RIGOL DSA875 - Manual (Page 16)

RIGOL
DSA800 Options and Accessories 12
7. Harmo Dist
Measure the power of each order of harmonic and THD (total harmonic
distortion) of the carrier. The highest order of harmonic available is 10 and the
fundamental wave amplitude must be greater than -50 dBm, or else the
measurement will be invalid.