High phase noise on Lime xtrx

[VytautasB]

Can you check if you are able to receive correct test signal:

Load default settings:

• Go to LMS7002M and RxTSP tab and modify settings as in screenshot
• set FCW to 0.0005 MHz and hit “Upload NCO”
• set DC_REG to 7FFF value and hit and “Load DC I” “Load DC Q”
  
  

You should get:

If you still seeing discontinuities in received signal, then something wrong with your software setup and data receive path.
I cannot reproduce your issue with GW 1.19 and limesuiteNG 0.2.0-g8023cde0, there are no discontinuities when using test signal or when using signal generator.

[mll2]

Test signal looks correct

[VytautasB]

The data streams look fine, and you’re likely seeing a similar issue as discussed in this thread:

Discontinuities in Rx signal

It bypasses DC corrector in LMS7 chip. Your signal oscillates around 0 quite slowly and it seems that on-chip DC corrector window is too small for that, so DC corrector kicks in trying to compensate DC offset and bring signal closer to 0.

You can try bypassing the DC Corrector and the DC Tracking Loop in the RxTSP tab to check if this resolves the issue.

Regards,
Vytautas

[mll2]

Thanks, it worked.

There are some distortions when increasing the sampling rate.

sample rate: 10 ms/s

sample rate: 50 ms/s

sample rate: 80 ms/s

sample rate: 100 ms/s

sample rate: 120 ms/s (gain 20)

In code i use:

SetParameter(0, 0, "DC_BYP_RXTSP", 1); 
SetParameter(0, 0, "DCLOOP_STOP", 1);

Is this correct?

There are also signal distortions when increasing gain:
sample rate: 120 ms/s (gain 40)

Is it possible to bypass them?