Specifications

Programming Guide 3-27
ESG Family Signal Generators Remote Data Transfer
Data Downloads Directly into Pattern RAM
Data Downloads Directly into Pattern RAM
Option UN8 or UN8/UN9 signal generators accept data downloaded directly into the data
generator’s pattern RAM. After downloading, this data can be used to stimulate the
baseband generator’s I/Q modulator. Direct downloads to PRAM allow you complete control
over bursting, especially helpful for designing experimental or proprietary framing
schemes.
This section contains information that will help you transfer user-generated experimental
or proprietary data from a system controller to the signal generator’s pattern RAM. It
explains how to download data directly into pattern RAM and modulate the carrier signal
with the data. It is divided into the following subsections:
Signal generators with Option UN8 contain a baseband generator assembly. This assembly
builds modulation schemes by reading data stored to a pattern RAM assembly and
constructing framing protocols according to the data patterns present in PRAM. PRAM
data can be manipulated (types of protocols changed, standard protocols modified or
customized, etc.) by the front-panel interface or by remote-command interface.
Typically, the signal generator’s firmware generates the required data and framing
structure and loads this data into PRAM. The data is subsequently read by the baseband
generator, which in turn stimulates the input of the I/Q modulator. The signal generator is
also equipped to accept data downloads directly into pattern RAM from a remote computer.
After using a program such as MatLab
 or MathCad to generate the data, the data can
be downloaded directly into PRAM in either a list format or a block format.
NOTE Because there is no parsing involved, block data format downloads are
significantly faster than list format downloads.
Data Requirements
There are two requirements for data downloaded directly into pattern RAM:
• Data must be in binary form.
The data must be in binary form because the baseband generator is designed to receive
data in binary form from the data generator.
• For every bit of modulation data (bit 0), you must provide 7 bits of control information
(bits 1-7).
The signal generator processes data in 8-bit bytes. Because the signal generator’s
firmware adds seven control bits to each bit of data to be modulated, each bit of
user-defined data is contained within an 8-bit byte, or “address” in pattern RAM. Each
byte in PRAM is organized as shown in Table 3-2. When designing waveform data for
subsequent direct download into pattern RAM, every bit of “modulation data” must be
accompanied by these other seven control bits, forming an 8-bit byte that will occupy a