|NI-SCOPE (English | Japanese)|
Spurious free dynamic range (SFDR) is the usable dynamic range before spurious noise interferes with or distorts the fundamental signal. The amplitude of the fundamental signal is usually -1 dBFS. SFDR is the measure of the ratio in amplitude between the fundamental signal and the largest harmonically or non-harmonically related spur from DC to the full Nyquist bandwidth (half the sampling rate). A spur is any frequency bin on a spectrum analyzer, or from a Fourier transform, of the analog signal. SFDR is expressed in dBc.
The following figure illustrates how SFDR is measured.