Ads-b and N number display

[johnsteichen]

I have both the dynon adsb unit and the mode s transponder.
Recently I have had friends flying nearby comment that I show up on their display with my N number showing up on their display. I have never seen another aircraft on my dynon Skyview with an N number displayed. What gives or how come?

 

[Dynon]

We don't currently display n-numbers of traffic targets, although it's possible in some cases. It's on the list to consider, though.

 

[johnsteichen]

The N numbers are not very important to me, I just thought something was missing from my system in their absence.
Was not complaining, just curious. :

 

[swatson999]

It's a great idea...and as an added benefit, would solve the "holy s**t!" problem when the system shows your own plane as traffic (which has happened on a few occasions, usually when maneuvering doing tight turns, etc.).

 

[dynonsupport]

Just some data on why we didn't do the work to show N numbers when we did ADS-B traffic:

1) Only a few percent of the GA fleet is equipped with Mode-S or ADS-B out. You can only see N numbers from these aircraft, so the vast majority won't show N numbers even if we did this. You'll see a lot of airliners if you are close to them though.

2) As of 7.0, we already filter your own plane out by N number. If the ground station marks a target with your N number, we won't show it. Before that, we were already filtering by ICAO address like the ADS-B specs require. The issue here is that when you get a ghost target, it is often because the ground station doesn't have any idea who that plane is, so it won't have a valid N number nor the right ICAO address. We're working with the FAA on all of this because it shouldn't be happening, and we're doing all the filtering we can.

3) We spent our time writing collision detection algorithms (the "TRAFFIC" callout) instead of just putting N numbers on the screen Some of the competition that puts N numbers up doesn't warn you when traffic is nearby, you have to watch the screen at all times.

 

[jakej]

DS - as a point of reference for Mode S Transponder users in Australia - we don't input VH (our equivalent to your 'N') into the setup parameters

Jake J

 

[dynonsupport]

Whatever you have set in your "OUT" is what we filter on the "IN." But since you don't have 978MHz UAT there, it's kind of moot since that's the only connection that can pass us aircraft tail numbers and it only works in the USA.

 

[swatson999]

Now that you mention it, I haven't seen myself as a target in quite a while, so your filtering seems to be working well.  I probably was recalling instances of it happening a while back, when first flying the new aircraft and before installing the ADS-B box and such.  Nice work!  That "traffic" callout (which we used to get A LOT in other planes w/ Garmin equipment which I flew) were quite startling when you looked at a traffic screen on the GPS and saw a target *at your altitude* right near you...until you got used to it.

Keep the good algorithms coming...you guys are doing a great job!

 

[stevengrasley]

Hello all,

I just got my RV-7A in the air on October 1 and am 30 hours into my Phase I testing. I have a full SV suite with ADS-B. SkyView is so great. I love it!!!

I am flying in the Florida Keys so I don't have the ability to get my transponder checked to legally use Mode-C/S. I have to get my plane to Miami area with a full avionics shop to do that. So, after some careful reading I realized I can turn the transponder simply "on" so it does not report altitude. This is nice because I can see all the traffic.

But, I get a real wake up when SkyView yells "TRAFFIC" at me and it is usually a ghost of me. It is always within 300 ft of my altitude (usually lower and it is right on top of me. Note that this is only occasional. In a 1.5 hour flight I might get yelled at 2-3 times and it is always a ghost of me. From what I can tell the rest of the traffic function is working very well.

I have not had the chance for a TCAS or traffic equipped aircraft to work with me and let me know how they see me. I'd like to do that.

Given the operation noted above, can it be confirmed that I am seeing myself as a ghost? Is this because Miami radar is telling me that through ADS-B? Or is it a filtering issue in SV? or is it something else?

Steve

 

[dynonsupport]

First off, FAR 91.413 says:

No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or Sec. 135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with Appendix F of part 43 of this chapter.

In our opinion that means you can't turn the transponder on at all. The test is not just for altitude reporting equipment, it is a test of the transponder as a whole.

Ignoring that, if you aren't squawking altitude, you aren't providing the system a lot of data to work with. It has the radar location for you, and it has an estimate of altitude, but the estimate is rough. I can see that at times, it would consider you two airplanes: One from a radar return with a iffy altitude estimate and one from a great ADS-B GPS position report. At some point, it will see those "planes" far enough apart and decide they are two aircraft and transmit two targets to us, one that gets filtered because it is you, and one that does not.

Not much we can do about this. The system was designed to work with planes squawking altitude. Let us know if it persists once you are using the transponder in ALT mode.

 

[cmarbach]

Try SALES@TROPICRADIO.COM They may be able to come to you for a complete static system and Xpndr check. Mark has done two of my planes.

 

[lolachampcar]

On 7 and see myself on a regular basis doing aerobatics. I suspect ground looses everything about me apart from the radar return and broadcasts me as an "unknown" target.

 

[dynonsupport]

The radar system has some rates built into it that aerobatics can exceed for sure, and this can lead to you showing up for a few seconds. Radar only sweeps about once every 3-12 seconds, so it has to make some estimates of who you are between sweeps.