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

Hi Getting back to time … The “long path” GPS is not going to give you the best time solution in a polar region. That plus the wonky tropo and ionosphere models for those regions (partly due to lack of data and partly due to physics) are also going to degrade your time solution. Bottom line

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

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:

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

I have been watching the thread and there is no reason for GPS not to work at the poles. Granted there can be solar events that upset it with things like severe multi-path but in general if the skies not glowing its most likely just fine. Also I believe the sats are somewhat low in the sky. Skips

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

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

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

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.

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

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

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

On Mon, 14 Aug 2017 18:19:56 -0700, jimlux wrote: >On 8/14/17 5:58 PM, Bill Beam wrote: >> GPS orbit inclination is 50-60deg. >55 degrees Current TLE show I= low of 51.7 to I= high of 56.6. >> At my latitude of 65N satellites are about 15deg above the horizon to the >> north. >That would be

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

On 8/14/17 6:15 PM, Bob kb8tq wrote: Hi If you are at ICBM mid course altitudes, there are a *lot* of sat’s visible …. (at least compared to being on the ground). But do you get good VDOP? I don't know how high the typical ICBM trajectory goes, I assumed it's fairly low (why burn to get

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

On 8/14/17 5:58 PM, Bill Beam wrote: GPS orbit inclination is 50-60deg. 55 degrees At my latitude of 65N satellites are about 15deg above the horizon to the north. That would be for satellites that are "over the pole" with respect to you? ___

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

Hi If you are at ICBM mid course altitudes, there are a *lot* of sat’s visible …. (at least compared to being on the ground). Bob > On Aug 14, 2017, at 9:04 PM, jimlux wrote: > > On 8/14/17 5:12 PM, Bob kb8tq wrote: >> Hi >> >> At the time all this was figured out, the

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

On 8/14/17 5:12 PM, Bob kb8tq wrote: Hi At the time all this was figured out, the idea of the military needing nav at the poles was pretty far fetched. They accepted a bit of degradation in those regions as a result of this thinking. I don't know about that - I think it was more that it

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

GPS orbit inclination is 50-60deg. At my latitude of 65N satellites are about 15deg above the horizon to the north. Regards. On Mon, 14 Aug 2017 16:45:22 -0700, Hal Murray 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

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

Hi At the time all this was figured out, the idea of the military needing nav at the poles was pretty far fetched. They accepted a bit of degradation in those regions as a result of this thinking. Bob > On Aug 14, 2017, at 7:45 PM, Hal Murray wrote: > > > The

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

On 8/14/17 4:45 PM, Hal Murray 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