[time-nuts] DHS Resilient PNT Conformance Framework

[Bob kb8tq]

Hi

> On Dec 19, 2020, at 8:34 AM, Magnus Danielson <magnus at rubidium.se> wrote:
> 
> Hi Bob,
> 
> On 2020-12-19 00:15, Bob kb8tq wrote:
>> Hi
>> 
>> You can always cycle the power … :)
> Comes to no relief for some cases, as they store state that keeps them
> "killed". If it was as easy of cycle the power, it would not have been
> an issue we discussed.
>> ===========
>> 
>> There also are the basic issues of 50 db gain antennas being attached to
>> 20 db compatible modules. RF rich environments (even without Lightspeed …)
>> will always be a challenge. Site design *is* part of this “mess”. 
> For sure. At the same time, we find sites which has numerous GPSes, each
> installed in a separate install campaign by different vendors/companies
> and "good enough" for that contract which didn't go into detail, so
> there is that too. That is for sure part of the problem the cross-hair
> is on.
>> =======
>> 
>> At least from what I saw, *most* modules did a pretty good job of handling the 
>> stuff they saw. You could always jam them if you had enough power. Most of 
>> them recovered from that and went back to running correctly. 
>> 
>> Indeed, a device that provided timing on a per band / per system basis would 
>> probably have taken care of all the issues I saw. Back in the day, those devices
>> …. not what you got in your low cost module ….
> 
> It's not necessarily of doing per band or per system receivers increase
> your PNT capability. It could in fact reduce it as you can not use
> remaining signals and combine them. I made this very point that it would
> be unwise to limit in such ways. That was also the result of an
> IT-security analysis gone wrong, without considering some basic facts
> and low-hanging fruit in making that more robust.

If the “per system / per band” timing information is all supplied up to the
smarts in the unit, you would have 3 bands x 4 systems = 12 somewhat
independent sources of timing to evaluate as part of your decision making
process. Nothing is lost unless the decision making process rejects it. 

Bob



> 
> Cheers,
> Magnus
> 
> 
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