What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

How Does One Test ADS-B?

J

jjhoneck

Well Known Member
We have the SkyRadar ADS-B system, coupled to our GRT Horizon HXr EFIS. This gives us ADS-B in, while our Trig Mode S transponder gives us ADS-B out.

We have gone for several flights lately where we visually saw traffic that never showed up on the EFIS, and it quickly became apparent that I had no idea if it was because the guy was flying without a transponder, or if the ADS-B ground transmitter was "down", or if my system was malfunctioning.

I'm wondering if there's a standard way to check the functioning of an ADS-B system in an airplane?

Thanks!
 
Jay,
I have an HX so your HXr is a bit different, but I see, in the lower right side of my map page, a box that says "ADSB -3" or something like that. The 3 in this case is the number of ground stations being received. I'm sure the HXr must have a similar feature.
 
Also, in the HXr set up menu, you can filter out traffic a certain altitude above or below you. Maybe you want to loosen up the limits until you are sure it works.

Also, you should be getting weather.
 
Not sure about the traffic, my system is using TIS from the Trig transponder for traffic. I do know that I can pick up TIS traffic in your area.

But you should be able to pick up weather info. Radar, METARS, TAFs should all be available.

If weather info is not showing up, go through the configuration options again.

Also, you should be able to connect to the Skyradar unit with an iphone or ipad. You can use that to verify that that part of the system is working.
 
Sorry, I should have been more clear -- we are receiving weather. And we have received traffic info on many flights, so I know the system is/was working.

My question pertains to an "on-the-fly" check. If I see traffic visually, and it's not displayed on the Horizon, how do I check to see that the system is working at that moment?
 
An adjunct question to this: On several flights I have received "Traffic Warnings" -- the pop-up window that gives a potential collision warning -- on what was probably US.

Here's the sequence of events:

1. The warning window pops up.
2. I look at the screen, and it paints a target at about the 11 o'clock position, which quickly slides behind us.
3. It then reappears, several times.

On one flight, it did this over and over for ten minutes.

Why? Why would it do that on some flights, but not all?
 
It may be just fine ....

jjhoneck said:
Sorry, I should have been more clear -- we are receiving weather. And we have received traffic info on many flights, so I know the system is/was working.

My question pertains to an "on-the-fly" check. If I see traffic visually, and it's not displayed on the Horizon, how do I check to see that the system is working at that moment?
Click to expand...

Jon,

I did a lot of the testing of the ADS-B stuff on the GRT system.
(See an article in the JULY issue of Kitplanes)

As others have mentioned, the lower right corner will tell you the number of ground stations that are being received. If you have a non-zero number, you should be getting stuff. If you have received any weather or METARS or WPT DETAILS, you are receiving.

Now, you need to make sure that the Trig is set up correctly for ADS-B out. Actually I think you said that you have SkyRadar which is dual band so the setting I was thinking about may not be an issue.

There are scenarios that I have encountered (with a WORKING system) where the traffic did NOT show up. ADS-B is still in the early stages and there are a few unique cases that I have seen where stuff is missed.

Contact me offline for more details.

James
jclarkmail blah blah gmail
803-238-2113
 
Adjunct question - response

Jay:

ADS-B "ghosting" is a common occurrence. VAF posters have reported it on occasion:


"...if you're within range of an aircraft with ADS-B out, you can see your own radar return on the traffic display, complete with latency and mode-C altitude reporting error..."

and

"...The ghosting would happen when crossing the same exact point because I was in range of two radar stations. Each station was reporting me as traffic..."

My theory is it arises when there's a conflict between positions reported by ADS-B (GPS-based) and radar (ground-based sensors), combined with latency of processing and transmission.

Dynon has filters which, if selected, will eliminate ghost images.
 
jjhoneck said:
I'm wondering if there's a standard way to check the functioning of an ADS-B system in an airplane?
Click to expand...

I have asked a number of controllers with the intent to learn if anything on THEIR scopes is different between ADS-B and non-ADS-B indications.

Usually the answer is "Negative" and said somewhat tersely. :mad:

However, I was up in the KAVL tower last week on a social visit :) and one of the controllers there said that the newer installations would have different indication iconography and the ability to retrieve more data if they went to the trouble to dive in a bit further.

