ashtech Reliance FS/2, Operation Manual

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Survey P
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Survey Planning 13
practically eliminated. If for some reason, the Reliance Processor cannot successfully
resolve measurement ambiguities, the system will automatically revert to Decimeter
processed results.
Although data collection for cm processing can be time consuming, it is very
rewarding in terms of accuracy. There simply is no faster, easier way to achieve
precise, GIS ready asset positioning than with Reliance CM Processor.
Decimeter System
For applications where the accuracy requirements are 1-3 decimeters, the Decimeter
system offers the total field asset management (FAM) solution. The Decimeter
system uses the same carrier phase measurements as the centimeter system, yet
important differences allow a static or moving rover to attain results as accurate as
one decimeter in as little as 20 minutes.
In order to achieve results as accurate as one decimeter for baselines up to 100 km, a
few basic criteria must be met. At least five satellites common to base and remote
receivers must be tracked continuously for a minimum of 20 minutes. The PDOP
index should remain below 3.5 for the duration of the session. Rover antenna setup
and reference coordinate errors add directly to resulting position errors, but with
careful field procedures they can be virtually eliminated. If satellite obstruction
becomes a problem at some point during feature collection, you can continue work in
the open for 20 minutes to ensure the continuity of decimeter results.
Without sacrificing accuracy for economy the Decimeter system provides the best of
both worlds for precision GIS and FAM applications.
Submeter System
The Submeter system provides the most economical method of field asset
management with the fewest limitations on field methods. Submeter positions can be
achieved static or moving, for baselines up to 500 km, provided only that five
common satellites are tracked by base and rover for at least 5 minutes, and PDOP is
less than 6.0. Submeter RTCM differential operation can also easily be achieved by
the use of a private or public reference station.
The Submeter system offers optimal economy of collection time, while producing
position accuracies adequate for most GIS and FAM applications.