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Re: EC so far......

PostPosted:Sun Jun 06, 2021 2:20 pm
by leemoore1966
Rjk983 wrote:
leemoore1966 wrote:@Rjk983
I think you have pretty much understood the issue
Ghosting would not occur, this is all resolved in software as we know internally which reports are direct vs indirect
Thx
Lee


Thanks Lee, as you can already resolve direct vs indirect then do you mind sharing why you decide not to send the signal from the ground?


The original design was to rebroadcast traffic which could not be received directly, at that time we never considered the situation we see with CAP1391

We have now put our thinking caps on ...
I am sure we can make a plan, and it literally takes minutes to push it to the entire field via the GRID network

Re: EC so far......

PostPosted:Sun Jun 06, 2021 3:15 pm
by ls8pilot
I think the issue of multiple output signals is one that needs some thought. As @Straight Level remarked SE2 has proved popular with the gliding community (probably 60% of pilots who fly XC at our club), and they will be transmitting both Flarm and CAP1391.

Looking at my own results the carbon fibre airframe seems to have minimal effect but the 85Kg of water and fat sitting in the cockpit does have an impact - with a RHS canopy mount I get reduced performance in the rear LHS quadrant. Ground reception in that quadrant appears to still be 5Km to 10Km so adequate for air:air, but if the receiving aircraft has some antenna shadowing then it's possible that the two together may combine to give poor performance. I'm not sure many glider pilots are aware of Vector to check their installation (I've been publicising it at our club).

I became aware that with gliders transmitting both protocols I needed a receiver that would combine the signals and apply a single approach to conflict detection - in particular I would get too many warnings from other gliders with SE2 if I had a separate ADSB based traffic system - so for that reason I've bitten the bullet and done a rather costly upgrade to PowerFlarm/ADSB which seems to work well & also improves my Flarm performance. I actually find the (non directional) Xpdr warnings are useful as they warn me of transponding traffic at or near my level & I can at least tell if it's getting closer . Note PowerFlarm will de-duplicate and favour the Flarm signal over ADSB - there is more information in the Flarm signal.

Most gliders will not be receiving ADSB at all (not everyone wants to spend £1,500 on a new Flarm system!) - it's very unlikely SE2 will be used for reception with it's GDL90 only protocol - I think most of us regard SE2 as a sort of electronic "Strobe Light" in the hope it will allow more power traffic to see us a bit earlier. It is at least relatively cheap (with the CAA rebate), does not drain the battery or add drag ! Just wish it was'nt white as it reflects badly in a glider canopy - limiting where you want it placed.

I would support @leemoore1966 that rebroadcasting CAP1391 for PAW users seems a good idea, provided the "ghosting" issue is catered for.

By the way if @uAvionix-Ramsey is reading - we had some confusion with the SE instructions which use the phrase "Tail Number" to specify the ADSB callsign - gliders (in UK and Europe at least) typically have a "Competition Number" on the tail - which is not the same as the G-REG, so many people entered this into the config, causing some tracker sites to Ghost the Flarm and SE signals, showing two gliders one with G-REG (off the Flarm DB) and Comp Number (presumably from the ADSB signal). I think "Tail Number" is maybe US usage?

Re: EC so far......

PostPosted:Sun Jun 06, 2021 7:15 pm
by gaznav
Miscellaneous wrote:I guess the manufacturers cannot be held responsible for installation. :wink:

Image


As Misc states, there are some pretty poor installs. I also like @VinceGod’s idea of sharing performance experiences from certain install areas on certain aircraft types. Here is a DHC-1 Chipmunk giving pretty good performance, with the SE2 mounted between the cockpits on the side window.

Image

This is what the Vector is showing using that set up (don’t forget that ADS-B is limited to 60km (I think?) on the ATOM - Vector set up).

Image

As for air-to-air performance. I watched G-BZXZ, a Bulldog, as shown below doing it’s wiffadils near Silverstone in excess of 40nm away. XZ has a DF17 ADS-B transponder. I also watched intermittently G-EDGA, a PA-28, transit between Silverstone and Turweston. I know it has a SE2 fitted, so is DF18 ADS-B, and I watched it tracking North of Turweston (it was solidly received from about 12nm). You can see EDGA in the top left of the screenshot.
Image

So I would offer that on the Chipmunk, the reception, and received transmissions on the ground, are pretty reasonable when mounted in this location.

Re: EC so far......

PostPosted:Sun Jun 06, 2021 7:29 pm
by gaznav
Now, compare the drop in performance to where I had it mounted to where someone else mounted it in the same Chipmunk (circled in red):

Image

Now look at the effect on performance:

Image

That is pretty stark. So the mounting of the SkyEcho is critical to getting good performance. Which is probably why uAvionix are quite clear about it in their installation manual:

SkyEcho is a completely self-contained portable device with no required installation for external antenna, power source, or physical installation into the aircraft.
Transmission and reception performance are affected by antenna placement within the aircraft and is subject to airframe shadowing. Best performance is achieved when the SkyEcho is placed vertically orientated on the aircraft window mounted with the suction cup mount in a forward or side facing window with clear line of sight visibility in the direction of travel and clear visibility to the sky for GPS reception.


