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Please confirm or correct my understanding.

akschu

Well Known Member
Patron
I'm studying ADS-b and trying to understand all of the variables.

I understand that there is 1090ES and 978UAT and that 1090ES is basically buying a new transponder that's updated to output ADS-b, while 978 UAT basically piggybacks on your existing mode-c transponder.

If I understand this right, then if you are using a 978UAT/OUT setup and squawking VFR/1200, then you will always be dealing with shadow if you are seen on radar, because the TIS-b signal you get from the ground doesn't have have any way to identify you, and thus your 978UAT/IN gear see's you as a target, but doesn't have any way to filter you out.

If that's true, does that mean that the only way to fix this is to get a squawk code, then enter it into the filter of your ADS-b/IN gear or use a combined ADS-b IN/OUT solution?

Seems to me the only way to absolutely get rid of shadow is to use 1090ES and put your hex code into the filter of your ADS-b/IN gear.

The major con to that, other than cost, is privacy. From then on, the FAA knows your every movement.... did I get that right?

Thanks,
schu
 
I still don't understand everything I know about ADS-B, but I "think" your ghosts will go away when you have ADS-B (out). The first time I got one of those TRAFFIC ALERTS! I just about soiled myself. That was when I had ADS-B (in) but not (out). I don't get them any more since I installed a Garmin GDL-82. I'm using Stratus/Foreflight for my ADS-B (in) and it knows who your "ownship" is and inhibits the panic alerts. Being a CSOB, I went with the GDL-82 UAT because it was inexpensive and easy to install. YMMV
 
"always be dealing with shadow if you are seen on radar"

Does not work that way. You will be transmitting your N-Number, in a different format, to the FAA and other UAT clients. The UAT packets have your N-Number in them. You will know your own packets and you will setup your equipment to handle your own aircraft. 1090ES is outbound only. Other 1090ES clients will read the packets, but the FAA only outputs (rebroadcasts) weather and traffic on UAT.
 
Okay, I think I get it....

If you have ADS-b out you will have a static ICAO code (regardless if it's 1090ES or 978UAT) and you simply put that code into your ads-b/in solution so that it knows it's you and to ignore it.

If you have 978UAT in anonymous mode, the ICAO code is randomly generated, and you will probably get your shadow back, unless your traffic display system is smart enough to filter based on heading, speed, and location.
 
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