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Re: [Discuss-gnuradio] *much* faster filtering --- plus vhf mountaintopp
Re: [Discuss-gnuradio] *much* faster filtering --- plus vhf mountaintopping
Wed, 11 May 2005 10:19:25 -0400
Mozilla Thunderbird 1.0.2 (X11/20050317)
I have successfully used an external USB 2 drive along with the usrp, no
problems. And that's with a USB hub with USB2 drive as well as a GPS
attached and spewing data. There's a trick, though.... compression. You
can make a fifo, ask gnuradio to write to it, and zip it.
In one window, make the fifo and start it:
#> mkfifo testfifo
#> cat testfifo | gzip -c > data.gz
In another, start up the capture, something like this:
#> usrp_rx_file.py -o testfifo
THE reverse step is to unzip,, like this (for example, with the wfm script):
#> wfm_rcv_file.py testfifo
In the other window, do:
#> gzip -dcf data.gz > testfifo
Seems to work barely on my laptop, which is a 1.6 GHz pentium M
machine.... HOWEVER, to aid things along even more, I did the captures
without using X-windows (you don't need it if your not using any guis).
You can switch consoles in linux with ctl-alt-Fx, where F7 is where your
x-windows is running. I switched to a console, killed X, used one
console for the usrp, the other for the piping and zipping.
How well did it work? I did a sweep of the entire front-end's range,
about 40 minutes of sampling incrementing by 400kHz about every second
from 50 Mhz to 860 MHz... this gave me a zipped file roughly 600MB.
For usrp source, complex samples, decim 8 (therefore, rate= 8Mbits/sec),
this worked out well. By the way, Chuck, I think that if you're using a
TVRX board, the downconverter 4937 has a 6 MHz bandwidth... so even
though you captured at 8Mhz, don't you only have just 6 of useable data?
Daniel O'Connor wrote:
On Wed, 11 May 2005 21:43, Chuck Swiger wrote:
for about 3 or 4 minutes each before filling up 20Gb free space. Still it's
nice to collect
field data for later slicing and dicing in the basement.
Looking for faster/bigger portable storage. The Adaptec SlimSCSI 1480 card
will only do
If you can power a mains appliance (car inverter?) you could use an external
I doubt you could run a USB enclosure and the USRP without running out of USB
bandwidth but firewire should be OK.
The enclosures I've used (Mapower) can keep up with WDxxxxJB drives which do
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