GPS Aerial Surveying - LiNav
The LiNav system is the real-time DGPS Aerial Navigation System designed for Aerial Surveying. The system provides real-time presentation of complex positioning information from various types of GPS receivers to the pilot in a transparent and simple format. Designed specifically for low level flying, the GPS Precision Navigation system has become the indispensable tool in airborne geophysical operations, photogrammetry and other aerial applications.
Theory
The GPS Navigation system uses a horizontal cross-track indicator for XY (left/right) directions and a vertical bar for the Z direction (altitude).
Horizontal navigation is performed using a pre-defined Flight Plan as a horizontal reference. The vertical (or altitude) reference is obtained from a gridded (using Geosoft) image of the area.
Reference Grid File
The reference altitude grid file can be generated using various methods.
1. Tie Lines of the survey area can be flown and the GPS altitude data gridded using Geosoft. This Tie Line Grid file can then be used by LINAV to provide pilots with exact vertical navigation to ensure Flight Lines intersect Tie Lines.
2. USGS 30 arc second digital elevation data can be purchased from the internet. This data should then be gridded using Geosoft and used by the Navigation system as an accurate vertical navigation reference.
3. Any other local “digital elevation data” converted into a Geosoft grid file can also be used.
The altitude (or vertical) data for the Navigation system is the GPS altitude. The LINAV is commonly used with real-time differential corrections, resulting in sub-meter DGPS data.
The Main Display shows the aircraft overlaid on the Flight Planned area. The third dimension is shown with an additional vertical ‘deviation’ bar on the Main Display. This vertical bar indicates the difference between the aircraft altitude and the reference altitude. If the aircraft is above the reference altitude, the bar goes down and if the aircraft is below the reference, the bar goes up. As with Horizontal Navigation, the Pilot ‘follows the bar’. The scale of both navigation bars can be set by the pilot in order to control accuracy.
Recorded Data
The LINAV can record aircraft Flight Path by storing X, Y, Z, altitude difference and heading to disk. This file can then be imported into Geosoft for verification and printing purposes.
The LiNav has proven for years to be user-friendly and successful in all applications that require accurate navigation. With excellent support from AG-NAV, you will feel that we are always with you to find the best solution for your challenges.
Click here for more information on the LiNav.