If you ignore that advice, then the performance will suffer :thumright:

Re: EC so far......

PostPosted:Sun Jun 06, 2021 7:56 pm
by Straight Level
gaznav wrote:If you ignore that advice, then the performance will suffer :thumright:


I seen this install a few weeks ago, the corresponding Vector plots were not impressive !
Image

Re: EC so far......

PostPosted:Sun Jun 06, 2021 8:21 pm
by skydriller
Why put it there? There is so much clear canopy on a Robin... and literally anywhere else is wood...

Re: EC so far......

PostPosted:Mon Jun 07, 2021 12:18 am
by Crash one
An attempt to make the conspicuity device as inconspicuous as possible. :D

Re: EC so far......

PostPosted:Mon Jun 07, 2021 12:30 am
by Cessna571
Image

Here’s ours from the rear right window on a PA28-140

Mounting is clearly critical.

Re: EC so far......

PostPosted:Mon Jun 07, 2021 8:38 am
by Shoestring Flyer
I think what traffic you guys are seeing, or rather not seeing, is terrible!
You need to get some proper EC kit. Here's mine with PowerFlarmFusion over a couple of days. Slightly concerned about the missing blank spot fowards though! :wink:

Image

Re: EC so far......

PostPosted:Mon Jun 07, 2021 8:47 am
by PaulisHome
ls8pilot wrote:By the way if @uAvionix-Ramsey is reading - we had some confusion with the SE instructions which use the phrase "Tail Number" to specify the ADSB callsign - gliders (in UK and Europe at least) typically have a "Competition Number" on the tail - which is not the same as the G-REG, so many people entered this into the config, causing some tracker sites to Ghost the Flarm and SE signals, showing two gliders one with G-REG (off the Flarm DB) and Comp Number (presumably from the ADSB signal). I think "Tail Number" is maybe US usage?


Is this not more likely to be that the Flarm is still using the default Flarm code (DDDXXX) rather than the ICAO code of the aircraft, thus is seen as two separate contacts by the tracking sites? I think they deduplicate on this, not on a registration lookup.

Paul

Re: EC so far......

PostPosted:Mon Jun 07, 2021 8:57 am
by Cessna571
Shoestring Flyer wrote:I think what traffic you guys are seeing, or rather not seeing, is terrible!
You need to get some proper EC kit. Here's mine with PowerFlarmFusion over a couple of days. Slightly concerned about the missing blank spot fowards though! :wink:

Image


This is EC, not intercept radar.

Looks like you can miss them by 60 miles, I miss them by a mere 10 miles

However, 10 miles is good enough for me.

Re: EC so far......

PostPosted:Mon Jun 07, 2021 9:21 am
by Cessna571
Image

I’ve been reading “Hostile Skies”, which is a fantastic book.

Presented with this situation, and climbing to 4000’ I decided too see if I could use my SE2 as they use their radar in the book.

I.E. I knew where he was, I’d go try and find him.

He started orbiting just north of the airfield, I flew just south with about 2000’ and approx 2 miles separation.

Wow!

It’s much much harder than you think, he was quite tiny, but eventually I spotted a little plane, amazed me how small he was, and he was painted bright white and I couldn’t spot him for a while.

What this showed me is that I don’t need to miss them by more than 3 miles…

Most of the stuff I miss in the air is hundreds of yards, be nice if everyone could emit ADSB, then we can all DEFINITELY miss each other.

Not until we all transmit though.

Invisible unless you transmit, regardless of whether the other guy is carrying SE2 or PAW.

3 miles is plenty though imho.

Re: EC so far......

PostPosted:Mon Jun 07, 2021 9:55 am
by Shoestring Flyer
Cessna571 wrote:
Shoestring Flyer wrote:I think what traffic you guys are seeing, or rather not seeing, is terrible!
You need to get some proper EC kit. Here's mine with PowerFlarmFusion over a couple of days. Slightly concerned about the missing blank spot fowards though! :wink:


This is EC, not intercept radar.

Looks like you can miss them by 60 miles, I miss them by a mere 10 miles

However, 10 miles is good enough for me.


The vector pic shown is what the PowerFlarm unit is picking up and not what I have restricted my displays to.
I now have the displays restricted to 3miles horizontally and 2000feet vertically.
Anything more than 2-3 miles I am not interested in!

Re: EC so far......

PostPosted:Mon Jun 07, 2021 10:48 am
by johnm
I may be missing something but how can vector know what you are receiving in the cockpit?

As I understood it Vector was designed to optimise positioning for transmission so other folk could see you.

It's to be expected that PowerFlarm would be similar in Performance to Mode S ES but........

Re: EC so far......

PostPosted:Mon Jun 07, 2021 11:00 am
by PaulisHome
johnm wrote:It's to be expected that PowerFlarm would be similar in Performance to Mode S ES but........


They are significantly different.

A PowerFlarm has a 50mW output (50 thousandths of a Watt), and usually uses an internal antenna. (PowerFlarm is a bit better than Flarm, but only a bit).

A transponder with ES is up to ~200 W, so 4000 times as much, and will have an external antenna. Even allowing for the extra bandwidth ADSB uses, that's a big difference.

Paul