Re: [Discuss-gnuradio] Coarse Frequency and related stuff

[Tom Rondeau]

On Tue, Nov 8, 2011 at 4:51 AM, Vanessa Gardellin <address@hidden> wrote:

Do you remember which parts you did not implement?

Apparently make the alamouti work is harder than I though...

Thanks
Vanessa

I know that we got the 2x1 (2 TX and 1 RX) working, and we did 1x2 with maximum ratio and equal gain (obviously not Alamouti). I know we were close with the 2x2 Alamouti, but we ran out of time and didn't manage to track down one of the major bugs. Neither of use has had time since to finish it.

Tom

 

On Thu, Oct 27, 2011 at 9:33 AM, Vanessa Gardellin
<address@hidden> wrote:
>> Dear all,
>>>
>>> I am trying to use the alamouti code implemented by trondeau.
>>> Studying the gr_ofdm_frame_acquisition I found several concepts that
>>> are not clear to me:
>>
>>
>> Wow, this code is pretty old, and we never did finish it. I hope you get it
>> working! I'd love to see the results.
>
> Yes I know... I am trying to implement alamouti and this is the only
> thing that I have found... do you know about newer code? and/or
> working one?
>
>>
>>>
>>> 1)  d_phase_count: what does it mean?
>>
>> We have a look up table for various phase rotations to use in the
>> calculations instead of recalculating them every time. This is the index
>> into the LUT.
>
> In the code you never used "d_phase_lut"... so this explain a lot of things...
>
>>
>>>
>>> 2) coarse_freq_comp(int freq_delta, int count): which is the meaning
>>> of this function?
>>
>> If the frequency offset is larger than a subcarrier spacing, we want to
>> correct for that. Once the number of subcarrier offset is found, we use this
>> function to recenter it. The fine frequency correct has already been taken
>> care of to center the signals to the center of a subcarrier.
>>
>>>
>>> 3) what "-M_TWOPI*freq_delta*d_cplen/d_fft_length" represents?
>>
>> This is the integer number of subarriers (freq_delta) and the phase
>> correction per subcarrier.
>>
>>>
>>> Thank you
>>>
>>> Vanessa
>>
>> Tom
>>
>
> Thanks
>
> Vanessa
>
> --
> Vanessa GARDELLIN, Ph.D.
> Researcher
> Institute for Informatics and Telematics (IIT),
> Italian National Research Council (CNR)
> Via G. Moruzzi 1
> 56124 Pisa - ITALY
> Phone: +390503153267
> Room: B65/c
> E-mail: address@hidden
> WWW: http://www.iit.cnr.it/staff/vanessa.gardellin/
> Skype: gardellin.vanessa
>



--
Vanessa GARDELLIN, Ph.D.
Researcher
Institute for Informatics and Telematics (IIT),
Italian National Research Council (CNR)
Via G. Moruzzi 1
56124 Pisa - ITALY
Phone: +390503153267
Room: B65/c
E-mail: address@hidden
WWW: http://www.iit.cnr.it/staff/vanessa.gardellin/
Skype: gardellin.vanessa