Figure 1. Using Two E4438C ESG Vector Signal Generators
Figure 2. Using Two E8267D PSG Vector Signal Generators
The figures above show you how to set up the signal generators (ESG or PSG) for the Multiple Antennas WiMAX Solution without Baseband Timing Alignment and RF Phase Coherence.
Two signal generators (with the same model number) are used and the 10 MHz references are connected between them.
The Event 2 connector on the master instrument is connected to the Pattern Trigger In connector on each of the two instruments. It synchronizes the start of the waveforms playback on both instruments. The synchronization occurs right after the software downloading the waveforms to the both instruments. The Signal Studio software will send a SCPI command to the master instrument to direct it to send a one-time event pulse through the Event 2 connector to itself and the slave instrument. Then, this pulse signal triggers the two instrument to playback the waveform with synchronization. Note that there is still an error of one cycle of the baseband generator clock between the master and the slave. Each instrument only recognizes the pattern trigger input the next time that the BBG clock signal has a rising edge, and since the two BBG clocks are not phase matched, the rising edge can occur as much as one clock cycle apart on the two signal generator. To achieve the baseband timing alignment, use the setup in Multiple Antennas (Two Antennas) WiMAX Solution with Baseband Timing Alignment, but without RF Phase Coherence topic.
The EVENT 2 signal works as both a Trigger Source and an actual Marker 2 output signal, but in different period of time. Before the waveform playback, EVENT 2 serves as the trigger source. Once waveforms are triggered to playback, EVENT 2 won't work as a trigger source and come back to the Marker 2 output whenever marker 2 is present in the waveform.
When you start Signal Studio for Mobile WiMAX, you will need to choose the (Mx2 in the simulated mode) in the System Configuration Wizard. You will be asked for connection information for the corresponding number of instruments. Both instruments must be the same model and both must have a valid license for N7615C Advanced Capability in order to have access to most of the software features for the multiple antennas.
When you generate the waveforms for multiple antennas, the Signal Studio for Mobile WiMAX software pre-calculates the waveform packets and applies the effects of specific channels, then loads the composite waveform into each instrument and applies it directly to the DUT.