Flight experience with Mode C

[DavidC]

I thought I'd share some general feedback and experience from a recent flight.

I flew up to Wellesbourne on Friday with the latest PAW software loaded. It was relatively easy to switch profiles while the engine warmed up at the hold, useful because I often fly different aircraft. Audio was plugged into my headset (which gives it lower priority than the aircraft radio). Physically, I still have some issues with separate PAW box and battery, loosely arranged on the coaming. The antenna are too big and don't fit vertically on the coaming of the PA28 - I'll consider trimming one down as per another post here. The audio cable was also clumsy - I overheard one PAW expert at Flyer Show say they use a Bluetooth link for that, so would like more info on that.

I saw my second ever PAW box onscreen which was the Wellesbourne tower. This showed up initially without, then with the hash marks on SkyDemon. Not sure why they appeared only later, when closer.

There was another aircraft rejoining the circuit as I was performing an overhead join and it was very useful to see and hear visual and audio warnings, allowing us to look carefully for where it should be - a bit further out that I might have expected from the radio calls. There were other aircraft around and I got a stream of other warnings/notices etc. Clearly some related to aircraft stationary on the ground. This was also the case on departure, where we got warnings about ground based/stationary craft. It was a fairly busy day, so there was a stream of activity and I'm sure plenty of transponders switched on.

On the return leg I got periods with several warnings of a Mode C 100 feet below us. It seemed to me this was almost certainly our own aircraft. It was quite disconcerting to think it might not be.

I didn't see any other PAW aircraft on the screen, only Mode S/C.

I believe that some (not all) Mode S equipped aircraft indicate a ground mode, driven by the GPS and enabled below a certain speed. Does PAW ignore those, and is it a significant proportion of Mode S equipped GA aircraft anyway?

[Admin]

Hi David

Can you tell us what configuration setup you have ?
Easiest to post an image of the configure page

Thx
Lee

[DavidC]

Config attached.

As you can see it's a "homebuilt" unit based on the recommended parts.
Pi 2B with 20161124 software, Ublox GPS dongle, Mini DVT receiver, Ralink Wi-Fi USB
Powered by a fully charged Anker power block.

I may make putting it into a single box a project for the Christmas holidays, but will post a separate thread for that.

[exfirepro]

Hi David,

Thanks for the post. Unfortunately you have given us a screenshot of the PAW 'Home' page. What Lee was asking for was a screenshot to show your 'Configure' page settings so we can see what setup you are running.

Do you have a transponder, and if so is it Mode 'C' or Mode 'S'?

You presumably have bearingless targets selected (viz. the coloured rings appearing round your aircraft). If you also have a transponder, in addition to setting your own aircraft ICAO hex address in both transponder and PAW, you must have Mode C/S Select set to Mode C/S +Filter (Beta) to ensure that PilotAware correctly filters your own transponder to prevent it potentially showing as a 'hostile' target. This will principally be what Lee is trying to check, but a screenshot lets us check all your settings at the one time without having to ask a whole string of questions. The Mode C/S Range setting, for example will determine the number of bearingless target alerts you will get in any given situation.

If you don't have a screenshot available, we can always do it the 'hard way' 

Regards

Peter

[DavidC]

Sorry about the misunderstanding. Herewith a screenshot of the Configure page.

Airfield QNH was between 1023 and 1025 that day (Friday).

[exfirepro]

Morning David,

You don't say if you had a transponder active, but in a PA28 and from previous posts I'd be surprised if you didn't. In this case you need to run Mode CS +Filter (Beta) to ensure PAW filters the mode 'C' 'altitude' responses - even if you are running a mode S transponder with the hex address in both units correctly set. I fell foul of this myself when first testing Mode C. This would account for your 100 ft below bearingless contact as that is the minimum altitude separation reportable within Mode C.

With regard to Wellesbourne appearing with and without the '#' 'brackets', that is due to selection of 'Alternate' in the 'Traffic Info' field and is quite normal for a PAW only transmission.

Glad you like the selectable profiles, should prove useful for lots of club flyers who use share or hire aircraft.

The QNH still showing on your configure screen in the screenshot BTW indicates that you haven't got GPS lock yet. (I appreciate you have just fired up the unit to provide the screen grab.) This is a throwback to the days prior to the PAW RF Bridge, when you will remember those not having a baro module had to set QNH manually. This box goes away when you get GPS lock and the QNH then appears on the home screen.

Comments noted re physical setup. It's difficult to make things tidy in a carry on situation,  though several have engineered their own solutions. Keep us posted.

Regards

Peter

[DavidC]

Thanks for the feedback. I will update the config to Mode CS+Filter(Beta) and see how that works.

Yes, Mode S transponder (GTX328) onboard.

I have ordered a big box to pack it all into and will post about that on the relevant thread.