Re: [Openbts-discuss] Device doesn't see network at all (openbts-uhd + usrp2 + wbx)

[Thomas T. <tt...@vt...>]

2011/6/11 Љубомир Самарџић <lj...@gm...>:
> News from me :) When I start kal with 95% gain I get something like this:
>
> ./kal -f 940.01e6 -v -g 95
> kal: Calculating clock frequency offset.
> Using GSM-900 channel 25 (940.0MHz)
>         offset   1: -7661.58
>         offset   2: -24499.12
>         offset   3: -24431.74
>         offset   4: -7659.51
>         offset   5: 39077.79
>         offset   6: -7624.26
>         offset   7: -7647.07
>         offset   8: 37708.44
...
> So, how should I interpret this? usrp's internal clock is definitely too
> much shifted but in which direction?

These are interesting values. While a certain degree of offset is
expected, what's strange here is the range of offsets. For comparison,
I get output like this when running kal against my own bts.

$ ./kal -b GSM900 -c 25 -A 1 -v
Using GSM-900 channel 25 (940.0MHz)
	offset   1: 10942.32
	offset   2: 10941.29
	offset   3: 10946.47
	offset   4: 10949.58
	offset   5: 10941.29
	offset   6: 10938.18
	offset   7: 10933.00
	offset   8: 10939.21

Have you looked at the spectrum of what you're trying to receive? You
can use rx_ascii_art_dft from the uhd examples or, if you have
gnuradio installed, uhd_fft.py

  Thomas