Follow Me Mode Weak Satellite

[Jussaguy]

One of us do not understand how this works. If I have understood correctly, the controller reads the the GPS phone/tablet from the phone and sends it to the bird. However, the controller cannot get "good data" from the phone, saying the GPS signal is too weak. The app knows where it is, showing it on the map. Somehow it is not able to send it via the cable to the controller. SW bug, I'm pretty sure. The controller and the bird communicates just fine, no transmitter issue.

Right you don't.

There is a hand shake for GPS via receiver and GPS unit.

There is a GPS unit in the bird and there may or may not be one in your tab/phone/rc.

The transmitter from your phone needs a good reading from the bird's GPS from it's transmitter (which is in the RC) in order to track your bird, get maps and do everything that has to do with GPS other than follow me and make dynamic homepoints.

There is a transmitter in the bird as well which reads the GPS in your phone/tab/rc and relies on the GPS signal in the tab. It is saying on mine no matter whether I use Android or iOS or where I am or whatever device I use that I cannot receive a new hp at the RC or use follow me, which with all the troubleshooting I've done indicates that I PROBABLY have a bad transmitter. It's electronics, it happens.

 

[Jussaguy]

I tried mine tonight with an iPhone 6s and Ruth as controller worked perfect definitely an issue with the iPhone 7plus intel version :-(

I wish that was true and am not sure it isn't but here it is not working in an Android phone nor an iOS phone.

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I am aware I am in an NFZ here but I was flying in a non-NFZ location (several of them to troubleshoot and anyway you can see I can set the bird's HP).

Also, I ran diagnostics on the NAV on each test.

I hope I'm wrong because if you are right, that can be worked around via a firmware code but since I bought from DJI and they are strict, I am playing it safe and I have tried like gangbusters to get it to work and was willing to keep it if it worked with the Android phone and when it didn't, that's when I gave up.

 

[ThorH]

There is a transmitter in the bird as well which reads the GPS in your phone/tab/rc and relies on the GPS signal in the tab.

Your use of the word "transmitter" is confusing me. A transmitter transmits radio signals, a receiver receives them. A two-way radio will have both. GPS is one-way. Our birds and phones are GPS receivers only, the GPS transmitters are in the satellites. The OS forwards the GPS data to the apps requesting it, and I think this is where the bug is.

But semantics aside, you mean that the bird makes the calculation on where it is relative to the controller/app, rather than the other way around? And that the two-way radio link that flawlessly relays flight commands and HD video suddenly is unable to send this small data?

Btw, I do not have a problem setting the RTH location!

It is an interesting debate, but as neither of us work at DJI, this is all speculations and beyond us to fix anyway.

 

[Jussaguy]

Your use of the word "transmitter" is confusing me. A transmitter transmits radio signals, a receiver receives them. A two-way radio will have both. GPS is one-way. Our birds and phones are GPS receivers only, the GPS transmitters are in the satellites. The OS forwards the GPS data to the apps requesting it, and I think this is where the bug is.

But semantics aside, you mean that the bird makes the calculation on where it is relative to the controller/app, rather than the other way around? And that the two-way radio link that flawlessly relays flight commands and HD video suddenly is unable to send this small data?

Btw, I do not have a problem setting the RTH location!

It is an interesting debate, but as neither of us work at DJI, this is all speculations and beyond us to fix anyway.

Bingo.

You have the idea right but semantics are also correct. While transmitters are most often used when describing radio waves, think of the tower as the gps transmitter and the TV as the receiver.

It most certainly is called a GPS transmitter and receiver and there is one going both ways. You buy GPS transmitters and GPS receivers if you are building your own. That's what they are called.

A lot of people don't have the problem, some do. Go look at my current thread on DJI.COM with Ken. He thinks I have bad hardware as well. He managed to duplicate the problem with one of his devices.

I think it probably comes down to firmware at the end of the day. I was finally able to make a Galaxy S6 barely work which just threw a wrench in my game.

I am going to act on my RMA which was authorized a couple days ago before they change their mind but my gut says it's probably firmware against all my testing which shows otherwise. I'm going back 3 firmwares (the first) and if that doesn't work, going back and I'll get the next one.

Thanks for the input.

 

[dmitriy]

My Verizon iPhone 7+ has the same problem with setting a new home point at the controller. However an android (yotaphone 2) device doesn't have any issues with the same Mavic/Controller combo.

