When ICAO introduced the Global Navigation Satellite System (GNSS) concept in 1993, it was to establish an earth-girdling network of navigation satellite constellations that would provide service “for the foreseeable future on a continuous worldwide basis, free of direct user fees.” The U.S. and Russia (then the Soviet Union) were first to sign up in 1996, followed several years later by Europe, China, Japan and India, which planned to launch constellations of their own. By 2020, there should be six constellations and close to 150 navigation satellites criss-crossing the Earth.
That planned abundance was welcomed in the early days, because receiver technology was initially limited to simultaneously tracking just four satellites from a single constellation, which occasionally resulted in coverage gaps, or “holes,” caused by poor fix geometry. But with many more satellites destined to enter orbit, ICAO expected that constellation “interoperability” would allow that gap to be filled by an aircraft’s receiver acquiring signals from better positioned satellites in another constellation, such as using three GPS satellites and one from the European Galileo constellation.
But holes are no longer a challenge. With approximately 30 GPS satellites in orbit, today’s advanced-technology airborne GPS receivers can simultaneously process signals from as many as 15 of them, with each incrementally refining the GPS position, without accessing another constellation. However, multi-constellation, multi-frequency (MCMF) operation remains a valuable technique, widely used in geophysical surveying and similar tasks where centimeter accuracy or better is required. Now, some airline people are reportedly promoting MCMF avionics. Superficially, that sounds smart. But some avionics experts assert it would be expensive overkill.
While GPS holes are no longer a concern, market protectionism is. In November 2012, Russia announced at ICAO that all Russian-registered aircraft planning to use satellite navigation would be required to use Russian-built Glonass receivers. GPS receivers could be used only if they were integrated with (built into) Glonass receivers. The use of stand-alone GPS receivers would be illegal in Russian aircraft, ships and in certain other applications, although personal use would be permitted.
While acknowledging that it was Russia’s right to impose such sanctions, the U.S. delegation at ICAO strongly opposed the move as contrary to ICAO’s position that the world’s airspace and its supporting systems should be available to all. Nevertheless, the Russian representatives refused to back down. Unspoken was their concern that without such a ruling, Russia’s fledgling satellite receiver industry would be stillborn, in the face of its massive U.S. competitors.
Logically, the next protectionist shoe to drop would appear to be China’s. With foreign-built small, lightweight GPS receiver modules now selling at commodity levels, a Chinese-packaged GPS/BeiDou/cellphone could outsell almost all the competition. China doesn’t build avionics (yet), but U.S. general aviation could offer intriguing possibilities.
Protectionism can take many forms. In December last year the Federal Communications Commission (FCC) announced that using foreign satellite signals in the U.S. required prior FCC approval and that foreign-built satellite receivers would require FCC inspection before being licensed for use in U.S. territory. GPS industry officials worry that U.S. GPS manufacturers exporting to a country that builds its own satellite equipment might run into reciprocal “difficulties.”
Yet the market is irresistible. No one knows how many satnav receivers have been produced, but one estimate says that by 2030 one in three people on Earth will own one.