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Re: [Discuss-gnuradio] Help : Where is the demodulation blocks implement
Marcus D. Leech
Re: [Discuss-gnuradio] Help : Where is the demodulation blocks implemented in gnuradio [ GMSK,PSK etc].
Thu, 07 Apr 2011 12:32:48 -0400
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On 07/04/2011 10:34 AM, ton ph wrote:
Gnu Radio is a generic digital-signal-processing framework. Which
includes *many* pre-built processing blocks, including demodulators
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 .
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.