Originally Posted by
1980AZ
I do not believe this is correct. WAAS do not have RAIM, since WAAS uses GEO satellite to send signal ( I believe there is one or two only). RAIM is used by old fashioned GPS and makes sure that the signal from the Satellite is not corrupted. So, it uses t least 5 or 4 plus a barometric altimeter. When the corrupted satellite is to be removed, RAIM requires 6 SATs. 6-1 bad one.
A WAAS equipped GPS receives information from the same constellation as a Non-WAAS unit. It additionally receives a
corrected signal form one or both of the geostationary satellites. This is why it is more accurate; an additional margin of error, at that specific time, has been removed. RAIM is the ability to monitor the constellation for a
corrupted signal. To my knowledge
all IFR certified GPS's have RAIM capability.