Issues w/ GPS, takes up to 20 mins to pick up sats (UPDATE)

[Mako79]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Have you tried making sure that the GPS connection is firm? You can pull the pins out of the 4 pin connector plug and redo them again to assure they are connected. you can then wrap or wedge something in the connector to stop it from moving.

 

[SteveMann]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Back to the GPS module, I'm not all that familiar on how they are supposed to operate....is the battery supposed to maintain a charge or is it normal that it is losing it's charge each time the p2 is powered off for an extended period of time? I would think a battery should hold its charge, and that either the battery is self-draining or their is a short somewhere causing it to drain (maybe more likely?). Am I way off base or is this how they are intended to operate?

There is a small amount of memory in the GPS module that the battery keeps alive. The memory is used to assist in the acquisition of satellites at power-up by allowing the receiver to generate a list of visible satellites based on the stored satellite positions and time last seen. Without a battery the cold-start will take 10 to 20-minutes.

For more info: http://gps.about.com/od/glossary/g/GPS_Almanac.htm

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Back to the GPS module, I'm not all that familiar on how they are supposed to operate....is the battery supposed to maintain a charge or is it normal that it is losing it's charge each time the p2 is powered off for an extended period of time? I would think a battery should hold its charge, and that either the battery is self-draining or their is a short somewhere causing it to drain (maybe more likely?). Am I way off base or is this how they are intended to operate?

There is a small amount of memory in the GPS module that the battery keeps alive. The memory is used to assist in the acquisition of satellites at power-up by allowing the receiver to generate a list of visible satellites based on the stored satellite positions and time last seen. Without a battery the cold-start will take 10 to 20-minutes.

For more info: http://gps.about.com/od/glossary/g/GPS_Almanac.htm

This part I understand...my question is more simplistic. Shouldn't the battery maintain its charge when power supply to the GPS module is terminated (i.e. Phantom powered off)? The battery on my GPS module is draining to 0 volts in less than a days time, maybe sooner but I haven't been around to confirm how fast. This goes against logic for me, I would think the battery should maintain charge. If it loses its charge then that explains the reasoning why it takes so long each time, as if it is powering up in a cold start mode.

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

So I don't think the battery is bad, I think it lost its charge and the gps just can't warm start itself. I suggest you allow the battery to charge and then disconnect the gps while the phantom is powered on and then reconnect the gps module. I think the gps the NAZA times out looking for the gps. If this doesn't work then after the battery has a decent charge turn off the phanton and turn it back on.

If this doesn't work then I feel the gps lost its configuration and I don't know how to reload or where to the configuration file. It is normally a fddi connection but DJI is a closed system and replacing the gps may be your only option, thanks DJI.

I think you may be on to something here Bill. I powered the P2 on inside my house for 15 mins with the intent of charging the GPS module battery. Powered it off, set it outside in the backyard, and powered back on. Checked my FPV monitor 5 mins later and had 10 satellites...finally!

Same thing this afternoon but a little different...I set it outside right off the bat and powered the P2 on. Gave it 10 mins and zero satellites. Powered it off and back on again and it picked up 8 sats within a minute. I think you may be right that the battery is draining and the P2 is timing out waiting for the GPS data. When I power it off and back on, the battery is now charged and it is able to load the GPS data.

Now to get to the bottom of this...I need to figure out why the battery is draining and how to replace the bad component (whether the battery itself or another component causing a drain).

Can someone please check my logic here and confirm if this sounds like the issue?

 

[Bill_Burkert]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

I started with 3DR APM based quads three years ago and dealt with a very similar problem with the same solution. I suspect DJI did not start with a clean slate and develop NAZA but rather some branch of the APM code. I wish I had a test NAZA to reverse enginneer

I bet you're back to normal so enjoy flying.

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

I bet you're back to normal so enjoy flying.

Don't think I'm back to normal yet. As far as I can tell thus far, in order to fly with GPS lock (I won't fly without), I need to power my P2 on for 15-20 mins before I want to fly in order to charge the GPS module battery (still have zero sats at this point). Then if I power off the P2 and back on again it will pick up sats within a minute or two as it should. Presumably this is because the NAZA is timing out waiting for a GPS signal while the GPS module is charging its battery and/or trying to obtain sats from a cold start scenario.

