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FMCOMSS1 - Tx part - spectrum analysis

Question asked by MiTfreak on Mar 27, 2015
Latest reply on Apr 8, 2015 by MiTfreak
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Hi all,

 

I am working on implementation of transceiver on ZedBoard+fmcomms1 . Currently I am testing what is happening

in analog part of fmcomms1. Because I am not able to solider jumpers to get DAC outputs directly from SMB connectors

(maybe there is technical reason for that, but really I do not know why those jumpers are set like that - it is not

easy to change configuration of the board, in future revisions you may consider to make this jumpers easy changeable)

we are trying to debug things by using RF output. Could you explain me me why carrier signal from IQ modulator is so strong?

I took sine wave as input to IQ modulator, at the output I get 2 shifted (when I do spectrum analysis) tones plus carrier. I do this

test because when I put I and Q branches of my OQPSK modulator as input to IQ modulator on spectrum analyzer I get spectrum

with really strong carrier?

 

tek00000.png

 

Thank you in advance on answer.

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