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Flarm Fusion with a mode C transponder.

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Bruce

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Aug 7, 2021, 9:26:55 PM8/7/21
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A couple of us in our club are using the new Flarm Fusion box. I have ADS-B out with my Trig TT22, The other pilot has a mode C transponder. When we were flying together today, I would see 2 targets in close proximity to each other when visually there was only one.

The other pilot complained that he saw a "ghost" follow him.

I occurred to me the we are seeing the ADS-R or TIS-B image on the Flarm Fusion. I did not check to see if the hex code for Flarm output and the ADS-R was the same. I'll do that on my next flight.

Has anyone else research this and have a answer on how to suppress the "ghost" gliders?

Bruce

Michael Bamberg

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Aug 7, 2021, 11:32:53 PM8/7/21
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Bruce,

I saw this when the other glider didn't have the "own" transponder set up correctly in the FLARM device. You are seeing both his FLARM and the transponder and he is seeing his own transponder on the FLARM.

If you have the PCAS setting enabled on your FLARM you will always see two of him.

Richard at Craggy Aero has an explanation on a setup that will help you, if you are willing to not be alerted for non-ADS-B aircraft. I think a search on RAS will show several setup values that you can use.

MB

Dan Marotta

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Aug 8, 2021, 10:53:57 AM8/8/21
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It seems there are a lot of non-ADS-B aircraft around Moriarty so I keep
the PCAS function active.  It's a pain when I see two of the same
aircraft, but that beats not seeing the transponder-only aircraft. 
There's still the need to look for the "silent" aircraft.

Dan
5J

Ramy

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Aug 8, 2021, 5:01:29 PM8/8/21
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Note that Fusion does not support PCAS for mode C transponder yet (it is supported for Mode S).
What is reported here is TIS-B.
A glider with powerflarm and Mode C transponder will he shown as 2 targets one near the other (flarm and TIS-B) at least part of the time. This is expected behavior.
For the glider with the mode C transponder they will see a ghost of their own aircraft most of the time. This should not be an issue with Mode S transponders. So owners with mode C transponders and fusion may want to consider disabling the TIS-B only (not ADS-R and not PCAS) if the ghosting bother them.
I described in another thread how to do it.

Ramy

Andy Blackburn

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Aug 8, 2021, 11:59:08 PM8/8/21
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What Ramy said.

IIRC Mode C transponders don't broadcast an ICAO code. The IACO code is the unique aircraft identifier that Flarm uses to disambiguate targets received across different sources: Flarm, ADS-B Out, TIS-B, ADS-R and PCAS. Without an ICAO ID every target (in this case TIS-B and/or PCAS) is assumed to be a separate aircraft since there is no way to uniquely identify targets without IDs. Mode S transponders don't have this shortcoming, and obviously ADS-B Out is even better.

Andy

9B

Bruce

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Aug 9, 2021, 9:37:49 AM8/9/21
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Yes that is what I figured out after studying it on a flight yesterday. It is interesting that the only place this seems to be a problem in the USA. The rest of the world has obsoleted Mode C and replaced it with S and or ADS-B. It's good that Flarm gave us a solution to handle the uniqueness of our situation.

Bruce
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