Forum: GNU Radio The correct way to receive pulses?

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82e297df8100b77340dcc209eb6c7c08?d=identicon&s=25 seph 004 (Guest)
on 2007-06-12 16:36
(Received via mailing list)
My question is about the correct setup to receive
pulses. I've managed to get my system to transmit 1
second pulses at 16 ms intervals.

I wanted to test how the usrp receives these pulses
again by routing the output of the basic TX board, to
the input of the basic RX board. This seems to work
for continuous wave signals, but when I try to route
my pulsed output back, the signal appearing on the
host pc appears to be saturated. I end up getting a
series of combs that don't seem to be related to the
incoming pulse in anyway.

The pulses are centred at 40 kHz and have 2 kHz bw.
I've set the decimation rate to 250, and used the
set_freq method to tune to 40 kHz. I know I can
receive a 40 kHz wave as I have done so with a
modified version of usrp_siggen.

Is there something Ive overlooked in terms of the
settings I've used?

Regards

Lance



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3596cfe1d579c65b9babd35e8787977c?d=identicon&s=25 Matt Ettus (Guest)
on 2007-06-13 06:09
(Received via mailing list)
seph 004 wrote:
> series of combs that don't seem to be related to the
>
What daughterboard are you using?  Only the LFRX and LFTX go down to 40
kHz.

Matt
82e297df8100b77340dcc209eb6c7c08?d=identicon&s=25 seph 004 (Guest)
on 2007-06-13 11:57
(Received via mailing list)
--- Matt Ettus <matt@ettus.com> wrote:

> > the input of the basic RX board. This seems to
> > The pulses are centred at 40 kHz and have 2 kHz
>
> What daughterboard are you using?  Only the LFRX and
> LFTX go down to 40 kHz.
>
> Matt
>

Thanks for replying.

I'm using the basic RX daughterboard. I know it's not
supposed to be able to pass such low frequency
signals, but I have used it to successfully receive
signals as low as 40 kHz. Those were continuous waves
though. Now that I'm trying to view pulses centered at
40 kHz, I get the behavior I described previously.

I made a mistake in my first email. My transmitter is
outputting 1 millisecond pulses, not 1 second pulses.

Could the behavior I'm seeing be caused by the PRI I'm
using? I'm not sure what to try next.

Regards

Lance


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