ashtech DG14, Reference Manual

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78 DG14 and DG16 Board & Sensor Reference Manual
successfully decoded by the DG16 will be Primary and all other corrections
marked with reference station ID’s are Secondary.
Automatic Primary-Secondary:
This mode operates similarly to the Manual operation except that the DG16
automatically chooses the primary and secondary sources of corrections based on an
internal set of criteria for the “best” correction source. Use the
$PASHS,RTC,SLC,WGH command to set the receiver in Automatic-Primary mode.
When the DG16 switches from one correction source to another, there can be decimeter-level
position jumps due to change in “quality” of corrections. Any reference clock offset differences
between the old and new correction sources, however, will be absorbed by the NavT/NavTdot
solution parameter without reflecting on the position/velocity solution. The “Quality” of corrections
includes accuracy of corrections, latency of corrections, frequency of corrections, age of
corrections, baseline length and network coverage, etc...
Multi-Base Differential Processing
With up to 8 individual correction streams (8 Ref ID’s), the DG16 offers the
following multi-base options:
• Nearest base station
• Base station solution yielding solution with lowest RMS
• Weighted multi-base solution (weight factors include: age of correction,
distance to base, satellite elevation at base, etc.) (WGH)
If the SBAS or beacon is set to Dual Mode, each Channel serves as a
separate source of corrections. If multiple serial corrections are available,
each set of corrections (based on reference station ID) serves as a separate
source of corrections.
In Multi-Base mode, you can choose to output the integrated differential
corrections on the serial port, and specify the format of the output corrections
to be either RTCM SC-104 or RTCA DO-217. Use the
$PASHS,FMT
command to choose the output.