Re: [Discuss-gnuradio] usrp1 harmonic issue

[Matt Ettus]

You are not seeing harmonics.  You are seeing DC offset, which you have 
not corrected for.  Also, you seem to be transmitting a very low power 
which results in your signal being below the DC offset level.

Matt

Quoc Lai wrote:
> Hello,
>  
> I am a beginner with USRP. Please help with my problem.
>  
> Please see the attached two pictures captured by a spectrum analyzer. In 
> usrp1_64MHz_harmonic.JPG, I just powered up the motherboard without any 
> daughterboard. I guess the harmonics comes from the fact that we have 
> 64MHz ADC. In rxf400_4MHz_harmonic.JPG, I transmit ofdm signal at 420MHz 
> using daughterboard RXF400. Beside the 64MHz harmonic coupling with the 
> transmit signal, I also see the 4MHz harmonics.
>
> Do you know why these happen and how to mitigate them? I appreciate your 
> answers.
>  
> Thank you,
> Quoc
>
>
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