[time-nuts] How well does GPS work in the Arcitic?

Magnus Danielson magnus at rubidium.dyndns.org
Tue Aug 15 16:50:26 EDT 2017


Hi,

The pre-cursor system Timation had polar orbit and worked essentially as 
good in the polar area as at the equator. The inclination of orbits was 
a compromise for better service while not requiring atomic clocks at the 
receiver.

Cheers,
Magnus

On 08/15/2017 06:34 PM, Bob kb8tq wrote:
> Hi
> 
> The “degradation at the poles” thing was very well understood in the 1970’s when
> they came up with the orbit plan. The questions about performance started being
> asked quite early. The earliest answer I recall hearing (in the late 70’s) was that polar
> operations were not a big part of the system needs.
> 
> Bob
> 
> 
>> On Aug 15, 2017, at 8:41 AM, Brent <brent.evers at gmail.com> wrote:
>>
>> Several vessels regularly work the poles and their data is publicly
>> available.  Here's one from the Healy on a cruise that went to 75N ( at
>> least).  I haven't looked at the data to know how much is there, but at a
>> minimum I should think you could look for gaps in the timestamp.
>>
>> http://www.marine-geo.org/tools/search/Files.php?data_set_uid=11624
>>
>> I used to work on the Palmer and never saw a glitch in our systems based on
>> latitude, although we used them for basic nav only (no 'science' done with
>> the signals).  We worked both poles and at times (very rarely - only for
>> drilling operations when we were on DP) had corrections sent to the ship
>> via satellite (Furgro corrections if I recall correctly).
>>
>> Not sure that the Military wouldn't have been very interested in polar nav
>> even in the early days of GPS - Subs were regularly transiting and hiding
>> in the arctic and I've got to think they might have wanted to pop up for a
>> fix now and again, even with MRU's/gyros.
>>
>> That said, a friend of mine regularly worked on the arctic ice sheet in the
>> 70-90's and most of his navigation was celestial via theodolite.  He did,
>> however, have an opportunity to test one of the earliest GPS's on the ice
>> before it was decommissioned.  Knowing the magnitude of what he had, he
>> asked and was able to keep the front panel.  I tried to send pics of it to
>> the list a year or so ago, but they bounced (size I guess).  I've tried to
>> attach a smaller version to this email.  Front what I can tell, this is the
>> 21st GPS produced.
>>
>> Brent
>>
>>
>> [image: Inline image 1]
>>
>>
>>
>> On Tue, Aug 15, 2017 at 6:22 AM, David J Taylor via time-nuts <
>> time-nuts at febo.com> wrote:
>>
>>> The satellite orbits only go so far north?  If you are far enough north for
>>> that to be a problem, can you pick up the satellites across the pole?
>>>
>>> I have several days of NMEA log files from 68 N.  I think it will be simple
>>> after I have done it, but it may be a while before I get time to plot them.
>>> Does anybody have (non-Windows) code to that?
>>> ===========================
>>>
>>> Hal,
>>>
>>> GPS worked fine for me on a cruise including 80 degrees north.
>>>
>>> Cheers,
>>> David
>>> --
>>> SatSignal Software - Quality software written to your requirements
>>> Web: http://www.satsignal.eu
>>> Email: david-taylor at blueyonder.co.uk
>>> Twitter: @gm8arv
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