Hardware issue? Hardly seeing any traffic and radio interference

[sdkellner]

Hello again

I'm sorry to be asking for help only a few weeks after doing so concerning getting PAW to communicate with my TRT800H transponder to give ADS-B out.  The good news is that ADS-B out seems to be working perfectly; every flight I have done since appears clearly on FlightRadar 24, and each radar station I have asked has reported a good strong signal.  The bad news is that pretty much every other aspect of my PAW installation seems to be not working.

The basic problem is that I am seeing hardly any traffic.  I have experimented with antenna position and settings but to no avail.  I have never had a bearingless alert, despite being based at Ashcroft at the bottom of the Low Level Corridor which is usually very busy.  I'm also near Hawarden, Liverpool and Manchester yet see hardly any of their ADS-B traffic.  Today I flew along the southern edge of the Manchester zone; they were busy - even the A380 had to enter the hold - but hardly anything appeared on Sky Demon; see attached pic.

I have installed PAW in my MT03 open cockpit gyrocopter.  I have the 'official' USB GPS mouse mounted on the top of the instrument binnacle and it receives strong satellite signals.  The PAW is installed behind the instrument binnacle.  Power is supplied via either the recommended Anker 12V cigarette socket adapter or my Anker 20100 power bank; the problems I experience are the same no matter which supply I use.

Until today I used the 1090 MHz aerial installed within my nose cone, near my VHF aerial.  To see if this was the problem I cut it down to 50mm as advised elsewhere on the forum (making total length 69mm) and flew my Manchester route with it 'up top' just behind the windshield; this will have given a great view forward, albeit blocked by my iPad behind.  This made no difference; still hardly any traffic.  I have now moved it back to within the nose cone, and also now attached the centre-fed dipole to the interior side of my nose cone, as close to vertical as I can get it (pretty close).

As well as seeing hardly any traffic, I'm also now having problems with the audio out.  There are no alerts for me to hear as I'm seeing no traffic, but even pressing 'test' on the PAW web interface is no longer producing the 'Pilot Aware' voice.

Whilst flying my Manchester route there was very considerable interference on my radio, which disappeared when PAW was turned off (by removing the power).  I don't remember this from previous flights; it was so bad today that I could hardly hear the airborne Manchester commercials.  I use the recommended ground loop isolator between PAW and my intercom.  This interference problem only seems to have been an issue today.

Finally, on the logging page I see many repetitions of the following - 'Use of uninitialized value $eth0_ip in concatetenation (.) or string at htdocs/index.cgi line 152.'

Have I done something horribly wrong?  Or might I have faulty hardware somewhere in the system?  Numerous pics attached to hopefully show more detail.

Many thanks for any help you can offer.

Stu

[Admin]

Hi Stu

From the screenshot, all looks well, you are receiving ADSB messages

Please post a picture of the traffic page, whatever is listed yere, should be on your display, if the filters are open wide enough

Regarding radio interference, my first guess, power supply, please provide full details of your power supply

Thx
Lee

[Ian Melville]

A screenshot of the config page of PAW would also be useful, as would the bottom section of the Navigation Settings used in SD.

BTW what is your pod made from? Hope it is not carbon as that will screen radio signals

[Ian Melville]

Finally, on the logging page I see many repetitions of the following - 'Use of uninitialized value $eth0_ip in concatetenation (.) or string at htdocs/index.cgi line 152.'

eth0 is the RJ45 ethernet port and will not be in use. Lee will know if this is an expected report. would not expect it to be related to the issues you are having.

[sdkellner]

Hi guys

Thanks for your replies.

