Technical data

Programming Fundamentals 28
Agilent N8201A Performance Downconverter Synthetic Instrument Module, 250 kHz to 26.5 GHz 589
Improving Measurement Speed
There are a number of things you can do in your programs to make them run faster:
“Turn off the display updates" on page 589.
“Use binary data format instead of ASCII" on page 589.
“Put ADC Ranging in Bypass for FFT Measurements for N8201A" on page 590.
“Minimize DUT/instrument setup changes" on page 590
There are additional things you can do to run faster if you are using a measurement
personality option (that is, instrument Modes other than the standard Spectrum Analysis
Mode). These considerations only apply to specific option modes.
“Using an Option Mode: Avoid automatic attenuator setting" on page 591.
“Using an Option Mode: Optimize your GSM output RF spectrum switching
measurement" on page 591.
“Using an Option Mode: When making power measurements on multiple bursts or slots,
use CALCulate:DATA<n>:COMPress?" on page 592.
Turn off the display updates
:DISPlay:ENABle OFF turns off the display. That is, the data may still be visible, but
it will no longer be updated. Updating the display slows down the measurement. For remote
testing, since the computer is processing the data rather than a person, there is no need to
display the data on the Spectrum Analyzer GUI display.
Use binary data format instead of ASCII
The ASCII data format is the instrument default since it is easier for people to understand
and is required by SCPI for *RST. However, data input/output is faster using the binary
formats.
:FORMat:DATA REAL,64 selects the 64-bit binary data format for all your numerical
data queries. You may need to swap the byte order if you are using a PC rather than UNIX.
NORMal is the default byte order. Use :FORMat:BORDer SWAP to change the byte
order so that the least significant byte is sent first. (Real,32 which is smaller and somewhat
faster, should only be used if you do not need full resolution for your data. Some frequency
data may require full 64 bit resolution.)
When using the binary format, data is sent in a block of bytes with an
ASCII header. A data
query would return the block of data in the following format: #DNNN<nnn binary data
bytes>
To parse the data:
• Read two characters (#D), where D tells you how many N characters follow the D
character.