GliderLink - New team soaring app for airborne location sharing

Moshe, there are lots of gliders overflying your airfield with flarm. Perhaps if you had flarm you would be aware of that traffic.

RR

It's a regional thing. I am a US based pilot and I am not aware of any gliders flown at my airfield that have Flarm. (Out of about a dozen.) In our soaring area there is relatively little civilian non-glider air traffic. And within the glider flying community it's a chicken-and-egg thing, it's useless since nobody else has it, so why buy it.

Correction: I think there is ONE pilot here with FLARM. Probably because he goes to contests elsewhere.

On Thursday, April 26, 2018 at 2:38:48 PM UTC-4, wrote:
Moshe, there are lots of gliders overflying your airfield with flarm. Perhaps if you had flarm you would be aware of that traffic.

RR

It's a regional thing. I am a US based pilot and I am not aware of any gliders flown at my airfield that have Flarm. (Out of about a dozen.) In our soaring area there is relatively little civilian non-glider air traffic. And within the glider flying community it's a chicken-and-egg thing, it's useless since nobody else has it, so why buy it.

Correction: I think there is ONE pilot here with FLARM. Probably because he goes to contests elsewhere.

You're right, RR. They're coming from elsewhere though - such as your club which is located a lot closer to the Big City. And there aren't enough of them over our heads so far to change the mindset in my club about FLARM. Yes the perception might differ from reality, as we don't know what we would have seen had we had FLARM. The one pilot with (IIRC) FLARM says he sees more GA (non-glider) traffic (via ADS-B) than he would otherwise be aware of. Still it's not a high-traffic area, and nobody here even thinks about transponders.

GliderLink is not really a replacement for Flarm. GliderLink can make you aware of traffic that you might not have seen otherwise, but it cannot give you warnings that you are on a collision course. This is because GliderLink only broadcasts your location every 20 seconds, a limitation imposed by the goTenna Mesh (5 transmissions per minute). If you don't have Flarm then GliderLink is certainly better than nothing, but I will be using both, personally. It would be cool if I could display Flarm traffic in GliderLink. I'll have to look into whether that is technologically feasible.

Regarding the frequency goTenna Mesh uses, their FAQ says:

goTenna Mesh will transmit at 1 W on 902-928 MHz in the United States, and will vary throughout other countries. For example: goTenna Mesh will transmit at 0.5 W on 869.4-869.65 MHz in Europe and other CE countries, and the device will auto-tune itself to the appropriate frequency band and power output based on the location where it's being used.

In my research on 902-928 MHz in the US, I could not find any specific prohibition against using the frequency while airborne. I asked goTenna if the Mesh was legal to use in the air, and they said they didn't know one way or the other. I did find that the original goTenna uses a MURS frequency that is not legal to use in the air, but MURS is not used by the goTenna Mesh. As far as Europe or other countries go, I haven't yet done any research on the legality of using the goTenna Mesh in the air. Anyone know?

Speaking of, I apologize to users outside the US for not having maps available right now. I believe I have a solution at least for Europe and I plan to add it to the app. I'd like to get confirmation on the legality of airborne use of the goTenna Mesh in Europe first though.

Regarding battery life, GliderLink is pretty easy on the battery from what I've seen. Putting your phone in airplane mode certainly helps conserve battery. Since GliderLink doesn't depend on the cellular network, you can do this and still use the app. The goTenna Mesh has it's own battery which should easily last all day with GliderLink. I've never drained the goTenna battery below about 50% if I recall correctly.

Regarding XCSoar and TopHat integration, it should be possible. I haven't talked to any of their developers, but I think it would be great if they wanted to integrate it.

One thing to keep in mind is that the goTenna Mesh, and GliderLink by proxy, requires Android 4.3+ and Bluetooth LE (4.0). Older devices like the Dell Streak don't meet either of these requirements, unfortunately. If you're wondering what Android phone to run GliderLink on, the Samsung Galaxy S series from S6 on have pretty bright OLED displays that are reasonably readable in sunlight.