Interestingly the Remote controller will display correct flight distance (lower right on the LCD screen) between it and the mavic even when its on the ground with props off and if you walk around with the controller in your hand without moving the Mavic at all. (though there is about 10-20seconds of lag on that). So the GPS seems to be working there somehow...?

 

[Jussaguy]

My Verizon iPhone 7+ has the same problem with setting a new home point at the controller. However an android (yotaphone 2) device doesn't have any issues with the same Mavic/Controller combo.

Interestingly the Remote controller will display correct flight distance (lower right on the LCD screen) between it and the mavic even when its on the ground with props off and if you walk around with the controller in your hand without moving the Mavic at all. (though there is about 10-20seconds of lag on that). So the GPS seems to be working there somehow...?

I thought I just answered this. Weird.

The GPS that shows you how far you are from tye but it's and all telemetry is through the GPS receiver in the bird, not the RC. It can get confusing but telemetry is with a transmitter from the RC and a GPS receiver in the bird.

Follow me and dynamic homspoints are from a transmitter in the bird and a receiver in the RC (phone/tab).

 

[HFMan]

Not sure what you are trying to say here. The distance between the RC and the Mavic is the result of a calculation of two GPS receivers... One on the Mavic, and one on the device (iPhone or Android) connected to the RC controller. There is not a GPS "transmitter" on either device. And to be clear, I don't think we know for sure if the calculation is done on the Mavic or the DJI phone. I suspect it is done on the Mavic, as the distance is reported on the RC whether a phone is connected or not.

 

[Johnmcl7]

It's difficult to tell as few sites go into much detail on the chips inside Apple devices, it appears that the Intel based iPhone is using a Broadcom GPS chip rather than an Intel one and from reading around the Qualcomm one uses the same GPS chip as it seems to have some other functionality as well:

Apple iPhone 7 Teardown

Is the iPhone 7/7+ compatible with the new Galileo navigation system? • r/iphone

https://blog.francis-fustier.fr/en/galileo-et-les-mobiles-apple/

What is clear though is that the iPhone6 and LTE iPads are definitely not using Intel modems yet people report the same weak signal issue with them as well. Also in regards to the earlier post about only the Intel modem having GPS issues for sports tracking, that's not true as it's easy to find plenty people having similar GPS issues with both iPhone 7 variants. I can't see how this is anything other than a bug in the DJI software, if the phone can pinpoint its own location in other apps using GPS then it shouldn't be an issue for the DJI app to do the same.

John

 

[HFMan]

Yeah, something is up. My LTE IPad Pro 9.7 has no issue with DJI Go 4... can use follow-me and set Home to RC Location without issue. I am NOT using the latest Go 4 for IOS- perhaps that has something to do with it.

 

[ThorH]

An answer of sorts from DJI was posted in one of the FB groups. Unable to find it now, but the short version is that DJI were to add to their support site that the feature is not supported on iPhone 7 (-+). I hope this is not their standard way of dealing with anything difficult...

 

[FlashGJ]

. I can't see how this is anything other than a bug in the DJI software, if the phone can pinpoint its own location in other apps using GPS then it shouldn't be an issue for the DJI app to do the same.

John, you may be correct, but there is also a lot of discussion on some of the 3rd party running app forums about inaccuracies in routes and distance being recorded when used on iPhone 7 & 7+ with the intel modem. So do those running apps have a similar bug that only crops up on those specific iPhones?
If it is a bug in DJI app, it seems to affect EVERY iPhone 7 with intel modem, but many users on different models are having no issues. (Works great on my 6s, but always get "weak GPS" error on my 7 with intel).

 

[wolfmad]

Same here

 

[HFMan]

To be clear for those with iPhone 7/7+ - have you ensured you have granted Location services privileges to Go 4? Seems unlikely this is the issue, but wanted to cross that off the list.

 

[HFMan]

Interestingly the Remote controller will display correct flight distance (lower right on the LCD screen) between it and the mavic even when its on the ground with props off and if you walk around with the controller in your hand without moving the Mavic at all. (though there is about 10-20seconds of lag on that). So the GPS seems to be working there somehow...?

No... in this scenario, the Home point has been uploaded to the Mavic. The Mavic knows where it is at any given time based on its GPS. The Mavic calculates distance to that static home point at least 10 times per second, and sends that calculated distance back to the RC. I'm sure if you were to walk a mile away from your launch point without resetting the home point, the RC would still show the original distance.

 

[Johnmcl7]

. I can't see how this is anything other than a bug in the DJI software, if the phone can pinpoint its own location in other apps using GPS then it shouldn't be an issue for the DJI app to do the same.

