High precision GNSS solutions have been around for well over a decade, primarily serving high value niche markets. Yet they are ill-suited to meet heightened demands posed by the current wave of technological innovation, of which autonomous vehicles are but one example. For one, their high cost, size, and weight make them unattractive for many mass market applications. More importantly still, they do not scale – a deathblow for a technology that as soon as a few years from now could be standard-issue in new cars.
Now, we are seeing next-generation GNSS hardware and correction services slowly start to overcome these barriers, bringing smaller, more affordable, and fully scalable high precision GNSS solutions to the mass market.
To benefit from today’s high precision GNSS services, positioning devices are required to send their approximate location to a correction service provider. By monitoring GNSS errors – primarily those induced by the ionosphere – using a network of GNSS reference stations, the service provider is then able to provide each of its customers’ correction data tailored to their application’s specific location.
Surveying and, more recently, machine control and agricultural applications, have benefited from centimeter-resolution positioning services for an annual subscription fee of around $600 – $1000 per GNSS receiver.
In addition to their high cost, these services often operate within a single country, sometimes even within a single state. While that may be well and good for a sedentary farmer, it’s a potential headache for other end users. Imagine driving across a national or state border with a connected vehicle or taking a UAV-based aerial surveying mandate abroad and having to deal with roaming contracts or additional costs to continue to benefit from high precision GNSS services at the new location.
Which brings us to scalability. Conventional high precision GNSS services use two-way communication over the cellular network to pass messages between the user’s application and the correction service provider. Keeping this up when thousands, or potentially millions, of devices are competing for bandwidth with other cellular data requests will make it difficult, if not impossible, to offer reliable access to the correction service. In particular, for safety critical applications, where loss of the correction service translates to less safety for users, this must be avoided.
We are right in the middle of a paradigm shift in high precision GNSS, as a new type of GNSS correction service is beginning to overcome these barriers, in part by doing away with the need for two-way communication between themselves and the end-users’ devices. Rather than sending each device location-specific information on GNSS errors, these new service providers continuously model all of the relevant errors for an entire geographical territory and broadcast this information via the internet or satellite. State Space Representation (SSR)-based technology is an example of this new school of GNSS correction services.