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

[brianh]

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.

To confirm the same issue, take yours outside and power on for 15 mins. If still at zero satellites, power off and back on and see if you pick up sats and let me know.

I saw where you mentioned in the other thread that it normally took you 5-10 mins to pick up sats and now it won't at all. This is exactly what mine did, also purchased in mid-December. My GPS has always seemed "finicky" because it seemed to take much longer than it should, but now it has gotten to the point where it won't pick up satellites at all unless I go thru the sequence I have talked about.

Sounds very similar to yours, but try that test and see if it works. I'll let you know what feedback I get from DJI.wreath

 

[N017RW]

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

What I meant by the 2-4 hours comment is that is about how often the ephemeris data is valid. I'm not positive on the exact amount of time but that is what I recall. So updating is constatnt

Yes it does seem odd that it takes so long but I don't believe it has anything to do with the s-cap. It is not a required component but the intent or purpose of it is obvious.

The replacement of the GPS antennas documented here and it's improvements in the TTF time is somewhat interesting.
The 'gain' they spec them at means they have reduced the beamwidth of the antenna to a narrower 'window' if you will and many spec these gain values with a 75x75 mm ground-plane. I'm not sure the of the GP size designed into the GPS module.

 

[Ericf]

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

To confirm the same issue, take yours outside and power on for 15 mins. If still at zero satellites, power off and back on and see if you pick up sats and let me know.

I saw where you mentioned in the other thread that it normally took you 5-10 mins to pick up sats and now it won't at all. This is exactly what mine did, also purchased in mid-December. My GPS has always seemed "finicky" because it seemed to take much longer than it should, but now it has gotten to the point where it won't pick up satellites at all unless I go thru the sequence I have talked about.

Sounds very similar to yours, but try that test and see if it works. I'll let you know what feedback I get from DJI.wreath

Thanks Brian! I have already done this and I didn't get anything. I am going to give it another try to see if I can replicate what you are seeing. My GPS has always taken a lot longer to fix than others (from what i've read online) and then, last week it just quit. Do you fly with a OSD and a screen? I have always noticed another odd thing while in GPS mode, the icon on the screen will flicker to ATTI while the switch is in the GPS position. I don't know if the issues are related or if that is normal. I hope DJI gets back to you with some good news. Thanks again.

 

[Ericf]

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

What I meant by the 2-4 hours comment is that is about how often the ephemeris data is valid. I'm not positive on the exact amount of time but that is what I recall. So updating is constatnt

Yes it does seem odd that it takes so long but I don't believe it has anything to do with the s-cap. It is not a required component but the intent or purpose of it is obvious.

The replacement of the GPS antennas documented here and it's improvements in the TTF time is somewhat interesting.
The 'gain' they spec them at means they have reduced the beamwidth of the antenna to a narrower 'window' if you will and many spec these gain values with a 75x75 mm ground-plane. I'm not sure the of the GP size designed into the GPS module.

Sorry, I misunderstood. That makes sense on the s-cap now. So you are saying that the higher the gain, the smaller window of the sky it has? I saw 100% success rate from people changing to a higher gain antenna, I figured I would try it for $5...but if it narrows the view of the sky, maybe it really isn't the best idea?

 

[N017RW]

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

I never had the problem with my P2.
I can't argue with the success demonstrated by the folks here with this.

I would not say that it sees a smaller view of the sky, sorry if I misled you, but rather it will have more gain in some reduced portion of it's view.
The thicker patch for a given size would produce a bit higher gain but the size of the ground plane is the most influential in determining gain.

Additionally the patch should be centered in this ground plane for beat results. Other wise the polarization becomes more and more elliptical which is not good as the GPS signal is [right-hand] circularly polarized

 

[Ericf]

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

I never had the problem with my P2.
I can't argue with the success demonstrated by the folks here with this.

I would not say that it sees a smaller view of the sky, sorry if I misled you, but rather it will have more gain in some reduced portion of it's view.
The thicker patch for a given size would produce a bit higher gain but the size of the ground plane is the most influential in determining gain.

Additionally the patch should be centered in this ground plane for beat results. Other wise the polarization becomes more and more elliptical which is not good as the GPS signal is [right-hand] circularly polarized

Ok, that makes a lot of sense! Thank you for the info.

