RIGOL DS1000B - Manual (Page 49)

RIGOL
User’s Guide for DS1000B Series 2-19
Term Explanations
FFT Resolution: The FFT resolution is the quotient between sampling rate
and the number of FFT points. With a fixed FFT points, the lower sampling
rate, the better the resolution.
Nyquist Frequency: The highest frequency that any real-time digitizing
oscilloscope can acquire without aliasing. It’s normally half of the sample rate.
This frequency is called the Nyquist frequency. Frequency above the Nyquist
frequency will be under sampled, causing a situation known as aliasing.