300 Chapter 5
Programming Fundamentals
Improving Measurement Speed
Programming Fundamentals
the Same Line” in the SCPI Language Basics section.
• If you are making the same measurement multiple times with small
changes in the measurement setup, use the READ command. It is
faster then using INITiate and FETCh.
• If you are changing the frequency and making a measurement
repeatedly, you can reduce transactions by sending the optional
frequency parameter with your READ command.
(for example, READ:<meas>? {<freq>}) These optional parameters
are not available in some personality modes such as Spectrum
Analysis or Phase Noise.
The CONFigure/MEASure/READ commands for measurements in
the option Modes allow you to send center frequency setup
information along with the command. (for example, MEAS:PVT?
935.2MHz) This sets the power vs. time measurement to it’s defaults,
then changes the center frequency to 935.2 MHz, initiates a
measurement, waits until it is complete and returns the
measurement data.
• If you are doing bottom/middle/top measurements on base stations,
you can reduce transactions by making a time slot active at each of
the B,M,T frequencies. Then issue three measurements at once in
the programming code and retrieve three data sets with just one
GPIB transaction pair (write, read).
For example, send READ:PFER? <Freq_bottom>;PFER?
<Freq_middle>;PFER? <Freq_top> This single transaction initiates
three different phase and frequency error measurements at each of
the three different frequencies provided and returns the data. Then
you read the three sets of data.
Using an Option Mode: Avoid automatic attenuator
setting.
The internal process for automatically setting the value of the
attenuator requires measuring an initial burst to identify the proper
attenuator setting before the next burst can be measured properly. If
you know the amount of attenuation or the signal level needed for your
measurement, just set it.
Note that spurious types of measurements must be done with the
attenuator set to automatic (for measurements like: output RF
spectrum, transmit spurs, adjacent channel power, spectrum emission
mask). These types of measurements start by tuning to the signal, then
they tune away from it and must be able to reset the attenuation value
as needed.
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