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GRT/Stratux/GTX330ES - Double Targets

RedRaider94

Active Member
Hoping someone might have some thoughts on an issue today.

My 1090 radio went bad in my stratux so I replaced it. My stratux has 1090 and 978 - both are working based on my flight today and the stratux GUI interface showing packets being received.

I believe my 330ES is getting 1090 traffic in also.

Both the stratux and 330es are wired to my GRT HX (actually I think the 330es is wired to my 430W which is then sending data to my GRT HX).

Problem I had when testing the stratus today and the new 1090 radio was seeing half of the traffic on the GRT HX as double or overlapping traffic. For example, all of the American Airlines targets had double images (same tail number and altitude and either directly on top of each other or slightly offset where you could tell it was the same plane but showing twice).

I thought Stratux filtered out identical targets such as a 1090 and 978 rebroadcast so I am at a loss as to why I would see doubles.

Is the GRT getting a 1090 target on both the Stratux and 330es and then GRT is showing both? Is it possible Stratux is not filtering and the doubles are a 1090 and 978 message?

Any thoughts would be greatly appreciated!
 
1. You may be getting a target from an adsb ground station, and via direct reception. Make sure in your adsb set up you are sending that you receive adsb-in on both frequencies (978 and 1090).
2. Your 330 transponder does not receive adsb signals but may (will) get TIS-A data if available in your area. I think you can turn it (TIS-A) off in one of the grt menus, see if that fixes the problem.
 
Thanks!! That helps me understand the difference in TIS-A and real ADSB. So it sounds like the TIS-A and 1090 are showing up on the GRT.

I couldn’t find anything in the settings to turn off TIS-A and wonder if I even want to do this. Is there not a way for the GRT to filter out duplicate identifiers? I have to believe others have a 330es and adsb coming into there GRT. I am going to keep looking at the GRT settings to see if anything else might affect it.
 
I would first check your adsb-out settings on the GRT menu. Make sure ‘adsb-in on both 978 and 1090’ (not sure of exact wording) is checked, and not ‘just 1090’ or ‘just 978’.
To see if TIS-A is causing the issue, check how the data is getting from the 330 to the grt. It may be via rs232, or ARINC. Whichever, turn the port off and see if the double images go away.
 
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