What's the status of FLARM ?

[Paul_Sengupta]

You would need to go via a DVB-T dongle as the FLARM chipset is different to the Bridge, so the format of the RF packets are not the same.

The proposal is that you'd just measure the signal strength, or just detect if a signal was present. Might detect garage door openers or something as well, but hey ho.

Remember that the FLARM RF stage runs a very low power of 10mW with a stated effective range of 3km-5km.  Using a DVB dongle for this will work, but with such low powers it doesn't take much interference/noise to swamp a signal.  Within the FLARM they have filtering on the RF stage to help reduce this and use dedicated hardware akin to the Bridge to handle this.

You can get an 868MHz filter here:

http://www.rtl-sdr.com/some-new-rf-filters-from-adam-9a4qv/

It wouldn't help with interference from the bridge transmitter though!

PS: Doesn't FLARM also use a frequency hopping RF system? Seem to remember reading that somewhere.

Is this the 868.2/868.4MHz thing?

[JCurtis]

Is this the 868.2/868.4MHz thing?

I don't think so, but it could be.  I would need to look back at some notes on the FLARM RF front end I have knocking about somewhere.  I've been re-organising my office/lab so know they are about, just got to figure out where they are!

Whilst I like electronic documentation, as it saves a huge amount of space, I have not yet scanned everything in...

[Easy Cruising]

It's been a while but I notice that the Stratux appears to be able to receive Flarm targets through its UAT receiver, if programmed to do so (although I'm not tech enough to know if it's really working air-to-air):

https://www.reddit.com/r/stratux/comments/6pa2nj/flarm_receiver_functionality/

Relying on special ground stations to relay traffic seems like a complex route to me, so this subject interested me. Might be something for PAW too.

Can anyone who understands these things confirm or debunk it ?

[Deker]

Flarms legal hounds would find it difficult to hunt the guys and individual enthusiasts on GITHUB who have implemented flarm on stratux.
However, Flarm do not allow use without first handing over several pounds of flesh for a licence (Flarm and a leg prices remember) and would almost certainly send Lee a letter along the lines of "stop or else" for unlicensed Flarm use.

I have powerflarm and PAW in my aircraft, the range is very poor flarm to my powerflarm (almost useless) and I prefer the significantly better range I get from OGN-R even thought the overage isn't 100%

Deker

[Easy Cruising]

Ok. Thanks Deker. OGN-R is non existent outside of the UK though. Flarm seems rather sinister somehow. Hopefully it'll die-out as ads-b solutions become cheaper and more widespread.

[exfirepro]

EC,

ADSB is not likely to provide the precise anti-collision alerts at extremely short range which gliders need to allow them to operate in close proximity (without alarms), e.g. while thermalling, yet get warnings of imminent collision when necessary - which FLARM is specifically designed to provide.

I have been involved with PilotAware since it’s early days, but I also run FLARM in parallel and integrated with PilotAware because there are two very active gliding sites in the area where I normally fly, which is outside the main area covered by the OGN-R network, though this area is expanding all the time and IMO OGN-R is definitely the way ahead - at least in the UK, though we do have a couple of fledgling sites in Mainland Europe.

Best Regards

Peter

[Admin]

Easy Cruising
Would you be interested in setting up an OGN-R
It is community driven and benefitted by all
We can help and subsidise

Thx
Lee

[peter.seddon]

From what I understand about pilot aware and flarm, pilot aware tells you of similar equipped aircraft in your vicinity by transmitting your gps data to the other aircraft. Flarm on the other hand also transmits gps position and height of your aircraft but on receipt of a flarm signal from another flarm equipped aircraft they calculate using your data and the other aircraft's data if there is a possibility of a conflict and gives an warning accordingly to both pilots. This is very useful when multiple gliders are circling in the same thermal as it will only give an audible warning in the case of a conflict. Because of this feature I doubt that flarm will die out in the near or distant future.

[Easy Cruising]

I think exfire was trying to explain that also, but it seems to me that the information from a waas gps + pressure sensor is the only data available to any of these systems (flarm doesn't tap the air-data or attitude etc from the transmitting aircraft does it?). In this case it's only the software that decodes this data that differentiates the systems, so => build out the ads-b based software and flarm becomes redundant. SkyDemon already can do this well from my experience using it. I'm not tech enough to understand the details of the protocols.

[exfirepro]

EC,

FLARM is a bit cleverer than that. Each unit continuously calculates its own 3-dimensional track 20 seconds or so ahead (possibly further for PowerFlarm) and transmits this virtually continuously, automatically updating the data as it goes. It then compares its own track with any received from other FLARM units in the vicinity to calculate likelihood of collision. Having determined this, any likely danger is monitored and alerts issued as necessary. All this designed in such a way as to NOT issue alarms during ‘normal’ glider flight in close proximity unless the tracks indicate imminent collision.

ADSB is only designed to do this sort of thing at the sort of levels of installation normally found in CAT aircraft. I would think it unlikely that this will change significantly at least in the near future.

Regards

Peter