Re: [Discuss-gnuradio] Problem with capture playout WBX daughterboard USRP N210

[Josh Blum]

On 08/23/2011 10:36 AM, Bastien Auneau wrote:
> Hi All
> 
> Using USRP N 210, WBX board, GPSDO, UHD 3.2.2, under Windows 7
> 
> We want to use the example scripts to capture then playout a signal we
> get from the air (satellite link with bursts). We proceed as follow :
> 1. capture using rx_samples_to_file.exe --type short --rate 10000000
> --freq 1057232000 --gain 10
> 
> 2. playout the newly captured file
> tx_samples_from_file.exe --type short --rate 10000000 --freq 1057232000
> --gain 2
> 
> 3. Using a spectrum analyzer, we expect to see similar things when
> looking at signal from air (few small carriers, bursty), than when
> looking at USRP played out signal.
> 
> But the USRP only output an around 2.5 MHz carrier, which does not
> contains the burst of the original carrier (looking on live signal the
> centered carrier constantly goes up and down). The carrier is extremely
> steady during all the playout time. Also, the doc
> (http://www.ettus.com/downloads/ettus_daughterboards.pdf) specifies
> 30MHz bandwidth, why can't we see the same bandwidth from played out
> signal than from original signal ?
> 
> Also, we use the rx/tx port of the WBX board to capture then to playout
> 

Here is my take on your method:
http://gnuradio.org/redmine/projects/gnuradio/wiki/CannedResponses#Flying-Blind

-josh