Garmin GPS 20A with Trig TT22 in Experimental Glider - OK?

On Saturday, December 19, 2015 at 8:12:21 PM UTC-8, Bill T wrote:
You no longer need to trigger ground stations to get TIS-B or FIS-B data on the UAT frequency.
I have a Raspberry Pi set up to receive UAT TIS-B and FIS-B data. Get great data with no "trigger".

BillT

You never had to do anything to get FIS-B data. It is just broadcast.

If you are seeing TIS-B messages (and are you discriminating between UAT direct, ADS-R and TIS-B?) then you are likely seeing transmissions made for client aircraft. And in some busy areas that might mean near continuous coverage. There are no ADS-R messages just transmitted blind.

I am receiving traffic data miles away from other aircraft. It is not triggered data meant for another aircraft. I have a Rasberry Pi set up to receive 978 UAT. Program is called STRATUX. The Pi rebroadcasts on wifi to my iPad and ForeFlight software.

FAA openly broadcasts TIS-B data on UAT, they opened it up this fall. From what I understand.

I was at 6500MSL over Searchlight NV and receiving traffic data in the Las Vegas Valley, 30 miles away. All I needed was line of sight to Black Mt., where the FAA ground station is located.

On Saturday, December 19, 2015 at 9:38:51 PM UTC-8, Bill T wrote:
I am receiving traffic data miles away from other aircraft. It is not triggered data meant for another aircraft. I have a Rasberry Pi set up to receive 978 UAT. Program is called STRATUX. The Pi rebroadcasts on wifi to my iPad and ForeFlight software.

FAA openly broadcasts TIS-B data on UAT, they opened it up this fall. From what I understand.

Unfortunately it is next to next to impossible for a user with an ADS-B receiver to work out what is going on, what ground station is transmitting data what for which client(s) aircraft. You at best can tell if a message was ADS-B direct, ADS-R or TIS-B. But you very likely cannot often find details of a client aircraft. And you expect to see some UAT TIS-B and ADS-R data for other client aircraft.

I am not aware of the FAA just retransmitting all this data without a client. Do you have a link to them talkign about doing this? Organizations like AOPA have been asking for that for a while, and getting pushback AFAIK. Retransmitting TIS-B blind seems a horrific bandwidth waste I'm not sure it is doable. The only thing I am aware of is the FAA threatening to clamp down and become more restrictive starting in January 2016 tightening up the requirement that client aircraft have compliant ADS-B Out (well SIL0 type GPS Specs). And there was a separate other change, all really covered here... https://www.faa.gov/nextgen/programs...3-15-webV2.pdf -- but again not what you are describing, but I could see how the description of some of those changes is possible to cause confusion.

I was at 6500MSL over Searchlight NV and receiving traffic data in the Las Vegas Valley, 30 miles away. All I needed was line of sight to Black Mt., where the FAA ground station is located.

Yes but that alone does not prove that there is blind re-transmission on UAT. All it likely means is there was one or more ADS-B or TIS-B UAT client aircraft somewhere near that traffic.

---

I am aware of Stratux, it is a very nice little project. I have not had time to play with it on my Pi yet.

On Saturday, December 19, 2015 at 6:56:16 PM UTC-5, Darryl Ramm wrote:
There is no excuse for a USA based manufacturer to be developing an ADS-B receiver today that is not dual-band/link layer.

On Dec 17, 2015, Bad Elf announced what they're calling a dual band receiver. Does this address your dual band concerns?

https://www.kickstarter.com/projects.../posts/1447126

The price went up to $549 on the dual band model, but it now claims to include non-toy AHRS and a rudimentary Flight Data Recorder.

I'm not saying that this is legit, but it is interesting.

On 12/20/15 5:31 AM, son_of_flubber wrote:
On Saturday, December 19, 2015 at 6:56:16 PM UTC-5, Darryl Ramm wrote:
There is no excuse for a USA based manufacturer to be developing an ADS-B receiver today that is not dual-band/link layer.

On Dec 17, 2015, Bad Elf announced what they're calling a dual band receiver. Does this address your dual band concerns?

https://www.kickstarter.com/projects.../posts/1447126

The price went up to $549 on the dual band model, but it now claims to include non-toy AHRS and a rudimentary Flight Data Recorder.

I'm not saying that this is legit, but it is interesting.


Yes, indeed that solves the dual-link issue I have. Thanks for pointing
that out. But it kind of ruined the point of having a good long rant...
:-) But still I am far from impressed with their "oh we wanted to bring
a weather and AHRS product to market first"... uh bull**** they *were*
positioning it as a ADS-B traffic solution. Yes if you dug int the
details they warned that you needed ADS-B Out for ADS-R via the FAA
ground stations to give you 1090ES traffic data. But still there is no
excuse in my books for companies to screw around with new products that
are single link only receivers. Just a very very bad idea.

I do believe this is a legitimate attempt to do a crowdfunded device,
and BadElf has delivered nice GPS products before. I'm not questioning
them on any of that.

The question remains why not just buy a Garmin GDL39 or GLD39-3D (with
AHRS) or Status S2? Especially compared to funding a much riskier
kickstarter project for a somewhat cheaper ($549 vs. ~$900) me-too
product, vs. buying from very well established current vendors. We'll
see if they even get funded (they want $500k). Some even preliminary
specs like battery technology/life etc. seem to be not available.

It is a small sample size but effectively everybody I know who is flying
GA aircraft with portable ADS-B In is using a Stratus. I hope they are
all Stratus S2 (i.e. dual-link), but I'm not sure. That is largely
driven by the popularity of Foreflight software and their bundling with
Status.

OTOH personally much more interesting to me is the Rasberry Pi Stratux
mentioned here by Bill. (Note the dig at Appareo Stratus). That's a
great hacking platform for technical folks to play with and understand
ADS-B, the latest of several software defined radio projects (mostly for
1090ES In), but probably the most flexible. Not of any interest to me to
actually want folks to fly with... but interesting for folks who want to
play/understand ADS-B, set up ground receivers/trackers, etc.

Thanks Darryl,
I'm still learning all the ins and outs of ADS-B. I remember the AOPA articles requesting the FAA open up the TIS broadcasts to all users.
I thought I had read something that it occurred this fall.

I see where FAA is considering after Jan 2016 to not rebroadcast traffic data on targets that are "non compliant" or NPE. This opens holes in the system after the FAA has allowed experimental aircraft to install equipment that meets specs, but not TSO'd. Will those targets not be retransmitted.

I realize I am flying within a busy Mode C Veil area and will have a lot of aircraft with valid ADS-B Out to trigger the TIS broadcast on UAT and 1090ES.
I did receive TIS data on UAT. From my location over Searchlight, NV. Any "expected" OUT aircraft would have been many thousands feet above and on the 1090ES frequency.

It is now 2016 ( for all practical purposes) and within 2-3 yrs we will need to install WAAS GPS and ADS-B out for the tow plane. Hopefully a reasonably priced single box unit. It would be interesting to see the results of the ANPRM study on transponder or ADSB requirement for gliders. We only have one club glider that has no electrical system with no radio/transponder capability. There are a few privately owned gliders with no transponder.

BillT