LMS TxLO noise

Alexander Chemeris alexander.chemeris at gmail.com
Sat Jul 21 21:57:39 UTC 2012


On Sat, Jul 21, 2012 at 12:44 AM, Thomas Tsou <thomastsou at gmail.com> wrote:
> On Fri, Jul 20, 2012 at 6:09 PM, Alexander Chemeris
> <alexander.chemeris at gmail.com> wrote:
>> On Fri, Jul 20, 2012 at 10:22 PM, Thomas Tsou <thomastsou at gmail.com> wrote:
>>> There are still other calibration issues, but phase noise is probably still
>>> a concern.
>>
>> You mean LO leakage and I/Q balance? Have you calibrated them? They're
>> very easy to do - I could guide you with Skype if needed.
>
> LO leakage is calibrated. I/Q balance is not. Are there steps for this
> somewhere? I read 4.10 in the calibration guide, but I'm still not
> sure how to proceed.

I've started documenting this at the wiki:
http://code.google.com/p/umtrx/wiki/LMS6002DCalibration#Tx_I/Q_balance_calibration
Is that a good enough description for you?

Note, that FPGA registers which control I/Q imbalance compensation has
been changed in the commit which introduced dual-channel Tx:
https://github.com/chemeris/UHD-Fairwaves/commit/3d80d881d82e93ed39e83f72d5ef5fac4f8ea56e
Host side hasn't been updated to accommodate those register changes
yet. I would appreciate if you could do that.

-- 
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru




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