The PXIe-7902 High-Speed Serial Instrument can send commands to the PXIe-3620 RF Upconverter and Downconverter Module and mmWave radio heads directly from the FPGA. By bypassing the host for configuration, you can configure a new gain more quickly. This is useful for applications that require low latency automatic gain configuration.
You can set a rough gain very quickly and adjust to an exact gain slightly later by using fine gain ranging and coarse gain ranging together. The benefits of using fine gain ranging and coarse gain ranging are described in the following table.
|Type||Implementation||Gain Configuration||Time to Apply Gain (Typical)||Configurable mmWave Port Switch||Receiving and Transmitting Support|
|Fine Gain Ranging||Using peer-to-peer (P2P) packets||Any arbitrary gain||3 μs to 5 μs, depending on other P2P traffic in the system||No||Simultaneously or one at a time|
|Coarse Gain Ranging||Using two PXI triggers||One of four values||<2 μs||Yes||One at a time|
To learn more about using the fast gain ranging feature, open the NI mmWave Reference Project at <NIDIR>/LabVIEW 2015/examples/instr/niMmWave/niMmWave Reference Project.lvproj and select the Gain Ranging Example VI from the Project Explorer window.