John, you may be correct, but there is also a lot of discussion on some of the 3rd party running app forums about inaccuracies in routes and distance being recorded when used on iPhone 7 & 7+ with the intel modem. So do those running apps have a similar bug that only crops up on those specific iPhones?
If it is a bug in DJI app, it seems to affect EVERY iPhone 7 with intel modem, but many users on different models are having no issues. (Works great on my 6s, but always get "weak GPS" error on my 7 with intel).

If anything, there's more reported GPS problems with the Qualcomm phones than there is the Intel ones - this is the first thread a search throws up and people believe the GPS issues are primarily on the CDMA (Qualcomm) iPhone 7's and particularly Verizon ones while there's a few posts about AT&T models (Intel modem) being fine and if there is an issue, a replacement has sorted it.

Admittedly I don't think it's specific to the Qualcomm or Intel modem, both report GPS issues and if they're using the same GPS chipset that makes sense and I've no idea what the Intel/Qualcomm split is as I believe Qualcomm iPhone 7's are sold in Europe even though there is no CDMA here. Even then the issues reported are different to what DJI Go 4 is returning - it's saying the signal is weak but when you read up on the GPS issues people are having, they are getting a lock but it's not accurate and can drift off.

I don't have or use an iPhone but I guess a simple test would be when the app is saying weak signal and refusing to function, can the iPhone correctly find its own location through another app? Then if it does do that, does the DJI App then acknowledge the GPS location? If it works in the latter case after the GPS is warmed up, the DJI Go App is possibly not waiting long enough to get a location back from the phone/tablet.

John

 

[Johnmcl7]

Not sure what you are trying to say here. The distance between the RC and the Mavic is the result of a calculation of two GPS receivers... One on the Mavic, and one on the device (iPhone or Android) connected to the RC controller. There is not a GPS "transmitter" on either device. And to be clear, I don't think we know for sure if the calculation is done on the Mavic or the DJI phone. I suspect it is done on the Mavic, as the distance is reported on the RC whether a phone is connected or not.

This doesn't sound correct as it that would mean the Mavic controller would need its own internal GPS as well to function without a phone/tablet however since it doesn't have GPS and it can work without a phone/tablet it can't be measuring the distance using a pair of GPS receivers. I assumed it must be working out the distance by measuring the latency from the controller to the drone and back.

John

 

[wolfmad]

I would like to hear of someone getting an intel iPhone working!!!!

 

[HFMan]

This doesn't sound correct as it that would mean the Mavic controller would need its own internal GPS as well to function without a phone/tablet however since it doesn't have GPS and it can work without a phone/tablet it can't be measuring the distance using a pair of GPS receivers. I assumed it must be working out the distance by measuring the latency from the controller to the drone and back.

John

I misstated what I meant to say. You are right... the RC controller doesn't have a GPS yet displays distance to home. That is because the Mavic knows where it's home point is (established at launch) and knows where itself is at any given time. I don't know which side does the calculation, the Mavic or the RC Controller. I presume the Mavic, and that is sent down with the telemetry. The only time the GPS on the phone is used is when using follow-me or setting Home point to RC Controller location.

 

[JLane]

Right you don't.

There is a hand shake for GPS via receiver and GPS unit.

There is a GPS unit in the bird and there may or may not be one in your tab/phone/rc.

The transmitter from your phone needs a good reading from the bird's GPS from it's transmitter (which is in the RC) in order to track your bird, get maps and do everything that has to do with GPS other than follow me and make dynamic homepoints.

There is a transmitter in the bird as well which reads the GPS in your phone/tab/rc and relies on the GPS signal in the tab. It is saying on mine no matter whether I use Android or iOS or where I am or whatever device I use that I cannot receive a new hp at the RC or use follow me, which with all the troubleshooting I've done indicates that I PROBABLY have a bad transmitter. It's electronics, it happens.

FWIW, I did a quick test on your theory about the problem being in the GPS transmitter in the Mavic.

Step 1 - With the Mavic on the ground in an open area with good GPS coverage, I blocked the Mavic's GPS signal so that it was only seeing a few satellites, forcing it into ATTI mode (ie. very poor GPS accuracy)

Step 2 - Walked with the RC several meters away from the Mavic and original Home Point

Step 3 - Successfully set a new Home Point to the RC's position

If your theory were correct that setting a Home Point relies on a good GPS reading from the Mavic, then my test should have failed.

 

[wolfmad]

I'll bet you were not using an iPhone with the Intel modem in it! LOL