Technical data

Agilent Signal Generators Programming Guide 321
Creating and Downloading User–Data Files
User File Data (Bit/Binary) Downloads (E4438C and E8267D)
PRAM. (Volatile memory resides on the BBG.) Table 6- 6 shows the maximum file sizes by modulation
format and baseband generator option.
For more information on signal generator memory, see “Signal Generator Memory” on page 309. To
determine how much memory is remaining in non–volatile and volatile memory, see “Checking
Available Memory” on page 313.
Determining Memory Usage for Custom and TDMA User File Data
For Custom and TDMA 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 × 4
bytes/bit).
Use the following procedures to calculate the required amount of volatile memory for both framed
and unframed TDMA signals:
• “Calculating Volatile Memory (PRAM) Usage for Unframed Data” on page 322
• “Calculating Volatile Memory (PRAM) Usage for Framed Data” on page 322
Table 6-6 Maximum User File Size
Modulation
Format
Baseband Generator Option
001, 601 002 602
Custom
a
TDMA
a
a.File size with no other files residing in volatile memory.
800 kB 3.2 MB 6.4 MB
CDMA
b
GPS
b
W–CDMA
b
b.File size is not affected by the BBG option.
10 kB 10 kB 10 kB