Using the MGT Streaming Roundtrip Example

The MGT streaming Roundtrip example uses an Aurora link to transmit data acquired on the PXIe-5842 to the associated FlexRIO PXIe-7903 coprocessor, which in turn sends the data back to the PXIe-5842 for generation.

Complete hardware setup for MGT streaming before using the MGT streaming example programs.
Note To evaluate actual stimulus and response for this example, you need to connect a second VST to the PXIe-5842. You can still run the example about a second VST, but the example will process only noise, not the actual stimulus and response of the instrument.
Complete the following steps to navigate and use the LabVIEW example that uses MGT streaming in a roundtrip configuration:
  1. Choose your PXIe-5842 instrument in vst resource name and choose the PXIe-7903 as the flexrio resource name.
  2. Define settings for the generation:
    1. Choose VST settings, such as the I/Q rate and carrier frequency.
    2. Choose whether the stream is infinite or finite; if finite, also choose the number of samples to stream.
      A finite stream runs for the number of samples you specify; an infinite stream runs until you stop it manually.
  3. Set streaming zero waveform length to a positive integer to define the number of zero I/Q samples the PXIe-5842 should generate before it begins generating RF signals from the I/Q data stream.
    Tip This value is important for roundtrip operation—the number of samples must be large enough to account for the worst-case roundtrip delay for I/Q data transferred from the VST, to the coprocessor, and back to the VST again, but it must be small enough to fit within the buffer on the PXIe-5842.
  4. Run the example, and on the Aurora Config tab, confirm that the following settings match between the PXIe-5842 and the PXIe-7903 coprocessor:
    • line rate
    • packets enabled
    • number of lanes
    • nfc immediate enabled
    • crc enabled
    • endianness

    When you run the example, the MGT streaming bitfile is downloaded to the PXIe-5842, a FlexRIO bitfile is downloaded to the PXIe-7903 coprocessor, and an Aurora link is established between the two. The Aurora Config tab reads and displays the Aurora link status.

    Once the Aurora channels are configured, NI-RFSA and NI-RFSG sessions begin. An NI-RFSG start trigger occurs and, when samples are first generated at RF, the generator portion of the VST sends a signal to the analyzer portion; this signal initiates the data stream from the PXIe-5842 to the coprocessor.

    The coprocessor buffers this I/Q data and transfers it back to the VST generator. Once any zero I/Q samples are generated, the VST reads the I/Q data it has received from the coprocessor.

  5. In the Stream Status tab, check the channel up and lane up status to confirm the link is working correctly.
    You can also view other information about the transmission.
    Tip You can calculate data throughput from the I/Q rate as follows:
    Throughput (Gbps) = I/Q Rate (Samples/s) × 4 Bytes Sample × 8 bits Byte

    For example, an I/Q rate of 1.25 GS/s, the VST transmit and receive throughput and coprocessor transmit and receive throughput are approximately 40.0 Gbps.

    If channel up indicates the channel is not functioning, check that the hardware setup and cabling are correct.
  6. Optional: During the stream, you can acquire records from the PXIe-5842 with the underlying NI-RFSA driver; select the RF tab to acquire NI-RFSA records or fetch snapshots of data on the coprocessor.
  7. Optional: If you have a second VST to evaluate actual stimulus and response, you can expand the program to encompass this functionality.
  8. If you selected an infinite stream, abort the stream by clicking STOP.