[USRP-users] Calibrate tool not work

Marcus Müller marcus at hostalia.de
Thu Sep 12 09:57:35 EDT 2013


Hi!

Um... you can't actually see anything with an external spectrum analyser 
"during" calibration; calibration basically is based on leakage between 
TX on RX on the same daughterboard, if I remember correctly.
After TX calibration, the image should be as good as gone. Since it is 
not affected, my wild guess is that it is not actually an image due to 
IQ imbalance.
However, the information you provided is a little to sparse for me to 
take an educated guess. Supply us with
- device type (USRP / daughterboard incl. version)
- signal type
- center frequency
- amplitude difference (in dB preferably) between original and mirror 
spectrum
- theorethic/measured (by absfft plot) spectrum of transmitted samples

Greetings,
Marcus

> Hi,
> I want to calibrate usrp i q imbalance. I use calibrate tool in uhd,
> but the calibrate result is not right. I watch the spectrum analyzer
> to observe the image signal during calibrate. but the image signal do
> not affected by the calibrate tool.
>
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