Lee - that was one of the 'better' screen grabs; frequently the ADS-B box is red, not green.  Unfortunately the PAW is still in the gyro; my installation makes it difficult to remove each time.  And the gyro's an hour away.  I can tell you that the traffic page behaves strangely, to my eyes at least; when I view it it is frequently empty, and then a few lines get added, and then they drop off again.  I have never seen it with more than 4 or 5 lines in total.  My filters are all wide open; 40,000 feet within SkyDemon plus bearingless targets, and all the config settings on PAW set to maximum range etc.  Power comes either from this https://www.amazon.co.uk/gp/product/B00VH84L5E/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 or this https://www.amazon.co.uk/d/Cell-Phone-Portable-Power-Bank-Chargers/Anker-PowerCore-20100-Capacity-Powerful-PowerIQ-Technology/B00VJSGT2A/ref=sr_1_1?s=electronics&ie=UTF8&qid=1490815830&sr=1-1&keywords=anker+20100 - problems are the same whichever I use.

Ian - a few other pics attached hopefully providing what you need.  Pod is GRP; radio aerial works fine within it. 

Thanks again.

Stu

[Ian Melville]

All the settings in PAW and SD look to be correct.

The Red ADSL marker in the last screenshot shows that no traffic has been received for period (not sure how long), yet it had worked. Wonder if you ADSB dongle is faulty?

[sdkellner]

One other thing I meant to add, which maybe important... I have never seen my own transponder on the traffic page; I know it's properly broadcasting because I can see it in FR24, but shouldn't it also appear in the Traffic page of PAW, to be then filtered out en route to Sky Demon?

[Ian Melville]

Your own transponder will not show because PAW knows your hex code and excludes it. There is no benefit in seeing your own shadow following you around.

[exfirepro]

Your own transponder will not show because PAW knows your hex code and excludes it. There is no benefit in seeing your own shadow following you around.

Ian, you are right that it won't show on your Nav Display, but mine (also ADSB Out) normally shows on the top line of the Traffic Table with a big strong signal in a red 'signal strength' box.

Stu,

The Traffic Screen is like a 'collection box'. All the live data received by the system is collected and held there while it goes through the filters with all the ADSB and P3i data plus only relevant Mode C/S data being passed to the audio and nav systems. This means that much of the data that appears in the traffic table will never make it past that stage. The traffic data drops off the table as it either goes out of range or in the case of Mode 'C' 'times out'.

I'm seriously confused by your lack of traffic though. My first thought was that your pod must be carbon fibre and is screening out the signals, but you have said this is not the case - if in any doubt, it would be worth double checking this, remembering that your airband radio operates on VHF, which will be less susceptible to screening than the UHF 1090MHz and P3i signals.

You seem to have the filter for known position (ADSB / P3i) targets set to 40,000ft in SkyDemon, so should at the very least be getting plenty of CAT ADSB. Your first Home Screen screen grab certainly shows some received ADSB traffic which might just have been out of range on your nav display, hence wouldn't show up. The Home Screen shows that P3i is transmitting Tx = - so the GPS fix is OK, but no received (Rx) P3i signals. This isn't unusual as they can still be thin on the ground - or should that be in the air?? It would be a good idea to open up your Mode C/S filters in your Config Screen to say +/- 5,000ft, or even greater and change Mode C/S Detect to 'Long Range' to see if this brings in more bearingless traffic. You can always narrow them down again later.

Let us know how this goes and please post some screen grabs of your traffic page if you can manage next time out.

Hope this helps

Regards

Peter

[sdkellner]

Thanks Ian and Peter.

The LAA approval for ADS-B out requires a screen grab of your own transponder appearing on the top of the traffic page - see http://www.lightaircraftassociation.co.uk/engineering/StandardForms/LAA-MOD-14%20-%20ADS-B.pdf.  I understand that this is then filtered out before being displayed on the nav device, but the fact it isn't appearing on the traffic page suggests that something is wrong.

