Units - Agilent Technologies EPM-P Series Programming Manual

Power Meter Remote Operation
Getting the Best Speed Performance

Units

The power meter can output results in either linear or log units. The
internal units are linear and therefore optimal performance will be
achieved when the results output are also in linear units (since the
overhead of performing a log function is removed).
Command Used
In Free Run mode, FETCh? must be used to return a result.
In other trigger modes, there are a number of commands which can be
used, for example, MEASure?, READ?, FETCh? Note that the MEAS? and
READ? commands are compound commands—they perform a combination
of other lower level commands. In general, the best speed performance is
achieved using the low level commands directly.
Trigger Count
To get the fastest measurement speed the a TRIG:COUNT must be set to
return multiple measurements for each FETCh command. For average
only measurements a count of 4 is required but 10 is recommended. In
normal mode (peak measurements) a count of 50 is required to attain 1000
readings per second.
Fast Mode
In the highest speed setting, the limiting factor tends to be the speed of
the controller being used to retrieve results from the power meter, and to a
certain extent, the volume of GPIB traffic. The latter can be reduced using
the FORMat REAL command to return results in binary format. The
former is a combination of two factors:
• the hardware platform being used.
• the programming environment being used.
1-74 EPM-P Series Power Meters Programming Guide
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