Graph Types for FETC:MEAS? Queries on the OBR

When pulling time-domain trace data remotely from an OBR using the FETC:MEAS? query, the graphType parameter tells the instrument which trace to return: Amplitude, Linear Amplitude, Amplitude (dB), Phase Derivative, or Polarization States. Some versions of the OBR User Guide list these in one order, but the instrument actually returns them in a different order — the same order they appear in in the GUI's drop-down menu.

We confirmed this by loading an .obr file into OBR Desktop Analysis and using the Remote Client Example tool (installed alongside the OBR software) to send remote commands and compare the returned data against what was shown on screen.

The User Guide lists the time domain (domain = 0) graphType order as:

But the order the instrument actually returns is:

For graphType values 0 through 3, you'll get the same number of points as FETC:FSIZ?. For graphType 4 (Polarization States), you'll get three times that many points, appended one after another: Amplitude (dB/mm) first, then S (dB/mm), then P (dB/mm).

If your script requests graphType 1 expecting Linear Amplitude, you're actually getting Amplitude (dB) instead — this is a common cause of extracted data not lining up with what's displayed in the GUI. If that's happening to you, try adjusting your graphType value against the corrected table above rather than the User Guide.

Corrected example:

As an example, the command "FETC:MEAS? A, 0, 1, 1" was intended to retrieve Trace A, time domain, Linear Amplitude, with decimation on — but per the tables above, graphType = 1 actually returns Amplitude (dB), and decimation was masking the true sample spacing.

The corrected command to get Trace A, time domain, Amplitude, at full (non-decimated) sample resolution is FETC:MEAS? A, 0, 0, 0.  Adjust the graphType value per the corrected table above depending on which parameter you actually need.