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Fast Gain Ranging

Last Modified: May 17, 2017

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.

Table 1. Fine Gain Ranging and Coarse Gain Ranging
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

Fast gain ranging features use PXI trigger lines. Ensure that specified triggers are reserved. If trigger writer and trigger reader modules are not in the same PXI trigger bus, ensure that the trigger lines are routed between buses.

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.


Once gain ranging is enabled for the receiver scope, you must disable gain ranging before changing any non-gain ranging configurations for the receiver scope. The same is independently true for the transmitter scope.

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