ADS-B on a GRT Horizon HXr -- Need help, Katie!

This is an addendum to my thread entitled "How does one test ADS-B Out?"

Today I spent several hours of quality time trying to my Trig TT-22 Mode S transponder (ADS-B OUT) configured properly, after I realized that I was seeing WAY too much traffic out the front window that was NOT appearing on my ADS-B screens. (I also have a Nexus 7 tablet, running Garmin Pilot, with ADS-B traffic and weather overlaid on that screen.) I realized I was receiving passive ADS-B "in", but obviously my "out" was not triggering the ground stations.

After phone calls to GRT, in which I spoke to Mark and Ben, and utilizing advice given by Katie here yesterday, I made some changes to the setup window that allowed the GRT GPS to "talk" to the TT-22. We also determined that I could install the TT-22 adaptor's recent software update through the USB port for the Horizon HXr. This was good news, indeed. (Previously, we thought we would have to send the unit in for an update.)

So, I ran back to the house, downloaded the TT-22 adaptor's update to a thumb drive, drove back to the airport, and...no joy. The Horizon could not "see" the .dat file on the thumbdrive.

So, I thought, perhaps it can't be placed in the root directory. Back to the house I go, download it again, this time into subdirectory on the thumb drive. Drive back to the airport...and no joy. The Horizon still could not see that .dat file.

So, I call GRT. Ben asks what computer I'm using to download the update file. I tell him a Chromebook. He tells me that he knows it works using PCs, but that Apple computers often do something to make the .dat file undetectable. He doesn't know what a Chromebook will do. Our only logical assumption is that the Chromebook is formating the thumbdrive in a way that makes the .dat file unreadable.

So...BACK to the house again, download it onto the thumb drive using our last remaining PC, drive back to the airport -- and success! This time the Horizon can see the .dat file, and it updates. The Horizon now shows that the TT-22 is talking to the GPS, and knows where it is in space. Success!

Here is what the set up screen looks like after the upgrade:



As you can see, it has a GPS position. Yippee skippy!

And here is the proof that ADS-B OUT is finally working! Garmin Pilot shows that we have FULL TIS-B (AKA: ADS-B out) working:



You wouldn't BELIEVE the amount of traffic we can see on the Nexus 7 now! So, all is well, right? WRONG!

Incredibly, I now have NO traffic showing on the Horizon HXr screen at all. Here is a shot of the screen, showing absolutely zippo for traffic, while the Nexus 7 was showing a LOT of traffic:



Okay, now here is where things get really, really weird. Immediately after take-off, after doing the update, traffic showed up on the Horizon for a brief time -- perhaps less than a minute. I was ecstatic, then crushed, when it all disappeared.

After flying for 40 minutes, and finding no way to make traffic reappear, I gave up and headed back to the airport. As I was on downwind, about to turn base, suddenly the screen came ALIVE with traffic! There it all was, in all it's glory, with over a dozen targets overlaid beautifully on top of the sectional chart.

I let our a yippee (which startled Mary), and decided to depart the pattern to see what this was all about. As I built up speed and started to climb, *poof* -- the targets ALL disappeared. I reentered the pattern and landed, without seeing them again.

WTH is going on here? What could possibly cause this sort of behavior? I've got perfect ADS-B weather depiction, the screen is showing as many as NINE ADS-B ground stations in sight, yet no traffic is being painted on the screen?

Just FYI: We've got the dual-band Skyradar system attached (via USB) to the Horizon, for ADS-B in, with external antennas mounted on the belly of the plane.

Any and all advice is appreciated!

Hi Jay,

This is a mystery. Dropping off the map like that almost sounds like TIS traffic behavior, like you're flickering in and out of the Corpus Christi TIS traffic range. Is it repeatable, or random? It's possible that traffic you're seeing on the HXr is from TIS and we don't yet have the ADS-B stuff showing up.

Flying around near Nashville with a GTX330, we could always predict about where the TIS traffic reception from Nashville's Class C would drop off the map. Also, the angle the airplane is pointed has much to do with traffic reception and "ghosting" images. It was always a given that I'd see myself on the G1000 traffic map turning crosswind for Runway 36 at Murfreesboro, just outside the Class C ring-- when I'd turn the belly of the plane (and transponder antenna) toward Nashville. (That was always a cruel joke to play on new students in the pattern... they'd see the traffic icon pop up on top of us and their eyes would get as big as saucers.)

We'll ask programmer Jeff when he comes in later this afternoon if he has any ideas...

If you do fly today, avoid that TFR near Corpus Christi!

Jay, I haven't seen you mention in either post whether or not you set up your discreet hexadecimal code in you transponder and the HXr. Just a thought.

I have almost the same setup as you with the exception of the transponder, I have the TT31 and mine works great.

Next time I'm at the airport I'll copy all the pertinent settings and send to you.

One thing to check if you can. On my transponder I can display the lat/lon tha't being fed into it by the GPS and/or I get an error message that says "No ADSB postiton". Can you display you lat/lon anywhere with the TT22?

Just a couple thoughts.

RV8iator said:

Jay, I haven't seen you mention in either post whether or not you set up your discreet hexadecimal code in you transponder and the HXr. Just a thought.

I have almost the same setup as you with the exception of the transponder, I have the TT31 and mine works great.

Next time I'm at the airport I'll copy all the pertinent settings and send to you.

