PAW occasionally loses GPS signal

[GeoffreyC]

I've been using PAW for just over a year now,  firstly with the inbuilt radar display and more recently with EasyVFR basic.

When using it with EVFR I noticed that occasionally the GPS lost signal.   My PAW was using the standard USB GPS and is mounted under the base bar of my flexwing, rear of the transponder.   Most of the time it got a good signal but occasionally it would lose and regain it - I guess because my legs shielded from time to time.

Mentioning this to Peter at Popham he suggested a separate GPS dongle which I bought and connected to PAW, placing it above the dashboard, just under the windscreen.

My next series of flights was a tour into Germany and for the first time I tried using SkyDemon.

All was good and I enjoyed the extra visibility of planes on the navigation display (although I think the antennae or filtering was off because I only saw relatively close targets).

But my problem was that on about 4 or 5 occasions I lost GPS connectivity on PAW.   On each occasion I got a message on SD something like "lost GPS signal, 9 satellites found" (which makes no sense to me),  and the only way to fix the issue seemed to be to reboot my PAW.

I tried leaving the PAW for a minute or so to see if it reconnected, but it never did,  and powering off the power brick my PAW is connected to and turning it on again to force a PAW reboot was the only solution.

No obvious pattern to the loss of GPS signal, it happened once 30 seconds after takeoff,  on other occasions it happened whilst in steady flight after an extended period of time.

As PAW lost the GPS this stopped SD navigation and also the GPS coming through to my Trig TT21.

On one occasion I was able to look at the PAW config on my phone.  It showed green for all bar the GPS which was red.  GPS showed "DGPS fix" mode=3D and Satellites=9

Any ideas?  This was the first time I'd used the external GPS dongle so it could have had an intermittent fault or the plastic of the screen be shielding the GPS,  but for almost all of the 25 hours of flying I did it worked perfectly and the screen and the SD error message still showed that it had a decent number of satellite fixes so I don't think that was it.

[Ian Melville]

Hi Geoffrey,
Which version of the software are you using?
There was found to be an issue with other devices present that, when asleep, caused the PAW issues. This was fixed a couple of issues ago.

[Paul_Sengupta]

Doesn't sound like that's the issue if the GPS is showing up red on the home page.

But it would be worth loading the newest update on anyway.

Have you tried plugging the GPS into a different USB port?

[Ian Melville]

Ah, I missed the red bit. Red and the associated status text are at odds. not seen that before.

[GeoffreyC]

Hi Geoffrey,
Which version of the software are you using?
There was found to be an issue with other devices present that, when asleep, caused the PAW issues. This was fixed a couple of issues ago.

I was using what was at the time the latest software version.  Will upgrade to the May 18 version and try to get some more screen shots if/when it happens again.

[Admin]

Hi Geoffrey

As Ian points out, there were 2 significant fixes to issues related to what you are reporting
The version 20180520 should not exhibit the problems you are describing

Thx
Lee

[GeoffreyC]

Hi Lee,  I have today upgraded to the latest software version.   Went flying and so far didn’t see any dropouts like happened before.

Found I was getting interference though on the radio on some channels.  Eventually traced it to the new GPS cable which was too near to the radio antenna so I’ve moved it and so far so good.

Thinking back I can’t be absolutely sure whether PAW was showing red or amber when it reported loosing the GPS.  Maybe it was amber.

If it happens again I’ll let you know.

[Steve6443]

My friend and I went flying yesterday and on my android phone (Note 3), using either SkyMap or just accessing the internal website, all was good however my buddy had a similar issue as mentioned above with SD running and losing the GPS signal, showing a message 'lost GPS signal, 9 found'.

On my Note, navigation was still there, as were traffic indications. I then actualised the PAW website and saw that all the boxes were green, that the GPS Fix was 3D, showing between 8 and 10 satellites. I was picking up traffic all over the place but SD was losing the signal regularly. SD would then pick up the signal for maybe 25 seconds, then lose it for a minute or so. Totally unreliable.

With regards the unit's software stand, it was recently updated but as it is currently in the plane as I speak, I can't check. It just surprised me that using the traffic radar or Sky Map, I was not having any issues yet my friend was getting extremely frustrated with the iPad and Sky Demon. Was one of the updates specifically to resolve this issue with SD?

FYI: my system has Flarm Eagle attached and I am using the Flarm Eagle GPS as the source of GPS position, not any dongle (I have one but disconnected it when I added Flarm Eagle....)

[Admin]

Hi Steve,
This sounds like a pretty complicated setup, so I think we need a full understanding.
I am going to make a guess, so please correct :-

1. Software Version
This is very important to know

2. connected USB devices
Flarm Eagle provding Traffic and GPS

3. Connected Wifi Devices
- Note
- iPad
were any other devices connected, for example if you have EVER connected another device iPhone etc, then it is highly likely that it will auto-reconnect when close to PilotAware. Prior to Version 20180520, this could cause a real issue due to devices auto connecting, then going into standby - PilotAware would keep trying to re-establish the connection, to the detriment of other devices.

Finally, If I can get the track for your flight that will probably give us the information we require.
I would add, that in tests I have performed using a flarm mouse, the GPS was a little disappoinging compared to the uBlox GPS we use.

Thx
Lee

[Ian Melville]

Lee, the GPS performance of the FLARM Mouse was less than Stella. The FLARM Eagle uses an external GPS antenna that looks a bit like the one we use, but with an SMA connector. I think the same one as they use for PowerFLARM. No Idea how that performs, but I would not tar it with the same brush as the Mouse.

[Steve6443]

Hi Lee,

when I get back to the plane, I will advise re software. To answer some of the questions:

I have two Samsung Notes (one the version 3, one the Note Edge) and I always have one or the other connected for traffic, the other is in flight mode to save battery. Both of these phones run Sky Map as moving map. My friend has an iPad running Sky Demon. Because of the issues yesterday, I switched my Note 3 over to view the Pilotaware homepage and saw all green, minimum 8, max 10 satellites seen.

Due to having real Flarm on board, I could access the signal strength website for transmissions and note that the average GPS accuracy is 2m so I don't think the issue is due to the GPS antenna, this is , as Ian noted, an external antenna similar to the Dongle I used to use, significantly smaller, SMA connector.

Once I get back to the airfield, I will download the track and check the software status. Thanks.

[Steve6443]

Hi Lee, it was using an old version from earlier this year so have updated it to May 20th 2018, will see if that helps. At the same time, do you want the tracks from the flights where the problem became apparent? I have 4 flights, each of around 1 - 2 hours duration over the past 2 weeks however the track file is a few MB large. I have uploaded them to my own server, if you want, I will PM you the link.....

[Admin]

if you want, I will PM you the link.....

Yes please, I can scan this to look at the GPS Messages.
And to confirm,. the GPS being used was from the FLARM device - correct ?

[Admin]

Hi Steve,
Do you have an update on this issue ?
Thx
Lee

[Steve6443]

Hi Lee, didn't you get my PM? Will send it again.....