So, to your point, I have no way to really know that the outbound signal is actually working or whether ATC is simply seeing my 327.

As a recent convert, I have to say ADS-B inbound is nice. Helped with wide spaced Tstorms yesterday and also with traffic that Center never mentioned.
 
I have a different brand of equipment but I can say that on occasion I do not receive some traffic but do receive weather all the time.
I have never had the ghosting.
I am hoping it is a FAA thing that will improve.
 
I think the one posted alluded to a issue I had. On your transponder out settings if you are not a dual band system you must make sure the transponder settings are for 978 out only. If you have it set for dual band out and are just 978 you will miss much of the traffic because the ground stations will not initiate full traffic uplinks to your aircraft.

George
 
sailvi767 said:
I think the one posted alluded to a issue I had. On your transponder out settings if you are not a dual band system you must make sure the transponder settings are for 978 out only. If you have it set for dual band out and are just 978 you will miss much of the traffic because the ground stations will not initiate full traffic uplinks to your aircraft.

George
Click to expand...

SkyRadar is dual band, so the Trig should be set up to be both bands out. I think?

So we've determined that the EFIS will display if ADS-B in is being received. How does one verify that ADS-B OUT is functioning?
 
Double check you are set to dual band out on the transponder. Easy and quick to check.
George

I just noticed there are two versions. One dual band and one not. It's also a in only system so not sure how it will interface with the trig. Your going to need a expert. Perhaps give James Clark a call.
 
Last edited:
sailvi767 said:
Double check you are set to dual band out on the transponder. Easy and quick to check.
George

I just noticed there are two versions. One dual band and one not. It's also a in only system so not sure how it will interface with the trig. Your going to need a expert. Perhaps give James Clark a call.
Click to expand...

We have the dual band Trig TT-22.
 
jjhoneck said:
We have the dual band Trig TT-22.
Click to expand...

Actually the Skyradar receiver may be dual band but there is no such thing as a "dual band" transponder. The setting on the trig tells the ground station how to broadcast the info to you either using the UAT 970 freq or the txpdr 1030 freq.
 
Okay, this was bugging me enough to go to the airport. (What a hardship, I know! ;) )

Below is the setup screen for the TT22, using the Horizon HXr's menu system. I was under the impression that in order to have ADS-B out, I needed to have a GPS "in" connection and position. We've bot the GPS installed, but it doesn't seem like the TT22 is "seeing" it, if I'm reading this setup screen correctly.

Whuddy'all think?

1891020_687080467994517_6400372044699888550_n.jpg
 
Walt said:
Actually the Skyradar receiver may be dual band but there is no such thing as a "dual band" transponder. The setting on the trig tells the ground station how to broadcast the info to you either using the UAT 970 freq or the txpdr 1030 freq.
Click to expand...

Not arguing here as I know little about the operation of ADS-B and my info is limited to what I have read here and there, but I recently upgraded my GTX 330 with ES and when I went thru the configuration, I saw options for 970 and 1030 that could be checked (turned on). At first I had only one of them checked and as a result I was not getting all the traffic on my display. when I changed the selection to both frequency on the GTX 330 I see many more traffic on the display.

Now, slightly different issue, once in a while I see traffic that disappears for a short duration, just to reappear again on my display (GRT and WingX) which I don?t have any explanation for but would love to know what is the cause of it. These are not traffic that is near my filter range to think that they go out of the range and come back within the lateral or vertical range.
 
jjhoneck said:
Okay, this was bugging me enough to go to the airport. (What a hardship, I know! ;) )

Below is the setup screen for the TT22, using the Horizon HXr's menu system. I was under the impression that in order to have ADS-B out, I needed to have a GPS "in" connection and position. We've bot the GPS installed, but it doesn't seem like the TT22 is "seeing" it, if I'm reading this setup screen correctly.

Whuddy'all think?
Click to expand...

John,
Did the GPS have a "fix" on your location (locked on)?
It should be showing a GPS position (lat & lon).
 
jjhoneck said:
I'm wondering if there's a standard way to check the functioning of an ADS-B system in an airplane?

Thanks!
Click to expand...

