On Sunday, September 18, 2016 at 10:53:06 PM UTC-7, WaltWX wrote:
I agree with Darryl Ramm's assessment that a PowerFlarm and Mode S transponder (Trig T22 in my case) in my glider is the best solution for collision awareness and "good aviation citizenship" with other powered traffic. That's what I have in my glider.

However, monitoring ADS-B UAT (978Mhz) aircraft directly will be important once 2020 and full equipage occurs for powered traffic. Right now, PowerFlarm does a nice integration of FLARM, PCAS, and 1090ES ADS-B targets on a variety of displays. I agree with Darryl that adding a GA based device and separate non glider ADS-B situational awareness display for ADS-B is an awkward and costly solution.

Let me propose another solution...

Why not add a device that monitors just for UAT ADS-B traffic (978Mhz), and rebroadcast it at very very low power 1090Mhz in the 1090ES format for the PowerFlarm to receive, process and display? I'm not an electronics engineer or software expert, but this device could be quite small, low power and not need a user interface at all. With such a device PowerFlarm could see all ADS-B traffic on both frequencies... and would not require the FLARM people to modify any software/hardware for the U.S. market.

Any engineers ... Darryl .. or anyone else care to comment on such a device?

Walt Rogers WX

Walt

Unfortunately this is not a good idea, practically or for deeper techcnial reasons.

You really don't want anything trying to transmit on 1090MHz anywhere near a ADS-B receiver. That is adding way too much complexity and potential problems.

I doubt there is a simple way to just add UAT In to a PowerFLARM, I expect it would take hardware as well a software changes within the box.

Unfortunately the USA ADS-B systems ended up such a mess that dual-link receivers are really what you want if mixing it up with GA aircraft. Certainly if buying a GA portable or fixed systems dual-link is the only receiver I would buy. ADS-B Out transmitter a whole different story, and if flying near gliders/gliderports I'd go 1090ES Out because I know PowerFLARM will see that.

How much UAT-Out vs. 1090ES Out traffic we'll see is really not clear to me.. I'm still noticing a lot more 1090ES out than UAT boing into GA aircraft, but that may be skewed at the higher end. So how important this really is I don't know. Depends on where you fly, the adoption of ADS-B out link technology, etc. The incremental add in benefit over having a transponder/ATC/TCAS/TCAD in other aircraft etc. in busy airspace is unclear. And yes I know Walt you had an unfortunate closer encounter than you wanted where that system did not help.

The best realistic technical solution would likely be for FLARM to implement ADS-R as Mike states. But that only gets you UAT traffic when within ADS-B ground station coverage, and only reliably with your aircraft has "2020 compliant" ADS-B Out. So still unclear how many glider owners that would actually help. I lose sleep worrying about the corner cases here, like a glider seeing UAT traffic via ADS-R then descending into a busy traffic pattern at an airport and all the traffic quietly disappears from the display... but is still really out there. But anyhow, until (unless?) we see mandatory ADS-B or TABS Out carriage required in gliders in the USA I'm just not too excited about PowerFLARM not supporting ADS-R, since almost nobody could use it today. And that mandatory Out equipage would certainly provide lots of capabilities (ATC and other ADS-B In equipped aircraft can see the glider, even if you can't see them. PowerFLARM would see gliders at longer distances, etc.).

That alternate solution is of a MUX box that merges UAT traffic with the Flarm dataport protocol is a non-trivial and has lots of challenges. But a benefit that it could see UAT direct without ADS-B ground infrastructure or requiring ADS-B Out in the glider. I'm not every going to hold my breath for this to happen, and I certainly am not excited about people trying to do that without a deep understanding of both FLARM and ADS-B technology. That is just not likely to go well.

The problem is the USA glider market is very small, I'm not sure how anybody justifies custom work for that size market.