PSS signal reception with LimeSDR-Mini.v2 at max sample rate(30.72MHz)

[nedsana]

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Hi,

I am inspecting the 4G sync signals reception. I found the pss_usrp.c test which is exactly the implementation I need to begin with. My test setup is the following:

• I run srsenb on one machine and LimeSDR-Mini as radio
• On another I run ./pss_usrp and LimeSDR-Mini as radio

The problem I am facing is related to the 'symbol_sz (-s)' argument pss_usrp. This actually represent the sample rate requested from the SDR, as far as I understand it. All seems great when I use small values (e.g. 128, 256, 512), respectively samples rates (1.92MHz, 3.84MHz, 7.68MHz). At 1024 symbol size (15.36MHz sample rate) the PSS peak is detected, but is unstable - now and then it will run back and forth and sometimes will settle, then run again. At 2048 symbol size (30.72MHz sample rate - maximal for LimeSDR) the PSS peak never settles, if detected at all. See the attached image.

This is how I run the tool:

1. /pss_usrp -f 2280000000 -i 1 -g 50 -vv -s 1024 -n 50000
2. /pss_usrp -f 2280000000 -i 1 -g 50 -vv -s 2048 -n 50000

From all experiments I did, I conclude that this is some hardware issue. Could you confirm this? My goal is to sample at 30.72MHz, but is this possible? Can you suggest some software tricks I could use?

I am using srsRAN 4G, release 22.10: commit e1d5f406efc1bd09f984d09a5f6847d851a89c1f I have tested this with 2 machines:

1. Laptop: Intel(R) Core(TM) i7-9850H CPU @ 2.60GHz, 24GB Ram, performance mode is turned ON
2. PC: AMD Ryzen 9 7950X 16-Core Processor, 64GB Ram, performance mode is turned ON

Thank you, Greetings!