Help me understand ADSB

A couple days ago I flew and a king air was departing an airport a couple miles off the nose. I watched him takeoff and disappear into the distance. He never showed up on my display. I have the navworx EXP model UAT transceiver. Here are a few questions: (He was heading towards class C airspace so I'm assuming all his equipment was working).
1. Can the FAA cause this by blocking a single for only the affected navworx units?
2. Mine is a single band unit. The king air was probably 1090 since they fly over
18K feet. Should/can I pick him up air to air? (I don't think so since I'm only
978 in).
3. If I can't receive his 1090 signal air to air, should I be able to receive it from
the ground stations by their "rebroadcast" single? (I would think so BUT....
one training video led me to believe this isn't the way it is because it would
create two signals, one a ghost, for the same plane on my display).

Hope I've asked the questions clearly enough.

Very few aircraft are ADS-B OUT equipped. He likely was not equipped.

In this case, the only way to see him is via radar (TIS-B), which requires you to be in a radar coverage area. Does your display system show if you are in radar coverage (not just seeing a ground station)?

He could have forgotten his transponder of course...

If I have ADSB in and out... I thought I would receive all aircraft that were in any type of radar coverage area... their signal being transmitted to the ground stations and uplinked to all adsb equipped aircraft like me? Like I said in my original post.... I am confused.

How high were you? Ground stations will only send you traffic if It is within 3500' vertically, and 15 miles horizontally (I think those are the numbers) from you. Your own system may have additional filters to reduce clutter.
The King Air may have needed to climb a bit before he could be seen by a ground station or radar.

Jordan1976 said:

Very few aircraft are ADS-B OUT equipped. He likely was not equipped.

In this case, the only way to see him is via radar (TIS-B), which requires you to be in a radar coverage area. Does your display system show if you are in radar coverage (not just seeing a ground station)?

He could have forgotten his transponder of course...

Click to expand...

I would bet this is correct, the experimental world is way ahead of the certified world on ADS-B in and out.

You might also check your ADSB-out settings. You should be telling the ground station that you are listening on 978 (UAT) only, not 1090. The ground station should then send you 1090 ADSB traffic, plus non ADSB radar traffic that it knows about, but again only if they are within 15 miles horizontally and 3500' vertically.

Due to having a Navworx unit, and the FAA's current issue with NavWorx, I think hey are not letting the NavWorx unit activate the ground stations to broadcast all traffic. I would guess this is the reason. Otherwise, he may not have been squawking on his transponder.

FAA does not know what ADS-B you are broadcasting from

That is why they ask you the brand/model when you ask for a compliance readout (which I never give them).

I flew yesterday with my EXP and am confident I was getting the "normal" traffic picture.

I do hope Navworx works out the problem --- great unit!

Ron

To answer Bobs question about position. I was about 2000 feet IIRC. I watched the king air take off about 2 miles ahead of me and climb above my altitude as it headed north west until he disappeared from my view. Like I said though, he never showed up on my traffic picture. He WAS showing up on my Zaon device so I know his box was getting hits from ATC radar.

NOTE: I was reviewing the Sportys Pilot Shop ADSB training video and they stated if you have adsb out single band... then thats all you'll need. That's me! My unit should wake up the ground stations and they should send me the "customized traffic picture" which was all aircraft as long as they have a transponder in the airspace IIRC 30 miles and + or - 3500 feet. Its not happening though and it's frustrating. I don't have any kind of filtering going on that I know of.

One other observation. When I first installed the navworx in May, I was seeing many many many targets and as time goes on I'm seeing fewer and fewer all the time. I'm really not paranoid or a conspiracy theorist but I can't help believe the FAA isn't in some way filtering out affected navworx boxes! Admittedly, that's just speculation.

Do you have a certified position source? I believe the FAA was talking about disabling station wake up for devices that don't have a proper position source, like most portable units.

gfb said:

Do you have a certified position source? I believe the FAA was talking about disabling station wake up for devices that don't have a proper position source, like most portable units.

Click to expand...

And like the Navworx GPS which is now in question.

Paul 5r4 said:

He WAS showing up on my Zaon device so I know his box was getting hits from ATC radar.

Click to expand...

The majority of transponder replies in the world are due to TCAS interrogations from air transport aircraft. Seeing a reply light on your transponder or another target on a Zaon doesn't mean you are in radar coverage.

There's only one way to know if you are in ADS-B radar coverage- your traffic display unit (EFIS, iPad, ???) must tell you if it is getting the service bits from the ground station. Without that data, you'll never know if missing a target is expected or not.

The Navworx box is a UAT, so you wouldn't get air-air traffic on 1090. Check what SIL you are configured for / sending on 978. If your SIL=0, then it might be getting ignored wrt TIS-B or ADS-R. SIL=3 should trigger the ground station to send you traffic. All this assumes that you are in range of a ground station. Does Navworx allow user configurable SIL?

maus92 said:

Does Navworx allow user configurable SIL?

Click to expand...

No. Nor does it show what you are transmitting.

Jesse said:

No. Nor does it show what you are transmitting.

Click to expand...

That's interesting. In my Garmin G3X Touch / GTX23 / GPS20A ADS-B installation, I configure the SIL value. Maybe because the transponder and position source have demonstrated a certain level of performance?

maus92 said:

That's interesting. In my Garmin G3X Touch / GTX23 / GPS20A ADS-B installation, I configure the SIL value. Maybe because the transponder and position source have demonstrated a certain level of performance?

Click to expand...

Because what you have is not a one box package, you need to tell the transmitter what position source integrity you have. But you need to have a reference: no one may just arbitrarily change the manufacturer's stated value.

My temporary plan B

My plan B.... to prepare for the potential removal of my Navworx EXP I've ordered one of the "homemade" adsb receivers, (dual band). It's to be delivered today. When it's up and running, I'll use my nexus for that and the ifly with the navowrx for a side by side comparison to see what each one is receiving.