Compensate Phase Results for Frequency Offset (Pulse)
Menu Path:
When the Compensate Phase Results for Frequency Offset checkbox is enabled, the reported per pulse measured and reference synchronized phase trace results are automatically compensated for each specific pulse's measured mean frequency offset from the current Center Frequency. In this way the per pulse measured and reference phase versus time trace results can be more easily viewed and compared even if the signals contain various frequency hopping pulses, in addition to the power-off (noise only) intervals.
The example below illustrates a signal containing four unique LFM modulated pulses, each defined with a different frequency start/stop (Hz), slope rate (Hz/s) and time length (s). Each pulse-on time width is varying, and the pulse repetition interval is fixed, resulting in varying pulse-off (noise only) time intervals. Notice that with the Compensate Phase Results for Frequency Offset checkbox enabled, each of the measured pulses exhibits the classic parabolic unwrapped phase response expected due to the LFM signal modulation applied.
Note that when the Compensate Phase Results for Frequency Offset checkbox is enabled, both the measured and reference phase samples are displayed only for samples which fall inside the per-pulse phase measurement analysis range, as determined by the Frequency/Phase Analysis Width (%) property. Additionally the reference unwrapped phase results are reset to 0 degrees at the nominal phase measurement analysis time start within each detected pulse (note that the interpolated nominal phase measurement analysis time start may fall in between result trace sample interval points).
When Compensate Phase Results for Frequency Offset checkbox is disabled as shown below, the measured unwrapped phase response now includes the effects of not only the pulse signal's frequency hopping LFM pattern, but also the pulse-off (noise only) intervals.
Note that when Compensate Phase Results for Frequency Offset checkbox is disabled, all uncompensated measured phase samples are displayed, but the reference phase samples are displayed only for samples which fall inside the per pulse phase measurement analysis range, as determined by the user specified Frequency/Phase Analysis Width (%) property. Also the synchronized reference phase trace results are automatically adjusted for each specific pulse's measured mean frequency offset from the current 89600 VSA software's Center Frequency value.
Default: On
