Keysight Technologies X-Series, Руководство по программированию

Страница: 327 / 398

Keysight CXG, EXG, and MXG X-Series Signal Generators Programming Guide 327
Creating and Downloading User–Data Files
User File Data (Bit/Binary) Downloads
User File Data (Bit/Binary) Downloads
The signal generator accepts externally created and downloaded user file data
for real–time modulation formats that have user file as a data selection (shown
as <“file_name”> in the data selection SCPI command). When you select a user
file, the signal generator incorporates the user file data (payload data) into the
modulation format’s data fields. You can create the data using programs such
as MATLAB or Mathcad.
The signal generator uses two file types for downloaded user file data: bit and
binary. With a bit file, the signal generator views the data up to the number of
bits specified when the file was downloaded. For example, if you specify to use
153 bits from a 160 bit (20 bytes) file, the signal generator transmits 153 bits
and ignores the remaining 7 bits. This provides a flexible means in which to
control the number of transmitted data bits. It is the preferred file type and the
easiest one to use.
With a binary file, the signal generator sees all bytes (bits) in a downloaded file
and attempts to use them. This can present challenges especially when
working with framed data. In this situation, your file needs to contain enough
bits to fill a frame or timeslot, or multiple frames or timeslots, to end on the
desired boundary. To accomplish this, you may have to remove or add bytes. If
there are not enough bits remaining in the file to fill a frame or timeslot, the
signal generator truncates the data causing a discontinuity in the data pattern.
You download a user file to either the Bit or Binary memory catalog (directory).
Unlike a PRAM file (covered later in this chapter), user file data does not
contain control bits, it is just data. The signal generator adds control bits to the
user file data when it generates the signal. There are two ways that the signal
generator uses the data, either in a continuous data pattern (unframed) or
within framed boundaries. Real–time Custom uses only unframed data.
You create the user file to either fill a single timeslot/frame or multiple
timeslots/frames. To create multiple timeslots/frames, simply size the file with
enough data to fill the number of desired timeslots/frames
If you encounter problems with this section, refer to “Data Transfer
Troubleshooting” on page 384 .
To verify the SCPI parser’s responsiveness when remotely using the
:MEM:DATA SCPI command to upload files, the file’s upload should be
verified using the *STB? command. Refer to the SCPI Command Reference.
For unframed data transmission, the signal generator requires a minimum
of 60 symbols. For more information, see “Determining Memory Usage for
Custom User File Data” on page 333 .