What is the difference between GPS and GNSS then?

In my previous post, I have used both terms GPS (describing the American Navigation System) and GNSS. The last terms is a popular umbrella term for all navigation systems including American, Russian, Chinese, European, Japanese and Indian ones.
I have recently read great GNSS book by Len Jacobson’s where he points out that this is not consistent with original definitions

GNSS term has been originally defined by International Civil Aviation Organization (ICAO) as “A worldwide position and time determination system that includes one or more satellite constellations, aircraft receivers and system integrity monitoring, augmented as necessary to support the required navigation performance for the intended operation”.

This includes not only augmentation constellation (EGNOS, WAAS and MSAS) but also the ground-based safety of life infrastructure - a much larger definition that we tend to use. Interestingly both the 2007 and 2012 ICAO documents list only GPS and GLONASS as part of GNSS. This is mostly to the fact that only L1 and G1 are protected frequencies worldwide. Galileo E1 should be soon accredited and protected as well.

Does it mean that we should properly say: GNSS, excluding ground components and Chinese Beiduo and Indian IRNSS? No, not really. It is a mouthful and you are most likely not be understood. I think it is more the interesting case of GNSS term hijack by the professional magazines.

BTW, as might be aware I will be presenting at ION GNSS+ 2016 in Portland, Oregon next week. If anybody is interested in learning more get in touch.

In the meantime I am flying and enjoying my new office:)