Napping with the Mavic 3 , Satellite Tricks.

[VenomXts]

@Phantomrain.org you keeping it? I need to make up my mind by the 31st was hoping to see the new firmware update come out today or Monday...

 

[zeusfl]

I am keeping mine. I just installed this on mine... This will make it easier to recover it because the color in case something goes wrong. Also I am installing the Firehouse Arc on Monday. I really like how it looks like.

 

[Phantomrain.org]

There is not a license for any GNSS, receiving and using the signals is free.

The cost involved is the hardware (chipset) that decodes and processes the GNSS signals. It seems that DJI has used a different chipset (maybe smaller and lighter weight - but most likely less expensive!) on the M3 which is not performing well, or their code that interfaces with the new chipset is not optimized for it.

When you mention Chip Set , Everything is making sense now. , CHIP SHORTAGE of course , The M3 is the result of a Chip Shortage all the way around from Zoom to Sats, Thus a firmware update might not even be a fix. Seems like I am back to the Silent Hill Alarm Sound coming soon.

Phantomrain.org
Gear to fly you M3 in the Rain. .

 

[Meta4]

When you mention Chip Set , Everything is making sense now. , CHIP SHORTAGE of course , The M3 is the result of a Chip Shortage all the way around from Zoom to Sats, Thus a firmware update might not even be a fix.

This doesn't fit with all the reports of the GPS working just fine before the first firmware update.

 

[Phantomrain.org]

@Phantomrain.org you keeping it? I need to make up my mind by the 31st was hoping to see the new firmware update come out today or Monday...

Yep < tonight I took it up in (7 degrees I had to battle the Devils Gate way for 5 minutes before the Devils Breath gave way and let me climb to 340 ft and gain 23 Sats and than it was smooth sailing. I think the 29Th for me is my silent hill day. I did a screen record but its a wreck, all vertical .

This doesn't fit with all the reports of the GPS working just fine before the first firmware update.

Could it make sense as to why they may have had to use the Beidou system in the first place. If there was a shortage of Chips for the GlONASS .


Phantomrain.org
Gear to fly you M3 in the Rain. .

 

[Meta4]

Could it make sense as to why they may have had to use the Beidou system in the first place. If there was a shortage of Chips for the GlONASS .

Not really.
They use chips like this:

UBX-M9140 series

u-blox M9 standard precision GNSS chips

www.u-blox.com

The chips can receive signals from 3 or 4 different sat systems.

 

[surfbird]

It's the drone, the controller has no effect on GPS satellite reception.
If you launch from your porch, you are probably blocking half the sky (and satellites there) so the drone can't receive their signals.

Actually the agps data is sent from the mobile device to the drone.
Its in the "DataFlycSendAgpsData" struct.

At least on older mavics, I don't have a mavic3 to check though.

 

[JooB]

The weather here hasn't got better but I found a slot with less winds and clouds to bring up the M3 for some minutes to test my new Tripltek 8.
And I stopped the time between powering up the M3 and hearing "The homepoint has recorded": About 45 seconds with the newest (!) firmware, the sky was half clouded. I think the new firmware speeded up the GPS fix again, I'm quite sure it took longer with the old firmware.

 

[vsasolutions]

The weather here hasn't got better but I found a slot with less winds and clouds to bring up the M3 for some minutes to test my new Tripltek 8.
And I stopped the time between powering up the M3 and hearing "The homepoint has recorded": About 45 seconds with the newest (!) firmware, the sky was half clouded. I think the new firmware speeded up the GPS fix again, I'm quite sure it took longer with the old firmware.

The new Tripltek 8 is freaking awesome. Loved I could take the sim from my iPad and use it in that. I purchased my M3 after the December update and did not have sat acquisition issues. After January update, sat acquisition is even faster for me. Also, none of the flying problems everyone else talks about.

 

[JooB]

Ok, forget what I wrote in my last post. Either the satellites were waiting for me that day or I was unable to read the watch properly...

Today was the day, no rain, less wind, cloudy, 9 degrees Celcius. I drove with my 3 drones to an open field, powered them up one after the other at the same spot and stopped the time until the homepoint was recorded. UAV Forecast said 20 satellites were visible.
Mavic 3 2:35 for 13 satellites (10 were fixed quite fast, the rest were found slowly)
Mini 2 0:45 for 10 satellites (7 were fixed quite fast)
Mavic 2 Zoom 0:40 for 9 satellites

So the Mavic 3 is slow. I still think it speeded up since the last firmware update and it needs more satellites to be ready than the other 2 drones, but it's really slow.

 

[GadgetGuy]

Actually the agps data is sent from the mobile device to the drone.
Its in the "DataFlycSendAgpsData" struct.

At least on older mavics, I don't have a mavic3 to check though.

Must be the other way around! The GPS comes from the drone, not the tablet!

I'm not seeing any improvement, after the latest January FW update that added panos. If anything, it has gotten worse.

