RF Loopback Test continuously failing

Projects LimeSDR
1

[ RF Loopback Test ]
->Configure LMS
->Run Tests (TX_2 -> LNA_W):
->On board loopback test:
Test 1:(SXR=1000.0MHz, SXT=1005.0MHz, TXPAD=8): Result:(-17.4 dBFS, 5.00 MHz) - PASSED
->Configure LMS
->Run Tests (TX_1 -> LNA_H):
->On board loopback test:
Test 1:(SXR=2100.0MHz, SXT=2105.0MHz, TXPAD=8): Result:(-22.9 dBFS, 5.00 MHz) - FAILED
->RF Loopback Test FAILED

2

I don’t think my 2 years old LimeSDR-USB ever passed those tests. This is the closest I got to passing them.

->Configure LMS
->Run Tests (TX_2-> LNA_L):
  CH0 (SXR=800.0MHz, SXT=805.0MHz): Result:(-15.5 dBFS, 5.00 MHz) - PASSED
  CH1 (SXR=800.0MHz, SXT=805.0MHz): Result:(-18.2 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_1 -> LNA_W):
  CH0 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-21.1 dBFS, 5.00 MHz) - FAILED
  CH1 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-20.7 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_2-> LNA_H):
  CH0 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-17.6 dBFS, 5.00 MHz) - PASSED
  CH1 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-15.1 dBFS, 5.00 MHz) - PASSED
->RF Loopback Test FAILED

I also acquired 2 brand new devices (LimeSDR-USB) for my client. When I first ran the tests, they both passed, and now they simply refuse to pass:

->Configure LMS
->Run Tests (TX_2-> LNA_L):
  CH0 (SXR=800.0MHz, SXT=805.0MHz): Result:(-15.5 dBFS, 5.00 MHz) - PASSED
  CH1 (SXR=800.0MHz, SXT=805.0MHz): Result:(-17.8 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_1 -> LNA_W):
  CH0 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-20.2 dBFS, 5.00 MHz) - PASSED
  CH1 (SXR=1800.0MHz, SXT=1805.0MHz): Result:(-19.2 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_2-> LNA_H):
  CH0 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-59.0 dBFS, -1.27 MHz) - FAILED
  CH1 (SXR=2500.0MHz, SXT=2505.0MHz): Result:(-59.6 dBFS, 1.59 MHz) - FAILED
->RF Loopback Test FAILED

The error is almost always at the same place. That’s if the test runs, I get this on 2 out of 3 devices (1 brand new, the other one is my 2 years old device) roughly 9 times out of 10. The other one is able to run the test every time.

->Configure LMS
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
SetPllFrequency: error configuring phase
LML TX phase search FAIL
Failed to set sample rate
->RF Loopback Test FAILED

HW=4, GW=2.23, all other tests pass. Also get LML RX phase search FAIL once in a while. No idea if those failures influence the signal quality, I’m only now starting to use them in a professional setting and will do proper evaluation for my client over the holidays.

3

Despite this, I can still use my device without any problem and I haven’t had any issues with it other than this test reporting failures.

4

TehWan - Have you ever used grgsm with limesdr

5

I have not.

Have you tried using gr-limesdr for the radio block? I know that helps.

6

Yes just installed gr-limesdr couple of days before, can you share your working .grc files