Ghost Image

[revenson]

Occasionally I get a traffic warning that appears to be right at my location. Very scary when it happens, but I think I'm seeing my own airplane.
Is there a setting that I'm not aware to
minimize this possibility??

[330drvr]

I get that also on occasion. Most often right after takeoff. Can't say I like it either!

[revenson]

Found this as one of the software changes made in 5c, and am wondering if this can fix the 'ghost image' problem:
"Add Flight ID and Mode S Address settings and filtering"

Does this refer to an option to put in one's own plane address such that it will not be displayed as traffic?

[gbrasch]

Ditto on that happening to me also on my Sport SX unit, really gets my blood pressure up until I figure out it is me!

[Bobturner]

Your GRT should look at the N numbers attached to the ADSB in data, and not show yourself. The problem is that your N number is not attached to the data stream coming up unless you have ADSB-out. So by 2020 the problem will go away. Or sooner if you install ADSB-out.

[revenson]

It maybe should check my n number, but is it programmed to do so?
I have both in and out ADSB, so that's not the issue. Guess we'll have to wait for GRT to respond.

[Bobturner]

You have to enter your N number and mode S hex code, just as you described in your previous post. But until 2020 this may not always be enough. The issue happens if the data uplink is based on data from FAA radar (which does not have your N number) when you are out of range of an ADSB ground station picking up your ADSB-out signal.

[330drvr]

Bob:

Thanks for the last posting. I have both ADS in and out and my N number and hex code in the settings. I get my "ghost" image right after takeoff. Now I realize it is when I have not linked with an ADS ground station yet. Once I am linked, the ghost goes away. Thanks for the explanation!

[jclark]

You have to enter your N number and mode S hex code, just as you described in your previous post. But until 2020 this may not always be enough. The issue happens if the data uplink is based on data from FAA radar (which does not have your N number) when you are out of range of an ADSB ground station picking up your ADSB-out signal.

What Bob said. Plus ....

There is a scenario wherein you can miss some aircraft depending on your settings.
During testing of multiple ADS-B receivers in conjunction with GRT, I found a case where my friend who had a NaVWorX box could be flying right next to me in formation and NOT show up!! He could be transponder "ON/ALT" and this happen. If he turned on HIS ADS-B equipment (978Mhz only ... UAT), then he showed up. It was a matter of the system "listening" for how you interact with the system and responding accordingly. Basically the problem was one of receiving on 978Mhz vs 1090 Mhz. Since I have a TT-22 (Trig) transponder (1090 Mhz) and I have a dual band receiver (SkyRadar D2), I thought that all would be well. Have to configure Trig to say that I was sending output on 1090 MHZ with regards to ADS-B.

Feel free to send me an email if you have questions about what I am doing a poor job of saying here.

James

[revenson]

Thanks the all these responses. At first I did not get it, but now that I've heard directly from Jeff at GRT, on second read your responses make sense. For everyone's info, here's my direct question, and his reply (posted here with permission):

My question:
Is entry of my n number (or mode s address) suppose to eliminate my aircraft showing up as traffic on my HX display? If not, I suggest you program this to eliminate the scary ghost image that sometimes appears.

Jeff's reply:
It only works with ADS-B Out and Mode S data received through an ADS-B receiver. There are a couple ways you could see a ghost.
If your plane is picked up by a Mode C radar, or the Mode S or ADS-B ground link isn't communicating, then the traffic data received by the HX will not
include your address, and the HX won't be able to filter it out.

TIS serial links don't include addresses, so it's possible you're getting ghost data from a TIS input. If you have a 330 or something else that
receives non-ADS-B TIS data, the address information is not included, so there's no filtering.