I'm still hoping that someone can confirm that this sounds like a logical explanation. I have come to this conclusion based on input from you and some others in this thread and verified (I think) it with some trial and error testing around the house. DJI is now communicating with me but just asked that I send it in with no attempt to help me resolve it. It already cost me $80 for shipping and three weeks to send it in last time. I am trying to explain my theory to them and see if they agree...if so I will see if they can send a replacement GPS module for me to swap out and see if that fixes the problem. Does that sound like a reasonable solution based on my issues?

 

[Bill_Burkert]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

You could still replace the battery. The top + looks to have a spring steel push-on cap that looks like it can be pried up/off, replace battery, push the cap firmly back on? Maybe DJI drained the battery to low and killed the battery?

 

[Bill_Burkert]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

viewtopic.php?f=4&t=13766

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

You could still replace the battery. The top + looks to have a spring steel push-on cap that looks like it can be pried up/off, replace battery, push the cap firmly back on? Maybe DJI drained the battery to low and killed the battery?

Agreed with replacing the battery but I'm going to save that as a last resort, it seems to be a fairly rigid piece holding it in. I tried to gently pry it a few days ago and it didn't seem close to budging. I don't want to risk messing anything up just yet. If I do it, I'll just need to make sure I have the right tools so I don't slip applying the force it needs and damage something. I also worry about getting a tight fit afterwards.

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

http://www.phantompilots.com/viewtopic.php?f=4&t=13766

Thanks, good information there

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

So after testing more last night and this morning, I can now say with 100% certainty that if the P2 has been powered off for more than 20 mins, that I must power on the P2 for at least 10 mins (0 sats at this point and will stay at 0 if I leave it on for up to 30 mins), then power off and back on. Once power cycled, it will pick up sats within a minute or two. Seems to pick up faster, within a minute, if I had previously left it powered on for 15-20 mins rather than 10 mins.

Just summarizing for anyone else experiencing similar issues. Surely I'm not the only one this has happened to. I've read through some older posts that sounded like people were having similar issues but never diagnosed.

Will update this once I either get a replacement gps from dji or if I have to replace the battery myself.

 

[Ericf]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

So after testing more last night and this morning, I can now say with 100% certainty that if the P2 has been powered off for more than 20 mins, that I must power on the P2 for at least 10 mins (0 sats at this point and will stay at 0 if I leave it on for up to 30 mins), then power off and back on. Once power cycled, it will pick up sats within a minute or two. Seems to pick up faster, within a minute, if I had previously left it powered on for 15-20 mins rather than 10 mins.

Just summarizing for anyone else experiencing similar issues. Surely I'm not the only one this has happened to. I've read through some older posts that sounded like people were having similar issues but never diagnosed.

Will update this once I either get a replacement gps from dji or if I have to replace the battery myself.

Any updates? I am having a similar issue. I can't get any satellites at all, no matter what I do. Curious to see what you found or what DJI did for you. Thanks!

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Had to send it back in, but DJI did provide a prepaid shipping label and ordered an escalated RMA, supposed to be a 7 day turnaround or something along those lines. Package was delivered to them on Friday so I should know more this week and will post an update.

Ericf, to confirm if the exact same issue, see if your P2 will pick up sats if you power it on for 15 mins, then turn it off and back on again.

I saw in another thread you mentioned you bought yours in December. I bought mine at the same time, potentially both in the same batch? I got mine from B&H.

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Also, if anyone has their P2 opened up, would you mind taking a voltage measurement across the GPS module battery after the unit has been powered off for more than a few hours and let me know what it measures?

 

[N017RW]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Also, if anyone has their P2 opened up, would you mind taking a voltage measurement across the GPS module battery after the unit has been powered off for more than a few hours and let me know what it measures?

It's not a battery it is a 'super cap' and is not intended to be replaced as it is spot welded into the holder.

The GPS data it backs up (ephemeris, almanac) is only good for 2-4 hours so the intent is that after your first flight your subsequent flights will fix the position faster.

