Air Force Polls Receiver Makers for Solutions to Satellite Problems

Air Force Polls Receiver Makers for Solutions to Satellite Problems
http://sidt.gpsworld.com/gpssidt/content/printContentPopup.jsp?id=3D60=
7645

Jun 30, 2009
GPS World

The U.S. Air Force GPS Wing seeks comments from receiver manufacturers re=
garding the=20
SVN-49 signal anomaly and the Air Force=E2=80=99s proposed solution. The =
Air Force has been=20
investigating the cause and effects of signal distortions, observed as an=
=20
elevation-dependent bias in ranging measurements, from the GPS IIR-20(M) =
spacecraft=20
launched on March 24, 2009 and not yet set operational. As recently as Ju=
ne 19, the GPS=20
Wing outlined solutions it planned to implement to compensate for the pse=
udorange errors,=20
but now it states that =E2=80=9Cit is not possible for the Air Force to e=
valuate the myriad of=20
civilian products and applications. Your help is urgently requested to [=E2=
=80=A6] evaluate [=E2=80=A6],=20
conduct tests [=E2=80=A6], and provide recommendations and advice to the =
Air Force.=E2=80=9D

Worldwide GPS users are not affected by the signal distortion, since this=
satellite is=20
still in early-orbit checkout and has not been introduced into the operat=
ional constellation.

A presentation currently being made to GPS manufacturers includes a detai=
led technical=20
explanation of the problem, with copious charts and figures, preceded by =
the language:

See: http://sidt.gpsworld.com/gpssidt/content/printContentPopup.jsp?id=3D=
607645

=3D607645
garding the
rce has been
spacecraft
ne 19, the GPS
udorange errors,
e the myriad of
=85] evaluate [=85],
rce.=94

I wonder which problems may rise for Ephemeris Extension solutions.
The computation of client-based or server-based long term ephemeris
maybe affected by the fix of the problem.