posted 12-09-2014 10:42 AM ET (US)
The global navigation satellite system receivers in present-day recreational-grade marine chart plotters tend to overwhelmingly be USA Air Force NAVSTAR GPS-only receivers. While GPS is the oldest global navigation satellite system (GNSS) available, today it is by no means the only system. GPS has 31-satellites in orbit, but there are presently a total of 89 GNSS satellites available for use, and in a few years that number is expected to increase to about 150 satellites.In the typical open sky environment found in marine use, GPS will usually provide eight or more satellites in view at any time and location. Eight satellites is quite sufficient to produce a position solution with a low dilution of precision (DOP), so there is not a pressing need to include other GNSS satellites for marine use.
Marine navigation is, however, only a tiny segment of total GNSS use these days. Almost every smartphone device has an embedded GNSS receiver, and these devices now constitute the major segment of GNSS applications.
A recent survey showed the following capabilities in popular smartphone device:
All recent APPLE iOS devices had GNSS receivers that could use
--GPS
--GLONASS (Russia)
--QZSS (Japan)
All recent ANDROID devices could use:
--GPS
--GLONASS (Russia)
Some ANDROID devices could also use
--QZSS (Japan)
--BEIDOU (China)
Depending on brand and model, a smartphone today can use three to four GNSS systems. Marine devices seem to be stuck with GPS-only.