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Re: [Discuss-gnuradio] usrp tx documentation/confusion
From: |
Matt Ettus |
Subject: |
Re: [Discuss-gnuradio] usrp tx documentation/confusion |
Date: |
Fri, 05 May 2006 16:09:33 -0700 |
On Fri, 2006-05-05 at 15:45 -0700, Erik Tollerud wrote:
> I've been trying to work out how to do some things on the transmit
> side of gnuradio, and I've noticed there's something of a dearth of
> documentation. Most of it amounts to "its just like receive, only
> backwards." That's probably fine for people with signal processing
> background (which may be the majority of this community...), but I
> find myself getting confused... by looking at some of the examples, I
> get a sense of how to initialize all the components in python, but if
> I do anything beyond them, I get unexpected results. For example, I
> took siggen_min2.py and modified it so that instead of outputting a
> pure sine wave, it output sin(wt)+cos(2wt). This did not put anything
> resembling sin(wt)+cos(2wt) on the output of the tx board.
> Furthermore, chaging w does not some to alter the waveform at all -
> only calling u.set_tx_freq changed the output freqency.
I agree that there is definitely a dearth of documentation, especially
for TX.
The [unstated] purpose of siggen_min2 is to transmit different signals
to TX daughterboard A and TX daughterboard B.
In general, without really changing the firmware, any signal sent to
DB-A will output the I signal on one output and the Q on the other. The
same goes for DB-B.
For what you are trying, I would suggest working with usrp_siggen.py
unless you want to use multiple TX daughterboards.
Matt