Found and/or locked sats?

[photo2be]

Hi, I come from Yuneec Typhoon H two month ago and now I'm a very satisfied Mini2 photographer. When at Yuneec it was very important to find a nbr of sats but also wait a cpl of minutes for the sats to lock! Could take 13minutes if you haven't been in the air for a week or so or moved more then 100-150km east-west or vice versa.
Is that the same with DJI Mini2 or can I fly when I've found the sats?

 

[old man mavic]

when the Mini has locked on to enough Sats and you hear the home point message ,then you are good to go, most of the mavics seem to like around 10 Sats locked before they give you the green light

 

[Phantomrain.org]

Once you have a min of 7 Sats your good to go and your home point has been recorded , sometimes you have to take off for the Home Point to trigger .

Phantomrain.org
Gear to fly your Mini 2 in the Rain/Snow

 

[DanMan32]

I have noticed the MM1 (or the M2Z for that matter) take a little longer to lock on sufficient sats to get a full lock for the first flight of the day. The difference maybe a minute or two at worst versus almost immediately. That could be more about the IMU getting fully warmed up.

 

[Meta4]

Once you have a min of 7 Sats your good to go

There are situations where 7 sats would not ensure good location data.
The flight controller will decide when it is satisfied that the GPS data is suitable and the home point will recorded.

 

[Meta4]

I have noticed the MM1 (or the M2Z for that matter) take a little longer to lock on sufficient sats to get a full lock for the first flight of the day. The difference maybe a minute or two at worst versus almost immediately. That could be more about the IMU getting fully warmed up.

The IMU has no effect on the GPS system.
The variation in time could be the difference between a cold/warm start for the GPS receiver or obstructions blocking some of the sky.

 

[DanMan32]

I know IMU and GPS aren't directly related, but DJI often oversimplifies what they report.

Actually when the M2Z delays coming out of "cannot fly", the details say no data from IMU sensor (or something close to that).
P3s say "warming up" where the apparent warmup time can be shortened by doing an IMU calibration while it's cold.

 

[Meta4]

I know IMU and GPS aren't directly related, but DJI often oversimplifies what they report.

Actually when the M2Z delays coming out of "cannot fly", the details say no data from IMU sensor (or something close to that).
P3s say "warming up" where the apparent warmup time can be shortened by doing an IMU calibration while it's cold.

And none of that has anything to do with acquisition of GPS sats which you alluded to in post #4.

 

[mini5]

The IMU has no effect on the GPS system.
The variation in time could be the difference between a cold/warm start for the GPS receiver or obstructions blocking some of the sky.

Does the drone use almanach data downloaded via phone's internet? I didn't see cold GPS start even after 1-2 months of non-usage. Never took me more than 1-2 minutes to get GPS lock (and I remember many years ago when GPS receivers started to be common that many times I had to wait 10+ minutes to get a lock).

 

[photo2be]

Is GPS LOCK the same as nbr of sats displayed on the app?

 

[Meta4]

Does the drone use almanach data downloaded via phone's internet? I didn't see cold GPS start even after 1-2 months of non-usage. Never took me more than 1-2 minutes to get GPS lock (and I remember many years ago when GPS receivers started to be common that many times I had to wait 10+ minutes to get a lock).

There's no way to download GPS almanac data using internet data.
The drone's GPS receiver has no way to access anything you might download.

 

[Meta4]

Is GPS LOCK the same as nbr of sats displayed on the app?

They are related, but are not the same.
You can have satellites displayed but not have what someone called "GPS lock", which is when the drone's flight controller is satisfied that the GPS position data is accurate and switches the drone to P-GPS or Normal Mode.

 

[photo2be]

They are related, but are not the same.
You can have satellites displayed but not have what someone called "GPS lock", which is when the drone's flight controller is satisfied that the GPS position data is accurate and switches the drone to P-GPS or Normal Mode.

Thanx! One more question.. what is P-GPS?

 

[mini5]

There's no way to download GPS almanac data using internet data.
The drone's GPS receiver has no way to access anything you might download.

It's called A-GPS (Assisted GPS) and is used probably on all recent mobile phones. And little googling suggests that also standalone GPS modules (like those from u-blox) now allow to get almanac data via other means from the system where they are integrated (u-blox has its own service called AssistNow).

In drones it would be the phone app which downloads the data, sends it via remote controller to the drone and the drone's CPU uploads it to the GPS module itself. So I guess DJI uses something similar, otherwise it would take more time to get a fix (complete almanac takes 12.5 minutes to download from the satellites and that is in case of good reception signal). For example my old Phantom2 (which did not have any phone app) was significantly slower in acquiring GPS fix and I don't think the difference is only more sensitive receivers, but also A-GPS usage.

 

[Meta4]

Thanx! One more question.. what is P-GPS?

It's what DJI used to call Normal Mode before they started calling it Normal Mode.

 

[Meta4]

So I guess DJI uses something similar, otherwise it would take more time to get a fix (complete almanac takes 12.5 minutes to download from the satellites and that is in case of good reception signal). For example my old Phantom2 (which did not have any phone app) was significantly slower in acquiring GPS fix and I don't think the difference is only more sensitive receivers, but also A-GPS usage.

Like all GPS receivers that I've used, the GPS receiver in your drone will downlaod almanac data itself from satellites - no need for internet data or apps.
It makes the difference between a cold stat and warm start.

 

[photo2be]

It's called A-GPS (Assisted GPS) and is used probably on all recent mobile phones. And little googling suggests that also standalone GPS modules (like those from u-blox) now allow to get almanac data via other means from the system where they are integrated (u-blox has its own service called AssistNow).

In drones it would be the phone app which downloads the data, sends it via remote controller to the drone and the drone's CPU uploads it to the GPS module itself. So I guess DJI uses something similar, otherwise it would take more time to get a fix (complete almanac takes 12.5 minutes to download from the satellites and that is in case of good reception signal). For example my old Phantom2 (which did not have any phone app) was significantly slower in acquiring GPS fix and I don't think the difference is only more sensitive receivers, but also A-GPS usage.

Thanx! Great explanations! I remember my old Yuneec H, it took forever.... to get in the air.

 

[Meta4]

Thanx Mini5! Great explanation! I remember my old Yuneec H, it took forever.... to get in the air.

He wasn't replying to your question.