Last chance saloon - PilotAware Mystery

[Garrick]

Hi All,

Quick bit of background - Last chance saloon is this forum, as everything else has drawn a blank. Basically I have a Pilotaware installed in a P&M 912Quik with integration to a Trig21 Transponder and a Samsung Galaxy Tab 3 and back up Samsung A5 phone. The installation is under the main central spar with GPS and aerials mounted on dash/front section.

The Issue:  Turning the system on it boots up as normal and works fine however when I transmit on the radio it causes the GPS to drop on the Transponder and the Skydemon will then lose Satellite reception but default to Seeking GPS Satellites circa 9 found - the PilotAwre Wifi is still on and the system is accessible. If I recycle the power to the Pilotaware then it reboots and starts working again.

 

Things tried :

1: Moving the GPS antennae and Pilot aware aerials away from radio 
2: Moved from Pilotaware to FLARM
3: Powering the Pilotaware from 2.1amp High Quality Powerpack 20000mah
4: Replaced leads to tablet and Pilotware with High Quality 20AWG cables
5: Formatted card and re-installed software


I have attached screen shots from when flying.

Any help would be much appreciated, I love the product but it just has not worked when I transmit.

[Seanhump]

You have a similar issue to mine (though I don’t get disconnected when transmitting ) .. your usb device list isn’t showing all of the devices connected in, even though you have a full sweep of greens above it ..

I’ve returned mine for investigation .. hopefully it’ll shed some light on the problem, which in turn may be of some help to you

[Garrick]

That is the first ray of light I have had

[PaulSS]

What radio do you have? Does the radio share the transponder earth?

I may be going straight down the wrong rabbit hole but the fact that it drops the GPS when you transmit makes me think of a grounding problem. Since the GPS is connected to your transponder then I'm wondering if the PTT ground is somehow interfering with the transponder ground and doing some weird stuff to the GPS via the transponder.

Is your GPS the dongle type or a mouse type?

[Admin]

As already pointed out
I do not see a USB/RS232 device listed in the USB table, so how is the transponder connected to your PilotAware

The first thing I would try
Disconnect the USB/RS232 from PilotAware, and see if that makes a difference.

Are you able to try that ?
Then we need to decide what to try next

Thx
Lee

[Admin]

As already pointed out
I do not see a USB/RS232 device listed in the USB table, so how is the transponder connected to your PilotAware

The first thing I would try
Disconnect the USB/RS232 from PilotAware, and see if that makes a difference.

Are you able to try that ?
Then we need to decide what to try next

And regarding dropping the GPS, that is not what is happening, something has got completely screwed because we are getting the message
GPS-USB Select/Read Timeout

This means it is totally hosed and not receiving any data as opposed to loss of satellites or something

Finally can you explain your connections from the USB to the Transponder

Thx
Lee

Thx
Lee

[Garrick]

Lee,

The USB RS232 is attached and was made professionally from Trig, what I think you are seeing is the Transmit button is pressed on the radio and I lose GPS connectivity because the Pilotaware somehow receives interference that knocks out the RS232 connection. The screen shots all show after I have pressed the transmit button and lost connectivity, prior to this everything is working and I see a GPS position on the Transponder Trig 21 and the Skydemon is reporting position , track and I see other aircraft on virtual radar etc.

Cheers

Garrick

[Garrick]

What radio do you have? Does the radio share the transponder earth?

I may be going straight down the wrong rabbit hole but the fact that it drops the GPS when you transmit makes me think of a grounding problem. Since the GPS is connected to your transponder then I'm wondering if the PTT ground is somehow interfering with the transponder ground and doing some weird stuff to the GPS via the transponder.

Is your GPS the dongle type or a mouse type?

Paul,

You may be onto something the only thing that connects the PilotAware , Transponder and Radio is the Earth - as I have tried using a powerpack but the Earth would still connect via RS232.

Using the Dongle type on a 50cm USB extension

[JCurtis]

That sounds like an interesting problem, where are you based?  If you can get to somewhere like Conington (EGSF) I could to take a quick look...

How is your radio quality and range on transmit? It might be worth trying, if easy to do, swapping the coax on the radio aerial just in case there is a bit of braid shorting in there. I had a similar issue with a video downlink from a heli before that was traced to a single strand of braid in the downlink antenna feed cable.

