[srsran-users] Trouble decoding E-UTRA 3.1 test model

[Andre Puschmann]

Hey,

looks like he's getting the PSS/SSS right but then fails with the PBCH 
for that cell. That usually happens when the gains aren't set correctly. 
Perhaps your signal is saturating the receiver or it's too weak. Play 
around with that and make sure you put enough attenuation on the wire.

Thanks
Andre

On 24/1/22 23:20, Ben Gribble wrote:
> Hi all,
> 
> I'm trying to decode a 5MHz E-UTRA 3.1 test signal using the PDSCH_UE 
> example and I'm having trouble.
> 
> I'm transmitting the test signal using a signal generator and I can 
> decode it perfectly well with a spectrum analyser, getting a solid EVM 
> of 0.9%. If I run the srsRAN ENodeB instead then PDSCH_UE works fine, 
> but when I run it against the test signal it never finds anything solid.
> 
> I'm using a BladeRF as the receiver at the moment, although I've also 
> tried a limesdr mini with pretty much the same result.
> 
> Here's the output from PDSCH_UE:
> 
>     user at usercontrolleuser@usercontroller2:~/repos/srsRAN/build/lib/examples$
>     sudo ./pdsch_ue -f 634500000 -d
>     Opening RF device with 1 RX antennas...
>     Available RF device list: soapy  bladeRF  zmq
>     Trying to open RF device 'soapy'
>     No Soapy devices found.
>     Unable to open RF device 'soapy'
>     Trying to open RF device 'bladeRF'
>     Opening bladeRF...
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>     RF device 'bladeRF' successfully opened
>     Starting AGC thread...
>     Tunning receiver to 634.500 MHz
>     set RX frequency to 634499998
>     Searching for cell...
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     *Found Cell_id:   1 FDD, CP: Normal  , DetectRatio=75% PSR=2.54,
>     Power=51.7 dBm
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     Decoding PBCH for cell 1 (N_id_2=1)
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>     Cell not found after 0 trials. Trying again (Press Ctrl+C to exit)
>     Searching for cell...
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>     /home/user/repos/srsRAN/lib/src/phy/rf/rf_utils.c:207: Could not
>     find any cell in this frequency
>     Cell not found after 1 trials. Trying again (Press Ctrl+C to exit)
>     Searching for cell...
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     *Found Cell_id:   1 TDD, CP: Normal  , DetectRatio=100% PSR=2.29,
>     Power=51.9 dBm
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     Decoding PBCH for cell 1 (N_id_2=1)
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>     Cell not found after 2 trials. Trying again (Press Ctrl+C to exit)
>     Searching for cell...
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     *Found Cell_id:   1 FDD, CP: Normal  , DetectRatio=75% PSR=2.21,
>     Power=51.9 dBm
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     Decoding PBCH for cell 1 (N_id_2=1)
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>     Cell not found after 3 trials. Trying again (Press Ctrl+C to exit)
>     Searching for cell...
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     *Found Cell_id: 274 TDD, CP: Normal  , DetectRatio=50% PSR=2.16,
>     Power=52.6 dBm
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     Decoding PBCH for cell 274 (N_id_2=1)
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>     Cell not found after 4 trials. Trying again (Press Ctrl+C to exit)
>     Searching for cell...
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     *Found Cell_id: 187 TDD, CP: Normal  , DetectRatio=25% PSR=2.31,
>     Power=52.2 dBm
>       Found Cell_id:   0 FDD, CP: Normal  , DetectRatio= 0% PSR=0.00,
>     Power=-inf dBm
>     Decoding PBCH for cell 187 (N_id_2=1)
>     Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
>     Cell not found after 5 trials. Trying again (Press Ctrl+C to exit)
> 
> 
> ...and so on. the correct cell id is 1 so it gets that right some of the 
> time but never seems to get any further.
> 
> Am I missing something obvious here?
> 
> Many thanks,
> 
> Ben.
> 
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-- 
Andre Puschmann

Software Radio Systems (SRS)
https://www.srs.io
andre at srs.io

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