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

[SteveHutt]

I accept your point, John, that the nature of GA does vary a bit geographically across the country and thus influence requirements.
Steve

[SteveHutt]

I have learned today from an authoritative source that ADS-B messages tagged as:

• Version 0 do not support/include SIL or SDA data.
• Version 1 do not support/include SDA data but do support/include SIL
• Version 2 does support/include SIL and SDA data, AND the definition of SIL was changed between Version 1 and Version 2.

Unfortunately, I currently have no details of the version 1 to version 2 change in the definition of SIL.

Information on the ADS-B spec I have seen mentions broadcasting SIL & SDA values 'within 10 seconds of them changing'. This caters for airliners that may have multiple GPS devices that can be switched between for feeding GPS position data to their transponder. As such, even CAT traffic setup to support SIL & SDA for ADS-B may not actually broadcast SIL or SDA very often. How TCAS is supposed to be able to rely on SIL or SDA is therefore rather unclear to me. By comparison, the latest firmware for Trig transponders for GA have been coded to broadcast SIL & SDA every 2.5 seconds when in 'Air' mode and every 5 seconds when in 'Ground' mode.

In case anyone is wondering about the voracity of the new PAW Traffic display, please bear the above in mind.

Steve

[Richard]

Steve,
   Thank you for the above post. You have answered one of my Questions, Also posted on a different Thread.

"The Screen shot shows another aircraft - SYG04 with an Alt of 34071 displaying data I would have expected to see this aircraft displaying a SDA or SIL number. but is 0 My aircraft GIRPW on the ground is displaying 0 as required.

What is NACp and NICa also VERS ? "

[SteveHutt]

Richard,

Vers = Version of ADS-B Message format
NACP—Navigation Accuracy Category For Position
NACV—Navigation Accuracy Category for Velocity
NIC—Navigation Integrity Category

I am sure there are newer ones but this old document is all I have managed to find online so far:
http://www.gpo.gov/fdsys/pkg/FR-2010-05-28/pdf/2010-12645.pdf

Search in this document for definitions. Note that SIL=0, SDA=0 is not covered in this doc!

Remember that data from the same aircraft comes in piecemeal in different ADS-B messages and PilotAware has to assemble these parts and join them up as they arrive. The most obvious example is aircraft where the Hexcode is known but there is no FlightID (=flightnumber or registration). The FlightID may well arrive in a subsequent ADS-B message broadcast. The same is true of SIL/SDA/etc.

Steve

[AlanB]

Latest version of the FAA document

http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&sid=3efaad1b0a259d4e48f1150a34d1aa77&rgn=div5&view=text&node=14:2.0.1.3.10&idno=14#se14.2.91_1225

Search for 91.225 and 91.227 paragraphs.

[ianfallon]

I have learned today from an authoritative source that ADS-B messages tagged as:

• Version 0 do not support/include SIL or SDA data.
• Version 1 do not support/include SDA data but do support/include SIL
• Version 2 does support/include SIL and SDA data, AND the definition of SIL was changed between Version 1 and Version 2.

Interesting - I don't see any SDA/SIL entries for our TRT800 transponder so I guess it's running "version 0". Does that equate to SIL=0 SDA=0 ?!!

[SteveHutt]

Interesting - I don't see any SDA/SIL entries for our TRT800 transponder so I guess it's running "version 0". Does that equate to SIL=0 SDA=0 ?!!

Ian,

Maybe, or they could be applying that CAT transponder model of hardly ever transmitting SIL or SDA. As I said, it appears the spec says to broadcast these within 10 seconds of them changing. You could meet that requirement by sending it once on startup and never sending it again. Miss that single broadcast and you'd be none the wiser. That is just supposition on my part. I don't actually know what a Funke TRT800 does in this respect. I wish I did. That is the model I have in the part-complete a/c in my garage at home.

I have been party to email communications on the subject of TRT800's that indicated that 'Mod 11' was required to support uncertified GPS ADS-B Out. I have emailed Funke in an official capacity from FASVIG asking if they could provide equivalent information to that on the FASVIG website provided by Trig for their transponders. I have not yet received a reply.

Steve

[SteveHutt]

FYI,

If you look back at the very first post I made on this thread, it refers to the LAA MOD Approval process for setting up ADS-B Out with a Mode S ES transponder and an uncertified GPS. The BMAA have a similar MOD approval process. Both LAA and BMAA MOD processes were originally setup to facilitate the MODs for those wishing to participate in the NATS Southern England ADS-B Trial. LAA have now made their MOD process permanent. The BMAA have not yet taken that step.

Yesterday I spoke with BMAA and shared with them the proposals I have made to LAA regarding information on make/model/firmware transponder uncert GPS compatibility and using PAW to verify ADS-B setups. I spoke with BMAA again today and briefed them on my proposals and the ADS-B/transponder activities that have been going on, plus the new PAW Traffic Display that allows owners to view the SIL/SDA data being broadcast by their transponders. BMAA were supportive of the ideas so hopefully we may be able to move these things forward with the LAA and the BMAA.

Steve

[Chris Parsons]

Aimed at Steve Hutt really - how do I check to see if my Funke TRT800 has mode 11? (if I have understood this correctly this is what is required to receive uncertified GPS signals and broadcast ADS-B out?)

I spoke to him at Flyer 2015 briefly and he mentioned checking the firmware revision/serial number of the transponder but I have now forgotten what he said!

Regards

Chris Parsons

[SteveHutt]

Hi Chris,

As per my earlier email (but for the benefit of others), I have seen communication between Funke and another TRT800 owner that said "Mod 11" was required to have been applied to the device.

I believe that "Mod 11" is Funke terminology for firmware. There is a "Mod Index" label on the back of the device that has the numbers blacked out for the Mods that have been applied to the unit.

I have emailed Funke directly myself asking on behalf of FASVIG for confirmation of minimum requirements for uncertified GPS ADS-B support. I am still awaiting a response.

Regards,
Steve

[ianfallon]

Looking forward to the answer! Ours is running Firmware v4.7 I think which I believe is one behind the latest v4.8 ( ? )
It appears to "work" with the ADS-B IN from the PAW but I don't see any SIL/SDA values output in the traffic list.

[SteveHutt]

FYI, there is a half-page article of mine entitled "Installing ADS-B Out in LAA PtF Aircraft" on page 9 in the Dec 2015 LAA Light Aviation magazine, which is just out. I have mentioned the new PilotAware Traffic display in the article as a means of checking the Mode S ES ADS-B Out transponder setup.

Steve

[Pete]

I have received my TRIG TT31 back from Trig with the latest s/w ( Turned around in 3 days and all free- Thanks Trig). I can now confirm that I am putting out ADS-B on the transponder ( using MGL Explorer Lite panel - NMEA 0183  protocol)  and I'm hoping tomorrow, to use PA to get the actual report on the Web pages from the  PA.
Some really useful info on this thread, thanks Steve for all your hard work on this.

[SteveHutt]

Funke have now supplied a document covering the TRT800A and TRT800H with regard to connecting uncertified GPS.

It appears that support for ADS-B Out commenced at v4.8 software but 100% support for ADS-B Out with uncertified GPS requires v5.3 software.

You can access the Funke document via the FASVIG website here: http://fasvig.org/funke-support-for-uncertified-gps-ads-b-out

Steve

[flying_john]

Just get a grey screen when I try and view the document Steve.