To answer your original question, very few shops currenty have the test equipment to actually do ground testing of ADS-B. Later this year when my transponder test equipment comes do for its annual certification I plan on adding the ADS-B & UAT upgrade options so I can actually test these things on the ground (big $$$ investment but like ADS-B any shop that plans on installing ADS-B in certified aircraft will need it).
 
An easy approach to check it ...

jjhoneck said:
SkyRadar is dual band, so the Trig should be set up to be both bands out. I think?

So we've determined that the EFIS will display if ADS-B in is being received. How does one verify that ADS-B OUT is functioning?
Click to expand...

If you have an iPad or a friend with one with any of the "apps" that do ADS-B **and** a compatible receiver, take it up with you on the flight. You should see YOUR N-number on the iPad.

If you have friends with ADS-B systems in their planes, go up and ask them if they see you **AND** your N-number.

This will give at least an indication that your Trig is reporting you.

I saw in your later post that you did not give the position of the GPS. Our RV's are about 8 meters, I think and the GPS location is given in relative postions. Not a big deal so much for an RV but for an AirBus 380 or a Boeing 787, knowing where the GPS is located and the wingspan helps the system position you and the space around you.

I have the Trig TT-22 and the SkyRadar D2 installed.
(Also from time to time the Dual and ILevil and FDS systems).
If you don't get it sorted out give a call and I will walk through my settings with you.

James
 
As an FYI, just because you are seeing ground stations doesn't mean they are uplinking traffic to you. So the number of ground stations seen tells you nothing about traffic status. It's only useful for weather data.

The ground stations send a "traffic status" bit to your plane. On SkyView this shows up as ADS-B FULL or ADS-B PARTIAL. If you are partial, you are not getting any level of reliable traffic.

If you aren't sending out your GPS position, the ground stations will never serve you with traffic, so you will only see other ADS-B out planes. Mode C and Mode S (without ADS-B) will not show up. Sounds like you are on the right track.
 
dynonsupport said:
As an FYI, just because you are seeing ground stations doesn't mean they are uplinking traffic to you. So the number of ground stations seen tells you nothing about traffic status. It's only useful for weather data.

The ground stations send a "traffic status" bit to your plane. On SkyView this shows up as ADS-B FULL or ADS-B PARTIAL. If you are partial, you are not getting any level of reliable traffic.

If you aren't sending out your GPS position, the ground stations will never serve you with traffic, so you will only see other ADS-B out planes. Mode C and Mode S (without ADS-B) will not show up. Sounds like you are on the right track.
Click to expand...

Thanks. My hunch appears to be correct -- we are receiving "passive" ADS-B traffic and weather, but our ADS-B "out" is non-functional. Thus, we are not triggering the ground stations, and not getting full traffic info.

It's frustrating that I could have flown with this system since last June, and not known this. There just doesn't seem to be any good way to test ADS-B out -- at least not until Walt gets his test gear set up!
 
dynonsupport said:
As an FYI, just because you are seeing ground stations doesn't mean they are uplinking traffic to you. So the number of ground stations seen tells you nothing about traffic status. It's only useful for weather data.

The ground stations send a "traffic status" bit to your plane. On SkyView this shows up as ADS-B FULL or ADS-B PARTIAL. If you are partial, you are not getting any level of reliable traffic.

If you aren't sending out your GPS position, the ground stations will never serve you with traffic, so you will only see other ADS-B out planes. Mode C and Mode S (without ADS-B) will not show up. Sounds like you are on the right track.
Click to expand...

True!
(What "dynonsupport" said here.)

Got me to wondering though ...

Is the question about determining if the system is set up and working properly at all or is it how to tell from time to time of traffic data is being received (or not).

I must say that with what I have as what I think is a working system, there **HAVE** been times wherein I physically saw traffic that did NOT show up and I assumed said plane in fact did have a functioning transponder.

Was not sure if it got through the cracks of a still developing ADS-B system or if plane had transponder on standby or if my system just dropped a couple of bits.

Reminded me that I STILL need to be vigilant and be looking OUTSIDE as well.

James
 
Walt said:
Ok "Jay", looks it time to dig back into the config settings again :eek:
Click to expand...

Yup. It's like Groundhog Day.

