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doc/Tx-cal-theory: update regarding our current FCDEV3B calibration being untrustworthy
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 13 Aug 2017 05:04:48 +0000
parents 615df2fb1ec3
children 7bcbbba94c41
comparison
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102:80281b67511f 103:16aab86384a7
77 30 dBm. It needs to be emphasized, however, that these results are quite 77 30 dBm. It needs to be emphasized, however, that these results are quite
78 specific to our current flock of FCDEV3B hardware, and your results will most 78 specific to our current flock of FCDEV3B hardware, and your results will most
79 likely be different if you are working with a different hw design such as a 79 likely be different if you are working with a different hw design such as a
80 non-FreeCalypso derivative of Openmoko's GTA02 design. 80 non-FreeCalypso derivative of Openmoko's GTA02 design.
81 81
82 Update: the above calibration observations for the FCDEV3B should be held
83 doubly in doubt because the calibration status of my CMU200 itself is in
84 question, i.e., it is not currently known if the measurements it reports are
85 really trustworthy. After the above paragraph was written, I replaced the
86 Rx/Tx module inside my CMU (the original one was good for Rx, but the Tx side
87 was dead), and after this internal module replacement the power measurements
88 reported by the instrument are 0.5 dB less than what it reported before. Which
89 raises the questions: are the new measurements low by 0.5 dB relative to the
90 real truth, or were the old ones high by 0.5 dB relative to the real truth? Or
91 is the real truth something else altogether? Until we raise a LOT more money
92 to get this CMU200 properly calibrated, we are limited to guesswork and the
93 true transmitter behaviour of our FCDEV3B hardware remains unknown.
94
82 Profiles for Tx levels calibration 95 Profiles for Tx levels calibration
83 ================================== 96 ==================================
84 97
85 Our fc-rfcal-txband program that performs the actual per-unit calibration of Tx 98 Our fc-rfcal-txband program that performs the actual per-unit calibration of Tx
86 power levels for each band requires a preconfigured txlevels calibration profile 99 power levels for each band requires a preconfigured txlevels calibration profile