4.5.3.2. GPS-Constants

4.5.3.2. GPS-Contants

The GART-2000^® CE software initialises GPS receivers using the constants in the Initial > Constants > GPS submenu. Alternatively, use the button shown above to choose this menu.

There exist the following settings:

GPS Application

The used differential correction formats can be chosen from a list these two fields. GART-2000^® CE supports the following differential correction formats for GPS receivers:

Ashtech CPD	Ashtech-internal correction format for Z- and mZ-series. Code and carrier-phase corrections. Produces coordinates with cm-accuracy.
Ashtech RTCM 2.0	General format for DGPS. Code corrections. Produces coordinates with m-accuracy.
Ashtech RTCM 2.1	General format for PDGPS. Code and carrier-phase corrections.
Ashtech RTCM ADV	PDGPS format broadcasted from German SAPOS-reference stations. Code and carrier-phase corrections. Produces coordinates with cm-accuracy.
Trimble RTK	Trimble-intern correction format for Trimble 4000 series. Code and carrier-phase corrections. Produces coordinates with cm-accuracy.
TPS RTCM 2.0	General format for DGPS. Code corrections. Produces coordinates with m-accuracy.
TPS RTCM 2.1	General format for PDGPS. Code and carrier-phase corrections. Produces coordinates with cm-accuracy.
TPS RTCM 2.2	General format for PDGPS. Code and carrier-phase corrections. Produces coordinates with cm-accuracy.
TPS RTCM ADV	Format for communication with SAPOS-reference stations. Code and carrier-phase corrections. Produces coordinates with cm-accuracy.
TPS CMR	TPS-internal correction format. Code and carrier-phase corrections. Produces coordinates with cm-accuracy.
Standard NMEA	Receiver independent message format. Control of various receiver types (e.g. for GIS-applications).

Datum

GART-2000^® CE transforms the WGS84 coordinates in real time into a user system using a 7P-transformation. The transformation parameters can be selected from a list, which contains three fixed, and seventeen user definable entries (e.g. User003) with pushing the button <OK>:

Use the button <Edit> to change the seven parameters.

The entries have the following meanings:

*Name*	Name of the set of transformation parameters (user-definable).
*Ellipsoid*	Ellipsoid of the user system.
*dX, dY, dZ*	Translations for X-, Y- and Z-axis.
*wX, wY, wZ*	Rotation with respect to X-, Y- and Z-axis.
*Scale*	Scale factor in ppm

The following ellipsoids are currently supported:

No.	Ellipsoid	Semi-major axis [m]	Semi-minor axis [m]
0	Bessel	6377397.15508	6356078.96290
1	Krassowski	6378245.00000	6356863.01877
2	WGS 84	6378137.00000	6356752.31425
3	Clarke 1880	6378249.14500	6356514.86955
4	Hayford 1924	6378388.00000	6356911.94600
5	Modified Bessel	6377492.01760	6356173.50760
6	Airy 1830	6377563.39600	6356256.90923
7	Modified Airy	6377340.18900	6356034.44793
8	GRS 80	6378137.00000	6356752.31425
9	International 1924	6378388,00000	6356911.94600
10	International 1910	6378388,00000	6356911.94600

Projection

In the projection dialog the projection for the user system can be selected. The following projections are currently supported:

    - Gauss-Krüger second to fifth sector
    - UTM
    - Lambert (Belgium, France, Estonia)
    - Soldner (Berlin)
    - NGO48 (Norway)
    - KKJ (Finnland)
    - UK National Reference System
    - Irish Grid
    - CH1903, CH1903+ (Switzerland)
    - Nederland RD

Further projections are in preparation or will be developed on demand. GART-2000^® CE transforms the WGS84 coordinates in real time into a user system using the 7P-transformation and the projection (e.g. UTM Zone 32). The settings for the projection are saved for every project; the settings for the 7-Parameter-Transformation are saved global for all projects.

Baudrates: Radio

GART-2000^® CE initializes the radio port of the GPS receiver with the baudrate set in here to communicate with the radio or cell phone (GSM)-modem.

Baudrates: Receiver

GART-2000^® CE initializes the controller port of the GPS receiver with the baudrate set in here to communicate with the Handheld PC.

During Initialisation of the mobile receiver, the receiver is set to this baudrate.

Average

In this field the number of measurements to be averaged when saving a coordinate can be entered. If the checkbox <fixed only> is activated, only measurements with fixed ambiguities will be averaged.

Auto Zoom

The Auto-Zoom function can be activated with the Yes radio button. In this case the zoom area of GART-2000^® CE is adjusted to the actual position. If the Auto-Zoom function is deactivated (No) the zoom area is kept constant.