[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Discuss-gnuradio] *much* faster filtering --- plus vhf mountaintopp
From: |
James Cooley |
Subject: |
Re: [Discuss-gnuradio] *much* faster filtering --- plus vhf mountaintopping |
Date: |
Wed, 11 May 2005 10:19:25 -0400 |
User-agent: |
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?
-jamie
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
20MB/sec.
If you can power a mains appliance (car inverter?) you could use an external
firewire drive.
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
around 30-50Mbyte/sec.
------------------------------------------------------------------------
_______________________________________________
Discuss-gnuradio mailing list
address@hidden
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio