Re: [Discuss-gnuradio] URSP noise

[mleech]

Dan:

That's generally good advice, with the single exception of the BASIC/LF card family--they don't have any gain--they're just ADC/DAC buffers, so it's generally safe to loop them directly.

 

 

On 2014-11-11 11:27, Dan CaJacob wrote:

Hi Lucas,

 

You say you connected TXA to RXA directly via a cox cable?  Did you put an attenuator inline?  I am afraid you may have damaged your RX side by transmitting directly into it without protection.  Most USRPs can be damaged with input power greater than -10 dBm.  Disconnect that cable immediately and try testing the RX side alone to make sure that it is not damaged.  Then, if you want to go back to a looback test, make sure that you put about 60 dB of attenuation between the RX and TX ports.

 

The noise you were seeing was almost certainly not a problem with your source block, but your RX being over-driven (dying).

 

Good luck.

Very Respectfully,

Dan CaJacob

On Tue, Nov 11, 2014 at 11:07 AM, Lucas Lopez <address@hidden> wrote:

hi everyone. i was working with the USRP1. I'm testing a MOD/DEMOD DBPSK. I have only one USRP, so, i connected TX_A( from  daughterboard LFTX-LF)  to RX_A ( from daughterborad LFRX-LF) with  a coaxil.  All system works well without URSP but when i taste with the USRP i get so much noise and the SNR give me -infinite. I checked the problem comes from "uhd ursp sourse" block, that make me think the problem is the noise from URSP. some suggestions?

Regards.

Lucas.

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