[leemoore1966]

@Flyin'Dutch'

Did they not have their TXPDR on for you to see them on your PAW with multilateralisation?

As I said, I didn’t get THAT close. I couldn’t see whether he had his transponder on or not and if he did I have no idea if he had C Mode S or just just Mode C.

Yet you are confident that he was using a SkyEcho that wasn’t performing?

It was emitting CAP1391
I have taken a look at the data, and it does not appear to perform that well I'm afraid
And that is when attempting to detect using something like a 4ft long 9db antenna from multiple locations !!

Another interesting fact, the aircraft in question was indeed being multilaterated and perfectly well I should add.

So here is the fly in the ointment, when the GRID network considers an aircraft for rebroadcast, it uses the following logic.

Does the aircraft (using a common ICAO) have an emitter type that can be seen directly by a PilotAware, in this case the logic says it is emitting
- CAP1391
- ModeS
- ModeC

As the aircraft is emitting CAP1391 and this is detected by multiple hi-gain antennas, then it is NOT considered for re-broadcast, now this is pretty unfortunate, because this means we will not uplink the multilaterated position from the ATOM/GRID network, which Paul would easily have seen from either Selsey, EGHJ, EGHN, Lasham, or IOWPara

We have debated internally this potential problem, we may have to rethink whether we should re-broadcast CAP1391 devices, as this situation clearly shows there is once again a problem.

[russp]

Sadly the Aircrew search is seriously clunky.. I can see my aircraft when I do an all aircraft search but search for my hex code and nothing! It does however show how often, even with an external aerial pilotaware install that I'm losing contact contact with a ground station. worryingly so.. now I realise why all those contacts suddenly disappear and become bearingless targets...

Hi Russ
Please try aircrew again - we did find an issue and fixed, this may fix your issue, if not please PM me and tell me how to reproduce.

Regarding uplink contacts, what distance were they from you, could they have been less than 10km ?
The reason I ask is as follows, if they are within 10km of you, then you will trigger an uplink
If they are not you are receiving them as a peripheral uplink, ie triggered by someone else.

In either case if the triggering aircraft goes beyond 10km, then the uplink will cease.
If you don't think this is the case, again, I would be interested in further information, you can PM me to send the track file of a flight where you observed this behavior

Thx
Lee

Lee - the search seems to be working now - here is the flight where I could see other aircraft appearing and disappearing in the air to be replaced by bearingless targets. Almost certain most were within 10k but not 100% sure but the aircrew plot shows the very frequent gaps in ground station coverage - I'll get the PAW log next time I'm at the airfield if it's still of interest - the PA is a permanent fixture in the aircraft with external aerials.

[VinceGod]

Today myself in an L-4 Cub and another L-4 flew to the Vintage Piper Aircraft Club‘s southern meet at Sandown and I took the opportunity to try out my two SE2 units air 2 air.

My aircraft has the SE2 mounted at the top, up front of spars in the windscreen so has a good view forward. I mounted my spare unit in the other L-4 on the starboard window of the glass house. The details of the other L-4 where entered via SkyDemon (thanks Tim) and all tested OK on the ground, so I took off. I could pickup the other L-4 for a few miles while he was still on the ground but once he took off it was outstandingly bad and I hardly saw him until we landed at Sandown. Even though he followed me about a mile behind at the same level (max 1500’) he didn’t pick me up either. So clearly positioning the SE2 1 foot behind a meat bag is not the brightest thing to do. I guess if the other L-4 had lead the flight the results would have been different.

For the flight home we moved my spare unit to the front as pictured below. This gave continuous reception of each other for the flight home so placement is critical to get consistent results. I did notice while at Sandown a Moth had SE2 mounted using a RAM mount on a strut at the front in the airflow with a Velcro strap for added assurance.

I have checked Aircrew ground station playback and Pilotaware Vector for todays flights of both units and it shows very little contacts where made with Skynet but then we where below 1500’ most of the time.

Need to do a bit more air 2 air testing to really understand how to get the best out of the SE2.

[johnm]

That's very interesting I need to do some experimenting with mine. Because of the curvature of the TB 20 screen it's quite hard to find a suitable place. I might try the top of a rear window next flight but I'll need to be sure it's charged up as the power lead won't reach that far.

