Ground Station

[AlanG]

Sorry Peter, not strictly true.
G-GDFF is definitely ADSB as I've just tracked him in the air right now, & as  EJM11 is displaying the full SIL & SDA data he must also be ADSB and I'd be extremely surprised if the other Ryanair, EI-EKW, wasn't ADSB too.
Strange but true.

Alan

[EricC]

The Grob was flying a race track pattern, the Sig 202 was the highest
I observed in the turn, guess transponder aerial on the under side of the aircraft.
The Bridge aerial is on the roof, adsb on the Paw in the loft space 1/4 wave
with ground plane.

[JCurtis]

Typical, go to drop off some orders and someone does a fly-by. 
From the reg it could be a Mode C only aircraft as nothing comes up on FR24 for the reg or hex code.  Have to wait an see if they spotted me, range reported as 7km to 9km

[exfirepro]

Sorry Peter, not strictly true.
G-GDFF is definitely ADSB as I've just tracked him in the air right now, & as  EJM11 is displaying the full SIL & SDA data he must also be ADSB and I'd be extremely surprised if the other Ryanair, EI-EKW, wasn't ADSB too.
Strange but true.

Alan

OK Alan, point taken, so I'm a bit confused now. My comments to Eric were based on the results shown in his traffic table. As you are aware, HEX + SQuawk + ALT  + SIGnal strength - with no DISTance is the known signature of a Mode S transmission (we've looked at plenty!!) - no horizontal position information, so PilotAware can't calculate its distance from your receiver.

So what Eric seems to have been seeing is a combination of clear ADSB (EI-EKN), clear Mode S (The Grob G-CGKS) and what appear to be Mode S responses from what you have clearly observed to be ADSB equipped aircraft - namely G-GDFF and EMJ11 (sorry Eric I overlooked the significance of the SIL /SDA entries in the case of EMJ11, but couldn't have known about G-GDFF - at least not without looking it up on FR24 or G-INFO).

Eric, I'm wondering - was it raining at yours at the time? You say your 1090MHz antenna is a 1/4 wave with ground plane inside your loft. Heavy rain or snow on the outside of a slate or tiled roof is a known cause of significant attenuation of radio signals at this sort of frequency. I'm beginning to think this might account for only the high power 'pulsed' CAT Mode S return from these CAT ADSB transponders being strong enough to 'punch' through the wet roof to your antenna, and hence the lack of an ADSB based positional DISTance in the table. Best explanation I can think of at the moment anyway. Anyone else got any ideas?

Regards

Peter

[EricC]

Attached is a picture of the  PAW in the loft space.

The roof was dry no cloud below the grob.

Just had a departure from about 800 yds away from my house

107ft Sig 189

[exfirepro]

Attached is a picture of the  PAW in the loft space.

The roof was dry no cloud below the grob.

Just had a departure from about 800 yds away from my house

107ft Sig 189

Hi again Eric,

Not too bothered about the Grob, I'm quite happy that was Mode S - as I say, the signal strength fits with an aircraft using a higher power transponder (such as a Trig TT22 or similar) - which outputs up to 250 Watts as opposed to my TT21,s 125 Watt maximum.

The problem is the entries that Alan is saying are definitely ADSB equipped aircraft, so should be showing a DISTance from you in your traffic table. One thought was attenuation from a wet roof, but you say the roof wasn't wet - I take it it's not made of, or lined with metal (e.g. aluminium foil on insulated plasterboard)?

Another thought was that you are very near Blackpool and quite close to Wharton. When CAT is on the ground, the ground radar returns are effectively mode S at very high power, and show up as such on the PAW traffic screen. During testing near Edinburgh Airport, we noticed these were often strong enough to trigger Mode S 'Danger' alerts from well over a mile away, which is why we developed the Ultra Short Range setting specifically to deal with this type of scenario. I also noticed that some of them don't engage ADSB until well into the climbout, which might have explained aircraft less than say 2,000ft, but not at the heights yours are showing at, so doesn't help to explain those.

I will give it some more thought.

Regards

Peter

[EricC]

From my Kinetic SBS1 base station only about half of the returns are ADSB
Comparing the logs as near as i can tell they are the same as the PAW.

[exfirepro]

Yes Eric,

PAW and ADSB both show in a similar manner on the PAW traffic screen, though PAW, being much less powerful transmitters, generally don't have a significant SIGnal strength. Also the SQuawk for a PAW transmission will be the group-ID (e.g. the default 'PAWGRP' or whatever the user has set) as PAW doesn't transmit a conventional squawk.

Regards

Peter

[EricC]

I was just illustrating that about half large public transport aircraft
do not transmit ADSB.
PAW users can expect  no distance info from many aircraft.

[exfirepro]

Hi Eric,

I was just illustrating that about half large public transport aircraft
do not transmit ADSB.
PAW users can expect  no distance info from many aircraft.

That's why I had no concerns with my original statement - until Alan picked me up on it  And let's not forget all those out there who either haven't bought or can't afford a transponder - or have one but fly with it switched off. That's what makes PAW with its definite gps-based location info such a bonus!

Regards

Peter

[EricC]

I agree wih you completely.
Only 15RX so far today.

[brinzlee]

Well another disappointing day of testing.....I flew overhead JeremyC at 2000 feet in Cambridge with no contact at 3pm.
I did have one contact from a ground contact at Old Buckenham but we were on the ground too right next to him with a rather poor range of 500 metres before I lost contact when I took off......
I have tried lots of options now....the aircraft was composite this time so I can't even blame my poor range on metal cladding which is what I thought was restricting my TX/RX. Tried a variety of Antennas.....Fully charged batteries.....Heavy duty power leads.....

[JCurtis]

Well another disappointing day of testing.....I flew overhead JeremyC at 2000 feet in Cambridge with no contact at 3pm.
I did have one contact from a ground contact at Old Buckenham but we were on the ground too right next to him with a rather poor range of 500 metres before I lost contact when I took off......
I have tried lots of options now....the aircraft was composite this time so I can't even blame my poor range on metal cladding which is what I thought was restricting my TX/RX. Tried a variety of Antennas.....Fully charged batteries.....Heavy duty power leads.....

Well if you were in G-OAWM I was seeing you, lost you at 7.6km. 
I know I TX something as I pickup the RF on a spectrum analyser.

I think you were literally almost overhead at one point, I could have stood outside and waved.

If this was you, could a potential local source of interference could be swamping the Bridge RX perhaps?

[brinzlee]

I think I must have a faulty Bridge.....I didn't pick you up at all.....I have tried various antennas and different aircraft.....So I don't think I'm swamping the input stage with noise....I will have to see what the guys at Hardware think ?

[exfirepro]

Definitely something strange going on Brinsley. Alan and I have been getting 5- 10 miles reliably with pretty much  standard kit. You will get some screening forward left and down from your engine with the P3i antenna in that position, but should have 'seen' Jeremy well before the point where that might have become an issue.

Assuming you were in G-OAWM and he saw you at up to 7.6km, you are certainly transmitting. A bit surprised that you lost your old Bucks contact at 500 metres too - definitely sounds like a receiver issue to me.

Peter