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annotate doc/Cable-config-howto @ 128:623340e2c475

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author Mychaela Falconia <falcon@freecalypso.org>
date Wed, 25 Dec 2019 05:27:25 +0000
parents b68301b38ff2
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b68301b38ff2 doc: Cable-config-howto and General-flow written
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1 One of the critical requirements for proper calibration of Tx power levels (and
b68301b38ff2 doc: Cable-config-howto and General-flow written
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2 of the Rx "magic gain" to a lesser degree) is that the insertion loss of the
b68301b38ff2 doc: Cable-config-howto and General-flow written
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3 cabling setup between your CMU200 and your DUTs (Calypso GSM devices to be
b68301b38ff2 doc: Cable-config-howto and General-flow written
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4 calibrated) needs to be precisely known and accounted for. Actually measuring
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5 the insertion loss of your cables at the center frequency of each GSM uplink and
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6 downlink frequency band with 0.1 dB accuracy is your responsibility; the rest
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7 of this article will merely tell you how to feed these cable loss numbers to
b68301b38ff2 doc: Cable-config-howto and General-flow written
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8 FreeCalypso RF calibration tools.
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9
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10 In our architecture the software component that takes care of adjusting the
b68301b38ff2 doc: Cable-config-howto and General-flow written
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11 power levels for the cable loss is fc-cmu200d; our fc-cmu200d reads the cable
b68301b38ff2 doc: Cable-config-howto and General-flow written
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12 loss numbers from a configuration file and instructs the CMU200 itself to
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13 perform the actual adjustments. Furthermore, our architecture allows for
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14 multiple cable configurations. Some Calypso GSM devices have SMA RF connectors
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15 for attaching the antenna, in which case the calibration coax needs to terminate
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16 in an SMA, others have MS-147 or Murata SWD/SWF RF test ports, in which case the
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17 calibration coax needs to terminate in an MS-147 or Murata probe connector. If
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18 you are working with different types of Calypso GSM devices, you will need to
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19 switch between the corresponding cable setups, as the cable loss numbers will be
b68301b38ff2 doc: Cable-config-howto and General-flow written
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20 different for each setup: even if you keep the same "main" coax going from your
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21 CMU200 to an SMA and add/remove Murata's SMA-to-SWD/SWF adapter at the end, the
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22 addition or removal of that extra adapter will change the total insertion loss
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23 along the full path, and this change needs to be accounted for.
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24
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25 Cable configuration files are kept in the /opt/freecalypso/rfcal/cableconf
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26 directory; it is up to you how you name your cable configs, but the following
b68301b38ff2 doc: Cable-config-howto and General-flow written
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27 convention is suggested:
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28
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29 * If you have a cable setup that terminates in an SMA connector for calibrating
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30 Calypso GSM devices with SMA antenna interfaces, the corresponding cable
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31 config file should be named "sma".
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32
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33 * If you have a cable setup that terminates in an MS-147 probe connector for
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34 recalibrating Mot C1xx phones or similar, the corresponding cable config file
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35 should be named "ms147".
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36
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37 * If you have a cable setup that terminates in a Murata SWD/SWF probe for
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38 working with devices like Openmoko GTA0x, the corresponding cable config file
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39 should be named "murata".
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40
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41 See cableconf-example for an example of the syntax, but please remember that
b68301b38ff2 doc: Cable-config-howto and General-flow written
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42 you are still responsible for putting in YOUR OWN numbers for the actual
b68301b38ff2 doc: Cable-config-howto and General-flow written
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43 insertion loss of your cable setups.
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44
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45 When you actually run fc-cmu200d to begin a calibration session (see the
b68301b38ff2 doc: Cable-config-howto and General-flow written
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46 General-flow article), you will select the cable configuration to be used
b68301b38ff2 doc: Cable-config-howto and General-flow written
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47 by name with the -c option to fc-cmu200d.