Analysis, Processing And Interpretation Of Data Taken From Different Measurement Instruments

MASTER OF SCIENCE IN ENVIRONMENTAL AND GEOMATIC ENGINEERING

NAVIGATION LABORATORY

Analysis, processing and interpretation of data taken from different measurement instruments

INDEX

(Objective Laboratory

(Location of data collection

(Preconceptions

(Instrumentation

(Standard of data transmission

(Laboratory First Part

• Description of data collection
•Elaboration of data
• Analysis of collected data

(Laboratory Second Part

• Description of data collection
• Elaboration of data
• Analysis of collected data

(Laboratory Third Part

• Description of data collection
• Analysis of collected data

(Objective Laboratory

The principal object is compare the accuracy of the different GPS receptors used in the datacollection, using a cinematic positioning.

Obtain results with the program goGPS in post-processing with or without differential corrections, with or without Kalman filter application. In particular, apply different Kalman filters (constant velocity, constant acceleration, vary the error models).

Use the differential GPS (DGPS), that increases notably the system accuracy. We want see the effectproduced applying DGPS.

The application of the statistical test χ2 , for do the data processing and for check the calculated data reliability.

This study involves other tasks, for example:

• Unification of different formats and different units.
• Statistical study of obtained results with the object of obtain conclusions from the work.
• Graphic representation for thecorrect interpretation of results.

(Location of data collection

The data collection has been executed in a place near from the University of Como, this place it´s a basketball court adjacent in South-Est with Soloni Ambrosoli street and in South-West with Aldo Moro street.

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(Preconceptions

• Global Positioning System (GPS)

The Gps positioning system is based on receivingradio signals from a constellation of satellites in orbit around the Earth. It 's designed in a way that permit in any place and time the three-dimensional positioning of objects in motion.

3 parts in the final system:
- Spacial segment: is the satellite constellation.
- Control segment: whole of stations in the Earth for the
system management.
- User segment: civil ormilitar users with one receiver.

• GPS message:

The on-board oscillators produce a signal, whose nominal frequency is equal to 10.23 MHz, which is very stable in time.

- Carrier phase: two sinusoidal signals L1 and L2

- Binary Codes: A binary code is a sequence of pulses equal to +1 and -1. The pulses transmission sequence, according to a proper decoding key,represents the signal content.

- Navigation message D:

A further binary code is generated, called navigational message D (f=50 Hz): it consists of 25 blocks, each 30 s long, with a resulting length equal to 12.5 min.
Each block consists of:
a counter to synchronize the receiver with the C/A and P code; the satellite ephemerides and clock offset parameters; parameters describingthe ionosphere; cyclic information about the state of the other orbiting satellites (almanacs).

• Observations

- Code observation:

After the identification of the satellite (by means of the C/A code), the receiver performs a correlation between its own code (generated by its oscillator) and the one received from the satellite: the observations and the corresponding equations canbe referred to both the C/A and P(Y) codes.
The delay between the received signal and the internal one is electronically measured.

- Phase observation:

The code observation is a measure of the difference in state between the binary code received from the satellite and the binary code internally generated by the receiver;
in the same way, an observation of the difference in phase...