588 Chapter 17
W-CDMA Downlink Digital Modulation for Receiver Test
Transmit Diversity Overview
Since two antennas are transmitting the same information for a single UE, the W-CDMA signal timing
(frame timing, system frame numbering, etc.) and transmission from both antennas must occur at the same
time. There are two methods you can use to synchronize the transmission between the two ESGs. One
manner of synchronization involves using either an external trigger source or the LF Output on the ESG.
However using either of these two sources does involve several steps in configuring the trigger signal.
The second method of synchronizing is designed into the ESG providing an easier method for setup. This
method utilizes a multiple ESG synchronization trigger whereby the first ESG outputs a synchronization
trigger signal to itself and ESG two. All that is involved in configuring this trigger signal is just selecting it
from the rear output signal menu. This is the method demonstrated in the task “Selecting the Rear Panel
Output Synchronization Signal” on page 593 and “Generating the Baseband Signals and Synchronizing the
ESG Transmissions” on page 597.