Re: Galaxy XV / PRN 135 WAAS signal unofficially healthy again ?

[macpacheco]

www.gpsworld.com informs that PRN135 is now back to full healthy,
available for aviation and other safety of life applications.
But there's no word to that end on http://www.nstb.tc.faa.gov/ as well
as http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/waas/news/
yet.
At the same time WAAS nstb SV status page shows PRN135 UDRE now at 50
meters. At this point PRN135 begins to really useful as a ranging
source for non precision approaches. This suggests that PRN135 has MT0
really removed. And this should mean absent any signal quality issues
in less than a day or two ranging UDRE improves to 7.5 meters (the
best possible for WAAS GEOs). UDRE 7.5 meters is useful for precision
approaches.

Marcelo Pacheco

[macpacheco]

On Mar 19, 10:46*am, macpacheco > wrote:
> www.gpsworld.cominforms that PRN135 is now back to full healthy,
> available for aviation and other safety of life applications.
> But there's no word to that end onhttp://www.nstb.tc.faa.gov/as well
> ashttp://www.faa.gov/about/office_org/headquarters_offices/ato/service_....
> yet.
> At the same time WAAS nstb SV status page shows PRN135 UDRE now at 50
> meters. At this point PRN135 begins to really useful as a ranging
> source for non precision approaches. This suggests that PRN135 has MT0
> really removed. And this should mean absent any signal quality issues
> in less than a day or two ranging UDRE improves to 7.5 meters (the
> best possible for WAAS GEOs). UDRE 7.5 meters is useful for precision
> approaches.
>
> Marcelo Pacheco

The VPL realtime charts show coverage to NW Alaska fully restored.
This confirms without doubt that PRN135 is fully healthy for WAAS
integrity/corrections.
PRN 135 still has 12 degrees west to go until it reaches its normal/
backup orbital slot.
Also its currently operating on a 50 meter UDRE for ranging, which is
useful for non-precision approaches, but is useless for LPVs. This is
probably due to PRN 135 still being repositioned. Ranging allows WAAS
GEOs to be used like a regular GPS satellite, except that they are
always less accurate than a regular GPS satellite (GPS satellites
reach 3 meter UDRE after they come in view of a lot of WAAS reference
stations, while WAAS GEOs are limited to 7.5 meter UDRE, even though
they are monitored by most reference stations 24x7).

Marcelo Pacheco