Basic questions about usrp_fft.py and usrp_oscope


#1

Hi,

Does anyone has some discription about the two programs usrp_fft.py
and usrp_oscope.py? I try to search in the archive but didn’t find any
basic discriptions. For example, I’m using digital-bert
benchmark_tx.py to transmit a sequence of 1’s, which modulated by
BPSK; on the other computer, I use python usrp_fft.py -f 900M -T B -R
TX/RX -d 32 to display the output.

I’ve some signals at the center frequency, but I don’t know whether it
is the signals at the transmitter side usrp or signals received in the
other usrp? Similar question to usrp_oscope.py as well, and I also
wonder what do the two lines mean, the red one and the blue one?

Thanks in advance. Your help is highly appreciated.


Best wishes,

Y


#2

On Sat, May 9, 2009 at 11:49 PM, Ankit S. removed_email_address@domain.invalid
wrote:

Suggestions?

Please post the exact command lines you are using on each USRP.

Johnathan


#3

I have a similar problem too as I’m just starting to use USRP and I
haven’t had a lot of success so far.

I’m trying to do a basic xmit/recv. to make sure my 2 USRP devices are
working fine. I’m using a RFX 2400 daugtherboard, and so I’m
transmitting at 2.5GHz.

I can transmit using the usrp_siggen.py program to transmit either a
100kHz or a 1000kHz sine wave, and the program runs fine.

But I don’t think I can see the signal on my receiver, which is the
second USRP device hooked up to a separate computer. I’m using the
usrp_fft.py and usrp_oscope.py programs for this purpose, and I can only
see noise in both cases.
The usrp_fft program shows a peak at the tuned frequency, but that’s
doesn’t really say anything, since it shows the peak no matter what
frequency I tune it to.

The two USRPs are next to each other, so I can’t imagine why I’m not
getting anything at all!

Suggestions?


#4

Is there a way just to determine if the transmitter is working or not? I
have an oscilloscope, but it’s limit is a few hundred MHz. And the
daughterboard I’m using (RFX 2400) starts working from 2.4 GHz.

Any ideas on that (and the previous post)?

-Ankit


#5

Johnathan C. wrote:

On Sat, May 9, 2009 at 11:49 PM, Ankit S. removed_email_address@domain.invalid
wrote:

Suggestions?

Please post the exact command lines you are using on each USRP.

Johnathan

On the transmitter side, I used usrp_siggen with the parameters:

-f 2500e6

(I’m using Stani’s python editor, so I don’t use command line to run).
Again, by daughterboard is RFX 2400, so my frequency choice is
definitely within the range.

On the receiver side I used usrp_fft and with no parameters! So the
program loads with default settings, i.e. it tunes itself to 2.5GHz
automatically.
I’ve tried playing around with the fft program but nothing useful really
happens.

What’s worse is, the oscope program sometimes randomly freezes up, so I
have to force quit the program to close it.
-Ankit


#6

What’s worse is, the oscope program sometimes randomly freezes up, so I
have to force quit the program to close it.
-Ankit

It may be overloaded with data. Unable to keep up with the data flow,
the GUI freezes.

Try ./usrp_oscope.py -n 5

…or pick another number greater than 1 and see what works.
./usrp_oscope.py --help explains this parameter. I was having a
similar issue with the oscope before using that.

Also, enable the gl scope if you are using 3.2SVN.

===========Taken from
http://gnuradio.org/trac/wiki/CompGrWxgui#GLSinks==============
Enable the GL Sinks

Rather than modifying existing programs, the GL sinks can be enabled
via a configuration file. To enable the GL sinks, edit or create
~/.gnuradio/config.conf and add the following lines:

[wxgui]
style=gl

Additional configuration options can be found in the README.gl.

Cheers,
Tom


#7

You can build a simple diode detector for your scope.

----- Original Message -----
From: “Ankit S.” removed_email_address@domain.invalid
To: removed_email_address@domain.invalid
Sent: Wednesday, May 13, 2009 9:19 AM
Subject: [Discuss-gnuradio] Re: Re: basic questions about usrp_fft.py
andusrp_oscope