[time-nuts] Recommendations for Mains Power Monitor / Logger

David G. McGaw david.g.mcgaw at dartmouth.edu
Tue Mar 13 15:08:44 EDT 2018


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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>
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