Re: [gpsd-users] epx, epy values never change

[Steffen Sledz]

Hi Eric,

we hit a similar problem like Jeff. Before your commit we used the values to 
decide if the other data are "good enough" to process.

On 21.10.2016 16:54, Eric S. Raymond wrote:
> The error estimates are computed from satellite geometry and a scalar
> multiplier called UERE, an empirical constant ralated to the physics
> of delay jitter in the ionosphere.  They tell you your uncertainty
> of location *if you have sat lock*.
> 
> Local consitions like tree cover don't uncrease or decrease this uncertainty,
> they control whether or not you can get sat lock.  One minor exception: if
> you can see three sats but not four, you get a 2D lock that doesn't give
> you altitude.

This may be right. But over the time the receiver and the satellites may change 
their positions in a way that the epx/epy values need to be recalculated.

Also we observed that if we restart the application multiple times over a short 
time, the reported values for epx/epy have great variations. We think this is 
an indication that your argumentation cannot be fully correct.

In summary in our opinion the patch did not (only) fixed a bug bur killed a 
feature.

Regards,
Steffen