Satellites

[xman4242]

What number of satellites is optimal for fast gps lock and great performance? I know more is better but what is a good number?

 

[Ismael Bugarin]

There are a couple of subjects that keep popping up by the newcomers. There is and has always been the misconception that the most important factor describing a GPS link is how many satellites were acquired in the initial search. Another preoccupation dwells around how quickly they are found. There are many informative discussions on this topic and if you are so inclined I implore you to search them out. I'm going to provide some very basic information to help this thread along. 1. The OEM Rev A and Rev B modules are a class M7n GPS which can only access 3 of the 4 available geosystems. The mRo, Here, and many others are of the M8n class and along with enhanced processing adds the fourth geosystem to the other 3. There's more as it applies to the difference between the A/B versions and the many varieties of after market GPS modules. 2. I feel compelled to put this in caps. The NUMBER of available SATs has very little bearing on the QUALITY of the link. HDOP is a measure of quality. Simply stated; the higher the QUALITY the better the RELIABILITY of the link. I want add detail but that washes out the less technically inclined so I'll leave it at that and let others fill in the gaps.

A post from Michael Lione from 3dr owners group, not from me.

 

[xman4242]

There are a couple of subjects that keep popping up by the newcomers. There is and has always been the misconception that the most important factor describing a GPS link is how many satellites were acquired in the initial search. Another preoccupation dwells around how quickly they are found. There are many informative discussions on this topic and if you are so inclined I implore you to search them out. I'm going to provide some very basic information to help this thread along. 1. The OEM Rev A and Rev B modules are a class M7n GPS which can only access 3 of the 4 available geosystems. The mRo, Here, and many others are of the M8n class and along with enhanced processing adds the fourth geosystem to the other 3. There's more as it applies to the difference between the A/B versions and the many varieties of after market GPS modules. 2. I feel compelled to put this in caps. The NUMBER of available SATs has very little bearing on the QUALITY of the link. HDOP is a measure of quality. Simply stated; the higher the QUALITY the better the RELIABILITY of the link. I want add detail but that washes out the less technically inclined so I'll leave it at that and let others fill in the gaps.

A post from Michael Lione from 3dr owners group, not from me.

Ok thanks. Is there an app to measure HDOP?

 

[Ismael Bugarin]

The sol

Ok thanks. Is there an app to measure HDOP?

The Solo app does it for you, had You read the manual.
Just tap under Satellites.

 

[Ismael Bugarin]

Next to The # of satellites

 

[xman4242]

Don't have a solo yet. Just doing my research[emoji3]

 

[xman4242]

Ok thanks

 

[LucianFlaitz]

Don't fly solo in anything higher than a 2.7 HDOP

 

[xman4242]

Don't fly solo in anything higher than a 2.7 HDOP

Ok. What does HDOP stand for?

 

[Deleted member 7413]

HDOP – horizontal dilution of precision. Therefore the lower the number, the better accuracy of your location. Here is a link that gives you a chart of what the range of values mean.

Dilution of precision (navigation) - Wikipedia

 

[xman4242]

HDOP – horizontal dilution of precision. Therefore the lower the number, the better accuracy of your location. Here is a link that gives you a chart of what the range of values mean.

Dilution of precision (navigation) - Wikipedia

Ok thanks[emoji3]

 

[Viper126]

There are a couple of subjects that keep popping up by the newcomers. There is and has always been the misconception that the most important factor describing a GPS link is how many satellites were acquired in the initial search. Another preoccupation dwells around how quickly they are found. There are many informative discussions on this topic and if you are so inclined I implore you to search them out. I'm going to provide some very basic information to help this thread along. 1. The OEM Rev A and Rev B modules are a class M7n GPS which can only access 3 of the 4 available geosystems. The mRo, Here, and many others are of the M8n class and along with enhanced processing adds the fourth geosystem to the other 3. There's more as it applies to the difference between the A/B versions and the many varieties of after market GPS modules. 2. I feel compelled to put this in caps. The NUMBER of available SATs has very little bearing on the QUALITY of the link. HDOP is a measure of quality. Simply stated; the higher the QUALITY the better the RELIABILITY of the link. I want add detail but that washes out the less technically inclined so I'll leave it at that and let others fill in the gaps.

A post from Michael Lione from 3dr owners group, not from me.

Great summary for the newcomers. I would elaborate that higher quality HDOP does not mean a higher number but greater strength which really equates to 0 to 2. At least for general purposes without reading further.
Just my humble opinion. And... all the apps for solo, so far, have the HDOP measurement available to view.

 

[Pedals2Paddles]

Also FYI, it isn't just HDOP and sat count that ArduPilot uses to determine if the GPS is ok or not. It is looking at how stable the position fix is. It's looking at the accelerators, gyros, and compass, then comparing to the GPS. The GPS drift needs to be less than a given amount, or it is rejected. This why you usually see lots sats, a good HDOP, it says 3D Lock, but still "Waiting for GPS".

 

[Greg Parker]

What number of satellites is optimal for fast gps lock and great performance? I know more is better but what is a good number?

With an M8N GPS unit I usually can get airborne with 9 or 10, typically I get 13 to 16 quickly and often 16 to 19 when up off the ground 20 or 30 feet. HDOP usually reported around .6

 

[xman4242]

Thanks for all of the info guys. Is there a way to figure out how many feet you are off by using you HDOP value? (I.E. 0.1 HDOP= 3 inches)

 

[Pedals2Paddles]

Thanks for all of the info guys. Is there a way to figure out how many feet you are off by using you HDOP value? (I.E. 0.1 HDOP= 3 inches)

Nope.

 

[KDan]

Hdop is also measuring magnetic storms in space around the earth.
The stronger the storm, the higher the hdop will be.

HDOP is not directly correlated with geomagnetic activity. That's not what it represents. HDOP is a complex calculation related to the angular separation of the satellites that the GPS has synchronized to. 12 Satellites widely spread around the sky will give a lower HDOP than 12 satellites that are mostly concentrated in a smaller area of the sky.

 

[Pedals2Paddles]

Hdop is also measuring magnetic storms in space around the earth.
The stronger the storm, the higher the hdop will be.

You're thinking of K-Index.