SOLVED! - Pilotaware & GPS problems?

[rikur]

Has anyone had problems with Pilotaware interfering with GPS signals?

I've been using an early Pilotaware without bridge for a few months, and it's been fine - if anything the GPS was quicker to get a location fix and more stable than the tablet's internal GPS.

I'm using Skydemon on a Nexus 7 2013.  The PilotAware is sat on the P2 seat.

My new PilotAware arrived last week - so have been trying that out.
Last week the GPS kept dropping out - I thought it must just be having a bad day (Murphy's law about doing live demos and all of that!).

Today it wouldn't even get a location fix.  I switched over in SkyDemon from Flarm to 'Location Services' (i.e. internal GPS) .... still no location fix (left it trying for 60 seconds).  I powered off the PilotAware .... within a couple of seconds I then got a location fix, and all was stable for 2.5hr flying  - albeit obviously without a PilotAware.

I'm going to try putting the GPS dongle on a USB lead to separate it from the rest of the PilotAware.

Admittedly this was in a C172, so the sky is obscured from most angles, but the GPS in my tablet has historically coped ok, and seemed to be fine today once I switched off the PA.

[Admin]

Hi

Sorry to hear you are having trouble, you mention that you had been using an old pilotAware without an issue

Can you tell us what GPS source you were using in this case, was this a ublox ?
If so, did you try swapping the GPS dongles from old to new ?

Also you say

Last week the GPS kept dropping out

Can you please describe the symptom ?

did you get a message from skydemon saying

Code: [Select]

lost connection to butterfly ...(this actually indicates a WiFi issue)

or

Code: [Select]

searching for GPS satellites(this indicates a GPS issue)

Another member reported an issue with a Nexus, but the issue was WiFi, not GPS

Edit: Just re-read your posting and it does sound like a GPS issue

Thx
Lee

[Paul_Sengupta]

I've not had a problem with the Ublox GPS getting a signal but I have a canopy aeroplane. It doesn't appear to be as sensitive as a tablet GPS.

However, I had a similar thing with my tablet last week, I switched to location services and couldn't get a GPS signal. I didn't try unplugging the PAW I don't think. My Garmin Aera didn't lose GPS signal however. I'm not sure if this could be a Sky Demon problem, as I quit SD, swiped it away to make sure it was completely closed, brought up the GPS monitoring app which showed loads of satellites, then restarted Sky Demon, and it then got the satellites from location services.

[Admin]

One other thing we are currently investigating, is a recent change to the WiFi configuration, which could possibly be affecting the GPS in some cases.

In the Beta release of PilotAware the Wifi was fixed at
Mode=b, Channel=9, Power=100mW

In the latest release
Mode=g, Channel=(1-10), Power=50mW

The channel selection is based upon a simple lookup from the Eth0 MAC address.
But, this could be affecting what you are seeing.

Richard what software version of PilotAware were you running in your previous version ?

Thx
Lee

[rikur]

The Skydemon error has been 'searching for satellites' 
(and if I go to the PilotAware status page in the browser, it shows 0 satellites on the GPS row - and no flashing green light on the dongle)

Separately I have had a couple of issues with WiFi dropping, but blamed that on one of the pair of GoPro's Wifi getting in the way (!!), and is probably unrelated to this issue.

In both cases I've been using the Ublox7 GPS dongle, and yes, I've tried swapping them around.

The bit that surprised me was that the tablet didn't seem to be able to get a location fix using its internal GPS until I powered off the PA - albeit that might be a coincidence, and I haven't been able to reproduce it this afternoon.

Previous version that was working ok was 20151219

I've got a USB extension lead, so will try putting a bit of distance between the GPS dongle and the various other interference sources.

[Admin]

Hi Richard

Interested to hear the results regarding the gps extension lead

I presume you are comfortable performing a disk reformat/install ?

If so, i would like to give you access to a relaese which reverts to the old wifi settings, this should prove/disprove the theory about the wifi settings affecting the gps

Are you able to try that ?

Thx
Lee

[rikur]

ok - usb cable tried....

If I put the UBlox7 on a 60cm USB cable number of satellites visible immediately goes from zero to 7 (keeping the U-blox in a fixed position and moving the PA away). 

If I then move the PA back towards the U-blox all is fine, until I hold the U-blox within a cm of the WiFi dongle and then drops to 4 visible.  If I plug back in directly in the same position also 4.

I've repeated this a few times, and the degradation results are not entirely consistent (anything between zero and 7) - but I am always getting 7 satellites visible when separated from the PA a little.

This would suggest that the performance of the GPS dongle is impaired a little when directly attached.  I observed that PA WiFi was on channel 6 during these tests.

Caveat:  Based on a small number of tests in one location in a 15 minute period!

Yes - happy to try another release (I'll probably stick it on another SD card so I can toggle between the two to compare)

[Paul_Sengupta]

How are you plugging in the dongles? Do you have the Wifi directly beside or above/below the GPS? I have mine laid out:

Top left - GPS
Bottom left - DVB-T
Bottom right - Wifi

Ok, the Wifi and GPS are still close, but not directly in line.

