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

[Vanessa Gardellin]

Do you remember which parts you did not implement?

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

Thanks
Vanessa

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