[Garrick]

Hi Curtis , very kind offer. I am hoping to get some ideas to try out of forum, most likely seems to be a potential Earth issue. If that fails I could be heading to EGSF

[tnowak]

Garrick,

"when I transmit on the radio it causes the GPS to drop on the Transponder and the Skydemon will then lose Satellite reception"

Do you mean you loose GPS reception on your SD device when you press your VHF radio's PTT button?
If so, does the same thing happen even when PAW is powered off?

If so, it sounds like your VHF transmission if causing the issue.
How do you ensure your transponder and VHF radio antenna ground planes are all earthed/connected?

Tony

[Garrick]

Hi Tony,

If I have PAW on and a Samsung Galaxy Tab connected to it with everything working and I press PPT then it appears that the PAW stays on and GPS dongle is connected but the data stops interchanging between the PAW and Skydemon and the PAW and Transponder. If I am just using GPS off tablet device or phone with PAW off then no issues, Transponder only takes feed for GPS off PAW so can't test that.

VHF radio has a great ground plane in nose of microlight and I have great reception and transmissionsthe Transponder antenna is 3 feet back with separate ground plane and has a strap from ground plane to the main spar. 

It feels like airborne interference but that does not seem logical - at the moment from the forum it is either - Issue with my PAW, Issue with common earth or airborne ... I think !

[Ian Melville]

Garrick, can you test ut with the PAW and Tablet running on batteries, and the USB link to transponder removed. I know you will lose the ADSB OUT, so this is just a test to find the issue.

You also mention moving the GPS antenna away from the radio. It needs to be well away from the antenna and if possible do not run the cable alongside other coax. GPS signals are very weak and easly swamped.

[Garrick]

Ian,

I'll do these tests tonight. I have tested on batteries before but never thought of testing with the RS232 disconnected as this would quickly show if it is the common earth or Transponder issue. I'll try and route everything to minimise chance of interference.

Cheers

Garrick

[exfirepro]

Hi Garrick,

Like Ian, I am a member of the PilotAware Development Team. I fly a GT450, with my PAW unit installed up inside the pod on a large Velcro ‘pad’ just above/behind (closer to you) where the front strut pops through from above. I have run various prototype and production versions of PilotAware in this position over the last 3 years including for the last few months one of the newest Rosetta Prototypes using a variety of GPS and antennas. My PilotAware(s) are powered from one of Jeremy (JCurtis)’s excellent ‘Charge 4’ power supplies.

Until I started testing Rosetta I mainly used a remote ‘mouse’ GPS fitted near the top of the slope towards the windscreen on the left hand side of the pod. This is fitted on the outside of the pod, though it could just as easily be mounted on the inside. With Rosetta, I have reverted to the standard internally mounted GPS with no issues whatsoever. In addition to Ian’s comments re keeping the GPS and cable as far as practicable away from other radio antennas, it is essential that you mount it in the clear (so it can see satellites) and that it is mounted the right way up as, if mounted upside down, the antenna is ‘hidden’ under the circuit board. With the standard u-blox 7, this means with the ‘Black Printed Side’ of the case uppermost.

As with the GPS, it is important to maximise (as far as practicable) separation between the PAW antennas and your VHF Radio antenna and especially your 120Watt transponder antenna (for this reason I have this mounted on a ground plane under the back of the skirt near the rear of my aircraft), and my PAW antennas are mounted as high up as possible down each side of my windscreen on self-adhesive cable-tie mounts.

I also run a Trig TT21, but I use a separate dedicated GPS source as I fitted this setup in my ‘pre-PilotAware’ days and in any case, I already use my ‘spare’ USB port for FLARM-IN. I have however helped several other users to fit and connect their PAWs to TT21s without issue.

Like the others above, I am suspicious of your PAW/Trig connection. You should be able to temporarily disconnect the cable from the PAW to see if this stops the breakthrough. Can you give us any details of the cable? - e.g. is at an FTDI cable? You say it was made up for you by Trig - they are only 10 minutes down the road from me and I have an excellent relationship with them, so can easily check with them direct on your behalf if we need to.

You obviously feel your VHF radio is the ‘source’ of the problem, yet haven’t replied to requests about the radio. What radio you are using - and where is it installed. Do you have any photos? Every little extra bit of information might help us solve the problem.

Looking forward to hearing from you.

Best Regards

Peter