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Setting Up Projects
Setting Up Projects
MicroStation contains an interface to Global Positioning System (GPS) devices. The Global Positioning System consists of a constellation of satellites in earth orbit that broadcast radio navigation signals from which GPS devices can calculate reliable positions on a cost-free, continuous, worldwide basis. For more information about GPS, see http://www.gps.gov/.
MicroStation recognizes GPS devices connected using serial protocol that send NMEA (National Marine Electronics Association) standard sentences (or strings) indicating position, heading, velocity, time, fix type and fix quality.
A GPS device is detected if connected to your computer using a standard serial cable attached to a serial port or through the Bluetooth™ protocol that creates a virtual serial port. If using a Bluetooth device, note the virtual COM port used, such as COM 8. Garmin™ USB devices using Garminīs proprietary protocol, such as the GPS 18 USB, that can be plugged into any GPS port are also supported. The supporting software is loaded by Windows Plug-n-Play protocol.
Before you can interact with a GPS device, you must first select a geographic coordinate system (GCS) for the active model.
MicroStation requires your GPS device to send these two NMEA sentences, at a minimum:
Showing the satellites in use on the user interface requires these NMEA sentences, so your GPS device should send them as well:
MicroStation processes the following NMEA sentences and makes the data from them available to applications, but it does not require this data. Sometimes this data is redundant with data from the sentences above.
MicroStation also processes the Leica proprietary “local position quality sentence,” GPLLQ. If it is present, the easting, northing, easting/northing fix quality, and elevation are acquired from it. However, the elevation is also in the GGA sentence.
Any other sentences that your GPS sends are not processed by MicroStation.
To capture a ground track from a GPS device without a live MicroStation session, use the standalone utility GPS Recorder provided with MicroStation. The utility can record from either NMEA or Garmin USB devices. It calculates the sequence of positions and all data transmitted from the GPS device to client programs. The GPS session data is saved to a file for playback.
The GPS Recorder window resembles the Global Positioning System dialog. The window has three tabs — Settings, Status, and Position, plus Record, Pause, and Stop buttons.
Before you can interact with recorded GPS session data, you must first select a geographic coordinate system (GCS) for the active model.