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How many GPS satellites seen from Hawaii?
PetalumaLoco
As the title says, how many sats can be seen in Hawaii? I have a friend there that insists a maximum of 3, because of it's remote location and what he says is "no need of GPS accuracy for thousands of miles around the islands".

I think he's wrong but I'm having trouble verifying it.

Dennis
Ken in Regina
I have no idea how many you can see there. But I have a problem with your friend's suggestion that GPS accuracy isn't an issue.

I suppose that means you won't run into anything. That's true if you're far enough away from things you could run into. But the closer you are to something and the poorer the visibility, the more important the positional accuracy becomes.

...ken...
PetalumaLoco
I agree with you about my friend's reasoning.

He also said the military didn't have a need for such accuracy at sea, which I found hard to believe.
Ken in Regina
For what it's worth, here is a discussion that says nothing about how many satellites can be seen but I have to infer from the "no problems" and "worked fine" comments that they saw more than three satellites or they would have mentioned it.

...ken...
PetalumaLoco
Yeah, but I'd love to see something definitive.
Ken in Regina
Okay, knock yourself out on this one:

GPS Talk - HawaiiThreads.com

They are discussing geocaching there, so they gotta have more than three satellites!

...ken...
Marvin Hlavac
Quote:
Originally Posted by PetalumaLoco
Yeah, but I'd love to see something definitive.
OK, I'm quite willing and able to go out to Hawaii to perform some testing for ya. I will just require return airline tickets and hotel for me and my family.

But to be honest, if your friend can only see three GPS satellites, something must be wrong with his equipment, or the reception where the equipment is placed.

I see no reason why he shouldn't see approximately as many satellites in Hawaii as others do in other parts of the world.


Image from wikepedia.com

There is a related discussion going on right now in the following thread: http://www.laptopgpsworld.com/1189-all-twelve-gps-satellites-all-time
PetalumaLoco
Marvin

That thread here you link to is what got me thinking about posting this thread.

I read the Wiki entry before and although it sure looks to me like you're right about how many you're liable to see, the way my belligerent friend is talking I guess I will have to buy you that ticket.

Just as soon as my lottery winnings from Nigeria get here.
Marvin Hlavac
LOL, that likely means we will not be vacationing in Hawaii this winter.

Perhaps your friend's car GPS is behind a tinted window that has metallic content in it. Such windows can make GPS signal reception is some cases impossible.
PetalumaLoco
Maybe that's it. He says he sees more sats on the mainland.
Ken in Regina
PetalumaLoco,

If you want something definitive, just pop a message into that Hawaii forum I posted the link to and ask the question there. Those are locals. They'll give it to you straight.

As I said in that message, you can't do geocaching successfully if all you can see is three satellites. But if you want the straight goods, it's so simple .. just ask them.

...ken...
Marvin Hlavac
... and do let us know your findings, as otherwise there is very little point of any of us ever going to Hawaii if we cannot use our GPS there. :rofl"
NickyBoy
Quote:
Originally Posted by Ken in Regina
I have no idea how many you can see there. But I have a problem with your friend's suggestion that GPS accuracy isn't an issue.

I suppose that means you won't run into anything. That's true if you're far enough away from things you could run into. But the closer you are to something and the poorer the visibility, the more important the positional accuracy becomes.

...ken...
If this helps I believe he is correct i live on the island of Oahu I have been flying my GPS drone for a year and it connects to only 3 GPS satellites. With only 3 accuracy is slightly compromised. Hovering at 75' my drone tends to drift approximately a 3' radius then returns to the locked position. When connected to only 2 GPS satellites the display indicates weak GPS signal.
Ken in Regina
Quote:
Originally Posted by NickyBoy
If this helps I believe he is correct i live on the island of Oahu I have been flying my GPS drone for a year and it connects to only 3 GPS satellites. With only 3 accuracy is slightly compromised. Hovering at 75' my drone tends to drift approximately a 3' radius then returns to the locked position. When connected to only 2 GPS satellites the display indicates weak GPS signal.
Thanks for the update and welcome to the forum!

Just for the record 3 satellites is usually the minimum required for decent fix. That still doesn't ensure a fix with any accuracy. If the 3 satellites are well spaced apart and are in a relatively triangular configuration it should be pretty decent. If the three are all very close together the fix will be much less accurate. And if the three are more in a line than a triangle you may have a fairly accurate fix in the orientation of the line but not in the other direction.

For a better understanding look at the first three pictures here:

https://gisgeography.com/gps-accuracy-hdop-pdop-gdop-multipath/

...ken...
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