Geodesy and GNSS



In the past, military geodesy was largely involved with the practical aspect of the determination of exact positions of points on the Earth’s surface for mapping or artillery control purposes. The determination of the precise size and shape of the earth had a purely scientific role. Modern geodesy yield answers to problems in satellite tracking, (global) navigation and operations.

Measuring the Earth or surveying based on horizontal and vertical angular and distance measurements is a basic technique for a surveyor. Combined with satellite geodetic techniques such as precise GNSS (Global Navigation Satellite Systems) relative positioning, surveying allows a accurate determination of the relative or absolute position of terrestrial objects in 3D space. These points are not exclusively bound to the surface of the Earth. The expertise of the research unit in this field allows to solve problems such as the verification of the alignment of north finding modules in favour of Defense or the society.

Current GNSS systems and their future developments promise for civilian and military users

This navigation capability is unprecedented but fails under several circumstances where a clear view of the sky is not available. In order to bridge the navigation gaps, GNSS systems are to be complemented by other navigation sensors. These sensors are of different type and use a broad range of processing and data analysis. Some examples are (MEMS based) inertial measurement units (IMU), laser distance measurement, signals of opportunity or visual odometry among others. Combination of several of these sensors and their techniques allow for seamless navigation even when GNSS signals are temporarily blocked.

Research projects


Galileo is Europe’s own Global Navigation Satellite System (GNSS) system, providing a highly accurate, guaranteed global positioning service under civilian control. The fully deployed Galileo system consists of 27 satellites, positioned in three circular Medium Earth Orbit (MEO) planes at 23 222 km altitude above the Earth, and at an inclination angle of 56 degree with respect to the equator. The Galileo Public Regulated Service or PRS is an encrypted navigation service designed to be more resistant to jamming, involuntary interference and spoofing. It is similar to other Galileo services, but ensures continuity of Service (CoS) to authorised users when access to other navigation services is denied, increases the likelihood of continuous availability of the Signal-in-Space (SiS) and provides an authenticated Position Velocity Timing (PVT) service. The Binary Offset Code (BOC) modulation used by the PRS navigation signals move the signal power away from the band centre, thus offering the potential for better code-tracking accuracy and multipath rejection. The high BOC modulation order of the PRS navigation signals, and the L1A signal in particular, are sensitive for false tracking of correlation peaks. This phenomena has been observed during PRS testing done by European Space Research and Technology Centre (ESTEC) in limited data sets. In order to obtain better insight in the environmental conditions and the correlation channel causing these false locks, this BE–Galileo PRS In Orbit Validation Service (BE-GPIOS) project proposes a methodology to benchmark the PRS signal tracking and PVT performance in operational environments. A second objective of the BE-GPIOS is to get a better understanding of the PRS navigation services, the security concerns related to the key management and key distribution, the concerns and expectations that Belgian users and user groups have. The aim is that Royal Military Academy–Department of Communication, Information, Sensors & Systems (RMA-CISS) will become and act as a center of competence for the Belgian Government and public entities who have interest in the use of the PRS navigation service for their operational use.

GSINTA - GNSS Signal-in-Space Integrity Assurance

The GNSS Signal-in-Space (SiS) Integrity Assurance project is addressing the underestimated and hazardous effects of external EM interference signals on GNSS SiS integrity, in safety critical air navigation applications.


Organisation of annual EUREF conference (june 2008)

Methodology of accuracy certification of satellite equipped total stations

De evolutie in de topografisch meetinstrumenten voor driedimensionale puntpositionering evolueren naar de integratie van twee complementaire technieken (totaalstation en GPS) elk zijn eigen voordelen en beperkingen. Als resultaat hiervan dienen de klassieke calibratie procedures voor theodolieten aangepast te worden voor de nieuwe generatie totaalstations. Logischerwijs heeft het GPS deel van deze theodolieten een heel specifieke testprocedure nodig. De procedure voor de calibratie van de electromagnetische afstandsmeter en de calibratie voor de hoekmetingen moeten eveneens bestudeerd en zo nodig aangepast worden. Bovendien wordt de software ingebouwd in het totaalstation vaak ten onrechte genegeerd bij calibratie van het instrument. Bepaalde fouten worden geïntroduceerd door limieten inherent aan de implementatie van bepaalde software algoritmes, ook bij het verwerken van ruwe satellietgegevens. Deze fouten zullen zich voortplanten in elke verdere berekening met puntcoördinaten, zoals bijvoorbeeld de berekening van voorwaartse en achterwaartse insnijdingen, berekening van oppervlakken, .... Een grondige test methodologie van de ingebouwde software is daardoor een noodzakelijke ontwikkeling.

Het voorstel beantwoordt aan de nood voor een grondige studie en suggesties voor procedure en uitbouw van een laboratorium nodig voor de calibratie van satelliet totaalstations. Dit type instrumenten belooft immers populair te worden in de topografische wereld, waar kwaliteitscontrole een belangrijk aspect is.


  1. A Muls. BE CPA Test results for PRS Initial Service Validation. Noordwijk, The Netherlands, September 2016. Royal Military Academy.
  2. A Muls and B Vermeire. BE CPA Scenarios for PRS Initial Service Validation. Eu restricted report, Royal Military Academy, May 2016.
  3. A Muls and B Vermeire. BE-GPIOS: Belgian Galileo PRS In Orbit Service validation. Interview by BE National Television Station VRT, December 2015.
  4. A Muls. From GPS to Galileo: the need for encrypted navigation services. Royal Military Academy, April 2014.
  5. A Muls. The Public Regulated Service of the European Galileo navigation satellite system. Royal Military Academy, June 2014.
  6. A Muls. BE-GPIOS: Belgian Galileo PRS In Orbit Service validation. Stavanger, Norway, December 2013. Royal Military Academy.
  7. A Muls. BE-GPIOS: Belgian Galileo PRS In Orbit Service validation. Royal Military Academy, November 2013.
  8. A Muls. Objectives of BE-GPIOS and results of the PPTI-1 PRS measurement campaign. Eu restricted report, Royal Military Academy, March 2013.