302 Chapter 5
Programming Fundamentals
Improving Measurement Speed
Programming Fundamentals
4. Trigger your DUT to send the burst.
5. Return the measurement data to your computer.
NOTE This process cannot be done by using with the current VXI plug-n-play
driver implementation. You will need to use the above SCPI commands.
Using an Option Mode: When making power
measurements on multiple bursts or slots, use
CALCulate:DATA<n>:COMPress?
The CALC:DATA:COMP? query is the fastest way to measure power
data for multiple bursts/slots. There are two reasons for this: 1. it can
be used to measure data across multiple, consecutive slots/frames with
just one measurement, instead of a separate measurement on each slot,
and 2. it can pre-process and/or decimate the data so that you only
return the information that you need which minimizes data transfer to
the computer.
For example: let’s say you want to do a power measurement for a GSM
base station where you generate a repeating frame with 8 different
power levels. You can gather all the data with a single
CALC:DATA:COMP? acquisition, using the waveform measurement.
With CALC:DATA2:COMP? MEAN,9,197,1730 you can measure the mean
power in those bursts. This single command will measure the data
across all 8 frames, locate the first slot/burst in each of the frames,
calculate the mean power of those bursts, then return the resulting 8
values.
NOTE For later version of firmware (after A.02.00) you can use equivalent
time values for the CALC:DATA<n>:COMP? query. The command
would then be CALC:DATA2:COMP? MEAN,25us,526us,579.6us,8
Let’s set up the GSM Waveform measurement:
• :CONF:WAV? turns on the waveform measurement
• :WAV:BAND 300khz sets a resolution bandwidth of 300 kHz
• :WAV:SWE:TIME 5ms sets a sweep time of 5 milliseconds
• :WAV:BAND:TYPE FLAT selects the flat filter type
• :WAV:DEC 4;DEC:STAT ON selects a decimation of 4 and turns on
decimation. This reduces the amount of data that needs to be sent
since the instrument hardware decimates (throws some away).
• :INIT to initiate a measurement and acquire the data
• CALC:DATA2:COMP? MEAN,25us,526us,579.6us,8 to return the
desired data
There are two versions of this command depending on your firmware
revision. Earlier revisions require the optional variables be entered in
terms of their position in the trace data array. Current instruments
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