GNSS receivers first reached the commercial domain in the early 1980s. They were bigger than your average carry-on suitcase, weighed more, and consumed so much power that they needed to be plugged into an outlet. But technology advanced quickly and by the mid-1980s commercial GNSS receivers were appearing in survey and marine markets.
Gen 1: The first generation of truly mobile receivers were L1 C/A code only, usually with very narrow front-end bandwidths of 2-5 MHz and were typically found in ruggedized handhelds used by outdoor enthusiasts for hiking and sailing. These first-generation architectures began appearing in mobile phones in the late 1990s, and were the key technology in enabling E911.
Gen 2: The second generation of mobile receivers added GLONASS satellites beginning in approximately 2010 when the GLONASS system became modernized and reliable. These receivers had to have wider bandwidths on the order of 20-30 MHz in order to support the GLONASS FDMA signals at a slightly offset frequency from GPS L1. However, both the GPS and GLONASS signals were utilized in a narrow band signal processing methodology.
Gen 3: The third generation of receivers added support for the Galileo system launched by the European Union and started appearing in mainstream cellphones in the 2014 timeframe. These phones still retained a single frequency front end in the L1 band but had separate digital processing chains for all 3 satellite systems.
Gen 4: The evolution to the 4thgeneration took some time as it added 2 new capabilities: 1) the ability to process the Beidou signals and 2) support for a single sideband L5 receiver where Beidou, Galileo and GPS all have modernized signals. Throughout this paper, we will refer to all signals from all constellations (L5, E5 and B2) in the 50 MHz band centered at 1192 MHz as “L5” for simplicity’s sake. Despite having been available in other markets earlier, these receivers only first appeared in phones in 2019 because of the added size, power, and complexity of supporting a dual band receiver in a mobile phone. Many expected that this would be the final generation of GNSS for cell phones as it seemed to have covered all the bases.
However, at oneNav we recognized several problems with these 4th generation receivers:
- A dual frequency front end was a huge burden on many phone models, especially with the rise of 5G.
- The L1 band still had reliability issues with jamming and interference but was needed to aid the acquisition of the L5 signals.
- The receivers only supported a single sideband at L5 and were not utilizing the full capability of the L5 band to further enhance sensitivity, improve accuracy, and mitigate the impact of multipath.
As a result, oneNavset out to build a fifth generation of GNSS receivers for mobile consumer products that had the following key characteristics:
- A single frequency design that only uses the modernized, wideband signals at L5.
- An acquisition engine sophisticated enough to acquire L5 signals directly.
- A navigation engine that utilizes Artificial Intelligence/Machine Learning (AI/ML) techniques to fully exploit all the signals in 50MHz wide band at L5, in order to increase accuracy by greatly reducing multipath errors.
