ADS B

[John Price]

Has anyone got any experience of hooking up a Bendix Skymap 3c to a Trig TT21 to give an ADS B out

Any comments would be appreciated.

John.

[tnowak]

John,

I don't have specific knowledge of connecting up a Skymap to a Trig TT21 but have done similar using a GPS mouse connected to my Trig TT21. This works very well.
You need to ensure you have the latest Trig firmware and the data input wire and gnd (to the Trig) in your wiring harness.
I had a quick look at the Skymap manual and I can't see any reason why it wouldn't work.
The Trig TT21 provides a means of verifying if it is receiving good GPS data as it will display Lat, Long and Ht on the "test" screen. Blank if it isn't getting data.

Hope this helps.

Tony

[John Price]

Hi Tony,

Thanks for the help.

So the Skymap has to be wired to both the aircraft ground and the trig ground? It'll have to come off the same pin then.

Seems a bit odd if its only giving the trig data.

I'll probably try it with and without the ground.

John.

[tnowak]

John,

If your Skymap is already connected to the common airframe ground then a second ground to the Trig may not be necessary.

Tony

[John Price]

Well for those that want to know I managed to get it all working, it rearly wasn't that hard in the end, and all the paperwork has gone off to mission control for stamping and the suchlike.

I must admit that when used through Pilot Aware and Sky Demon it gives a good situational awareness tool.

John.

PS Other products are aviable but I haven't bought them yet!

[tnowak]

John,

Glad you got it all working okay in the end.
Tony

[Flying John]

May I ask a similar question, but for the FUNKE TRT800 Txpdr as I had a GPS connected for ADSB and have now an AVMAP Utra EFIS with serial NMEA data output connected.

Although I can see our aircraft on Flight Radar 24 and it reports a position derived from ADSB (not TMLAT) people with ADSB receivers (Stratux, PiltoAware, Ping) do not see me on their Skydemon screen ?

[tnowak]

Hi John,

If you are 100% sure your Mode S transponder is sending valid position data then there is no reason I can think of why you show up on FR24 but not SkyDemon etc.

From your description it seems like you aren't transmitting position data..

Does the TRT800 have a diagnostics page where you can view the transmitted position data (the Trig TT21 does).

Tony

[Flying John]

I thought the same, but if I disconnect the data feed from GPS to Txpdr then on FR24 when we track our flight it still shows up Mode S but with TMLAT in the information field. When we plug the GPS back in then we see one of the radar idents (eg EGKA6 or EGLF2) .

My understanding of FR24 is that TMLAT returns are triangulated ModeS and the so called "Radar" i.d's are when ADSB GPS position reports are received - happy to be corrected.

The TRT800 has a test mode. In Test Mode a "P" (capitalised) is displayed when a valid position is received via RS232 interface. and sure enogh I get a "P" in test mode, but cannot see our own aircraft on a PiotAware or a Stratux receiver.

[Ian Melville]

Hi John, I know nothing about the kit you have, but do have quite a bit of experience with PilotAware.
There are two reasons why ADSB receivers may not see you.
1. They cannot see the transmissions. As you are transmitting on the Transponder antenna, I suspect this will be on the belly of the aircraft. It's not quite as clear cut line as drawn in the recent LAA magazine, but aircraft above and possibly at the same level may not get such a strong signal.
2. PilotAware does not have filters for ADSB, but SkyDemon does. To take SD out of the equation, find someone with a PilotAware and get a screenshot of the traffic table. Does your aircraft appear in that? This is required to LAA approval anyway, so worth doing.

I would offer but Hellfire Corner is a bit far away.

[John Price]

John ,

Try this.

When the mode s is operating and giving ADSB out try moving a good distance from the aircraft, the output from the transponder can saturate the receiver in the tablet or pilot aware and you end up seeing nothing.

Also, if using pilot aware check that the hex code and aircraft I'd are changed from those for your aircraft these are added to filter out your aircraft in flight but when ground testing that is exactly what you want to see.

John.

[Flying John]

Thankyou guys - a few things to check, I see that receiver saturation is a likely cause, since when I have my Raspberry pi ADSB receiver in the hangar and the aircraft is 100 metres away, it may be a very strong RF signal. So will wait until a flight and I will get someone on the ground to monitor the screen, or traffic table in a browser, to see if we appear.

Its the fact that FR24 is a network of (probably) Raspberry pi's and SDReceivers on 1090 that do see us and I am bamboozled why I cannot see us with my own Pi.

Even the traffic table of Mode S (non ADSB) does not list us in the traffic table, and yet Southend tell me they have a mode S return and can identify us with callsign.

Plot thickens...

[Ian Melville]

Also, if using pilot aware check that the hex code and aircraft I'd are changed from those for your aircraft these are added to filter out your aircraft in flight but when ground testing that is exactly what you want to see.

I'd forgotten all about that. No you will not see yourself on your own PilotAware and you will have entered the hex code so that it should ignore your own aircraft. Otherwise in flight you will have a shaddow following you everywhere causing alerts. You need to use a PilotAware from someone else to verify for the LAA, or if just testing deliberatly change the hex code in yours to something else to prove the point. Don't forget to change it back.

[Flying John]

Thankyou - yes I have it set to 000000 for testing at the moment.