Spurious signals in PXIe 5641R IF transceiver

[SunJab]

Hi all,

I am using the example named 'RFSG Single Tone Generation.vi' to generate a signal from the RF signal generator and give its output to PXIe 5641R IF transceiver. And then using the FPGA example named 'Analog Input' for PXIe 5641R IF transceiver, i tried to view the spectrum of the generated signal. The spectrum shows some spurious signals that disappear with the reduction in signal span. I have tried it with different Signal Span options and the results are shown in the files attached. I am getting these spurious signals even if i don't give any input to the IF transceiver. 

Any ideas why is this so?

Thanks

[johnsold]

Sandee,

Those look like harmonics (except for the DC componnent). The second harmonic is down >30 dB from the fundamental.

What are the specifications of the signal generator at this frequency and power output level?

Lynn

[SunJab]

The center frequency of the generated signal was 2MHz and power level was -30dBm.

I have attached another image that shows the results when there is no input connected to AI port of PXIe 5641R. I get this peak of a very high level at the specified AI center frequency.

[johnsold]

Does you signal have a DC component?  This can produce large zero-frequency results in the spectral analysis.

What is the harmonic output specification of your signal generator hardware?

Lynn