Flarm suppression of ADS-B out on Tow Planes

This sounds like an interesting possibility as the powerflarm core has a USB port. I’ll let Darryl analyze it...

Ramy

On Friday, March 22, 2019 at 12:44:48 AM UTC-7, Ramy wrote:
This sounds like an interesting possibility as the powerflarm core has a USB port. I’ll let Darryl analyze it...

Ramy

LXNav is waiting for FCC approval for the PowerMouse, which uses the new chip. Updates will probably come after that.
Jim

On Friday, March 22, 2019 at 10:13:51 AM UTC-7, JS wrote:
On Friday, March 22, 2019 at 12:44:48 AM UTC-7, Ramy wrote:
This sounds like an interesting possibility as the powerflarm core has a USB port. I’ll let Darryl analyze it...

Ramy

LXNav is waiting for FCC approval for the PowerMouse, which uses the new chip. Updates will probably come after that.
Jim

I think it would be great to see ADS-R and maybe TIS-B support in FLARM devices.

FLARM has two chips and associated software currently available to OEMs, the actual FLARM chip and a new 1090ES In chip. The new 1090ES In chip is different than what is used in PowerFLARM.

Unfortunately (and this confused me in the past as well) the LXNav PowerMouse does *not* use the new FLARM 1090ES In developed chip, it uses their own developed technology in conjunction with the FLARM chip. The LX Navigation Eagle *does* use the new FLARM 1090ES In and FLARM chips.

I say unfortunately as this may create differences in how these otherwise similar products operate. I guess we'll have to wait and see. Personally I would rather all this technology came from FLARM and all OEM products operate identically. LXNav clearly makes great products so maybe they'll pull this off OK, buy I am concerned that their decision to roll their own stuff here may not have been the best decision.

This stuff is not as simple as "just support xyz protocol", there are for example going to be devil is in the details of different $PFLAU and $PFLAA FLARM warnings being generated for ADS-B direct, ADS-R and TIS-B traffic. There are also operational things that can help improve ease of use and safety that I'd hope vendors implement (from understandable documentation about what TIS-B and ADS-R support there is and the implications of that to say the receiver detecting and warning if the own-ship 1090ES Out does not exist or is not transmitting the capability code for 1090ES In).

A FLARM device comes with more than usual ADS-B In traffic receiver capabilities, the precise traffic warmings, relatively low false alarm rate, ability to operate on tow or in a gaggle etc. The positional accuracy of ADS-R and TIS-B is less than ADS-B Direct, or FLARM and in the case of TIS-B the positional error is much more. So adding extra ADS-R and TIS-B data comes with some challenges, not insurmountable, but this likely needs to be done with a good technical understanding of both the FLARM traffic algorithms, and understanding of how ADS-R and TIS-B works in practice in the USA.

I hope vendors have been testing this stuff in a realistic simulated USA ADS-B/TIS-B/ADS-R environment before any USA product release, and that they explain implications of what what they implement for ADS-R and especially TIS-B (if supported) to users. (Don't forget for reliable operation both ADS-R and TIS-B require your aircraft to have TABS or 2020 Compliant ADS-B Out).

BTW technical aside... be careful when talking about "TIS-B" especially in more technical conversations with vendors. TIS-B can refer to the relay of SSR data from ground stations over ADS-B as implemented in the USA today (as I used it above). But to a more technical person TIS-B may also mean the general data message format used for both that FAA TIS-B and ADS-R services, for example if an engineer is reading the RTCA DO-260B standard they would implement support for the TIS-B message format to receive ADS-R data and might talk about that as "TIS-B support".

On 3/22/19 1:44 AM, Ramy wrote:
This sounds like an interesting possibility as the powerflarm core has a USB port. I’ll let Darryl analyze it...

Ramy


The PingUSB just uses USB for power, data goes out over Wi-Fi, typically
to a tablet.

On Friday, March 22, 2019 at 11:04:34 AM UTC-7, kinsell wrote:
On 3/22/19 1:44 AM, Ramy wrote:
This sounds like an interesting possibility as the powerflarm core has a USB port. I’ll let Darryl analyze it...

Ramy


The PingUSB just uses USB for power, data goes out over Wi-Fi, typically
to a tablet.

Right. And a third party MUX box that can receive that WiFi could merge it with FLARM serial data. But ah if the data is lower-resolution ADS-R or TIS-B targets does that MUX take it upon itself to generate FLARM $PFLAU target messages? Can it even tell what the source of the data is? Does it assign higher $PFLAU priority that FLARM targets? Does it rewrite existing FLARM generated $PFLAU messages? How does the behavior of those algorithms compare to FLARM's proprietary implementation? Does it only generate $PFLAA messages for this other traffic? That may be OK but what happens when a target gets close and the user does not get the high-priority FLARM warning they might otherwise expect? How will different FLARM displays handle any strangeness here?

Again it depends on what you are trying to achieve. The GDL-90 protocol serial data provided by most of these ADS-B out devices does not contain all the information you would want to build the most comprehensive integrated FLARM and ADS-B In system. You can provide coarse traffic information akin to what ADS-B In systems do today, and that may be fine but there are critters hiding below the surface of the swamp even there. It's possible to provide better integration if working on the "other side" of the interface, e.g. before the information is tuned into GDL-90 serial data, and that's a benefit of say the approach taken with the FLARM provided FLARM chipset and 1090ES receiver chip. That unfortunately does not get you UAT-direct. I just can't imagine there is a way for FLARM to invest time in UAT hardware for the small USA glider community.

I am glad some progress is being made but just want to caution not all this stuff is a simple as it might seem (Hi Andy :-)) . If it was we'd likely have stuff doing this today.