SOLO GPS signal instability issues

thefrog · Jul 1, 2015

Over the weekend I have experienced situation where I have 10 sats but no lock for 15 minutes for the first time.

Yesterday I have updated SOLO, all OK, re-calibrated and it locked indoors to 7 sats within 2 minutes.

Guess what, minutes ago going for quick backyard test, never ending "Waiting for GPS" happened again showing 8-9 sats, but this time I quit after 10 minutes as I have to go. Galaxy S6 showed at the same time and place 16 locked satellites, 3D fix within seconds.

This drives me really crazy.

Seems 3DR is trying to figure out what is going on, while ATX Rc guys in the link below experienced unexplained SOLO crash on Orbit in open space, far above ground:

Crash in orbit:
Foggy explanation: jump to about 13:00

update: Another GPS instability case - totally open space, 10 sats but never ending waiting for lock:

I can't imagine GPS being lost flying in open space. What is wrong with SOLO?

Rich · Jul 1, 2015

Maybe nothing wrong, what was the HDOP?

Solo pays attention to the geometry of the gps signal. If your hdop is too high, it won't use the position as it could have too much error in it. Phones and other devices may not care about hdop. Hdop is a function of the birds, not your drone

Google GPS HDOP to understand it.

So what was your hdop? If too high, maybe this was the issue. If it was OK, it could be something else?

1013D · Jul 1, 2015

New firmware is supposed to help, suspect those vids are old firmware. I would occasionally get the same thing. Found out power cycling the solo only works, and get how lock quickly.

Sucks it ocasionally happens, but it's an easy work around at least.

NYG · Jul 1, 2015

Those videos are on the older firmware. I wouldn't freak out just yet. If you continually have the problem then seek help from 3DR. If you open the app and toggle the extra information on the top line you can see the number of sats and hdop. Last night i did a quick test flight and it took a little while for my hdop to get down to 2.

thefrog · Jul 1, 2015

Below is the GPS issue clearly demonstrated. I really love 3DR, but this is not good.

Average 3DR SOLO customer with no prior UAV experiences can't determine if such loss is normal or not. It is definitely not. Some even believe it is a "solid performance". OMG. I can fly P3 under much denser foliage and still have 16 sats locked in. Even my stupid phone does.

SOLO however loses sats like crazy, even if it have big GPS patch antenna. WHY?

According 3DR long waiting times for GPS are OK as well as loss of signal under the trees.

I'm saying - No way can GPS 3D lock be lost with few sparse tree canopies around.

Tree test with GPS loss:

rrmccabe · Jul 1, 2015

One thing going against him here is he is VERY close to hi-voltage power lines and commercial radio tower on other side of those.

thefrog · Jul 1, 2015

Hi-voltage power lines, nor cell towers have no significant influence on GPS signal, well... unless you are inside of a closed cell tower with your SOLO.

Hi-power lines have wires spacing many times larger than GPS wavelength and cell towers are just simple obstructions causing partial sky obstruction and some slight multipath. But none of these can be reason for GPS signal loss.

Question is, what it is then?

rrmccabe · Jul 1, 2015

Might not effect GPS signal but it definitely can cause issues with the electronics that are connected to the GPS module. RF can cause all kinds of issues.

thefrog · Jul 1, 2015

I have completely disassembled and re-assembled my SOLO: all PCB's uses solid ground planes and the behavior is rock solid upon firing 100W ham transceiver with antenna right at the SOLO body.
Cell phone signal from close to SOLO body signal does nothing bad to GPS, even if the local RF field is many times larger than from cell tower 100ft away.

I will consult SOLO GPS with a friend working in EMC test lab. Will see what he can find with lab full of RF test equipment.

rrmccabe · Jul 1, 2015

Well it would be hard to replicate as you really dont know what frequencies and spurious emissions were in that environment.

I would be surprised if its a common issue anyway

What kind of 100w transceiver?

Greg Parker · Jul 1, 2015

@thefrog

"I have completely disassembled and re-assembled my SOLO: all PCB's uses solid ground planes"

It is unclear whether you found that the "ground planes" were there as OEM or that you added them yourself.

DodgeP · Jul 1, 2015

I have been unable to go any further than 500' before I lose connectivity with the controller. I'm a lot pissed off right now.

Raybro · Jul 1, 2015

DodgeP said:
I have been unable to go any further than 500" before I lose connectivity with the controller. I'm a lot pissed off right now.

Could be some interference Dodge. I took mine out a little further than I have previously, to 1500 with no problem other than my GoPro battery going dead and lost the video feed. Used the maps to navigate back.

DodgeP · Jul 1, 2015

Raybro said:
Could be some interference Dodge. I took mine out a little further than I have previously, to 1500 with no problem other than my GoPro battery going dead and lost the video feed. Used the maps to navigate back.

I would tend to agree but the first time was this afternoon in Princeton NJ in an open field and again about half an hr ago in Philadelphia at my normal flying space where my furthest distance was 1800'

NYG · Jul 1, 2015

DodgeP said:
I have been unable to go any further than 500" before I lose connectivity with the controller. I'm a lot pissed off right now.

I was limited to 600-700' until I ditched the stock antennas.

Operator74656 · Jul 1, 2015

are people using the fpvlr antenna?

thefrog · Jul 1, 2015

Greg Parker said:
@thefrog

"I have completely disassembled and re-assembled my SOLO: all PCB's uses solid ground planes"

It is unclear whether you found that the "ground planes" were there as OEM or that you added them yourself.

Ground planes are on the PCB boards in the SOLO - as designed by 3DR designers - this is indication of good EMC design

thefrog · Jul 1, 2015

rrmccabe said:
Well it would be hard to replicate as you really dont know what frequencies and spurious emissions were in that environment.

I would be surprised if its a common issue anyway

What kind of 100w transceiver?

It's my father's YEASU, it actually have only 50 watts in UHF as I have learned, but the field close to the antenna is huge at 70cm

rrmccabe · Jul 1, 2015

Whats your fathers call?

thefrog · Jul 1, 2015

If you wouldn't mind, I would like to keep privacy on who is my father and what is his name, as these what his callsign will tell. I see no reasons to have him engaged into this discussion.