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Also, if anyone has their P2 opened up, would you mind taking a voltage measurement across the GPS module battery after the unit has been powered off for more than a few hours and let me know what it measures?

It's not a battery it is a 'super cap' and is not intended to be replaced as it is spot welded into the holder.

The GPS data it backs up (ephemeris, almanac) is only good for 2-4 hours so the intent is that after your first flight your subsequent flights will fix the position faster.

Thanks N017RW. I saw your previous post in this thread about the supercap but mistakenly thought you were talking about a different component.

The reason I asked for someone else to verify voltage is because I am not convinced that its not abnormal for the supercap (what I have been calling battery) to read a low voltage after turning off power for a few hours. Do you have any idea how long it should hold its charge? Based on your description, sounds like it is mostly effective for a quick position fix within shorter time periods, on the order of a few hours. I also realize that the supercap isn't required, but it does help for a quicker fix if within a shorter time period.

Ultimately, I am still trying to determine why my Phantom will pick up zero sats upon the first power up after it has been off for roughly an hour or more, no matter if I leave it on for up to 30 mins with available sats and clear view. Then if I power it off and back on, it will pick up sats within a minute or two.

Hopefully DJI will sort it out and provide a description of the issue. At this point, I just want to understand why this is happening. Surely I am not the only one this has happened to, but can't find much else on the forums about this.

Thanks for the help

 

[N017RW]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

OK. And of course I can only comment on my experiences. I only have one battery and I always have about the same TTF (time to fix) regardless of whether its been a day or a few weeks since flying last.

I live in south Florida and fly in a low-density urban environment at local parks etc.

My TTF is about 1.5-2 minutes after battery turn-on and as far as I recall it has always been about that amount of time.
I have a second battery on order so eventually I'll be able to see if there is a reduction in TTF with back-to-back flights.

 

[Ericf]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

OK. And of course I can only comment on my experiences. I only have one battery and I always have about the same TTF (time to fix) regardless of whether its been a day or a few weeks since flying last.

I live in south Florida and fly in a low-density urban environment at local parks etc.

My TTF is about 1.5-2 minutes after battery turn-on and as far as I recall it has always been about that amount of time.
I have a second battery on order so eventually I'll be able to see if there is a reduction in TTF with back-to-back flights.

Good info! I'm with Brianh though....there is some defective component that is causing our Phantoms to take a really long time to fix on satellites. In my case it never does. If that supercap was only designed to hold power for 2-4 hours then that doesn't sound like the issue.

 

[brianh]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

OK. And of course I can only comment on my experiences. I only have one battery and I always have about the same TTF (time to fix) regardless of whether its been a day or a few weeks since flying last.

I live in south Florida and fly in a low-density urban environment at local parks etc.

My TTF is about 1.5-2 minutes after battery turn-on and as far as I recall it has always been about that amount of time.
I have a second battery on order so eventually I'll be able to see if there is a reduction in TTF with back-to-back flights.

This is what I would consider "normal" operation. The issue that I have is my Phantom WILL NOT pick up ANY satellites unless I power it on for 15+ minutes AND THEN power cycle the Phantom. This is the only way I will pick up sats after it has been powered off for more than an hour or so.

Like Ericf said, there must be a defective component causing this, whether the supercap, GPS module, or something on the main board. This is what I am trying to figure out...what would cause this sort of behavior? I will update i get any answers from DJI.

 

[Ericf]

Re: Issues w/ GPS, takes up to 20 mins to pick up sats (UPDA

Ultimately, I am still trying to determine why my Phantom will pick up zero sats upon the first power up after it has been off for roughly an hour or more, no matter if I leave it on for up to 30 mins with available sats and clear view. Then if I power it off and back on, it will pick up sats within a minute or two.

Hopefully DJI will sort it out and provide a description of the issue. At this point, I just want to understand why this is happening. Surely I am not the only one this has happened to, but can't find much else on the forums about this.

Thanks for the help

I'm with you on this one Brianh! I can't seem to find anything online except a couple of threads on this forum. We must be some of the "lucky" few :lol: Keep us posted on what DJI says. I'm working on starting a warranty claim as well but I already did the 5db antenna mod, hoping that would solve the problem....it didn't.