It did it again !!

[flying_john]

Some weeks (months) ago I was testing a previous version and found that the display on, RunwayHD, of Mode S E.S equipped aircraft (mostly airliners) seemed to overload the App and all of the altitude boxes started flashing and the screen effectively locked out any user input and the aircraft depicting our own position stayed in the same place.

I reported it on the forum and was advised to tell the RunwayHD chaps of this as  it sounded like a problem with their App. I did this and never heard any more from them and I didn't see this happen with a new version of PAW software so thought it had gone away.

Now my installation still has the 1090 aerial within the aircraft and we keep it tucked into the passenger footwell pocket , really just to reduce the number of aircraft returns that are of no interest i.e they are 10's of miles awayand we do this by attenuating the received signals on 1090 with the aerial in the footwell.

However when we bring the aerial up onto the panel and (courtesy of a blob of bluetac) stick it on the panel top, the App, again seems to get so much NMEA data streaming in it goes into this condition where the altitudes flash and the screen wont accept any input.

Does the PAW team have any technical contacts to point this flaw out to them (if it is RunwayHD's problem) becuae if it is, they dont seem to take any notice when I reported it.

John
PS how does one enable the audio output and display of non ES transponder returns ?

[Moffrestorer]

Hi John,

It sounds as though you have got the altitude limit for the "FLARM" input to your Nav program set really high (useful for testing the display of ADS-B returns from CAT aircraft). Have you tried reducing the limit to something more sensible for your flying, like 10,000 ft or less? Hopefully this will stop the data overload by filtering out the higher stuff, or are you CAT and/or pressurised too ??

[Admin]

I have forwarded this to Tim at Airbox, hopefully he could shed some light on what could possibly be happening here.
Thx
Lee

[flying_john]

But even with the Alt set to a low figure the NMA sentences will still have to be parsed to determine the height before discarding or keeping the data.

My guess is that the Ipad / App is just  having to service so much data on the NMEA input side (is it IRQ driven)  that it never gets back to the primary task of position and Nav plotting.

Perhaps the Ipad mini is not up to the job.

[Admin]

My guess is that the Ipad / App is just  having to service so much data on the NMEA input side (is it IRQ driven)  that it never gets back to the primary task of position and Nav plotting.
Perhaps the Ipad mini is not up to the job.

This is possible, in which case, I would add some pre-filtering before sending the messages to ensure we send a minimum not to overload the iPad.
Having said that I do a lot of testing on an iphone6 plus, and I do not see this issue with SD or EasyVFR.
It may be a simple issue to fix in RunwayHD, lets wait for Tim at Airbox to investigate before we do anything further.

Thx
Lee

[Tim]

Hi John,

Thanks for reporting the issue and apologies that this got missed the first time around.

Can you give me a bit of back ground on the number of returns you have on screen?
What do you set the altitude filter to? Agreed the application will then still need to filter the results, but interesting to know.

Thanks, Tim

[flying_john]

Hi Tim, At the moment I set the altitude to 20,000ft , yes it is high, but this gives confidence that it is working if you see airliners. But we keep the antennae inside the cockpit to limit the number of received signals (a crude attenuator) . When we bring the aerial to the top of the panel, and would be similar if using external antennae, then we get perhaps 20+ returns (it is busy in the S.East) and this is when the altitude boxes start flashing on/off and we are unable to do anything on the ipad screen and our own position is not updating. Once the antennae is placed back in the footwell the returns reduce and after a short interval RunwayHD returns to normal.

Hope this helps
PS - no other apps running on iPad mini

[flying_john]

In-case there was too much for the old Pi B to manage I have ordered the Raspberry Pi 2B and hopefully this will also give me the audio warning enhancement (thanks for listening) and update to latest build.

John