Sending a Sinusoidal Signal


#1

Hello,

i am currently working on the USRP2 board with the LFRX and LFTX
daughterboards. My big goal is to send and receive a signal with FM
transmission (I am using RFX2400 boards for that). But for now I just
want
to transmit a sinusoidal signal over a cable from LFRX to LFTX.

http://www.nabble.com/file/p22535722/loop_test2.grc.jpg

I am using the middle filter to use float signal but that is not a must.

I am ready to change everything such that I just can get the sinusoidal
signal on Scope Sink at the receiver. Please help me!

Thank you

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#2

To give more detail,

even in the following simple configuration i cannot receive the exact
signal
I am sending. I am very new to USRP2 and SDR.

My simplified system:

http://www.nabble.com/file/p22535780/loop_test.grc.jpg

My TX graph:

http://www.nabble.com/file/p22535780/graphTx.jpg

and finally what I receive:

http://www.nabble.com/file/p22535780/graphRX.jpg

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#3

Hi dbeken,
I’m very much a radio newbie and don’t even have a USRP yet, so take
this with a pinch of salt.
It looks like your signal is saturating the receiver, i.e. the output
power is too high. Try putting an attenuator inline - maybe start
with 40dB or so? Can you turn down the TX power and see if that
helps?

Good luck,

Henry


#4

Ok, i will try it. But here is another question. This looks like some
kind of
clipping as you said it, and from signal processing, I remember that
there
were some sort of Millican Terms (can be millian too, can`t figure out
right
now) with %9 overshoot at the edges of a rectangular signal (resulting
from
the addition of many sinusiodal signals). Well if that signal is coming
out
at my receiver, (and i am not sure of it too) what could be the reasons?

Thanks again

Henry Hallam-2 wrote:

I am sending. I am very new to USRP2 and SDR.

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#5

I did set the amplitude in the signal source to 0.001. But still i don´t
get
a smooth output signal.

http://www.nabble.com/file/p22536861/saturation.jpg

What may be the problem in sampling rates, interpolations, decimations.

Thanks

Dincer

Henry Hallam-2 wrote:

I am sending. I am very new to USRP2 and SDR.

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