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For context I have an ADS-B 1090 OUT and 978 IN. I also have a Stratus portable Dual channel receiver in my plane, so I have the option of comparing the traffic between systems.

What I’ve been noticing is that lots of 1090 targets that I can see on Stratus connected iPad, I can never ever see it on my display connected to 978 IN avionics. My understanding is that my setup should:

A) Receive direct reports from aircraft equipped with UAT/978 OUT hardware. (Air-to-Air) (Working Good)

B) Receive ADS-R rebroadcast traffic from ground stations, for 1090 targets. (Not receiving)

C) Receive TIS-B traffic from ground stations, for Mode-C targets that aren’t participating in ADS-B network. (Good)

So my question is, why do scenario B seem not to be working for me?

I pulled ADS-B Performance Report for my flights and I see:

  • OUT capability is correctly listed as 1090 and IN capability is listed as UAT. This should indicate the Ground Stations that I need 1090 targets as part of rebroadcast (ADS-R) to me. I contacted FAA on it and they agree too

Any thoughts? is it something I am missing in the ADS-B OUT configurations or could it be Ground Station issue?

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  • $\begingroup$ Have you checked your configuration against the info here: faa.gov/nextgen/equipadsb/capabilities/ins_outs ? $\endgroup$
    – Gerry
    Sep 26, 2018 at 16:25
  • $\begingroup$ @Gerry - Yes I did. The ADS-B OUT configurations are correctly listed in the PAPR report as well. OUT - 1090, IN - 978 $\endgroup$
    – Karthik
    Sep 26, 2018 at 17:10

1 Answer 1

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Ground stations only send ADS-R/TIS-B messages for targets within a certain distance horizontally and vertically of ADS-B targets with the CDTI (Cockpit Display of Traffic Information, aka "ADS-B In") flag set. Assuming your CDTI flag is set correctly, the targets you're missing probably aren't close enough to qualify.

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