 

[Crouching Leopard]

So at what number of satellites would you guys consider as optimum for safest flight and lowest for bringing it home. I have a mini, an M2 pro and an FPV

 

[mobilehomer]

Must be the other way around! The GPS comes from the drone, not the tablet!

I'm not seeing any improvement, after the latest January FW update that added panos. If anything, it has gotten worse.

The Agps comes from the phone to the drone. The drone has no data other than what it receives from the device. Both drone and controller have GPS. How DJI routes and parses the data is unknown. THAT is where the discrepancy lies. DJI has changed something for the M3.

 

[Meta4]

So at what number of satellites would you guys consider as optimum for safest flight and lowest for bringing it home. I have a mini, an M2 pro and an FPV

That's not how GPS works.
There is no single magic number of sats to answer your question.
Just wait until the flight controller determines that the GPS data is reliable.

 

[GadgetGuy]

The Agps comes from the phone to the drone. The drone has no data other than what it receives from the device. Both drone and controller have GPS. How DJI routes and parses the data is unknown. THAT is where the discrepancy lies. DJI has changed something for the M3.

There is no AGPS coming from the tablet to the drone. That has been repeatedly confirmed above. It is the drone that must use its own GPS chip to establish the Home Point. Whether the tablet has GPS or not is irrelevant to establishing the Home Point. Yes, something has been changed in how quickly the Home Point is acquired by the drone since the December update, and the January update did not improve it.

 

[surfbird]

The Agps comes from the phone to the drone. The drone has no data other than what it receives from the device. Both drone and controller have GPS. How DJI routes and parses the data is unknown. THAT is where the discrepancy lies. DJI has changed something for the M3.

Exactly!

>How DJI routes and parses the data is unknown
For the mavic3 that is. The AGPS messages has been the same for ages. I doubt they change that.
I think it's more how the firmware decodes the data, if it does at all.
The AGPS-data is not the ordinary AGPS-data. It consist mostly of lat/lon and time from what I've seen.

 

[GadgetGuy]

That's not how GPS works.
There is no single magic number of sats to answer your question.
Just wait until the flight controller determines that the GPS data is reliable.

To clarify, as you have previously stated, the GPS icon changes from red to yellow, and finally to white when the GPS data is reliable and the Home Point is first set, and if it changes back from white to yellow, it is no longer reliable. The Mavic 3 can switch back and forth from white to yellow, even after the Home Point is first set, causing concern. Purely for reference purposes only, 12 satellites will now generally be enough to establish the Home Point on the Mavic 3. It may occur earlier than 12, but I have rarely, if ever, seen it exceed 12 before the Home Point is set.

 

[JooB]

The number of fixed satellites is a good point. The Mavic 3 needs 12 or 13 fixed satellites to establish a Home Point, that's more than other DJI drones need and takes more time.
Mini 2 needs 10, M2Z needs 9 fixed satellites for a Home Point if I counted right.
I don't think AGPS is the problem here but loading down the almanac data that come with the GPS signal and processing them to get faster fixes. Perhaps DJI changed the algorithm...
And those almanac data are valid just a defined time. So if I understood it right if you fly your drone every 2 or 3 days you will get faster fixes than flying it just every 2 or 3 weeks because in the first scenario the almanac data are up to date, in the second they are outdated and have to be renewed.

 

[Meta4]

The number of fixed satellites is a good point. The Mavic 3 needs 12 or 13 fixed satellites to establish a Home Point, that's more than other DJI drones need and takes more time.
Mini 2 needs 10, M2Z needs 9 fixed satellites for a Home Point if I counted right.

There's a lot of misunderstanding around this topic so I'll try to clear up some of it.

There is no single number of sats required to record the home point (except that it must be 6 or more).
The number of sats you observe when your drone records the home point is not fixed and will vary.
If you had an early DJI drone that only used the US GPS constellation, you might find that it recorded the homepoint with 6 sats, if they were well spread across the sky.
If some were bunched, you would need more.

When later drones started using Glonass sats as well as GPS, you still needed a minimum of 6 sats, but with two different constellations, the chance of some sats being bunched was greater, so you might need 9 or 10 before you could record a home point.

With the Mini 2, Air 2S and Mavic 3 using three different constellations, you still need a minimum of 6 sats, but by the time your drone has found 6 with a good spread, you will always have many more than six, having so many more sats in your sky for the drone to pick up.
But with three different constellations, there will be even more that are too close together to provide good triangulation.

The big problem with the Mavic 3 and sat reception is that even after waiting 5 minutes, it still might only have 8 or 9 sats, when it should have found >20.

 

[zinko]

Turn on your mavic 3 wait that connect to 8-9 satelites. By mine is this in 20-30 secounds. Turn off wour mavic wait 5 secounds and turn it on. Mavic will record home point imediatly! And with 8-9 satelites. Just try it and report back.