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doc/Rx-cal-theory: typo fix
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 28 May 2017 05:10:32 +0000
parents 131abadbd74d
children
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We don't have a TI calibration document that exactly matches the
Calypso+Iota+Rita chipset we are working with, but we do have two different
documents from other points in TI history:

ftp://ftp.freecalypso.org/pub/GSM/Calypso/rf_calibration.pdf

https://www.freecalypso.org/LoCosto-docs/Production%20test%20and%20calibration/i_sample_rf_test_and_calibration_13_03_04_01991%20-%20v026.pdf

The rf_calibration.pdf document we found back in 2011 dates from well before
our Calypso+Iota+Rita chipset and describes TI's much earlier Sara RF, whereas
the LoCosto document naturally deals with TI's LoCosto/I-Sample platform.

To the best of our understanding of TI history, Sara RF is two generations
before our Rita RF (as far as we know, the evolutionary line went from Sara to
Clara to Rita), whereas LoCosto (combining the baseband processor and RF
in the same chip) was a later development after the Calypso, hence our chipset
and the corresponding TCS211 firmware fall right in between the two calibration
docs we have.

The details of the calibration procedures that are correct for our
Calypso+Iota+Rita chipset and closely match those that have been performed by
Openmoko's factory have been reconstructed by Mychaela Falconia after very
careful scrutiny of both Sara and LoCosto calibration documents, combined with
detective analysis of calibration artifact files found in Openmoko-made GTA02
units; neither the Sara document nor the LoCosto one is particularly instructive
by itself, and a *lot* of intelligent filling of the blanks was required.