Warning Occur When Using Certain AM Modulation Frequency

Updated May 8, 2024

Reported In

Hardware

  • PXIe-5841

Driver

  • NI-RFSG

Issue Details

I want to using PXIe-5841 generate AM modulation with 250Hz. When I configurate the AM frequency to 250Hz in RFSG Soft Front Panel, it will automatic change the value to 763Hz and pop out Warning: AM Modulation frequency has been coerced within the minimum modulation frequency on the device.

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However, I can't find PXIe-5841 supported AM modulation frequency range mention in specification. How should I know whether it can support generate AM modulation frequency that I wish to?

Solution

The IQ rate  have the relationship in 25 multiplication of AM modulation frequency.

When configurate the AM modulation frequency 250Hz, the IQ rate will be:
250 x 25 = 6250 samples.

Based on PXIe-5841 specification, the IQ data rate is 19 kS/s to 1.25 GS/s. Since 6250 samples is out of the range, it will pop out warning and coerced to it supported minimum frequency.

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