F.M. deviation measurements

The technique used for a frequency modulation measurement depends upon various factors such as the value of modulation index and frequency deviation. Even with the same set of variables more than one method of measurement may be available and the choice of method is decided as much by its ease of application as by its inherent accuracy.Some of the more commonly used methods of frequency modulation measurement are discussed and the conditions under which each is used are examined. The errors aris ing in the use of these methods and the precautions which must be taken to minimize these errors are also examined. Finally, a commercial type of f.m. meter is described. This instrument depends for standardization on one of the basic methods but covers a wide range of application with good accuracy.