Primarily for general aviation discussion, but other aviation topics are also welcome.
  • 1
  • 28
  • 29
  • 30
  • 31
  • 32
  • 43
By johnm
FLYER Club Member  FLYER Club Member
#1845198
@Miscellaneous I assumed that everyone knew that PAW receive is tightly integrated with Atom Grid and that Atom Grid has holes in it.
By johnm
FLYER Club Member  FLYER Club Member
#1845226
Miscellaneous wrote:@johnm it's not about what people know. It's that the statement is plain wrong without the qualification.


No it isn't, any fule kno that PAW receive and Atom Grid are tightly coupled, even I have got my head round that :roll:
By Crash one
#1845245
Paw was working perfectly well before the Atom was invented. (Put the comma where you like).
Paw works just the same as SE2, it sends and receives on its own protocol, P3i for Paw and ADSB with SE2.
The Paw also receives ADSB

Paw and Atom grid are not tightly coupled. The Atom grid merely allows Paw to receive more than it can by itself (Flarm etc).
This is a head banging exercise, I am convinced that people believe that Atom coverage is required before Paw will receive anything.
For the love of God, READ THE ‘KIN MANUAL!!! For Christ’s sake!!
lobstaboy, Aerials liked this
User avatar
By Miscellaneous
#1845247
johnm wrote:No it isn't, any fule kno that PAW receive and Atom Grid are tightly coupled, even I have got my head round that :roll:

So your statement is incorrect as is the case for me and as demonstrated by the Flyer trial. That is all my original post stated. Now for someone who complains about their SE2 not detecting aircraft that are not flying I suggest it unsafe to assume you understand the implications of detecting gliders with a PAw and without being in Atom grid range. Which I think would be highly likely for periods during the 'complaint' flight.
By Straight Level
#1845257
Miscellaneous wrote:
johnm wrote:No it isn't, any fule kno that PAW receive and Atom Grid are tightly coupled, even I have got my head round that :roll:

So your statement is incorrect as is the case for me and as demonstrated by the Flyer trial. .


You mean the the Flyer trial using calibrated and certified instruments to an internationally recognised test protocol by in independent expert company, that one? :D @gaznav :wink:
By johnm
FLYER Club Member  FLYER Club Member
#1845258
@Miscellaneous All of the receive scenarios have limitations as must be obvious to all by now. You can't separate PAW from ATOM grid and missing ATOM grid connection is much like shielded SE2. However the anecdotal evidence in terms of the probability of seeing traffic suggests a properly installed PAW with an external antenna stands the best chance because of its intimate relationship with ATOM grid.

All that said I rather suspect I'd see a different balance if I crossed the channel as in normal times I often do......It may be that you see a different balance in your neck of the woods too, being remote from human habitation :D

I think at least 2bn angels can dance on the head of a pin. :roll:
User avatar
By lobstaboy
#1845260
johnm wrote:. You can't separate PAW from ATOM grid :


If you switched off all the ATOM receivers, PAW wouldn't work. Is that what you mean?
Because that's not right.
As @Crash one said above.
By johnm
FLYER Club Member  FLYER Club Member
#1845261
lobstaboy wrote:
johnm wrote:. You can't separate PAW from ATOM grid :


If you switched off all the ATOM receivers, PAW wouldn't work. Is that what you mean?
Because that's not right.
As @Crash one said above.


No that isn't what I mean :roll: :roll: but its broad coverage would be severely compromised under those circumstances and that appears to be one of its key features.

still 2bn angels on that pin.....
User avatar
By gaznav
#1845267
@johnm

You can't separate PAW from ATOM grid and missing ATOM grid connection is much like shielded SE2.


That is probably untrue and let me explain why.

The SE2 ‘shielding’ is unlikely to give zero range detection as the attenuation generated by airframe, engine or human obscuration is only likely to reduce detection range, not completely blank it. So let’s say that FLARM reception, the weakest signal, is normally 4nm. That signal will likely still be detectable at say 0.5nm even if there is lots of skin, bone, body fluid, engine and airframe in the way - but it will be reduced. (BTW @Straight Level that could be scientifically modelled quite easily and has been done for mobile telephone attenuation in many studies - give it a Google :thumleft: ).

Now, the other way around for PAW. If you are out of range of an ATOM ground station and can’t receive the OGN/FLARM uplink, it doesn’t matter how close you get to your threat aircraft if it is FLARM only [edit] - you will never see it. It is absolute, and your aircraft and your FLARM-only threat aircraft will need to move toward the ground station to see each other.

So in your above example, the air-to-air detection “fails safe” as eventually you will detect the threat the closer you get, whereas the ground-uplink detection just “fails” until you and your conflict get closer to the ground station - which unless you are flying in formation until you do, is an unlikely scenario for the latter.

PS. Here is one such quantitative analysis of the effect of the human body and other materials on 2.4GHz signals: https://www.dataloggerinc.com/wp-conten ... uation.pdf If you do the maths, it is tricky to get down to 100% attenuation (called a Faraday Cage) and so everything is likely to be detectable, but just at reduced range in the air-to-air scenario.
Last edited by gaznav on Thu May 06, 2021 9:22 am, edited 5 times in total.
User avatar
By Miscellaneous
#1845269
johnm wrote: However the anecdotal evidence in terms of the probability of seeing traffic suggests a properly installed PAW with an external antenna stands the best chance because of its intimate relationship with ATOM grid.

All that said I rather suspect I'd see a different balance if I crossed the channel as in normal times I often do......It may be that you see a different balance in your neck of the woods too, being remote from human habitation :D :

Not remote from human habitation, population is irrelevant anyway. In an area where there is no atom grid is the relevant fact.

Consequently PAw stands no chance here. :D
gaznav liked this
User avatar
By gaznav
#1845272
Just thinking about this, the SkyEcho was originally going to have Mode S/C proximity detection and also PAW detection. They dropped both as they couldn’t get Mode S/C to give a worthwhile warning (something I agree with as using received power to measure levels of threat is too inaccurate due the variation of transponder output and the antennae attenuation issues already discussed), they also dropped the PAW detection. I think the latter was a shame as if there are 3,000 or so PAW units kicking around the UK, and they could be detected along with the many more FLARM units (probably twice as many in the UK and 3 times as many worldwide). So, when they were developing SkyEcho2 the PAW Classic was still the main device and I suspect they thought that PAW would potentially whither (incorrect).

If the SE2 could receive PAW then it would likely have less criticism thrown at it by the ‘PAW Brigade’ as SE2 would see PAW and PAW already sees SE2. An opportunity missed, I think so...
lobstaboy, ls8pilot, Straight Level and 1 others liked this
User avatar
By lobstaboy
#1845273
gaznav wrote:Now, the other way around for PAW. If you are out of range of an ATOM ground station and can’t receive the OGN/FLARM uplink, it doesn’t matter how close you get to your threat aircraft - you will never see it. It is absolute.

Oh come on! That's a really misleading statement. PAW will directly see adsb, mode c/s and other PAW. It doesn't need the ground station for that. The ground stations allow you to see Flarm, which otherwise you can't see, and give you a bearing for mode S (which otherwise is shown as a bearing less target).
johnm, gaznav, PaulSS liked this
User avatar
By PaulSS
#1845288
@gaznav Here's a present for ya:
Now, the other way around for PAW. If you are out of range of an ATOM ground station and can’t receive the OGN/FLARM uplink, it doesn’t matter how close you get to your threat aircraft if it is equipped with only Flarm - you will never see it. It is absolute, and your aircraft and your threat aircraft will need to move toward the ground station to see each other. You will, however, still receive Mode C/S 'bearingless' information, ADSB and, if you're really close, the ADSB from an SE2 :D


PS: I do agree with your thoughts on SkyEcho missing a trick with PAW detection and was genuinely disappointed the one-stop-shop reduced its product range. I also recall some people in this parish recoiling at the suggestion of a licence charge being made to receive PAW information. Funny those same people are happy to pay a greater fee to receive Flarm :wink:

Edited to add: Damn it, I was typing when Gaz was amending his post, so I probably make less sense than I normally do. But I'm not going to delete it all as that would be a waste of fingerprints :thumleft:

PPS: That's really funny that Gaz's amendment is almost wot I writ :mrgreen:
gaznav liked this
  • 1
  • 28
  • 29
  • 30
  • 31
  • 32
  • 43