Fred Wright <fw@fwright.net> writes:
The actual values of prRes are also "interesting". Although the
quantity is nominally defined as signed, I don't see how a residual
can possibly be negative. But many of the values reported by both
ubxtool and xgps are negative, with some strange scaling between the
two that also seems inconsistent with the definition (the doc says
0.1m units).
residual is
measurement - [expected measurement calculated from estimated parameters]
so definitely it makes sense to be signed.