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

[Ben Gribble]

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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