More accurately, it's 1989 again, and I'm configuring a network between two 386SX's, all over again. lol

*sigh* I eventually got that to work reliably, too.
 
You may also need to confirm that you do indeed have the GPS serial data line correctly wired to the Tt22.
 
Last edited:
Quick & easy test, on the ground

James Clark proposed, in this thread, a method to confirm you are transmitting your position out: use a standalone tablet (iPad, etc) with an ADS-B receiver and display app, while your Trig is set to broadcast.

Won't even require avgas.
 
Question for Walt

To meet the 2020 standards, does an approved position source (say, a 430W) have to be hard-wired directly to the UAT or mode S-ES; or can it go thru an uncertified intermediary, like the HXr?
 
esco said:
James Clark proposed, in this thread, a method to confirm you are transmitting your position out: use a standalone tablet (iPad, etc) with an ADS-B receiver and display app, while your Trig is set to broadcast.

Won't even require avgas.
Click to expand...

Actually, we fly with a standalone ADS-B set up in the back seat, a GDL-39/Nexus 7 combo. You're right -- looking at that screen should verify that ADS-B out is working once I get this ironed out. Easy peasy.
 
BobTurner said:
To meet the 2020 standards, does an approved position source (say, a 430W) have to be hard-wired directly to the UAT or mode S-ES; or can it go thru an uncertified intermediary, like the HXr?
Click to expand...

As I understand it, to be in compliance you have to have the Mode S transponder (providing ADS-B out) connected to a WAAS GPS. The Horizon is just the display -- behind the panel is a WAAS GPS.

Which my set up is apparently not seeing. Yet. :(
 
It's not really a WAAS gps that is required. It has to be certified by the FAA for use as a ADSB position source to be compliant in 2020. That's what makes it so expensive at the moment. The GPS cost more then the rest of our panel.

George
 
sailvi767 said:
It's not really a WAAS gps that is required. It has to be certified by the FAA for use as a ADSB position source to be compliant in 2020. George
Click to expand...

While that is true per appendix 2 of AC20-165 via many comments about permissibility of TSO-129 units with supplementation to provide items missing from 129 units, from a practical standpoint purchase of a newer WAAS is likely more expedient than developing the "supplementation".

I remain convinced that the most economical retrofit for someone with no compliant GPS is the certified Navworx ADS600-BG since it includes a cert GPS.
 
Hi Jay,

I may have missed it in the thread, but what type of GPS do you have wired to the TT22 for ADS-B broadcast?

If it's a GRT GPS module, the GPS INPUT setting should be NMEA0813 and the baud rate 4800 (regular VFR WAAS module) or 57600 (RAIM module).
 
Check that you have the latest software update for your Trig. I installed a Trig/GDL 39/Garmin 796 system and could not wake the ground stations. Eventually (after repeated configuration, wiring, antenna checks) I discovered that a later version of Trig software was available. Sent the unit off for update, got it back a week later, everything worked. My Trig briefly displays the software level on the control head at powerup.

The stateside Trig service center is MidContinent Instruments+Avionics. The phone numbers for the Kansas location are:
800.821.1212
316.630.0101

With the GDL-39/796 combo, the display indicates separately receipt of air-to-air data and ground station data. If you can borrow a set from someone you can use it as a check to see if your transponder is waking the ground stations. They communicate via bluetooth, so a temporary setup is easy.

Joe Lofton
RV-3
 
One additional note - if you send your Trig unit for update they will need both the control head and remote unit.
 
I noted on your TT22 setup page that the GPS Certification Level is set to 'Uknown or Uncertified I suspect it will not receive TIS on 1030 unless that setting is Certified. Can you change it to Certified to see if that get you the TIS data?

John Salak
RV-12 N896HS
 
KatieB said:
Hi Jay,

I may have missed it in the thread, but what type of GPS do you have wired to the TT22 for ADS-B broadcast?

If it's a GRT GPS module, the GPS INPUT setting should be NMEA0813 and the baud rate 4800 (regular VFR WAAS module) or 57600 (RAIM module).
Click to expand...

It is a GRT module. I will change those settings ASAP, and give her a whirl.

Re: a software update for the Trig, yeah, I have been getting a message on the Horizon, stating that an update for the TT-22 is "available". I was hoping there was a way to do this through our USB data port, but it sounds like I will have to send it in. What a PIA.

