W dniu 07.03.2014 06:06, zhenhua han pisze:
>
> 2014-03-04 21:55 GMT+08:00 Perper mailto:per...@o2.pl>>:
>
> > Hi Perper,
> >
> > I took a look at your code, and I found this
> >
> > //set_frequency(d_freq_offset);
> >
> > It seems you have turned off the the frequency o
> Hi Perper,
>
> I took a look at your code, and I found this
>
> //set_frequency(d_freq_offset);
>
> It seems you have turned off the the frequency offset correction as
> you said.
> Do you know the reason of the introduced instability by this part?
>
> Best,
> Zhenhua
Hi Zhenhua,
The reason o
OK, I've got it.
Thank you for your help.
Cheers,
Zhenhua
2014-03-04 10:28 GMT+08:00 Tom Tsou :
> On Mon, Mar 3, 2014 at 8:32 PM, zhenhua han wrote:
> > I'm reading the code of Airprobe and I found this function.
> >
> > double gsm_receiver_cf::compute_freq_offset(const gr_complex * input,
> >
On Mon, Mar 3, 2014 at 8:32 PM, zhenhua han wrote:
> I'm reading the code of Airprobe and I found this function.
>
> double gsm_receiver_cf::compute_freq_offset(const gr_complex * input,
> unsigned first_sample, unsigned last_sample)
>
~
>
> It calculates the frequency offset with "freq_offset = p
2014-03-04 9:32 GMT+08:00 zhenhua han :
> Hi guys,
>
> I'm reading the code of Airprobe and I found this function.
>
> double gsm_receiver_cf::compute_freq_offset(const gr_complex * input,
> unsigned first_sample, unsigned last_sample)
> {
> double phase_sum = 0;
> unsigned ii;
>
> for (ii =
Hi guys,
I'm reading the code of Airprobe and I found this function.
double gsm_receiver_cf::compute_freq_offset(const gr_complex * input,
unsigned first_sample, unsigned last_sample)
{
double phase_sum = 0;
unsigned ii;
for (ii = first_sample; ii < last_sample; ii++) {
double phase_di
Hi Perper,
I took a look at your code, and I found this
//set_frequency(d_freq_offset);
It seems you have turned off the the frequency offset correction as you
said.
Do you know the reason of the introduced instability by this part?
Best,
Zhenhua
2014-03-04 1:42 GMT+08:00 Perper :
> W dniu 28
W dniu 28.02.2014 15:31, zhenhua han pisze:
> Hi,
>
> As I have known, GSM uses GMSK modulation which BT = 0.3 and it
> uses Viterbi algorithm for demodulation. And I took a look at the code
> of GMSK demod code in GNU Radio, it use quadrature_demod but not
> Viterbi as demodulation method. So whic
W dniu 28.02.2014 15:31, zhenhua han pisze:
> Hi,
>
> As I have known, GSM uses GMSK modulation which BT = 0.3 and it
> uses Viterbi algorithm for demodulation. And I took a look at the code
> of GMSK demod code in GNU Radio, it use quadrature_demod but not
> Viterbi as demodulation method. So whic
On Fri, Feb 28, 2014 at 1:54 PM, Nick Foster wrote:
> On Fri, Feb 28, 2014 at 10:21 AM, Tom Tsou wrote:
>> I don't have much to add, but Nick and Sylvain touched on the largest
>> difference between the Gnuradio GMSK demod and GSM/TDMA type burst
>> processing - and it's not the Viterbi. The use
On Fri, Feb 28, 2014 at 10:21 AM, Tom Tsou wrote:
> On Fri, Feb 28, 2014 at 11:51 AM, Nick Foster
> wrote:
> > I'm working on a generalized CPM demod based on Achilleas's previous
> work in
> > gr-trellis/src/examples/test_cpm.py, and I have it more or less working
> > although there are plenty
On Fri, Feb 28, 2014 at 11:51 AM, Nick Foster wrote:
> I'm working on a generalized CPM demod based on Achilleas's previous work in
> gr-trellis/src/examples/test_cpm.py, and I have it more or less working
> although there are plenty of little bugs to work out. Since the Viterbi part
> was more or
Nick,
Are you going to release the non-coherent timing recovery improvement as a
separate block too (not baked into a GMSK hier block)? Thanks!
Very Respectfully,
Dan CaJacob
On Fri, Feb 28, 2014 at 11:51 AM, Nick Foster wrote:
> I'm working on a generalized CPM demod based on Achilleas's p
It's already a separate block, so yes.
On Fri, Feb 28, 2014 at 9:15 AM, Dan CaJacob wrote:
> Nick,
>
> Are you going to release the non-coherent timing recovery improvement as a
> separate block too (not baked into a GMSK hier block)? Thanks!
>
> Very Respectfully,
>
> Dan CaJacob
>
>
> On Fri
I'm working on a generalized CPM demod based on Achilleas's previous work
in gr-trellis/src/examples/test_cpm.py, and I have it more or less working
although there are plenty of little bugs to work out. Since the Viterbi
part was more or less worked out for me, synchronization is the hard part;
my
Also as a side note, you can't demod GSM and then slice it. You have
to demod it burst by burst so that you can lock to the training
sequence of each. So the demod block of GR is pretty much useless
here.
airprobe has a viterbi demod (which is probably one of the few good
part of airprobe to re-us
On Fri, Feb 28, 2014 at 10:12 AM, Marcus Müller wrote:
> Hi Zhenhua,
> as Aditya pointed out: Viterby is /not/ a demodulator.
> You should read something on digital communication that explains the
> difference between channel coding and modulation, then everything will be
> clearer to you.
>
> Gre
Hi Zhenhua,
as Aditya pointed out: Viterby is /not/ a demodulator.
You should read something on digital communication that explains the difference
between channel coding and modulation, then everything will be clearer to you.
Greetings,
Marcus
On 02/28/2014 04:04 PM, zhenhua han wrote:
What co
What confused me is the Viterbi algorithm. I saw it can be used to
demodulate GMSK in more than one place (such as here:
http://www.mathworks.cn/cn/help/comm/ref/comm.gmskdemodulatorclass.html )
I think it's better for me to read some materials of Viterbi and find out
what really it is.
Cheers
Zh
>
>
> As I have known, GSM uses GMSK modulation which BT = 0.3 and it
> uses Viterbi algorithm for demodulation. And I took a look at the code of
> GMSK demod code in GNU Radio, it use quadrature_demod but not Viterbi as
> demodulation method. So which one is better in doing demodulating GMSK?
>
>
Hi,
As I have known, GSM uses GMSK modulation which BT = 0.3 and it
uses Viterbi algorithm for demodulation. And I took a look at the code of
GMSK demod code in GNU Radio, it use quadrature_demod but not Viterbi as
demodulation method. So which one is better in doing demodulating GMSK?
Moreover,
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