Technical data

592 Agilent N8201A Performance Downconverter Synthetic Instrument Module, 250 kHz to 26.5 GHz
28 Programming Fundamentals
Make sure the attenuation is set manually. Do NOT use automatic attenuation as this
requires an additional burst to determine the proper attenuation level before the
measurement can be made.
3 Create a small loop that will serial poll the instrument for a status byte value of binary
128. Then wait 1 msec (100 ms if the display is left on/enabled) before checking again,
to keep the bus traffic down. These two commands are repeated until the condition is
set, so we know that the trigger is armed and ready.
4 Trigger your DUT to send the burst.
5 Return the measurement data to your computer.
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 preprocess and 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 eight 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 eight frames, locate the first
slot/burst in each of the frames, calculate the mean power of those bursts, then return the
resulting eight values.
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