[srslte-users] Low Leve PHY sync method usage

[Andre Puschmann]

Hi,

On 11/9/19 20:28, Sylvain Munaut wrote:
> Hi,
> 
>> May I ask what exactly you are trying to achieve? In general, the
>> pdsch_ue example is probably the better tool to work with. Note that if
>> you're trying to feed it with a file, the captures need to be time
>> synchronized. So you can't just load captures made with osmocom_fft, for
>> example. Try to use the usrp_capture_sync example instead.
> 
> So it's been a while but I'm coming back to this issue.
> 
> What I'm trying to do basically is I have a stream of samples at
> 30.72Msps and I want to find the precise frame alignement (assuming I
> already know the cells params).
> What would be the way to do that with srsLTE ?
> 
> I must be doing something wrong, because even just doing :
> 
> int frame_size = 153600; // 30.72M * 5ms
> srslte_pss_t lte_pss;
> srslte_pss_init_fft(&lte_pss, frame_size, 2048);
> 
> takes forever ..

Just tried

$ ./lib/src/phy/sync/test/pss_usrp -f 806000000 -i 257 -s 64

with both an RTL SDR and a USRP and both work fine. Note that the PSS is
only in the center 6 PRB, so a small FFT size is enough.

The init for the longer FFT sizes takes a lot longer because all the
pre-computation is for much longer filter lengths.

Hope that helps.

Cheers
Andre