On 05/23/2018 10:46 AM, kunal sankhe via USRP-users wrote:
Hi,
Using *uhd_cal_tx_iq_balance* and *uhd_cal_rx_iq_balance*, I am able
to find the coefficients of IQ Imbalance. However, I am having
difficulty in interpreting these results.
1) In calibration file, at lo_frequency=915MHz,
correction_real=-0.00548 and correction_imag=0.00960. How can I
estimate gain error and phase error from these coefficients
as described in the Wikipedia of IQ Imbalance
https://en.wikipedia.org/wiki/IQ_imbalance?
What are the last two columns '*measured*' and '*delta*' mean?
2) Now, as mentioned in
https://files.ettus.com/manual/page_calibration.html, we can ignore
calibration files. However, how to use this feature in USRP
Source/Sink block in GRC?
It's automatic. If you look in the "FE corrections" tab in a UHD
source/sink, you can control whether the corrections are applied. The
default is that they
are applied.
3) When we run GRC file with USRP sink/source blocks, does USRP
perform calibrations every time or use values stored in calibration
file stored in /.uhd/cal/?
The corrections are applied from the stored calibration files--which
were previously produced with the cal_ utilities.
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