ADS-B in display on ipad

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RickC

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RIckC
I've been flying with a Stratus 3 and an Ipad mini 4 loaded with Fltplan Go. My ADS-B out is a uAvionix Tail Beacon. Most of the time, my ADS-B position shown on the display is right on top of my GPS position, but occasionally my ADS-B position will begin to trail behind my GPS position at some point in the flight. Anyone know the cause of this?
 
Delay in the adsb processing and reporting back to your hardware? Happens to me too. Could be the FAA hardware not updating fast enough.
 
Matthew Rogers said:
Delay in the adsb processing and reporting back to your hardware? Happens to me too. Could be the FAA hardware not updating fast enough.
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That seems like the most obvious explanation, but it just seems like the underlying system would be more robust. Wondering if it's not some kind of intermittent failure in the Stratus, ipad or EFB, or the position reporting of my ADS-B out setup.
 
Is there some inherent delay between the transponder and the TailBeacon, on the transponder side?
 
Using a Stratux with FltPlanGo it was necessary to tell the Stratux what my Mode S Code was to keep from showing my own plane. I don't know if that is necessary for the Stratus.
 
RickC said:
I've been flying with a Stratus 3 and an Ipad mini 4 loaded with Fltplan Go. My ADS-B out is a uAvionix Tail Beacon. Most of the time, my ADS-B position shown on the display is right on top of my GPS position, but occasionally my ADS-B position will begin to trail behind my GPS position at some point in the flight. Anyone know the cause of this?
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My guess is computing delay in the FltplanGo. When there are lots of ADS-B hits nearby, it may take a few extra milliseconds to process the data and display their positions. Alternatively, it is possible your iPad is doing something else leaving less CPU power for the FltplanGo.
 
farmrjohn said:
Using a Stratux with FltPlanGo it was necessary to tell the Stratux what my Mode S Code was to keep from showing my own plane. I don't know if that is necessary for the Stratus.
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just figured out how to do that, want to get rid of that distraction. The bigger question is, if my position is obviously not accurate, how accurate are the displayed position of everyone else around me?
 
RickC said:
I've been flying with a Stratus 3 and an Ipad mini 4 loaded with Fltplan Go. My ADS-B out is a uAvionix Tail Beacon. Most of the time, my ADS-B position shown on the display is right on top of my GPS position, but occasionally my ADS-B position will begin to trail behind my GPS position at some point in the flight. Anyone know the cause of this?
Click to expand...

I think this is an issue with the design of the Stratus devices. They seem to not do a good job of handling a strong signal that is nearby, that is the AGC can't compensate for the short distances and strong signal. I have also seen what I call the "behind me syndrome" where the indicated position falls further and further behind the true position. Remember the SkyBeacon is only 10 to 20 feet from the Stratus and is broadcasting once every second. The ADS-B Out from your SkyBeacon is being received at the Stratus. The broadcast is totally independent of the FAA system and the Stratus, so if the ground stations see your broadcasts showing where the aircraft is located, so should the Stratus when it receives the signal from 20 feet away. I have seen Stratus that won't receive a nearby ADS-B Out signal until you physically move the Stratus to more than 50 feet from the airplane. I think it is a design deficiency and possibly a software bug in the Stratus.

If you don't tell the EFB software what the ICAO ID is of the own ship, then an algorithm needs to be able to detect the SkyBeacon that remains near your GPS position and altitude and then once it makes that determination, it should suppress the display of that ADS-B source as being a target and in fact is flying in near formation with you because it is you. Otherwise it will appear as a ghost target that is not real.
 
John Collins said:
I think this is an issue with the design of the Stratus devices. They seem to not do a good job of handling a strong signal that is nearby, that is the AGC can't compensate for the short distances and strong signal. I have also seen what I call the "behind me syndrome" where the indicated position falls further and further behind the true position. Remember the SkyBeacon is only 10 to 20 feet from the Stratus and is broadcasting once every second. The ADS-B Out from your SkyBeacon is being received at the Stratus. The broadcast is totally independent of the FAA system and the Stratus, so if the ground stations see your broadcasts showing where the aircraft is located, so should the Stratus when it receives the signal from 20 feet away. I have seen Stratus that won't receive a nearby ADS-B Out signal until you physically move the Stratus to more than 50 feet from the airplane. I think it is a design deficiency and possibly a software bug in the Stratus.

If you don't tell the EFB software what the ICAO ID is of the own ship, then an algorithm needs to be able to detect the SkyBeacon that remains near your GPS position and altitude and then once it makes that determination, it should suppress the display of that ADS-B source as being a target and in fact is flying in near formation with you because it is you. Otherwise it will appear as a ghost target that is not real.
Click to expand...
Interesting, thanks for the explanation
 
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