What is the deviation ratio of an FM phone signal having a maximum frequency swing of plus or minus 5 kHz if the highest modulation frequency is 3 kHz?

The deviation ratio in an FM signal is calculated by dividing the maximum frequency deviation (also called frequency swing) by the highest modulating frequency. This ratio helps determine the required bandwidth for the signal. In this question, the maximum frequency swing is given as 5 kHz, and the highest modulation frequency is 3 kHz. Simply divide 5 by 3 to get 1.666..., which rounds to 1.67. A common mistake is inverting the formula by dividing the modulation frequency by the deviation (3 / 5), which yields 0.6. Always remember that the deviation ratio puts the maximum deviation in the numerator.