On 04/11/2018 09:08 PM, Serge Malo via USRP-users wrote:
Hi all,
In this Ettus UHD Manual page:
http://files.ettus.com/manual/page_calibration.html#calibration_self_utils
It is written to "*Disconnect*any external hardware from the RF
antenna ports" before executing the calibration tool.
Q: What is the exact reason for disconnecting external h/w from the RF
ports? Is it only to protect external devices from the strong signal
transmitted during the calibration? Could we leave passive elements
connected during calibration without affecting the result?
The calibration is sensitive to other things that could be leaking into
the ports and disturbing the measurements.
Q: Do you have a rough idea of how long the calibration is good for (a
few days vs a few months)?
I'm not sure that anyone has ever asked that question before. Certainly
component-aging plays some role in shifting I/Q and DC-offset "balance", but
I'm not sure about time-scales. The other factor is
temperature--things like fine-scale group delay can change on analog
components with
temperature, and unless the heating is uniform, it will be
very-slightly different on different parts of the board.
Thanks,
Serge
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*Serge Malo *
CDO & Co-founder, Skydel Solutions
Cell: 1-514-294-4017
www.skydelsolutions.com <http://www.skydelsolutions.com/>
Twitter: @skydelsol <https://twitter.com/skydelsol>
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