Spectra Precision FAST Survey Reference Manual - Manual (Page 352)

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Tutorial 5: Standard Procedures for Conducting GPS Localizations
This tutorial is intended to assist users with the recommended localization method for FAST Survey. Other methods can
be used and it is up to the individual users to determine which is best for them.
File Extensions
Localization File: *.dat
Geoid Model File: *.gsf
Coordinate File: *.crd
Raw Data File: *.rw5
Projections
It is essential that the proper plane coordinate projection is selected prior to creating a localization file. This should be
the first step performed during the creation of the job file and be performed easily through File Job Settings GPS.
Geoid Model
An important item to note is if the user intends to use a geoid model (typical for localizations that contain less that 3
control points), the geoid model must be applied prior to the creation of the localization file.
A local portion of the geoid grid must be extracted from the Geoid Model using Carlson X-Port, SurvCOM, Survey or
Civil/SurvCADD, and the geoid model file must be installed prior to the creation of the local geoid file. It is also highly
recommended that the local geoid file grid size does not exceed 100 miles.
Web Link to the Geoid Files
http://update.carlsonsw.com/public/CarlsonGeoidGrids.exe
Transfer or Enter the Known (local) Points
It’s a good idea to simplify the process by transferring the known (local) points to the data collector prior to going to the
field. Conversely, the user can keyboard enter the known coordinates for these points into the CRD file, one at a time,
using File List Points Add. It is not recommended that the user keys in the local coordinates from within the
localization process as transpositions can occur easily. However, this can be done as well.
Collect the GPS Locations with Averaging
Using the Survey Store Points routine, specify your point ID. It is good to use something that will relate to the
original known point. Example, if the known point for the first control point is 1, then you may want to collect the
measured location as 1001.
Use the average reading icon <A> to collect several epochs of data at each point. Typically when using a 1 Hz receiver,
10 to 30 readings will be collected to ensure that the RTK solution is consistently reporting the same position for 10 to
30 seconds. On a 5 Hz receiver, the user may want to collect 50 or more readings as 50 readings would be 10 seconds.
Create the Localization File
Once the data collector has points that represent the known (local) coordinates and the measured data for these points,
the localization file can be created.
Select Equip Localization Add to enter each point into the localization file.
Local Point
The first dialog presented to the user will be the Local Point dialog shown below. Enter the known (local) coordinate
point ID or coordinates. If the point does not exist in the CRD file and coordinates are entered into this dialog, do not
enter a point ID. Select OK when the known (local) position has been defined.