[Discuss-gnuradio] Fwd: Do RX and TX of USRP2 work independently ?

[Songsong Gee]

FFT plots are not much clear, but I can give some comments on your questions.
Without connecting RX, there is a value '-100 dB' at the bottom on the
y-axis in the FFT plot.
However With connecting RX, it seems all values on the y-axis are
greater than '-100 dB'
which means it receives a stronger signal.
Although it doesn't look like TX signal it might receive something.

And connecting TX with RX directly is dangerous.
RFX series board has LNA (Low Noise Amplifier) chip on it.
and it is apt to be broken when connecting TX and RX directly.
Once it is broken, receiving a signal might not work well and it is
hard to fix in your country.
Thus, connecting an antenna to TX and another to RX is safe. (It
causes a signal to be attenuated)
Check whether your LNA chip is out of order or not.

It seems receiving doesn't work well for LNA chip issue.
So thus the FFT plot shows a stronger but distorted signal compared to
that without connecting RX.

And without connecting RX, it is quite strange.
I think a PC confuses a signal which has been received with a signal
which is to be sent.
Because there is only one ethernet connection between the PC and the USRP
(But I'm not sure about this problem you might see other's advices.)


2011년 5월 10일 오후 3:38, 김보미 <address@hidden>님의 말:
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> Hello :-)
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> I am using USRP2 with RFX2400.
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> I know that TX and RX work independently.
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> But the result of my experiment says that it doesn’t work properly.
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> The result is as follows.
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> The signal is transmitted as below. (Fc=2.45GHz Fs=4MHz)
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> The right figure is seen through the spectrum analyzer.
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> When RX is directly connected to TX, FFT plot of RX is as below.
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> But, When RX is connected to nothing, it looks more like the transmitted 
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> Could you tell me how to understand this situation?
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> Regards, Bomi.
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--
Seokseong Jeon (aka Songsong Gee)



-- 
Seokseong Jeon (aka Songsong Gee)