Satellite navigation systems can pinpoint a user by measuring the distance between this user and at least three known positions (of the constellation satellites). The distance to one of the satellites will define a sphere of possible solutions while the intersection of the three spheres will whittle this down to the user’s position. Distance readings are obtained by multiplying by the speed of light the difference between the satellite emission time and the user reception time. To synch the user clock to the system’s reference time, a fourth unknown has to be solved: the user clock error. This 3-parameter location of our position together with the single time parameter calls for at least four satellites in view at the same time.

 

Back in 1973 GPS first took up its cue from the United States’ Navy Navigation Satellite System (NNSS or TRANSIT); the first satellites were launched in the early eighties; GPS as a system has been up and running since the early nineties. The story of GMV’s GNSS expertise dates back to the early nineties, starting with orbit- and clock-determination, receivers and civil applications, mainly aeronautics. Since the mid-nineties GMV has been heavily involved in the design and development of Europe’s EGNOS and Galileo systems, developing key elements of both systems. At the same time GMV has become a pioneer of GNSS applications, mainly geared towards the transport sector and other areas such as agriculture.

GMV has become a GNSS innovation powerhouse, covering all the following areas: development of GNSS and augmentation systems (SBAS), development of receivers, development of applications, new positioning technology, etc. This has won GMV a position as world GNSS leader, building up an unparalleled experience in a great number of areas. Innovation implies, among other things, a certain ability to forecast how GNSSs and applications are likely to develop in the future. Back in 2011 GMV’s idea of the future trend of navigation systems could be summed up in the following concepts:

• A single GNSS built up from the contributions of different countries.
• A set of regional satellite-navigation systems with the goals of improving geometry, transmitting navigation information and providing additional services at regional level.
• As set of Satellite Based Augmentation Systems (SBAS) integrated with regional systems to provide services for potentially life-threatening situations.
• New positioning algorithms that benefit from the availability of readings in various frequencies, phase measurements and advanced, user-level Precise Point Positioning (PPP) algorithms.
• Integration with other non-satellite positioning technology.

Ten years on we can now look back at how GNSSs have actually developed and also look ahead once more towards future trends.

At system level there has as yet been no successful development towards a contribution-aggregating global system, though this has clearly occurred at application level. The great majority of today’s receivers integrate all GNSSs. As things stand, the factors of national sovereignty and security balk the construction of a global system based on inputs from different countries, but the various systems are designed to be highly compatible and interoperable. For users, therefore, the fact that their navigation application’s positioning fixes are habitually obtained from readings from several constellations is transparent. The crucial economic importance of satellite navigation now makes it highly likely that international cooperation will increase into the future.

Regional navigation systems have proliferated in recent years. They have been set up in India, Japan, China (regional components of Beidou) and many other countries or regions are mulling over the possibility themselves. Regional systems are a great alternative in terms of improving performance and providing users with additional services. These services now look likely to continue emerging in upcoming years.

Classic SBASs phase integrity into global systems. They have yet to take off on a worldwide level, however, remaining within reach of only the biggest countries like USA and Russia, or blocs of relatively unified countries like the EU. They do call, after all, for complicated, costly and cumbersome political agreements that are hard to reach for smaller countries. In recent years advanced systems have been developed based on the service-provision concept and covering a wider range of users, beyond the aviation field. This helps to make them much more affordable. Systems like Galileo, which transmit the navigation signal in several civil-use frequencies, make it feasible for a worldwide SBAS to be set up within relatively small areas or countries by means of a service-providing operator. An example of these systems is the operational prototype developed with GMV’s contribution in Australia and New Zealand. We expect this service-based Global SBAS concept, associated with additional services like PPP, to boost the number of these systems in coming years.

PPP is now here to stay. Systems like Galileo incorporate it through its High Accuracy Service, (HAS), to the benefit of many applications. The combination of PPP with integrity is being taken up for the development of autonomous vehicles. This technology allows users to establish their position to a few centimeters and surmount the limitations of traditional positioning systems. PPP with integrity is revolutionizing the world of GNSS applications and is set to do so even more in the future.

The integration of other positioning technology with GNSS is crucial in many applications and will continue evolving in coming years as new technology crops up. GNSS is probably is the only technology capable of providing absolute timing and positioning, while the rest of the technologies can fine-tune this solution with relative positioning data. Witness the autonomous car, integrating GNSS with cameras laser, 5G, odometers and inertial navigation systems, etc.

The phasing in of non-positioning technology may enrich GNSS even more. The new mega-constellations of communication satellites promoted by companies like SpaceX, OneWeb and Amazon, are likely to spawn the launch of thousands of LEO and MEO satellites to provide worldwide broadband. This will shake up the GNSS world anew, if not directly from the use of these satellites for navigation applications, at least indirectly by boosting communication capacities. The merger of technology like Artificial Intelligence and the Internet of Things (IOT) could broaden the range of applications to benefit from the GNSS-provided positioning information.

The system will continue to evolve into the future to meet evermore demanding user requirements. Developments likely to ensue in coming years, like increased security, interference resistance and complementary positioning systems, will all help to make navigation even more fascinating as the fuller picture unfolds.

Author: Miguel Romay Merino.