I'm as certain as I can be that my pod is GRP and not carbon fibre.  The flight and maintenance manuals do not specifically say, but they do list almost everything else as being GRP and offer carbon as an option (which mine doesn't have) for the tail assembly only.  I am no materials expert, but it doesn't feel like carbon fibre - it indents easily to the touch, whereas I thought carbon was rigid.  Nevertheless, it was to address this specific possibility that I flew yesterday's flight with the 1090 MHz aerial above the pod and directly behind the perspex windshield as in the pic on yesterday's post, and at the same time I halved the length of the aerial (a) to tune it and (b) so it would fit!  It was in this configuration that I flew along the south border of the Manchester zone and saw hardly any traffic; again yesterday's screen shot demonstrates.

I have since opened up my C/S filters to the maximum, but I doubt this will make any difference.  Where I fly is a pinch point between the Liverpool and Manchester zones, with lots of traffic, for which all the GA must be below 1,500 feet; so my existing settings should have displayed lots of traffic.  They should also have allowed through all the CAT, of which there was a lot!

The weird nature of my traffic page, with hardly any appearing and it shuffling quickly down to zero, the fact that I have never seen C/S traffic despite flying in a busy area, the fact I am seeing probably 10% (if that) of ADS-B CAT, and even then only temporarily, the significant radio interference - for a while I have thought the same as Ian, that I have a faulty ADS-B dongle.  I ordered a replacement from HK a week ago and it arrived whilst I was flying yesterday.  I will try this at the weekend and report back.  But if it isn't this I don't know which way to turn as I am running out of ideas.

Best

Stu

[brinzlee]

The USB ADSB receiver sounds suspect to me.....Did you buy the kit from PilotAware or build it yourself.....the Power lead if not man enough could be an issue.....but my bet is on the ADSB receiver.....I had one do something very similar to that....When it appeared red on the config page, slightlty bending it in the the USB socket for about 5 seconds remade a dry joint or broken track within the module....I never found it, but replacing it solved the problem

[sdkellner]

I bought the PAW classic ready built from PAW Hardware and am using the original power lead together with two (one at a time!) of the recommended power sources.  Sounds ever more likely that the ADS-B dongle is the culprit.

Best

Stu

[exfirepro]

Stu,

I was just about to ask if it was a home build or a 'Classic'. I am also now pretty sure there must be something wrong with your SDR Dongle or antenna cable - e.g. a dodgy connection inside the antenna base - easy to check as the bottom can be carefully prised off, or the cable - you can check continuity with a multimeter. Check centre pin to antenna and braid to outer ring of mcx plug and also check no short circuit between the two.

If the problem is with either of those, contact Dave Styles at PilotAware Hardware and he will arrange replacement.

The interference issue is puzzling. You could have a dodgy USB adapter. At these prices even Anker must get the odd dodgy one. I take it your Anker battery was fully charged for your tests? If so that should have dealt with any power feed line issues, but it might be worth trying a couple of ferrites on your main power lead.

The missing test audio is also puzzling, though I have also experienced this many software versions back during testing. Try plugging a set of (cheap and cheerful) earphones or a small speaker straight into the PAW audio out socket, reboot the PAW and reconfigure the volume setting and see what happens. Please let us know.

Best regards

Peter

[sdkellner]

Thanks Peter.  I have purchased replacement ADS-B dongle and aerial as a pack as listed in the recommended hardware so will replace both and see how I get on.

Yes my power brick was fully charged. 

I will also try the audio out test.

Hopefully I'll be able to make it back over to the airfield during the weekend; I'll let you know how I get on.

Thanks again guys.

Stu

[Ian Melville]

Worth checking that it is not the antenna, I had one with a disconnected centre wire that would intermitantly receive. I cut the antenna off and stripped back the outer sheath to a bit longer than the antenna for PAW frequency. Pulled the centre wire through the screen, and cut both to correct length. Feed both into a straw (nicked hole in middle) so they are at 180 degrees to each other. A Spot of hot melt glue at the junction made it solid.
Use the smallest diameter straw you can find, and put a rubber sucker on each end to stick to window. Just use it for testing, or if you like the rig, stick it inside your Perspex screen.