How is a frequency modulation measurement made?
The Analog Frequency Modulation measurement measures the frequency deviation and, if enabled, the total harmonic distortion and modulation frequency, for frequency modulated analog signals (such as AMPS transmitters). Measurements are performed after any filtering, de-emphasis, and expansion are performed (selected by the user in the setup parameters). The FM deviation and distortion measurements are not affected by a static (constant) frequency error on the input signal as long as the input signal is within 2.5 kHz of the expected frequency. This measurement is not used for digital signals.