[rikur]

Hi Paul,
I had GPS in top right above WiFi.
I'm now trying a different WiFi configuration that Lee sent over last night which so far has seemed better.
I noticed first thing this morning that it took a good 2 - 3 minutes TTFF (from a SE facing window ledge) but once it had got its first fix it has seemed stable.
There now seems no difference in the number of satellites regardless of whether I plug the GPS dongle in directly, or on the USB extension lead.
I have noticed however, that when located in the same location - the dongle reports 'Satellites=6' whereas my Nexus 7 reports 11 satellites in use - so i guess the dongle is also lower sensitivity.
Richard

[EricC]

The most energy-efficient type for double glazing is low emissivity (Low-E) glass. This often has an invisible coating of metal oxide, normally on one of the internal panes. This lets in light and heat but cuts the amount of heat that can get out.

I have found by testing my unit that the gps does not receive any satellites if located behind my double glazing.
Works without any problems located in loft room.   Std tiled roof with fiberglass insulation

U-blox7.

I also turn OFF location determined by wi-fi on my Samsung Tab.  ( unsure if this helps )

[Tony Crome]

Tested in flight  today using RunwayHd. It worked well with no intermittent loss of 'Flarm Data' warning. However after takeoff the iPad GPS position was inaccurate while using the PilotAware GPS. It slowly started to show the correct track but with a serious 'map shift' position error. I switched to the iPad GPS and the position was immediately corrected and all well for the remaining 30 mins of flight. On the return flight I again used the PilotAware GPS, this time no problems.

Occasionally there is a contact showing at my position usually about 200ft above. I have entered my hex address and also my Trig Tx does not transmit GPS position so I assume it is somehow picking up my PilotAware transmitted position ??

Tony

[Admin]

Occasionally there is a contact showing at my position usually about 200ft above. I have entered my hex address and also my Trig Tx does not transmit GPS position so I assume it is somehow picking up my PilotAware transmitted position ??

Hi Tony,
Do you have Mode-S enabled ?
If so what are your settings ?

If you connect to your PilotAware from a computer (just connect to the WiFi)
You can download the track of your flight(s), including all of the contacts seen using a web browser
http://192.168.1.1 -> ListTrack

Format of files is
2016-05-25_10-56.trk

Whereby your start time is ... YYYY-MM-DD_HH-MM.trk

Can you send me the track data, I can work out what that contact at 200ft was, whether it was your own transponder or
not. Unfortunately for RunwayHD, it only shows relative height and not the contacts Reg, but I can obtain that from the track file

Thx
Lee

[Tony Crome]

Hello Lee

Yes Mode S enabled - no special settings that I am aware of, just aircraft reg and hex code.

The unit is at the aircraft , I'll get the file next visit.

Many thanks Tony

[Admin]

Hi Tony,

Well there is a lot of data in here.
Pretty certain what you were seeing were Mode-S contacts - I presume you have these enabled

You mention 200ft above, so the Mode-S contacts at 200ft Above (but could be 5 miles away) so 200ft is approx 60 Metres

Unfortunately RunwayHD does not display the Reg.
We are still tuning the Mode-S for the power/range estimation, what do you have your mode S settings ?

In fact there were a lot of contacts at close relative heights to you , all of the following were within +/- 300Metres, so I guess your settings were probably +/-1000ft ?
Most likely N2923N

Legend:      HeightDiff ICAO!REG

      -60 A2FFB6!N2923N
      -57 A2FFB6!N2923N
      -54 A2FFB6!N2923N
      -42 A2FFB6!N2923N
      -40 A2FFB6!N2923N
      -38 A2FFB6!N2923N
      -36 A2FFB6!N2923N
      -34 A2FFB6!N2923N
      -32 A2FFB6!N2923N
      -31 A2FFB6!N2923N
      -28 A2FFB6!N2923N
      -26 A2FFB6!N2923N
      -24 A2FFB6!N2923N
      -23 A2FFB6!N2923N
      -20 A2FFB6!N2923N
      -19 A2FFB6!N2923N
      -17 402C86!G-BPCL
      -16 402C86!G-BPCL
      -16 A2FFB6!N2923N
      -15 402C86!G-BPCL
      -14 402C86!G-BPCL
      -14 A2FFB6!N2923N
      -11 A2FFB6!N2923N
      -6 A2FFB6!N2923N
      -5 40522B!G-NWFC
      -4 40522B!G-NWFC
      -3 40522B!G-NWFC
      -2 A2FFB6!N2923N
      0 A2FFB6!N2923N
      3 402C86!G-BPCL
      3 A2FFB6!N2923N
      4 402C86!G-BPCL
      4 A2FFB6!N2923N
      5 402C86!G-BPCL
      6 402C86!G-BPCL
      7 402C86!G-BPCL
      7 A2FFB6!N2923N
      11 402C86!G-BPCL
      12 402C86!G-BPCL
      13 402C86!G-BPCL
      14 402C86!G-BPCL
      15 402C86!G-BPCL
      16 402C86!G-BPCL
      24 40522B!G-NWFC
      25 40522B!G-NWFC
      26 40522B!G-NWFC
      43 402C86!G-BPCL
      47 A2FFB6!N2923N
      48 A2FFB6!N2923N
      49 A2FFB6!N2923N
      50 405EDF!G-SCSC
      50 A2FFB6!N2923N
      51 A2FFB6!N2923N
      52 A2FFB6!N2923N
      56 40522B!G-NWFC


Thx
Lee

[Paul_Sengupta]

You are at North Weald, and I claim my 50p!