What is the deviation ratio of an FM phone transmitter having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz?

The deviation ratio in a frequency modulation (FM) system is defined as the ratio of the maximum frequency deviation (often called the maximum frequency swing) to the maximum modulating frequency (the modulation rate). To calculate the deviation ratio, divide the maximum frequency swing by the maximum modulation rate. In this case, dividing 5 kHz by 3 kHz gives 1.666..., which rounds to 1.66. Common distractors result from setting up the formula backward. For example, dividing 3 kHz by 5 kHz gives 0.6, which is incorrect because the frequency swing must be the numerator.