One thing to check if you can. On my transponder I can display the lat/lon tha't being fed into it by the GPS and/or I get an error message that says "No ADSB postiton". Can you display you lat/lon anywhere with the TT22?

Just a couple thoughts.

Click to expand...

If you look at the the first picture in my post (the black screen) you will see a lat/lon position. That is apparently what the TT22 is "seeing". I'm pretty sure we've got that set up correctly, now.

I have also verified that the unit IS transmitting my "N" number, as it can now be seen in Garmin Pilot on my tablet. I verified that it disappears when I turn off the TT-22.

I believe I set up the hexadecimal code in February. I will double check.

The weird thing about this is that now I'm starting to wonder about whether I've been seeing ADS-B traffic at all on the last few flights. The last time I remember seeing traffic was on the flight where I had the severe "ghosting" of my own aircraft, 4 - 5 flights ago. Since then...? Who the heck notices the ABSENCE of something?

So now I'm starting to wonder whether my SkyRadar has gone Tango Uniform. Although it's still receiving/displaying weather perfectly...

I'm confident that the GRT folks will come up with a solution.

KatieB said:

Hi Jay,

This is a mystery. Dropping off the map like that almost sounds like TIS traffic behavior, like you're flickering in and out of the Corpus Christi TIS traffic range. Is it repeatable, or random? It's possible that traffic you're seeing on the HXr is from TIS and we don't yet have the ADS-B stuff showing up.

Flying around near Nashville with a GTX330, we could always predict about where the TIS traffic reception from Nashville's Class C would drop off the map. Also, the angle the airplane is pointed has much to do with traffic reception and "ghosting" images. It was always a given that I'd see myself on the G1000 traffic map turning crosswind for Runway 36 at Murfreesboro, just outside the Class C ring-- when I'd turn the belly of the plane (and transponder antenna) toward Nashville. (That was always a cruel joke to play on new students in the pattern... they'd see the traffic icon pop up on top of us and their eyes would get as big as saucers.)

We'll ask programmer Jeff when he comes in later this afternoon if he has any ideas...

If you do fly today, avoid that TFR near Corpus Christi!

Click to expand...

Thanks, Katie. (The "TFR" is really a "PFR" -- it's been there for years. That's where the Navy flies their Predator drones out of Corpus NAS. They climb to 18,000'...and disappear. No one really knows where they go, but we assume border patrol.)

I don't think this problem is related to the ground based system, as the GRT was reporting nine different ground stations in sight. I have the luck of being based on an island airport, which means that there is an ADS-B ground station just 1.8 miles from my hangar. This lets me ground test the system after making setting changes -- something that is impossible in most locations.

I've been racking my brain, trying to think of what could possibly have caused the behavior I witnessed. Here are the basic facts about flight conditions when the system suddenly worked properly:

1. Speed. Departing and entering the pattern, ground/air speed was relatively low. Could there be a filter in the GRT that is set wrong, so that it's NOT reporting traffic above a certain speed?

Edit: It may be worth noting that it was NOT displaying traffic on the ground, at "zero" airspeed, even though I had an excellent signal from our nearby ground station. So my theory, above, seems even less likely.

2. Altitude. Again, departing and entering the pattern was the lowest portion of the flight. I know there is an altitude filter (it's set to "Unlimited"), but could this be acting up?

3. Vibration. Could changes in RPM at takeoff and landing be jarring...something? A loose connection? The SkyRadar is connected with a USB cord which seems to be connected perfectly well, but...I'm just grasping at straws.

At this point, the only other thing I can think of is a problem with the SkyRadar box itself. Can it fail in a mode that would cause ADS-B weather to still work?

Jay, here are SNAPS of all the screens in the HXr that I have ADSB information. Your's are probably the same except for Transponder Type. I have my TT31 listed as a GTX330 instead of the Trig. My 31 would not work if I told the GRT is was a TRIG.



General Setup, First page asks for Aircraft info.



Traffic Altitude Filter Line



Traffiv in View line



Traffic Alert Window



ADSB Status line



My Configuration pages in the TT31 are as follows

1 Aircraft Address Hex Code
2 VFR Squak Code 1200
3 Flight ID Tail Number
4 Aircraft Speed 15-300
5 Aircraft Type Light Fixed Wing
6 Squat Switch Source Not Connected
7 TIS Output Garmis Remote +TIS
8 GPS input Garmin ADS-B
9 GPS/TIS line Speed 9600
10 GPS certification (GTN650) mine is B
11 Select GPS NAC velocity Unknown
12 Aircraft Length and Width 8,m 8m
13 GPS refeerence offset Unknown
14 1090 Receiver installed Yes
15 UAT Receiver installed Yes

Then I have a GREY code display page an it shows

AAA BBB CCC D
421 421 421 4
00000000000

I'm not using GreyCode, but the unit displays thses numbers anyway.. must be some voodoo in there.

Hope all this helps you track your problem. Once you get it working you're going to be amazed at all the traffic you don't see..

Thanks! I will check my setup against yours tomorrow.

I flew for two hours today, and had traffic visible nearby only sporadically. Meanwhile, I could see traffic 150 miles away, in the Austin/San Antonio areas, just fine.

I wonder -- could this be pointing to a ground-based, Corpus Chrisit- only area problem?

Wouldn't THAT be a kick in the butt? lol