(Lee Elson) wrote in
om:

We've been getting RAIM errors in Southern and Central
California with our GX60 in the past couple of months.

RAIM warnings (not errors) occur when the unit predicts
satellite reception that doesn't give acceptable precision in
calculating position. It's usually satellite geometry problems.
The GPS satellites aren't stationary, but move around the earth
in approximately (but not exactly) 12 hour orbits. Sometimes
all the satellites are directly overhead, or on the horizon, or
not enough are visible. When all satellites in view are
directly overhead, or nearly so, the position error is greater.

--
Regards,

Stan