Typically supported instruments are available for all tests. All instruments shown in the tree window, whether or not connected, appear as selections in the test setting windows. It is up to the user to ensure that selected test instruments are connected and configured to support the tests.
The PXB Baseband Generator and Channel Simulator generates baseband signals and provides additional testing enhancements for its channels. Since it generates baseband level signals, it requires the use of connected signal generators to upconvert to RF. The PXB controls these signal generators.The selected test and how the waveforms are set within the software determines the number of PXB baseband generators (BBG)/channels and connected signal generators.
For example in LTE Clause 7 tests, if each signal in the test setting window used PXB (BBG 1) for the signal generator selection, than only one channel and one signal generator is used. But if one signal used PXB (BBG 1) and another used PXB (BBG 2), then the PXB would use two channels and it requires the connection of two signal generators. Whereas for LTE Clause 8 tests with the PXB selection, each signal uses a separate BBG in the PXB. So the PXB requires a signal generator connection for each signal.
Whether to use the PXB is dependent upon the test needs. The software allows the use of only one PXB. But the PXB provides multiple capabilities for signal generation:
generates a single waveform (one real-time signal or waveform file) when configured with a single baseband generator (BBG)
This is commonly referred to as a single channel configuration
generates multiple waveforms (multiple real-time signals or waveform files) when configured with multiple BBGs—one waveform per BBG
So if it is using two BBGs, it is considered a two channel configuration and so on.
provides fading for each channel as determined by each test in accordance with the 3GPP standards
provides MIMO setup as determined by each test in accordance with the 3GPP standards
adds AWGN to the channels as determined by each test in accordance with the 3GPP standards
When using the PXB, the Signal Studio software must be licensed to use it, but the Signal Studio software does not have to be licensed to use the signal generators connected to the PXB.
To use the PXB:
Select it from the tree window.
Configure the PXB settings.
Select the PXB in the test settings window
For more information on the PXB, refer to the PXB online documentation.
The software enables the use of either a single signal generator or multiple signal generators. To add more signal generators than what is displayed, use the Add Instrument button.The signal generators are used in some tests as standalone instruments, or in other tests, such as for LTE, in combination with the PXB or an instrument such as an external fader.
When the signal generator is connected to another instrument that is supported by the software, the signal generator may then be controlled by that instrument, such as with the PXB. But when the signal generator is used with an instrument that is not controlled by the software such as with the external fader, then the software typically controls the signal generators.
The LTE Clause 7 and 8 tests provide examples of these various use cases of the signal generators.