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srsran / srsRAN_4G

Open source SDR 4G software suite from Software Radio Systems (SRS) https://docs.srsran.com/projects/4g
https://www.srsran.com
GNU Affero General Public License v3.0
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decoding using npdsch_ue failed #1299

Closed ahmedelbushra closed 3 months ago

ahmedelbushra commented 3 months ago

Issue Description

I am using RTL-SDR to detect and decode NB-IoT, I was able to detect but not decode it.

Setup Details

step1: run ./cell_search_nbiot -b 20 Screenshot from 2024-03-12 16-17-28

step2: ./npdsch_ue -f 815.9e6 Screenshot from 2024-03-12 16-19-00

Expected Behavior

image

Actual Behavior

Screenshot from 2024-03-12 16-21-30

andrepuschmann commented 3 months ago

The cell ID detection might not work super reliably depending on your RF situation. Have you verified there is an NB-IoT carrier at all in on that frequency? You can do that with any spectrum monitoring app.

ahmedelbushra commented 3 months ago

I am RTL SDR Gqrx to view the spectrum : the cell_search_nbiot detected 2 cells, Screenshot from 2024-03-13 12-14-59 The output of the Gqrx : Screenshot from 2024-03-13 12-16-32 It show no signals in that range.

andrepuschmann commented 3 months ago

Hard to say if there is an NB-IoT carrier at all. The NPSS power is very low, too low to reliably sync on it anyway. Maybe try to get closer to the cell. See here how the spectrum should look like.