GPS

[TyphoonPete]

OK, ok, ok, no flaming please or telling me to read this or read that, (unless it is in basic English of 2 syllables or less).
I need basic information that a 2 year old can understand. No wait, make it that an old fart can understand. 2 year olds are wayyyyy too smart for me.
I know it's been asked before, but.....
Why do I need to find so many satellites?
As I understand it, gps satellites are in geostationary orbit, ie, in a fixed position relative to a position on earth.....
If I am standing at my regular flying spot, the number of satellites visible to my receiver is a fixed maximum number, less maybe dependent on surrounds and weather. Moving around over even a few hundred yards is unlikely to change that number
3 sats are required to "fix" a location, more for a tighter location fix, which is only down to a couple of meters in civilian life.
Why then does the system need such a large number of sats and why does it take so long? Especially when the system doesn't use them all.
As soon as I turn my car on my sat-nav has my position and can follow that instantly.
As a scientist who had a program on tv here in Australia many many years ago used to say..."Why is it so??"
Cheers all
Pete

 

[AH-1G]

Your not flying a car!

 

[TyphoonPete]

Your not flying a car!

No, but you still need a 3 dimensional plot.
I had a small hand held gps unit that would tell my altitude as well as a 2d fix and that was a **** of a lot quicker than this system

 

[AH-1G]

Think of this way, it is what it is.
Just enjoy flying and don't worry about the little things.

 

[TyphoonPete]

Think of this way, it is what it is.
Just enjoy flying and don't worry about the little things.

Yea, I know...curiosity killed the cat, you're better off not knowing etc etc.

It's fast approaching 40c here and may well get close to 50.
We're having a real heatwave here.
I'm bored and want to go flying
On here is next best thing!!!
That's a worry in itself
cheers

 

[AH-1G]

Ouch that is hot!.
this might help to cool you down.

 

[TyphoonPete]

Ouch that is hot!.
this might help to cool you down.
View attachment 13731

As much as I dislike cold and snow, I could really go that right now.
Awesome
Thanks for that

 

[DoomMeister]

Each satellite in the GPS constellation orbits at an altitude of about 20,000 km from the ground, and has an orbital speed of about 14,000 km/hour (the orbital period is roughly 12 hours - contrary to popular belief, GPS satellites are not in geosynchronous or geostationary orbits).Mar 11, 2017
The Ohio State University › astronomy › ...

EDU​

If you fly every few days, you will find that you will acquire GPS much quicker. If you fly only once a week or less it is best to let the TH sit powered up for 12 to 15 minutes to update the almanac of satellites. The more satellites acquired the better your fix will be.

 

[DCH]

One doesn't need many sats to triangulate one's position, ...roughly. And your car isn't using GPS to drive itself, it's telling the driver where it thinks the car is on a map. Considering that these sats are hundreds of miles away, and the possibility of the slightest parallax being amplified, the more sats you have the smaller any error will be. Given the level of accuracy required for autopilot functions, the more sats the more accurate the averaged calculated position will be, and remain. As the systems become more advanced, the number of sats required increases. Earlier GPS systems I have had that did not use a satellite almanac and required far fewer sats, made position adjustments in feet, sometime yards!

That can cause the puckermeter to peg if you have trees nearby!

The best sagely advice is summed up by @AH-1G...

Think of this way, it is what it is.
Just enjoy flying and don't worry about the little things.

 

[PatR]

My iPhone still tells me I've arrived at a destination when it's obvious it's still several hundred feet away. So does my older Garmin GPS.

 

[TyphoonPete]

Makes you wonder how "autonomous" vehicles ever stay on the road...
Electric autonomous vehicles...now that takes the fun out of driving.
That is ONE thing I can say I will never own
Love to see an autonomous vehicle trying to stay on track in a blizzard
ROFLMAO
That remins me, there was an ad during one of the playoff games last weekend.
Didn't realise it was a send up at first, but 6000 or 9000 batteries (can't remember which) with an automatic ejection system when they go flat.
What a laugh!!!

 

[h-elsner]

Electric autonomous vehicles

They use a lot more sensors as only GPS. RADAR, cameras in all directions, IoT communications with other cars nearby and so on...
This is really complex, not simply comperable with our drones. You can see those differences already if you compare drones that only stabilized by GPS with other products that have more sensors like cameras to ground (permanent IPS) etc.

br HE

 

[jandjfrench]

OK, ok, ok, no flaming please or telling me to read this or read that, (unless it is in basic English of 2 syllables or less).
I need basic information that a 2 year old can understand. No wait, make it that an old fart can understand. 2 year olds are wayyyyy too smart for me.
I know it's been asked before, but.....
Why do I need to find so many satellites?
As I understand it, gps satellites are in geostationary orbit, ie, in a fixed position relative to a position on earth.....
If I am standing at my regular flying spot, the number of satellites visible to my receiver is a fixed maximum number, less maybe dependent on surrounds and weather. Moving around over even a few hundred yards is unlikely to change that number
3 sats are required to "fix" a location, more for a tighter location fix, which is only down to a couple of meters in civilian life.
Why then does the system need such a large number of sats and why does it take so long? Especially when the system doesn't use them all.
As soon as I turn my car on my sat-nav has my position and can follow that instantly.
As a scientist who had a program on tv here in Australia many many years ago used to say..."Why is it so??"
Cheers all
Pete

Hi Pete,
I didn't see anything truly definitive so I'll hazard a guess. It seems logical that if the drone was in an urban area with many tall buildings some of the satellites would be blocked. Having as much redundancy as possible would minimize the problem. It appears that the designers planned for a worst case scenario.
Jim F.

 

[DCH]

I didn't see anything truly definitive

Really? ...Hmm.

 

[jandjfrench]

Really? ...Hmm.

By definitive I meant something like "I spoke to the development team and they said..."