Programming instructions

Downloading and Using Files
User File Data Downloads
Chapter 4 167
User File Data Downloads
The signal generator accepts user file data downloads. The files can be in either binary or bit
format, each consisting of 8-bit bytes. Both file types are stored in the signal generator’s
non-volatile memory.
• In binary format the data is in multiples of 8 bits; all 8 bits of a byte are taken as data and
used.
• In bit format the number of bits in the file is known and the non-data bits in the last byte
are discarded.
After downloading the files, they can be selected as the transmitting data source. This section
contains information on transferring user file data from a PC to the signal generator. It
explains how to download user files into the signal generator’s memory and modulate the
carrier signal with those files.
Framed and Unframed Data Types
There are two modes that can be used: framed mode and pattern mode.
• In framed mode, user file data is inserted into the data fields of an existing or user-defined,
custom framed digital modulation format, such as DECT, PHS, or TETRA.
The signal generator’s firmware generates the required framing structure and inserts user
file data into the data field(s) of the selected format. For more information, see “User Files
as Data Source for Framed Transmission” on page 170.
NOTE Unlike pattern RAM (PRAM) downloads to memory, user files contain “data
field” information only. The control data bits required for files downloaded
directly into PRAM are not required for user file data.
• In pattern mode, the file is modulated as a continuous, unframed stream of data, according
to the modulation type, symbol rate, and filtering associated with the selected format.
When a user file is selected as the data source, the signal generator’s firmware loads the
data into waveform memory, and sets the other seven control bits depending upon the
operating mode, regardless of whether framed or unframed transmission is selected. In
this manner, user files are mapped into waveform memory symbol-by-symbol; one symbol
equals one byte and occupies one address in memory.