GPS confusion

[Rsfitz]

Warned you guys that I am new to this. I am completely confused where it comes to GPS. Today I went out flying. Solo was taking forever to get a GPS lock. I am not a patient man so a few minutes = forever. App showed 10 seats and HDOP of 1.6 - 2.0. Solo would not lock and let me take off. Had done the firmware update. Tried right stick down and to the right to start motors. Have done this before, motors start and GPS locks. Today it would not start the motors until I switched to manual.

Came home did the App update. Went out in the yard and got 7 sats and HDOP of 2.1 and it locked. I don't get it. Can anyone explain?

Also have an app that shows satellites and estimated HDOP. There are all kinds of satellites on this app. Which ones does Solo read or connect to or whatever it does?

 

[Raybro]

Were you out away from trees and buildings? I usually fly right outside my door and it generally takes 2 to 3 minutes to get a lock and I think it is because the house and my trees in the yard are blocking what would be an open view of the sky.

It does not use all the satellites, not the Glonass system any way. You should have been able to fly with 10 Sats and a low HDOP.

Many threads have been posted about GPS and some say when you fly from the same location that it will get a lock much quicker after a few flights. Supposedly keeping the satellite data in memory?

I have not experienced this yet and I wonder if it is because I don't leave my battery in the Solo when I'm not flying.

 

[Rsfitz]

When I had lots of satellites and low HDOP but no lock I was in an open field. In the yard I was close to the house. That explains less satellites and higher HDOP.

I was in a new area in the field. Just don't understand why it would not lock. As soon as I start the motors in manual mode it locks.

I guess if the thing has a memory it would explain the quick lock in the yard.

Solo uses GPS satellites? Sometimes my app shows I should read 8-9 satellites. Solo show more than that. Anyone know what other satellites it reads?

 

[erikgraham]

The number of satellites and the hdop don't directly correlate to GPS lock - anymore. With respect to number of satellites, you could see a bunch but if they are transiting along the horizon they aren't as useful as fewer satellites that are more directly overhead.

With respect to HDOP, I don't think they even look at that anymore in the pre-arm checks. The EKF "looks at the receiver accuracy and noise, and won't start until they have been within limits for 10 second. This was added to prevent crashes caused by GPS glitches during take-off, which is where they are most likely to occur. Relying on just the number of satellites and HDOP was allowing users to take-off in GPS mode with bad interference from on-board cameras, etc or in locations where they should not be using GPS, eg indoors, under tree canopies, etc."

If I dig up more info, I'll post links, but bottom line is that just because you see a lot of satellites and have a good hdop, doesn't mean your Solo will pass prearm checks.

(Solo only uses GPS, no glonas)

 

[Raybro]

Warned you guys that I am new to this. I am completely confused where it comes to GPS. Today I went out flying. Solo was taking forever to get a GPS lock. I am not a patient man so a few minutes = forever. App showed 10 seats and HDOP of 1.6 - 2.0. Solo would not lock and let me take off. Had done the firmware update. Tried right stick down and to the right to start motors. Have done this before, motors start and GPS locks. Today it would not start the motors until I switched to manual.

Came home did the App update. Went out in the yard and got 7 sats and HDOP of 2.1 and it locked. I don't get it. Can anyone explain?

Also have an app that shows satellites and estimated HDOP. There are all kinds of satellites on this app. Which ones does Solo read or connect to or whatever it does?

You must be doing pretty well flying in manual. That's the only way to truly learn.

 

[Earldgrayjr]

Were you out away from trees and buildings? I usually fly right outside my door and it generally takes 2 to 3 minutes to get a lock and I think it is because the house and my trees in the yard are blocking what would be an open view of the sky.

It does not use all the satellites, not the Glonass system any way. You should have been able to fly with 10 Sats and a low HDOP.

Many threads have been posted about GPS and some say when you fly from the same location that it will get a lock much quicker after a few flights. Supposedly keeping the satellite data in memory?

I have not experienced this yet and I wonder if it is because I don't leave my battery in the Solo when I'm not flying.

It actually doesn't use hdop, but rather another calculation including effectively hdop, vdop, and pdop., that comes up with total accuracy, alomg with some timimg logic (it has to have good values for so long). Hdop is horizontal only.

I forget the name of the value, but if you search GPS, you should find the thread that discusses it.

 

[Burkeam]

I was told by 3DR to re cal the compass if you move to a new location. This might help in a quicker acquisition of sat lock. Additionally I was told to make sure the foil shield is not making contact with the GPC pcb where the battery can be drained and loss of gps memory. I haven't been back in to inspect this. waiting for gimbals on Monday and hop fully two new pods soon after.

FYI Earl I ordered it July 15 directly from 3DR - saw your question on another post.

 

[Raybro]

I was told by 3DR to re cal the compass if you move to a new location. This might help in a quicker acquisition of sat lock. Additionally I was told to make sure the foil shield is not making contact with the GPC pcb where the battery can be drained and loss of gps memory. I haven't been back in to inspect this. waiting for gimbals on Monday and hop fully two new pods soon after.

FYI Earl I ordered it July 15 directly from 3DR - saw your question on another post.

3DR told you about checking the foil shielding? Just wondering. I saw a user post regarding this.
Thanks for the info.
Ray

 

[Rsfitz]

You must be doing pretty well flying in manual. That's the only way to truly learn.

Staying away from all structures and trees as much as possible. Learning. Love the pause button = air brake. Gave me a lot more confidence. Flying is fun. This GPS stuff just baffles me. Did search it before I started this thread. Just got more baffled.

 

[Burkeam]

3DR told you about checking the foil shielding? Just wondering. I saw a user post regarding this.
Thanks for the info.
Ray

Yes 3DR during my phone call. It was a new thing they heard found out about the previous day from a customers email. Could be the same one that posted.

 

[Raybro]

Here is that thread:

http://www.3drpilots.com/threads/interesting-simple-gps-mod-from-facebook.1049/#post-14892