Navigation Measurement Techniques

Study Notes

Track points are part of a track and are automatically recorded
Track points are interval based including time and changes over time
Waypoints are points of interest (POI)
Measured data captures information purposefully, independently, and with meaning

Location is measured as the distance between ranging master and object
Deviation is the difference in the measured distance caused by random noise
Random noise includes scintillation and multipath
- Scintillation is caused by sudden variations in the refractive index
- Multipath is caused by indirect signals
Distance (L) is determined by the speed of light (c) and the difference between the measured time intervals (t2−t1t_2 - t_1 t2−t1)
- L=c∗(t2−t1)L = c * (t_2-t_1)L=c∗(t2−t1)
For systems with 3D capabilities, distance is determined by the square root of the sum of the squared differences in the x, y, and z coordinates:
- L=sqrt((x2−x1)2+(y2−y1)2+(z2−z1)2)L = sqrt((x_2-x_1)^2 + (y_2-y_1)^2 + (z_2-z_1)^2)L=sqrt((x2−x1)2+(y2−y1)2+(z2−z1)2)

Internal problems within space segment include Satellite clock errors, Ionospheric delay, and Troposphere delay
Multipath and receiver noise are the most common errors, impacting the performance of the measurement system
Applying a system of satellites and ground stations that provide GPS signal corrections can significantly improve position accuracy

Time-based measurement is collected at regularly spaced intervals
Location-based measurement is triggered when a position is different from the previous one, or when it falls within a certain proximity
Change-based measurement is triggered by the occurrence of a specific event at a particular location
Event-based measurement is triggered when specific events occur, such as phone calls, SMS messages, or public speech

Current operational GNSS systems:
- GPS (United States): Largest global coverage
- GLONASS (Russia): Smallest global coverage
- BeiDou-2 (China): Largest global coverage
- Galileo (European Union): Smaller global coverage
GNSS components:
- Space segment: Satellites transmitting signals
- Control segment: Base stations correcting signals by uploading correction files
- User segment: Receivers interpreting the signals