If my Phantom had facial expressions, it would have a very annoying smirk right now... I just took it outside and powered it on to let it "charge" the s-cap like Brianh advised. It had 5 satellites in less than 30 seconds and a full 7 sat lock in under 1 minute. I let it sit for two more minutes and it had a max of 9 on the ground. I took it up to 100 feet and it maxed out at 11 satellites. I don't know if I am relieved or infinitely more frustrated. It hasn't shown a single satellite the last 4 times I've powered it up in 3 different locations. I am letting it sit for an hour or so and then out to try again and see what the results are. Intermittent problems are worse than not working at all in my opinion. Thanks for all the help everyone!

 

[brianh]

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

Haha, never fails!

When was the last time it was powered on prior to doing this? if somewhat recently, that may be the reason. Or perhaps you have a different issue. I agree, intermittent issues are more frustrating!

I'm not convinced it's the s-cap, especially after the recent insight from N017RW, but whatever the issue is, that is the method I have to use to get gps lock.

Keep us posted and good luck.

 

[Ericf]

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

Haha, never fails!

When was the last time it was powered on prior to doing this? if somewhat recently, that may be the reason. Or perhaps you have a different issue. I agree, intermittent issues are more frustrating!

I'm not convinced it's the s-cap, especially after the recent insight from N017RW, but whatever the issue is, that is the method I have to use to get gps lock.

Keep us posted and good luck.

Yeah, I don't like it when my electronics have a sadistic sense of humor. :twisted: I haven't powered it on since Saturday evening. On that day I tried powering it on for 20 minutes, then off, then back on and still not a single satellite. I am curious to see what DJI does for you. Forgive me if you mentioned it previously but did you send the whole Phantom back to them or just the GPS puck?

 

[N017RW]

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

Do you have Naza and IOC enabled?

If so do you get the rapid greens to indicate Course Lock/Heading setting or storage after 30-45 seconds?

 

[Ericf]

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

Do you have Naza and IOC enabled?

If so do you get the rapid greens to indicate Course Lock/Heading setting or storage after 30-45 seconds?

Yes and yes. That seems to be functioning correctly.

 

[brianh]

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

Do you have Naza and IOC enabled?

If so do you get the rapid greens to indicate Course Lock/Heading setting or storage after 30-45 seconds?

Yes, NAZA and IOC enabled. I tried switching back to Phantom mode once and still had the same GPS issues, but then switched back to NAZA.

I can't say with 100% certainty, but I do not think I got the rapid greens to indicate course lock/heading until the unit picked up satellite lock. Most of the time, I would power it on, watch it for a minute or so along with my FPV monitor and then leave it outside while I monitored satellites with the FPV monitor. It seems that I would not get the rapid greens for course lock/heading until I got a GPS lock. I would get two sequences of flashing green not far apart, presumably one for course lock and one for GPS lock.

If relevant to this, my unit has required compass calibration more frequently than normal (indicated by flashing lights upon power up). I also received the compass calibration required light sequence after landing one time when the compass was calibrated prior to the flight (it was a soft landing). Also the compass has failed to calibrate 2-3 different times where I have had to turn it off and back on. Can you make any connection with that?

Thanks again for the help.

 

[N017RW]

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

I always get the Course Lock rapid set first but sometimes my two sets of green rapids seem to occur sequentially and I do a restart to be sure both are individually confirmed.

No connection with this problem to the compass, I believe, unless this is something common to both which is the "main" PCB (or of course you also have a bad or gauss-ed compass).

On my P2-NV, the main PCB interfaces everything to the Naza via the "EXP" port except the motor speed signals, the USB port, X3 (which is Naza Vcc power) and X2 (from the control receiver's S-Bus (same as DJI D-bus)). These connect to the the Naza directly.
There's also a second connector from the OEM receiver to the Naza but I have replaced my receiver with a Futaba so it is no longer there and I don't remember what Naza port it was connected to (X1 but just a wild guess).

 

[Ericf]

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

Haha, never fails!

When was the last time it was powered on prior to doing this? if somewhat recently, that may be the reason. Or perhaps you have a different issue. I agree, intermittent issues are more frustrating!

I'm not convinced it's the s-cap, especially after the recent insight from N017RW, but whatever the issue is, that is the method I have to use to get gps lock.

Keep us posted and good luck.

Another update: I powered it on and had to wait 15 minutes for any satellites, then it locked. Powered it off and then back on again and had 9 satellites instantly. It definitely seems to be cold starting unless you are powering it back on, seconds after it was powered off. hmmm....seems to be working-ish. Still seems like 15-30 minutes for GPS lock is evidence of a malfunction of some kind.

 

[N017RW]

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

Absolutely.

