Verifying Mode S ES ADS-B Out transponder setup - Can PilotAware help?

[Welsh Pilot]

If anyone has a Becker BXP6401 transponder (I recall Welsh Flyer does), I complained to the company about them setting SDA=2 after they indicated they would NOT update the firmware, and the SDA setting also seemed at odds with the fact that SIL was set to zero. I let  them know that they appeared to be out of step with other manufacturers in these matters.

I received a reply from their General Manager that they will update their ADS-B offerings to support this but we will have to wait until second quarter of 2016.

Thank you for the heads up.

That's great news and thanks to all who pushed Becker on this.....

[SteveHutt]

Air Avionics have now supplied me with a document covering their VT-01, VT-02 and VT-2000 transponders with regard to connecting uncertified GPS.

The following all support ADS-B Out with an uncertified GPS position source:

 VT-01 Ultracompact, Partnumber VT-0104, compact 57mm Mode-S Transponder
 VT-02, Partnumber VT-0201, radio stack Mode-S transponder (KING KT76/A retrot)
 VT-2000, Partnumber VT-0201, radio stackMode-S transponder (KING KT76/A retrot)

The following supports ADS-B Out with an uncertified GPS position source, with a minimum firmware level:

 VT-01, Partnumber VT-0102, two-block57mmMode-S Transponder: Firmware version 1.10 or later

You can access the Air Avionics document via the FASVIG website here: http://fasvig.org/air-avionics-support-for-uncertified-gps-ads-b-out

[SteveHutt]

I'm trying to get to the bottom of all this as well, as I am looking into replacing my non ES transponder with a TT31/KT74 (same innards, different panel).

I have now received confirmation from Bendix King that their KT74 Mode S ADS-B Out transponder does NOT support connection of an uncertified GPS position source.
They also confirmed that they have no plans to provide such support.

Steve

[GrahamB]

I was thinking about a KT74 as well so I contacted BK (not Burger King!) to ask and they replied with a list of items that are "configurable" (see below)
-------
The KT74 can't "set" the SIL and SDA values,,,, that's all part of the GPS input and how the KT74 is configured.  Our KT74 is STC'ed for certain GPS units (see attached AML).  Configuration of the KT74 is accomplished via the front panel buttons.  We have a selections for:

1.  GPS source - Aviation Format NMEA 0183, Nex Na mini, FreeFlight, KGX, Garmin ADS-B+ Out, BendixKing GPS Express (KSN770).
2.  Interface Speed -- 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115K
3.  GPS Certification -- (From the GPS manufacturer) Level B, Level C, Level D and uncertified.
4.  GPS NAC Velocity -- Unknown, 3 meters per second, 10 meters per second.
5.  Measurement Units -- meters and feet
6.  GPS Reference Offset -- Auto set by GPS, Manual Set here and Unknown.

The above information is not inclusive of all configurable items,,, it's just the ones I thought would be applicable to your question.
------

As the KT74 can set the right bits for Levels B, C and D to conform with the standard, I would have thought that setting the correct bits for an uncertified unit would have been viable too. Perhaps I am just being naive.

Anyway BK have passed my question on to Trigg (who they openly identify as being the design authority etc) to see what they say. Not looking good but may be still worth pressing a little further.

The way it is looking the solution may be to the unit as a Mode S and see what comes out if a non-certified GPS is connected (obviously with the collaboration of CAA/FASVIG etc), may be as an adjunct to the trial.

[SteveHutt]

Hi Graham,

Thanks very much for posting that. What I reported above is what BK Tech Support told me this evening.

However, I have since gone back to them to ask whether it is in fact the BK Technical Support Dept that does not support uncertified GPS ADS-B Out on the KT74, rather than the KT74 hardware and software itself. BK have confirmed that they themselves have done no testing of uncertified GPS ADS-B Out.

I did point out to them that it would look rather strange if their policy was not to support uncertified GPS ADS-B Out if the device hardware & software did I fact support it. Your post tends to highlight that issue.

I will have a chat with Trig too.

Steve

[ianfallon]

This whole thing is a farce. I wonder:

a) How many uncertified GPS + Mode S ES transponder combinations are out there which actually pass the requirements of the trial/LAA-mod and have successfully joined the trial/LAA mod, compared to combinations that do not.

b) How many a/c are flying around with combinations connected that do not pass the requirements because it 'appears to work'.

