the frequencies are very high, the frequency counter uses a high speed prescaler that reduces its frequency to operate digital circuitry.

Specifications of a Frequency Counter

 
Frequency counters operate on the principle of gating input frequency into the counter for a predetermined time. A digital frequency counter finds wide applications in industries like to provide high degree of accuracy with RF signals. Frequency counters are also used to calibrate other equipment that does not have displays such as a signal generator.

 
Types of Frequency Counters

  
There are several types of frequency counters which differ in frequency ranges and the number of digits that can be displayed.
 
Handheld devices tend to be battery powered smaller devices often with an lcd display, while bench top or rack mounted are larger devices that are powered from a wall outlet.

 
Frequency Range

Frequency counters can measure from the Hz range where 1Hz is one pulse per second up to the Ghz range, where generally higher frequencies require better and more expensive devices.
  

Some frequency counters have multiple channels and can measure multiple signals at the same time.
 

Sampling Rate

Sampling rate is the frequency at which a digital meter tests the analog signal and converts to a digital value.
 

Display

Frequency counters can have either digital or analog displays. Although most displays are digital, an analog display can be helpful for determining frequency changes.

 
Some frequency counters can output the frequency as a digital output such as USB or RS232.
 

Standards

TB 9-6625-1996-35 - Calibration procedure for frequency counter