I can't locate a link at the time but 38 or so seconds is the 'cold-start' TTF for the U-blox NEO 6Q GPS engine. Add some overhead for SNR or local interference issues and some system communication latency (benefit of the doubt), etc. and to me 1- 2 min. TTF is reasonable for a system of this quality.

 

[kirk2579]

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

Haha, never fails!

When was the last time it was powered on prior to doing this? if somewhat recently, that may be the reason. Or perhaps you have a different issue. I agree, intermittent issues are more frustrating!

I'm not convinced it's the s-cap, especially after the recent insight from N017RW, but whatever the issue is, that is the method I have to use to get gps lock.

Keep us posted and good luck.

Another update: I powered it on and had to wait 15 minutes for any satellites, then it locked. Powered it off and then back on again and had 9 satellites instantly. It definitely seems to be cold starting unless you are powering it back on, seconds after it was powered off. hmmm....seems to be working-ish. Still seems like 15-30 minutes for GPS lock is evidence of a malfunction of some kind.

I would order the 931-1126 -nd from digikey or 1015 for about 5 bucks and 4 dollars ship and just see what happens . No downside at all, only thing that might happen is your concerns go away.
I have updated both my p2 v1 and p2 vision plus a month ago and simply go out , power up wait about 1 minute for both course and sat lock. Then I fly in cloudy, sunny, snowy ,under trees , next to house and cars without dropping sat lock.
Prior to update I waited and waited and sometimes never got lock
Now I get solid sat reception inside my house.

dji may or may not fix anything and take forever to do it or not. 3 or 4 days and this is done from order to install provided you can do basic soldering

good luck and good flying!

 

[Ericf]

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

I would order the 931-1126 -nd from digikey or 1015 for about 5 bucks and 4 dollars ship and just see what happens . No downside at all, only thing that might happen is your concerns go away.
I have updated both my p2 v1 and p2 vision plus a month ago and simply go out , power up wait about 1 minute for both course and sat lock. Then I fly in cloudy, sunny, snowy ,under trees , next to house and cars without dropping sat lock.
Prior to update I waited and waited and sometimes never got lock
Now I get solid sat reception inside my house.

dji may or may not fix anything and take forever to do it or not. 3 or 4 days and this is done from order to install provided you can do basic soldering

good luck and good flying!

Thanks Kirk, I have done the 1126 antenna upgrade. I actually ordered both part numbers because they are so cheap. This hasn't changed my situation for the better. It still takes FOREVER to get a sat lock or sometimes it just doesn't get any satellites at all. I think it's a different issue. Thanks and happy flying to you too!

 

[kirk2579]

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

if it were mine I would be thinking;

1. send away for check out repair---long time and big$

2. order new gps module ----170 or so- b&hdid have a used one till last week at 119

3. watch b&h used dept for a p2 used --349 at times---- everything you need to test with bonus quad to fly (420 new without rc)

mess with gps connector while watching sat status to see if that is issue

hope you figure it out and someday soon weather will break here in ohio , for some better flying time. I see maybe 30's this coming week Yea!

 

[Ericf]

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

if it were mine I would be thinking;

1. send away for check out repair---long time and big$

2. order new gps module ----170 or so- b&hdid have a used one till last week at 119

3. watch b&h used dept for a p2 used --349 at times---- everything you need to test with bonus quad to fly (420 new without rc)

mess with gps connector while watching sat status to see if that is issue

hope you figure it out and someday soon weather will break here in ohio , for some better flying time. I see maybe 30's this coming week Yea!

Thanks! Those are good things to consider. It's too bad DJI's service isn't up to par with it's production. If I ever get a solution of some kind, I'll update this thread. Hope your weather turns around! We have had a super mild winter in northern Idaho. I've been flying more than skiing, which is not normal! Thanks again!

 

[Ericf]

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

Well...I did the copper tape mod and decided not to ground the copper based on a lot of mixed reviews out there. I fired it up for the first time after 2 weeks of no power and had 8 satellites within 5 seconds!! WOW!! It has never been that fast. It sounds like DJI is adding a larger copper shield on the new versions and they will install it IF you call them and get an RA and send your ENTIRE Phantom in. They would NOT just send me the copper shielding. Oh well, I got it done without paying for shipping and it works great! I also added a couple of ferrite clamp chokes to the zenmuse cable coming from the gimbal to the board and another one around the signal out from the mini-iOSD. From what I am understanding, it is the go-pro that is one of main culprits with GPS interference. I don't have an RF meter so I just guessed what might be making an RF mess under the hood. I may be totally off but it works :lol: Here are pictures: