Author Topic: PAW - ATOM Grid Station Reception  (Read 571 times)

Kurt37

PAW - ATOM Grid Station Reception
« on: October 22, 2020, 12:59:37 pm »
Hi there,

seeking for advice:

I am flying a C172 with PAW onboard (as most know linked up with a Powerflarm).

The Receptions air to air, especially from the Flarm is pretty good. That is mostly due to the FLARMBooster, that boosts the Flarm reception. However the sending part of flarm signal is just let thru, and is not boosted, since that is against the law. The Flarmbooster has also a filter install, so the noise is not boosted (It operates between 865 + 875mhz)

My Target:

I would like to improve PAW -> Atom Grid Station Reception, since I am living in Germany and there are not yet enough stations. My objective is to see Mode S traffic as a bearing.

Idea:
I would boost the reception of the PAW Antenna, so it can receive an Atom Grid Signal better. The sending part of the PAW will be untouched/unboosted.

Question:
Is boosting the PAW Reception enough? I can't make sense on my own, when Mode S MLAT Traffic is being rebroadcasted to PAW. Does it need a Signal / trigger from a PAW deviceor just a receiving connection to a PAW to upload Info?


Thanks for your help!

Kind Regards,

Patrick

 
« Last Edit: October 22, 2020, 07:26:49 pm by Kurt37 »

Kurt37

Re: PAW - ATOM Grid Station Reception
« Reply #1 on: October 25, 2020, 08:21:28 am »
Hi there,

I tried a practical experiment yesterday with a PAW (boosted and unboosted) and a atom ground station.

I went as far as the signal reached with a boosted PAW reception and then tried an unboosted PAW reception signal. The transmitting signal of the PAW was unchanged, so was the entire PAW station.

Result:
There was no difference, between a boosted PAW reception and an unboosted reception. Since the PAW transmission was unchanged, that says to me that only boosting the PAW reception makes no difference.

Can some one confirm that, Lee/Peter/Keith?

Kind regards
Patrick
« Last Edit: October 26, 2020, 06:51:12 am by Kurt37 »

tnowak

Re: PAW - ATOM Grid Station Reception
« Reply #2 on: October 26, 2020, 07:59:26 am »
For users of PAW and SkyDemon, how will the user know if they are in range of an ATOM Grid ground station and, therefore, assured they will be able to pick up MLAT's Mode S aircraft?
Thanks
Tony

exfirepro

Re: PAW - ATOM Grid Station Reception
« Reply #3 on: October 26, 2020, 08:33:03 am »
Hi Tony,

If you are running the latest PAW and SkyDemon software, the Ground Stations now display as ‘Masts’, so you can see them on screen provided you have ‘Display Ground Stations’ enabled in PAW Configure. They change colour between Green, Yellow and Red, but this isn’t significant to uplink reception.

Ground Station uplink is also indicated top right on the PAW Radar Screen by number of ATOM stations being received, together with nearest Metar Airfield and its QNH.

Regards

Peter

exfirepro

Re: PAW - ATOM Grid Station Reception
« Reply #4 on: October 26, 2020, 10:10:02 am »
Patrick,

Technically, the PAW ATOM station needs a signal from PilotAware ‘requesting’ data, to generate the uplink, (though in some cases you will still receive an uplink when the ‘trigger’ has come from another aircraft closer to the ground Station than your own). That would tend to negate any potential benefit achieved by boosting the gain of a received PAW signal in the aircraft - and boosting the transmit could cause the output power to exceed the legal maximum for the frequency, which (at least in the UK) is set at 500 milliwatts (0.5 Watt) Effective Radiated Power for our part of the 868/869MHz Band.

In my experience efforts are best directed to maximising antenna positioning - towards externally mounted antennas wherever possible - preferably mounted on the underside of the aircraft - to maximise potential ground Station receive range. There is also a school of thought that emphasises trying to minimise electrical ‘noise’ within the aircraft, though this is not easy to achieve - especially in powered aircraft.

Research into both these areas is ongoing.

Best Regards

Peter

Admin

Re: PAW - ATOM Grid Station Reception
« Reply #5 on: October 26, 2020, 09:12:12 pm »
I am not sure but reading the spec on the flarm booster
The max power out is 100mw, so this may degrade transmit performance

Thx
Lee

tnowak

Re: PAW - ATOM Grid Station Reception
« Reply #6 on: October 27, 2020, 09:15:57 am »
Peter,

So what is the significance of the three colours that PAW/OGN masts will be displayed in SD?

Thanks

Tony

exfirepro

Re: PAW - ATOM Grid Station Reception
« Reply #7 on: October 27, 2020, 10:14:58 am »
Hi Tony,

Under ‘resting’ conditions (i.e. with no traffic to uplink), the Ground Station transmits its position regularly every couple of seconds or so. This is fed by the airborne PilotAware to SkyDemon, which then shows the station as a Green Mast. As traffic density and uplink requirement increases, the station automatically reduces its identity transmissions to optimise air time for traffic uplink (and other data such as Metar). This reduction in identity transmissions apparently triggers the Mast colour change to Yellow or Red. I am not clear whether or not this is intended to indicate a variation in reliability, or in accuracy of Ground Station position - though in practice, it merely indicates that the station is working harder and uplinking more traffic.

Lee has indicated elsewhere that he has it on his ‘to do’ list to do some further work on this with SD, so in the meantime I wouldn’t read too much into the colours.

Regards

Peter
 

Admin

Re: PAW - ATOM Grid Station Reception
« Reply #8 on: October 27, 2020, 01:05:03 pm »
it is simply that PAW stops sending position reports of ATOM stations to SD, so they start ti time out.
This does not mean they are not emitting data, it means that reporting their own position has been de-prioritised as it is more important to send traffic reports

thx
Lee

tnowak

Re: PAW - ATOM Grid Station Reception
« Reply #9 on: October 28, 2020, 08:40:20 am »
Thanks for the info.
So, what about this scenario:
I am flying from Blackbushe to Land End at 1500 ft AGL and only use the SD map (on my smartphone) for navigation.
How do I know if I am in range of an ATOM grid station and therefore able to receive uplinked MLAT (from Mode S only) and FLARM (from gliders) transmissions?
I have no idea where the ATOM grid stations are located in the vicinity of my track and wouldn't be looking on the SD map for towers to "appear".
Is there no other indication on SD providing some kind of status that I am in range of Atom grid?
 
Thanks

Tony

exfirepro

Re: PAW - ATOM Grid Station Reception
« Reply #10 on: October 28, 2020, 09:39:53 am »
Hi Tony,

I agree, it would be nice to have a general coverage symbol (similar to how SD advises that weather data is being received) or even some sort of audio notificationsm, but we can only work with what the display providers will allow - we can’t force them if they aren’t willing.

Considering the time it has taken to get SkyDemon to accept the principle of Ground Station uplink and display them as Masts - instead of reporting them as aircraft on the ground with associated warnings, I think the recent developments are to be commended in the circumstances! IIRC it was Tim in the early days who insisted that we add the option to allow Display of Ground Stations to be disabled because he wasn’t convinced of their reliability or benefits. Even now SD carries a warning requiring the user to accept responsibility for using certain aspects of PAW with SD before allowing connection.

In your scenario, you could easily check for Ground Station locations during pre-flight planning on for example Glidertracker ( http://Glidertracker.org )to give you an idea of likely coverage (the PW Stations are easy to differentiate from ‘pure’ OGN sites as the PW ones have dual naming for the OGN and PW sides). Coverage (both OGN and P3i) can also be checked over recent or longer periods using the OGN Range maps on https://ognrange.glidernet.org

In flight, the Ground Station Masts will appear on screen and should be obvious even when just glancing at the screen to check for traffic or to confirm you are still on track.

Alternatively, if you also run PilotAware Radar or Aircrew as a separate traffic device, they are clearly reported.

I have high hopes that we can improve things further as we move forward - especially with further data uplink, but we need to progress carefully and take the display system developers with us by demonstrating that the uplinks are dependable and reliable and convincing them of the benefits of using our data. Trying to force the issue simply doesn’t work.

Best Regards

Peter
« Last Edit: October 28, 2020, 09:42:02 am by exfirepro »

Admin

Re: PAW - ATOM Grid Station Reception
« Reply #11 on: October 28, 2020, 03:36:54 pm »
Working on it, I think we can come up with a way to indicate ATOMs are being received is SD ....

Thx
Lee