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PRN01/SVN49: Another GPS Satellite Anomaly
September 8, 2009
From monitoring at the University of New Brunswick and elsewhere around =
the globe, it=20
appears that normal signals from the L1 and L2 transmitters on the GPS sa=
tellite=20
PRN01/SVN49 were unavailable for more than two hours on the morning of Se=
ptember 4.
The satellite was not transmitting useful signals on L1 and L2 from about=
12:00 to 14:11=20
UTC, as evidenced by the observation records of some International GNSS S=
ervice stations=20
in Europe. The L5 test signal continued to be tracked by some receivers b=
ut not others.
=E2=80=9CA report has come from Europe that some receivers are tracking L=
5 (but not L1 or L2)=20
signals, so, it seems that only the L1 and L2 transmitters are affected a=
t the moment,=E2=80=9D=20
explained Richard Langley, GPS World=E2=80=99s Innovation and Almanac con=
tributing editor.
One possible explanation for the inability to track PRN01 is that the sat=
ellite rejected=20
an upload and automatically went into non-standard mode, resulting in GPS=
receivers being=20
unable to track the L1 and L2 signals. In other words, the L1/L2 transmit=
ters were still=20
on but transmitting a non-standard signal.
=E2=80=9CIt is not known for sure what actually happened with the satelli=
te, but perhaps it is=20
related to the ongoing issues with the signal reflections on the satellit=
e and that the=20
GPS Wing was conducting further tests,=E2=80=9D Langley said. =E2=80=9CLu=
ckily, the problem was short=20
lived.=E2=80=9D And as to why some receivers continued to track the L5 si=
gnal but others did not,=20
Langley speculates that some receivers may need to acquire and track the =
L1 signal before=20
they can track the L5 test signal.
http://www.gpsworld.com/gnss-system/news/prn01svn49-another-gps-satellite=
-anomaly-8842?print=3D1
Sam Wormley wrote:
> the globe, it appears that normal signals from the L1 and L2=20
> transmitters on the GPS satellite PRN01/SVN49 were unavailable for more=
=20
> transmitters on the GPS satellite PRN01/SVN49 were unavailable for more=
> than two hours on the morning of September 4.
>=20
> The satellite was not transmitting useful signals on L1 and L2 from=20
> about 12:00 to 14:11 UTC, as evidenced by the observation records of=20
> some International GNSS Service stations in Europe. The L5 test signal =
>=20
> The satellite was not transmitting useful signals on L1 and L2 from=20
> about 12:00 to 14:11 UTC, as evidenced by the observation records of=20
> some International GNSS Service stations in Europe. The L5 test signal =
> continued to be tracked by some receivers but not others.
>=20
> =E2=80=9CA report has come from Europe that some receivers are tracking=
L5 (but=20
>=20
> =E2=80=9CA report has come from Europe that some receivers are tracking=
> not L1 or L2) signals, so, it seems that only the L1 and L2 transmitter=
s=20
> are affected at the moment,=E2=80=9D explained Richard Langley, GPS Wor=
ld=E2=80=99s=20
> Innovation and Almanac contributing editor.
>=20
> One possible explanation for the inability to track PRN01 is that the=20
> satellite rejected an upload and automatically went into non-standard=20
> mode, resulting in GPS receivers being unable to track the L1 and L2=20
> signals. In other words, the L1/L2 transmitters were still on but=20
> transmitting a non-standard signal.
>=20
> =E2=80=9CIt is not known for sure what actually happened with the satel=
lite, but=20
>=20
> One possible explanation for the inability to track PRN01 is that the=20
> satellite rejected an upload and automatically went into non-standard=20
> mode, resulting in GPS receivers being unable to track the L1 and L2=20
> signals. In other words, the L1/L2 transmitters were still on but=20
> transmitting a non-standard signal.
>=20
> =E2=80=9CIt is not known for sure what actually happened with the satel=
> perhaps it is related to the ongoing issues with the signal reflections=
=20
> on the satellite and that the GPS Wing was conducting further tests,=E2=
=80=9D=20
> Langley said. =E2=80=9CLuckily, the problem was short lived.=E2=80=9D A=
nd as to why some=20
> receivers continued to track the L5 signal but others did not, Langley =
> speculates that some receivers may need to acquire and track the L1=20
> signal before they can track the L5 test signal.
> signal before they can track the L5 test signal.
> September 8, 2009
>=20
> From monitoring at the University of New Brunswick and elsewhere aroun=