Fwd: UmTRX UHD firmware

Alexander Chemeris alexander.chemeris at gmail.com
Sat Apr 21 08:00:31 UTC 2012

Hi all,

Attached is an UHD-based FPGA image for UmTRX. We've just fixed one
last bug in the Tx chain and I think it's a good time to let everyone
know about the progress. Corresponding host software could be built
from the 'fairwaves/umtrx-dboard' branch in our repo:


 1. UHD code doesn't touch LMS configuration at all. So all LMS
configuration should be done before you run UHD tools with the help of
'umtrx_lms.py' utility. This includes turning on LMS Rx/TX modules,
tuning, calibration, amplifiers configuration, etc:

 2. So far only Tx has been tested and is known to work fine. Rx
testing is our next target.

 3. LMS works at 13 MSPS and UHD allows you to go up to this rate.
Interpolation in Tx chain is known to work well, so you could also use
fractions of that rate, like 0.270833 MSPS ;)

 4. It's strongly recommended to tune VGA1 DC offset in a LMS before
using - it reduces LO leakage by very nice 25 dB.

 5. We still have to figure out how to tune I/Q balance in UHD.
Without calibration LMS doesn't perform very well. I know it should be
pretty straightforward to do, but we have to figure out how.

Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
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