Global Navigation Satellite Systems (Lecture 7) PDF
Document Details
Uploaded by IntelligentYttrium
Wageningen University & Research
Tags
Summary
This document provides an overview of Global Navigation Satellite Systems (GNSS), covering various aspects like measured data, error sources, and different measurement methods. It includes details on the operational GNSS systems – GPS, GLONASS, BeiDou, and Galileo – and their components: space, control, and user segments.
Full Transcript
## Measured data - Track points - Automated - Part of a track - Interval based (time, change based) - Waypoints = Point of Interest (POI) - On purpose - Independent - Have a meaning ## How does the pace segment work? (example) - Location: Where between ranging master and object....
## Measured data - Track points - Automated - Part of a track - Interval based (time, change based) - Waypoints = Point of Interest (POI) - On purpose - Independent - Have a meaning ## How does the pace segment work? (example) - Location: Where between ranging master and object. - Deviation: The difference in the measured distance cause by. - Random noise: (signal power) - Scintillation: Sudden variations (part of the Refractive Index) - Multipath: (indirect signals) - Distance (L): - $c = speed of light$ $t_2 = t_1(seconds)$ $L = c * (t_2-t_1) $ - 3D: (systems with 3d) - Exact point: GPS - $L = c * (t_2-t_1)$ - $3D: L = sqrt((x_2-x_1)^2 + (y_2-y_1)^2 + (z_2-z_1)^2)$ ## Error Sources - **Internal Problem:** (Space segment) - Satellite clock errors - Ionospheric delay (ionosphere) - Troposphere delay (humidity) - **Most common (Indirect signal)** - Multipath (Use of segment) - Receiver noise - System of Satellites and ground stations that provide GPS signal corrections - Even better position accuracy ## Off Measurement Approaches - **Time-based:** measured at regularly spaced time moments - **Location-based:** Triggered when a position differs, from the previous one even, or community close to it - **Change based:** When a certain event occur(in particular location) - **Event-based:** triggered when certain events occur. - When certain activities are performed (phone calls, SMS or public talk) ## Global Navigation Satellite Systems (lecture 7) - Current operational GNSS - GPS(US) (**Global**) _bigger_ - GLONASS (**Global**) _smallest_ - BeiDou-2 (**China**) _biggest_ - Galileo(**EU**) _smaller _ - GNSS Components - Space segment: Satellite transmitters - Control segment: base stations, correct signals (uploading correction files) - User segment: receiver