(...)
Regarding XCSoar and TopHat integration, it should be possible. I haven't talked to any of their developers, but I think it would be great if they wanted to integrate it.


From what I could observe on the https://forum.xcsoar.org/index.php (BTW, it stopped working for me some time ago), their reply is usually like: 'Open a ticket' and 'You need it? Do it!'

Don't get discouraged, please. It would be terrific to have the 'targets' on XCSoar. We really don't need yet another display in the small glider cockpit...

At 21:30 26 April 2018, Ben Hirashima wrote:

...
Regarding the frequency goTenna Mesh uses, their FAQ says:

goTenna Mesh will transmit at 1 W on 902-928 MHz in the United
States, and will vary throughout other countries. For example: goTenna
Mesh will transmit at 0.5 W on 869.4-869.65 MHz in Europe and other
CE countries, and the device will auto-tune itself to the appropriate
frequency band and power output based on the location where it's being
used.

In my research on 902-928 MHz in the US, I could not find any
specific prohibition against using the frequency while airborne. I asked
goTenna if the Mesh was legal to use in the air, and they said they didn't

know one way or the other. I did find that the original goTenna uses a
MURS frequency that is not legal to use in the air, but MURS is not used
by the goTenna Mesh.

As far as Europe or other countries go, I haven't yet done any
research on the legality of using the goTenna Mesh in the air. Anyone
know?

...

See IR2030/1/19 for EU or 2014/88/UK June 2014 for UK. Other
countries may have different regulations.

- IR2030/1/19 2014/88/UK June 2014 -
Non-specific short-range devices.

** Equipment may be used airborne.**

869.40 - 869.65 MHz 500 mW e.r.p.

Techniques to access spectrum and mitigate interference that provide at
least equivalent performance to the techniques described in harmonised
standards adopted under Directive 2014/53/EU must be used. This can
include for example Listen Before Talk. Alternatively a duty cycle limit of

10% may be used.
EN 300 220 2013/752/EU Band No.54b.
...

Don't you love bureaucratic language! "Let's make sure the 'plebs'
don't understand and then fine them thousands of £/$ for infraction"!

The GoTenna limit of five messages per minute probably equates to the
maximum 10% duty-cycle for the protocol that they have chosen.
FLARM at ~868 Mhz limit their transmission to a very short data burst
at 10mW once per second - much less than required but adequate for
the their purpose.

The GoTenna (sounds like Lady Tena:-) map -
https://www.imeshyou.com/ indicates a good cluster in UK but sparse
population in Europe. I assume these ground stations (mostly mobile
and not 24/7) in non-gliding areas [cities] and not always active) could
relay signals between gliders and other traffic?

All five of my small, UK club gliders and most of our 20+ private gliders
have basic FLARM (£700, no ADS-B). Whilst your app may be more cost
effective than FLARM it requires an Android 'phone and has no collision
avoidance algorithm. I expect little take-up in Europe except for glider
pilots who already have a GoTenna and an Android 'phone.

OTOH, a network of GoTenna ground stations could provide better
coverage than OGN.

Good luck with your excellent project!

Alan (UK)

On Friday, April 27, 2018 at 12:00:08 PM UTC-7, Alan Saunders wrote:
See IR2030/1/19 for EU or 2014/88/UK June 2014 for UK. Other
countries may have different regulations.

- IR2030/1/19 2014/88/UK June 2014 -
Non-specific short-range devices.

** Equipment may be used airborne.**

869.40 - 869.65 MHz 500 mW e.r.p.

Techniques to access spectrum and mitigate interference that provide at
least equivalent performance to the techniques described in harmonised
standards adopted under Directive 2014/53/EU must be used. This can
include for example Listen Before Talk. Alternatively a duty cycle limit of

10% may be used.
EN 300 220 2013/752/EU Band No.54b.

Alan (UK)

Thanks Alan! That's good news. I know that goTenna does implement "listen before talk", meaning it waits until the frequency is clear before transmitting.