Antenna Tracker Release Notes:
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AntennaTracker 0.7.8 10-Jun-2016
Changes from 0.7.7
1) Bug fix to VBAR dataflash logging
2) VPOS dataflash logging message captures vehicle position
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AntennaTracker 0.7.7 31-May-2016
Changes from 0.7.6
1) SERVO_TYPE parameter split into SERVO_PITCH_TYPE, SERVO_YAW_TYPE to allow different servo types for each axis
2) ALT_SOURCE parameter added to allow selecting vehicle's GPS as an altitude source instead of vehicle's baro
3) VBAR dataflash log message added to capture vehicle barometer data
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AntennaTracker 0.7.6 08-Feb-2016
Changes from 0.7.5
1) Fix logging of attitude and mode to dataflash 
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AntennaTracker 0.7.5 27-Dec-2015
Changes from 0.7.4
1) Add dataflash logging
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AntennaTracker 0.7.4 23-Dec-2015
Changes from 0.7.2
1) Request baro pressure from vehicle at 1hz
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AntennaTracker 0.7.2 1-Aug-2015
Changes from 0.7.1
1) Fixed Pitch
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AntennaTracker 0.7.1 29-May-2015
Changes from 0.7
1) Added support for continuous rotation (CR) servos
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AntennaTracker 0.7 17-May-2015
Changes from 0.5 (skipped 0.6 to avoid confusion after the wrong version number was communicated on diydrones.com)
1) added support for 4th MAVLink channel
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AntennaTracker 0.5 29-Apr-2015
Changes from 0.4
1) add SERVO_TEST mode which moves the servos to the position specified by a do-set-servo command (normally from MP's extended tuning page)
2) add DISTANCE_MIN parameter (default to 5m).  Vehicles must be at least this distance away for the tracker to track them.
3) add SYSID_TARGET parameter to specify which vehicle to follow which is useful if multiple vehicles are sharing the same network.  This param defaults to zero which means track the first vehicle.  Set to "0" to track the first vehicle found.
4) send request to vehicle for position updates at 1hz.  Improves reliability when used with copter which won't sent position data by default.
5) Listens for vehicle position updates on all channels
6) bug fix for LED on pixhawk so it flashes blue or green (instead of yellow) when waiting for he vehicle's position
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AntennaTracker 0.4 31-Jan-2015
Changes from 0.3
1) Init Telem2 port so it can be used to communicate with GCS
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AntennaTracker 0.3 28-Jan-2015
Changes from 0.2
1) MAVLink routing replaces Proxy mode
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