Keysight Technologies X-Series, Руководство по программированию

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Keysight CXG, EXG, and MXG X-Series Signal Generators Programming Guide 333
Creating and Downloading User–Data Files
User File Data (Bit/Binary) Downloads
For more information on signal generator memory, see “Signal Generator
Memory” on page 321 . To determine how much memory is remaining in non–
volatile and volatile memory, see “Checking Available Memory” on page 325 .
Determining Memory Usage for Custom User File Data
For Custom user files, the signal generator uses both non–volatile and volatile
(PRAM/waveform) memory: you download the user file to non–volatile
memory. To determine if there is enough non–volatile memory, check the
available non–volatile memory and compare it to the size of the file to be
downloaded.
After you select a user file and turn the format on, the signal generator loads
the file into volatile memory for processing:
— It translates each data bit into a 32–bit word (4 bytes).
The 32–bit words are not saved to the original file that resides in non–
volatile memory.
— It creates an expanded data file named AUTOGEN_PRAM_1 in volatile
memory while also maintaining a copy of the original file in volatile memory.
It is the AUTOGEN_PRAM_1 file that contains the 32–bit words and
accounts for most of the user file PRAM memory space.
— If the transmission is using unframed data and there are not enough bits in
the data file to create 60 symbols, the signal generator replicates the data
pattern until there is enough data for 60 symbols. For example, GSM uses 1
bit per symbol. If the user file contains only 24 bits, enough for 24 symbols,
the signal generator replicates the data pattern two more times to create a
file with 72 bits. The expanded AUTOGEN_PRAM_1 file size would show 288
bytes (72 bits x 4 bytes/bit).
Calculating Volatile Memory (PRAM) Usage for Unframed Data
Use this procedure to calculate the memory size for either a bit or binary file.
To properly demonstrate this process, the procedure employs a user file that
contains 70 bytes (560 bits), with the bit file using only 557 bits.
1. Determine the AUTOGEN_PRAM_1 file size:
The signal generator creates a 32–bit word for each user file bit (1 bit
equals 4 bytes).
Table 6-6 Maximum User File Size
Modulation
Format
Baseband Generator Memory Option
Standard 021 022 023
Custom
a
a. File size with no other files residing in volatile memory.
32 MB
256 MB
512 MB 1024 MB