Author Topic: ADSB out &PAW  (Read 3315 times)

peteD

ADSB out &PAW
« on: May 08, 2018, 05:00:59 pm »
I'm fortunate to have Approved ADSB  out(Trig&gtn under stc) so presumably I don't need PAW out, as all PAW users can see ADSB out.
The advantage of this would be that the large PAW aerial would no longer be required?
Can I do this by removing it and using PAW in "ground station RX" mode?
And if I can, I have a redundant ELT aerial(enclosed in rear fin coaming) which could be used for receive, I realise technically it's far to long but would it suffice? it could be shortened, or could I screen most of it?
Any thoughts gratefully received
Pete

Keithvinning

Re: ADSB out &PAW
« Reply #1 on: May 08, 2018, 05:29:20 pm »
Hi Paul

Your logic is correct up to a point. However if you remove the PAW antenna you will not transmit P3i and therefore you will not trigger a local OGN-R station to give you information about gliders in the locality that are using FLARM. You will therefore be missing a lot.
Regarding the 1090 MHz reception the optimum length of the whip is 69mm which is 1/4 wavelength. You could use 1/2 wavelength. However as 1090MHz transmissions are so powerful at 70W+ you can afford to have an inefficient antenna.

peteD

Re: ADSB out &PAW
« Reply #2 on: May 08, 2018, 06:01:53 pm »
Hi Keith
Thanks for your prompt reply.
So if I use ground mode rx and remove the antenna I won't damage the PAW output stage and the altitude reporting will work ok?
I take your point about OGN-R, but presumably any PAW in the area will trigger info which I will be able to see, my location means that gliders are not usually an issue.
Finally can I screen the lower end of my 121.5 ELT antenna to give 69mm?
Thanks
Pete

Ian Melville

Re: ADSB out &PAW
« Reply #3 on: May 10, 2018, 12:10:40 am »
If you set ground mode and remove the P3i antenna, you will not be able to see PAW only equipped aircraft. Not an issue if you leave the antenna in use.

Admin

Re: ADSB out &PAW
« Reply #4 on: May 10, 2018, 06:02:05 am »
Hi Pete

PilotAware transmissions act as an interrogator to the ground station
It basically says “I am here”
The ground station looks at your position and uplinks glider traffic in your vicinity

The locality of vicinity has been left quite wide for the time being
To conserve bandwidth, we will soon tighten the vicinity

So if you rely on passive interrogation from others, you will see traffic in their locality, and not yours, this is not useful to you

Thx
Lee

peteD

Re: ADSB out &PAW
« Reply #5 on: May 10, 2018, 11:18:16 am »
If you set ground mode and remove the P3i antenna, you will not be able to see PAW only equipped aircraft. Not an issue if you leave the antenna in use.
Ah...thank you, wasn't sure which antenna did the PAW in bit, we'll stay as is!