I expect 1/R^2 would prevent such a scheme from working as the
terrestrial transmitters would vary widely in signal strength in a way
that GPS satellites do not and could overload the receiver.
David N1HAC
On 3/12/18 9:54 AM, Peter Reilley wrote:
Reading this paper makes one wonder if there are other improvements that
can be made to increase the robustness against jamming, software bugs,
solar events
or hostile attacks to the GPS system
A suggestion:
Create a parallel terrestrial GPS system. This would be a system of
GPS transmitters
mounted on cell phone towers. They would masquerade as GPS
satellites (but unusually low
and stationary). It would be ideal if they could have unique
identifiers and be integrated
into the GPS receivers timing and location calculations as any other
satellite. If there
is no room in the existing ID space then the terrestrial node would
take over the ID of
a satellite that is below the horizon. When the satellite reappeared
the terrestrial node
would simply take over a different below the horizon satellite's ID.
Such a system could be built out as needed. It may not require any
alterations to existing
GPS receivers. It would not disrupt the operation of the existing
satellite constellation.
It would protect against attacks on the satellite system by either a
human enemy or a natural
one, the sun.
Each node need not contain an accurate time source like a cesium
standard. They could
derive timing from a neighbor. Cesium reference nodes would be
periodically placed around the
system. Timing derivations would be more accurate since the
distances would be much closer and
thereby encounter less environmental disturbance.
GPSDO units would prefer such close and stationary references vs
distant moving ones.
Pete.
On 3/11/2018 5:26 PM, Magnus Danielson wrote:
Hi Andy,
On 03/11/2018 08:40 PM, Andy Backus wrote:
Thank you for your posting, Magnus.
Your information is very interesting.
Do you mind saying a little more about the "incident" on
26-JAN-2016? I don't find reference to it in the link. And my own
TE plot for then shows no obvious disturbance.
Thanks.
Please read this:
https://na01.safelinks.protection.outlook.com/?url=https:%2F%2Frubidium.dyndns.org%2F~magnus%2Fpapers%2FGPSincidentA6.pdf&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Ca4a010b972b74eba0aa208d5890f2665%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636565620521190534&sdata=DvYknd%2F9wuMeyr0DaSNwdZPuPunA8I8XBmSp1nXnm38%3D&reserved=0
In short, the GPS to UTC time correction polynomial got screwed up.
I got email from NASA, ended up having to call NASA HQ and got invited
to Washington DC to present before the US PNT advisory board.
Among the stranger things I've done in my life, but it was fun.
Cheers,
Magnus
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