Re: [Discuss-gnuradio] USRP2 high data throughout for WiFi 802.11 processing or GALILEO E5

[Nick Foster]

On Fri, 2010-10-29 at 14:48 +0200, Fabrizio Tappero wrote:
> Hello guys,
> I suppose some people out there are interested, like me, in doing
> stuff with relatively large-bandwidth signals like 20MHz WiFi stuff or
> even 50 MHz GALILEO E5.
> on a linux ubuntu 10.04, USRP2/XCVR2450, GNURadio 3.2 (I think) with
> two week old FPGA firmware, I am trying to collect some data file with
> the command:
> sudo usrp2_rx_cfile.py -v -s -e eth1 -f 2462.0M -g 25 -d 5 -N 250M wifi_d5.bin
> 
> and (with a WBX front end) also this:
> sudo usrp2_rx_cfile.py -v -e eth1 -f 1575.42M -s -g 25 -d 14 -N 700M
> galileoE1.bin
> 
> 1) I however do not seem to set the decimation d=4, for the XCVR2450
> front end. Is it a firmware problem? Does anybody knows why?

I don't understand what you are asking here. The daughterboard should
not affect decimation or sample rate in any way.
> 
> 2) Regarding the USRP 2 bandwidth, digging into the GNU Radio forum I
> found people confirming this:
> 
> In (USRP2) RX path:
> if ADC sampling = 100MHz,
> and if Min decimation = 4
> => max IF bandwidth = 25MHz
> => Max IF Ethernet rate = 4 bytes per sample * 25 MSPS = 100 Mbyte/sec
> = 800 Mbit/sec (Every thing is clear)
> 
> My question is: with a decimation of 4 you get a fs = 25MHz and
> therefore I would think that the bandwidth that you can capture is
> actually half that, meaning ~12MHz. Could somebody explain to me why I
> am wrong?

Complex sampling.

> 
> Thank you in advance for your attention
> Regards,
> Fabrizio

--n

> 
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