Perhaps the manufacturers will get their act together in the future, but it does feel like those of us that bought an early Mode S transponder because it had ES/ADS-B "capability" have been somewhat taken for a ride.

[SteveHutt]

Ian,

This is part of the challenge when trying to 'change the rules'. Don't be so down on everything 

In the US they have mandated that the GPS position source must be certified. Hence American transponder manufacturers are wary in the extreme about the thought of allowing use of their kit with uncertified GPS.

So, with the US having gone certified GPS-only, the rest of the world sort of followed suit, until now, here in the UK. So no need to guess why the transponder manufacturers have not found it straightforward to address uncertified GPS. There was a distinct lack of clarity on the regulations.

I am trying to bring some clarity, and in doing so it is flushing out the issues we are seeing. Would you prefer that we did not surface these issues?

Chin up.  We are making progress 

Steve

[ianfallon]

Steve your work is brilliant and I am 100% for it, and grateful for it.

I'm not sure fully certified GPSs would work with early Funke Mode S+ES transponders either though if the transponder is hard coding the SIL/SDA (or just not transmitting it at all). Surely these have to come from the GPS (in which case it should pass them on) ?

Do keep up the good work!

[GrahamB]

I spent some time reading what I could from the US standards and it is interesting that much of the configuration of the ES is about off-sets from the GPS aerial location and the tail height and wing span. It would seem that the fascination of accuracy relates to the use of ADS-B on the ground for taxi-way work (i.e. not sticking big expensive wing in the wall). Given that our wingspans are often less that half an airliner tail the degree of precision seems to stand out as somewhat overcooked.

This really highlights the value of Steve's work to try to get the increased positional awareness available into GA. I feel it is likely to be a bit of an uphill struggle as US manufacturers seem to have a problem in recognising that there are markets other the the US that may also have requirements, but as we are just trying to use the facilities that appear to be there the suck it and see methodology may be our best way forward.

[Paul_Sengupta]

The way it is looking the solution may be to the unit as a Mode S and see what comes out if a non-certified GPS is connected (obviously with the collaboration of CAA/FASVIG etc), may be as an adjunct to the trial.

Rob P has a KT74 with an uncertified GPS connected - Skyforce? - but didn't see anything out. Maybe if there are settings, using a PAW and the manual for the transponder, someone could have a play.

[Andy Fell]

This whole thing is a farce. I wonder:

a) How many uncertified GPS + Mode S ES transponder combinations are out there which actually pass the requirements of the trial/LAA-mod and have successfully joined the trial/LAA mod, compared to combinations that do not.

b) How many a/c are flying around with combinations connected that do not pass the requirements because it 'appears to work'.

Perhaps the manufacturers will get their act together in the future, but it does feel like those of us that bought an early Mode S transponder because it had ES/ADS-B "capability" have been somewhat taken for a ride.

I have one of the early TT21's... Trig have told me I can have a SW upgrade for free (to allow SDA and SIL = 0 etc).  I just have to send it in.

At this stage anyway it doesn't make much difference probably, since ATC are not using the ADS-B data for anything in particular.

[Richard]

Wobblewing,
   I did just that.... All back and fitted in 3 days.... Make me wonder if is may be cheaper for others just to replace their transponders for a Trgg???

[tnowak]

I now have my Trig TT21 ADS-B out configuration working and, more important, validated by NATS!
I used a US GlobalSat BR-355-S4 GPS receiver to connect to my Trig. It wasn't quite "plug and play" but not far off.

Tony (EGHP)

[Smaragd]

Just got this screen shot with the latest software.
Somhow did same attachment twice, cant work out how to remove!

(Admin, removed for you, btw, lots of traffic here!)

I'm just getting to use my PilotAware; could someone please tell me how to get a screenshot like that in the reference link?

[Admin]

I'm just getting to use my PilotAware; could someone please tell me how to get a screenshot like that in the reference link?

From your nav device (iPad/Android) Connect to the PilotAware Hotspot, then run up a web browser and go to
http://192.168.1.1

Then select the 'traffic' button to go to the traffic listing

Now use whatever method your device requires for generating a screenshot.

Thx
Lee