On Thursday, September 21, 2017 at 4:23:14 PM UTC-7, Andrzej Kobus wrote:
On Thursday, September 21, 2017 at 6:34:01 PM UTC-4, wrote:
Clarification...

Trig TN72 with Trig TT22 WILL be seen as having a non-zero quality indicator. (good)

Trig TN72 with Brand X Mode S/ADSB out, almost certainly has a zero quality indicator (not good).



On Thursday, September 21, 2017 at 4:34:34 PM UTC-5, WaltWX wrote:
You make a very good observation...

So, what's the point of using a TABS TN72 with a Trig system if no one can see it?

Daryl... do you have any insights on this?


Yes discussed many times over. But aw heck lets go over that and some other stuff again. Well because this stuff is better than dietary fiber...

This has been discussed here many times over. The GPS source alone is not approved. It is the combination of the GPS and the mode S transponder that is approved. Please read up on the FAA website first about approved combinations, then search through this forum for additional information.

Well the GPS sources are approved in they may meet say meet TSO-C145 or TSO-C199 or "meets requirements of TSO-C145", or maybe meet none of those of a COTS GPS etc. and that stuff is important to understand.

Trig is correct in what they say. Certified ADS-B In receivers and the ADS-B ground infrastructure will ignore all ADS-B out systems using COTS GPS. Airliners, fast jets, etc. not receiving any of that crap. (that does not stop TCAS seeing the aircraft via transponder interrogation).

The Trig TT22 with 1090ES Out driven by a TN72 GPS source, all properly installed, will be seen by all aircraft with 1090ES In, both portable and certified/fixed install systems. It will also be seen by all aircraft with UAT In if within ADS-R service coverage. However you can only install a TN72 in an experimental aircraft. Certified aircraft, including gliders, requires you use a TN70 as all ADS-B Out installs in certified aircraft must meet 2020 compliance requirements (which effectively require an actual TSO'ed TSO-C145 GPS source in a certified aircraft, including glider).

An ADS-B Out 2020 complaint install (which sticking with Trig, requires a TN70 not a TN72 GPS source) will be seen by all aircraft. Wether that is with a TSO-C145 GPS source (for certified aircraft), or a "meets performance requirements of a TSO-C145 source (an option for experimental aircraft).... as long as they are all properly installed of course. trig foes not have a lower cost "non-TSO but meets performance requirements of TSO-C145 GPS source".

In an experimental aircraft not intended to fly where the 2020 carriage mandate applies (pop quiz: where do gliders need ADS-B out even with the carriage exemption? No it's not above 10.000') can install any GPS source as long as the ADS-B Out sets the correct quality parameters, and any old COTS GPS will require SIL=0 to be set which will guarantee that is ignored by aircraft with certified ADS-B In systems. It will still be seen by many portable ASD-B receivers, and certainly will be seen by PowerFLARM 1090ES In (assuming we are talking 1090ES Out).

The Trig TN72 is a TABS/TSO-C199 device, it is not TSO-C145, you can not install it in any certified aircraft (including gliders) and you can't use it to meet 2020 Carriage mandate requirements, but you can install it in an experimental aircraft for use outside ADS-B Out required carriage areas (including for gliders anywhere the 2020 carriage exemption lets you fly without compliant ADS-B out)...

And if your experimental glider is so equipped with a TN72 GPS source driving a Trig TT22 and it's properly installed then it *will* paint your glider on certified ADS-B In systems, both via direct 1090ES and via ADS-R for UAT In equipped aircraft. The TT22 importantly also ensures TCAS II systems can issue a RA (resolution advisory) against the glider, a pure UAT Out systems with no transponder cannot and will not cause TCAS to issue an RA. UAT Out equipped aircraft are also never visible to PowerFLARM (they can trigger PCAS if also transponder equipped), so for that reason avoid UAT Out use in gliders and towplanes.

A properly configured TT22 and TN72 GPS source will also trigger ADS-B ground services for your aircraft when in range of ADS-B ground stations (which won't help at all with PowerFLARM which can't decode any of those ground based services, to receive ADS-R, or TIS-B, or FIS-B ground services you also need a separate ADS-B In/non-PowerFLARM receiver as well as a suitable ADS-B Out system. And with reception on UAT to receive FIS-B).

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On mixed installs with other potential ADS-B Out systems I would want to see the details of what exact ADS-B Out transponder is being used, but a TN72 in an experimental aircraft may well work with multiple different transponder options. TSO-C199 was intended to provide interoperability like that. And that will get you ground services and visibility on certified ADS-B In receivers. But be sure to ask the vendor if not Trig that they guarantee all that works... In practice the way to go today for ADS-B Out in gliders in the USA is to start with a Trig TT22 and use the TN-70 or TN72 and follow Trig's install documentation exactly.

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Unfortunately Trig, who makes great stuff--their TT22 and associated GPS are great products, is saying some stuff that is a little sloppy again, their comment about triggering traffic services for gliders is made without the warning that a PowerFLARM can't receive those services. And they don't qualify TN72 is only for experimental gliders... I wish we had regulations that provided installs of that in certified gliders, as far as I understand we do not. I wish there were regulations (and maybe a STC) that allowed that. I'll talk to Trig and see if they can help be clearer here.