Coprocessor Harness

RTG supports custom capabilities on a FPGA-based coprocessor.

The RTG uses VST hardware to generate up to four targets with delay, attenuation, and frequency shift. It also provides a way to add additional custom processing capabilities. These additional custom capabilities reside on an FPGA coprocessor. The supported FPGA coprocessors are as follows:

  • PXIe-6594
  • PXIe-7903

To support a coprocessor, the RTG configures the VST to stream the baseband data over an MGT link using the Aurora protocol to the coprocessor. This baseband data is the same I/Q data that is the input to the RTG target processing algorithm. The coprocessor can perform any additional processing on this data then stream it back to the VST.

The signal path for the coprocessor is independent of the RTG signal path. These two signal paths can be selected independently or together.

The RTG does not impose any limitations on the algorithms that can be included on the coprocessor. Refer to the following table for the minimum latency, and thus minimum target delays, of the supported coprocessors.

Table 4. RTG/Coprocessor Characteristics
RTG Coprocessor Sample Rate for Baseband Data Approximate Minimum Latency
PXIe-5830/5831/5832/5841 PXIe-6594 1.25 GS/s ~2.7 µs
PXIe-5830/5831/5832/5841 PXIe-7903 1.25 GS/s ~2.7 µs
PXIe-5842 2.50 GS/s ~5.2 µs

The RTG installs an example project that takes data into a coprocessor, from an RTG, and sends it back without any additional processing. Use this example as a starting template for custom RTG coprocessing projects.

RTG Signal Paths

RTG supports three types of signal paths:

  • RTG and Coprocessor—The signal path for the coprocessor is independent of the RTG signal path. These two signal paths can be selected independently or together.
    Figure 1. RTG and Coprocessor Signal Path


  • RTG then Coprocessor—The signal path for the coprocessor is dependent on the RTG signal path. The RTG signal is cascaded with the coprocessor custom algorithm.
    Figure 9. RTG then Coprocessor Signal Path


    Note RTG then coprocessor signal path is only supported on systems with PXIe-5830/5831/5832/5841 VSTs.
  • Coprocessor then RTG—The signal path for the RTG system is dependent on the coprocessor. The coprocessor custom algorithm is cascaded with the RTG signal.
    Figure 10. Coprocessor then RTG Signal Path


    • Refer to Incorporating the RTG Coprocessor Harness for more information about the coprocessor hardware and software components, how to create the LabVIEW FPGA code, and how to interface with the RTG Local LabVIEW API.