Yes 'Sweep' is mostly referring to a variation in the Frequency. Maybe a term like , " Power dynamic range" or "Power Linearity range" of DUT is better?
Why are there steps in the plot? are there Changes of internal attenuations ?
Edit:
Content revised 2/10/015The D815-TG 'Power Sweep' mode is for testing an Amplifier, etc. for its Output Linearity. Such as the 1dB Compression Point, etc.
Pages 2-42, 43 of the Rigol DSA800 User Guide shows that Power Sweep steps up 1dB in amplitude as frequency span increments up. Rigol may not have explained the Power Sweep mode sufficiently, leaving some users not appreciating it fully, or understanding what its purpose is.
Power Sweep provides an increase in TG output amplitude as frequency Span progresses. The frequency Span is kept to a absolute minimum (100Hz) so that the test results aren't effected by the Bandwidth of the device
being tested for amplitude input/output linearity.
You can determine if Power Sweep works in your DSA815-TG by connecting a coax cable between the DSA815-TG's 'TG Output' and 'SA Input', and then selecting the following settings:Preset (Green key),
FREQ: 750MHz (the Test Frequency),
SPAN: 100Hz,
RBW: 100Hz (
Required if 10Hz RBW Option is installed),
TG: On,
TG Level: -20dB,
Power Range: 20dB,
Power Sweep: On,
AMP: Auto Scale,
Scale/Div: 2dB,
Ref Level: -1dB (or A/R).
You should see the results of Power Sweep with its 1db amplitude steps over a 20dB range. Although 1 or more of the steps may have 2 steps lumped together as a 2dB ramp up (probably a Bug).