Modulation Sinad Measurement Concepts; Purpose; Measurement Technique - Keysight N9030A Measurement Manual

Concepts

Modulation SINAD Measurement Concepts

Modulation SINAD Measurement Concepts

Purpose

Modulation SINAD (SIgnal to Noise And Distortion) measures the amount of
Modulation SINAD contained in the modulated signal by determining the ratio of
fundamental power to harmonic and noise power. Modulation SINAD is the
reciprocal of the modulation distortion provided by the Modulation Distortion
measurement. This is another way to quantify the quality of the modulation process.

Measurement Technique

Modulation SINAD is defined as:
Equation 2-5
First, the received signal is demodulated and filtered to remove DC, then the filtered
signal is transformed by an FFT into frequency domain. Next, total power in the total
filter band is measured as P
as P
is the signal's Modulation SINAD. It can be expressed as dB.
dB =
ModulationSINAD
where: P = the power of the total signal,
total
P = the power of the wanted modulating signal, and
signal
P - P = the total unwanted signals which include harmonic distortion and
total signal
noise.
, the square root of the ratio of P
signal
P
× total
20 log ---------------------------------- -
P – P
total
, the peak power of the modulated signal is computed
total
to P
total total
36
signal
- P is calculated. The result
signal