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Re: [Discuss-gnuradio] Help : Where is the demodulation blocks implement

From: adib_sairi
Subject: Re: [Discuss-gnuradio] Help : Where is the demodulation blocks implemented in gnuradio [ GMSK,PSK etc].
Date: Fri, 8 Apr 2011 06:51:58 -0700 (PDT)

the demodulation and modulation is done in GNU Radio. the raw digitized
signal from USRP will be proccessed by gnu radio  either we want to
filtered, do FFT, demodulate and etc. all is done using GNU Radio. 

USRP is the hardware to interfare the digital world with the analog world..

anil ph wrote:
> Thanks Marcus for your valuable information .
> Now as per you have said that the usrp/gnuradio doesnt do any default
> demodulation , that means if i apply a demodulation technique to the
> captured file from usrp_rx_cfile.py , i will get the required output.For
> example if i apply GMSK demodulation to the captured file i ll get the
> properly formatted output as per the GSM protocol ... right.
> Thanks
> On Thu, Apr 7, 2011 at 10:02 PM, Marcus D. Leech <address@hidden>
> wrote:
>> On 07/04/2011 10:34 AM, ton ph wrote:
>>> Hi guys ,
>>>  I Just want to confirm a thing regarding the demodulation of the
>>> digital
>>> dat in the gnuradio as the signals are received from the usrp. The doubt
>>> are,
>>>  1. Where is the demodulation is implemented in the gnuradio .
>>>  2. What demodulation is implemented by default in the urp_rx_cfile ...
>>> please do help me someone in clearing my doubts .
>>> Thanks
>> Gnu Radio is a generic digital-signal-processing framework. Which
>> includes
>> *many* pre-built processing blocks, including demodulators
>>  and modulators, correlators, detectors, etc, etc.
>> There is no *default* demodulation scheme anywhere in the basic
>> architecture, and usrp_rx_cfile is used to simply copy samples as they
>>  come off the USRP hardware into a file.
>> The USRP hardware doesn't do any demodulation--the signal you see
>> delivered
>> to the host PC is just filtered/decimated baseband
>>  samples as they come off the ADC, appropriately scaled for use inside
>> Gnu
>> Radio.  The USRP hardware doesn't know anything
>>  about modulation or demodulation, per se.  All of that is the
>> responsibility of the host software.  Correspondingly, the transmit
>>  side of the USRP hardware doesn't *know* anything about modulation,
>> either.  It is entirely up to the host software to provide
>>  appropriately-modulated samples for the hardware to dutifully turn into
>> analog signals and then (usually) up-convert to the
>>  desired RF band of interest.  Generally, the host interface operates in
>> "baseband" mode--the (complex) samples are centered at DC.
>> Cheers
>> _______________________________________________
>> Discuss-gnuradio mailing list
>> address@hidden
>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> -- 
> Phenomenon
> # Life is the most precious phenomenon ever happen ...
> # Lets pray and give emotional strength to the innocent brave victims of
> japan
> # they are human and m also a human which implies we are one.
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Mohd Adib Sarijari
Universiti Teknologi Malaysia
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