I wonder if they would do a swap?
 
I can install the software update for you if you're ever up in this neck of the woods :D
 
jclark said:
You should see YOUR N-number on the iPad.

If you have friends with ADS-B systems in their planes, go up and ask them if they see you **AND** your N-number.


James
Click to expand...

I have the Hxr, SkyRadar D2, GNS-430W, and GTX-330ES and have been flying this combination for over a year. I have never seen a tail number on any traffic I have observed. Does this mean my ADS-B out is not working?:confused:
I fly in a pretty high density traffic area, including air carrier, so would be surprised if I wasn't around other ADS-B out airplanes fairly regularly.
 
12vaitor said:
I noted on your TT22 setup page that the GPS Certification Level is set to 'Uknown or Uncertified I suspect it will not receive TIS on 1030 unless that setting is Certified. Can you change it to Certified to see if that get you the TIS data?

John Salak
RV-12 N896HS
Click to expand...

For the sake of avoiding confusion, remember TIS and ADS-B are two different things-- TIS is radar-based and picked up by a Mode S transponder, not related to ADS-B receivers and towers.

For the TT22 and GRT EFIS, the Certification Level setting for a GRT GPS module should be LOW: VFR or Uncertified. (Legal til 2020, when a GPS certified specifically for ADS-B will be required.) You are not supposed to enter "Certified" in the ADS-B GPS Certification Level unless your GPS is specifically certified FOR ADS-B (such as a FreeFlight Systems or NexNav ADS-B GPS). Simply being "WAAS" or IFR approach-certified does not meet the 2020 standard. The Certification Level setting will give ATC more confidence in your position when they use ADS-B for traffic separation.
 
dmaib said:
I have the Hxr, SkyRadar D2, GNS-430W, and GTX-330ES and have been flying this combination for over a year. I have never seen a tail number on any traffic I have observed. Does this mean my ADS-B out is not working?:confused:
I fly in a pretty high density traffic area, including air carrier, so would be surprised if I wasn't around other ADS-B out airplanes fairly regularly.
Click to expand...

Hi David, Jeff is working on an option to show the N-number on our ADS-B display. Your SkyRadar will display it on an iPad app. Personally I think this would just clutter up the map, which is why we didn't include it originally, but some people like it if they are flying in a loose gaggle with friends.
 
Not shown on HXr ....

dmaib said:
I have the Hxr, SkyRadar D2, GNS-430W, and GTX-330ES and have been flying this combination for over a year. I have never seen a tail number on any traffic I have observed. Does this mean my ADS-B out is not working?:confused:
I fly in a pretty high density traffic area, including air carrier, so would be surprised if I wasn't around other ADS-B out airplanes fairly regularly.
Click to expand...

The N-numbers are NOT shown on the HXr. A design decision to keep down the clutter. Maybe if enough people want it, GRT will add it. They get the info, just don't show it.

What I meant was that on some other systems (e.g. Dynon, Garmin) and on the iPad or Android tablets with certain apps, you can show the N-number.

I was fortunate enough to have friends with all sorts of systems around and had about six DIFFERENT apps on my iPad to test so I was able to see what was working and what was not from various angles.

Was in a meeting with some local ATC people last night. Asked if they had anything to show ADS-B traffic yet. NOPE. NOTHING. NADA.

So to know if you are being seen by others, you need to become one of the others and if you always have traffic showing you probably are working just fine as MOST people do NOT have ADS-B and therefore most planes are NOT "waking up" the system.

Grab an iPad with WingX. Connect it via wifi to your SkyRadar. if you are "out there" your N-number will show up on your iPad.

James
 
Dave,

I have the Skyradar and HX.
The HX does not show N numbers - I presume to keep the map from being overcrowded. But an iPad (wi fi connection to Skyradar) does show N numbers (or airline flight numbers), running either WingX or SkyRadar's software.

(internally the HX knows N numbers and/or mode S addresses-that is how it filters out "own ship" traffic. But I do not know how or if it can display that data. It would make the screen very busy with the HX sized display.)

Wow! I must type slowly, all above replies came while I typed!
 
Last edited:
You must log in or register to reply here.
Back
Top