[gfry]

My experiences with SE2 are also kak.

I regularly fly 4 different aircraft each with their own SE2 unit. Since August last year i have only seen 2 aircraft with them. I have been flying in the circuit with three of those aircraft in the circuit and we could not see each other.

I then went flying with PAW and SE2 in the same aircraft and two Ipads (one for each device). PAW detected several aircraft, SE detected zero.

[VinceGod]

My experiences with SE2 are also kak.

I regularly fly 4 different aircraft each with their own SE2 unit. Since August last year i have only seen 2 aircraft with them. I have been flying in the circuit with three of those aircraft in the circuit and we could not see each other.

I then went flying with PAW and SE2 in the same aircraft and two Ipads (one for each device). PAW detected several aircraft, SE detected zero.

Then I suggest you review the placement of the units and make adjustment accordingly. Without giving details of the placement your statements above are not helpful in understanding the problem. The placement of SE2 in my Cub (up front) seems to work well and picks up ADS-B and FLARM contacts as I expect but always fails to detect PAW only aircraft.

I as others do, believe we need one standard for advertising our conspicuity and this in reality is ADS-B out. A Trig transponder with Trig GPS & antennas would be my preferred setup but with no power in the Cub and £2.5k its not going to happen. So a SE2 is my only option to get ADS-B out and I’d like to get the best out of it.

[skydriller]

The placement of SE2 in my Cub (up front) seems to work well and picks up ADS-B and FLARM contacts as I expect but always fails to detect PAW only aircraft.

...well obviously...SE2 only detects ADSB. Flarm if you pay the SD fee.

[Straight Level]

Using Aircrew Ground station playback and electing a random time yesterday to show CAP1391 (18) devices it is very encouraging to see how many gliders have fitted CAP3191 devices.
Easy to tell as they show a typical saw tooth altitude profile and regular circling.
At that particular time a very rough estimate would suggest more gliders carrying than powered aircraft!

However, as mentioned in previous posts there appears to be a huge difference in performance, from some CAP1391 devices being tracked very well to others that are effectively useless. Why is unknown, possibly simply poor positioning ?
Screen grab below shows two gliders in the same area at the same time, one being tracked very well the other shows a very broken [horizontal] trace. Fibreglass vs carbon glider or relative track to ground station, perhaps, but certainly there remains a significant difference in performance. Performance variation can be repeated by selecting various aircraft anywhere in the country.

Now this could simply be air to ground anomalies as the SE2 being designed primarily for air to air. Anecdotal evidence as above suggests otherwise.
The much lower power Flarm is generally tracked more consistently.

[VinceGod]

...well obviously...SE2 only detects ADSB. Flarm if you pay the SD fee.

I guess that’s the point with more ADS-B receivers coming to the market PAW is only every going to be seen by PAW (or Stratux EU). Take the Sentry it will receive SE2 or big boys Transponder with ADS-B out but not PAW. As SL mentioned many gliders are now transmitting ADS-B out alongside FLARM and I suspect are also receiving both but probably not receiving PAW.

I do not think this is “obvious” as there seems to be a lot of half information been given out when it comes to EC. So to state the obvious again “unless you transmit ADS-B OUT not everyone will seen you” and even if its only 1/2 mile before it’s picked up, it may save your life!

PS. There is no substitute for the MK1 detection device we all have

[leemoore1966]

So to state the obvious again “unless you transmit ADS-B OUT not everyone will seen you” and even if its only 1/2 mile before it’s picked up, it may save your life!

This is not correct, Classic Flarm (of which there are many) does not see ADS-B, it only sees Flarm

However, as mentioned in previous posts there appears to be a huge difference in performance, from some CAP1391 devices being tracked very well to others that are effectively useless. Why is unknown, possibly simply poor positioning ?

This is now much more concerning because even those "effectively useless (CAP1391)" as you phrase it, will still have intermittent detection via the ATOM/GRID big HI-Gain antenna located in free space on a pole, this same detection is almost certainly not going to be reproduced using a standard 6.7cm 1090/ADS-B TED Antenna

In this bizarre scenario, the CAP1391 is now masking the detection of the other EC technologies normally provided via uplink, under the assumption that direct detection will be achieved, can this assumption be relied upon? it would appear not.
I think we no longer have an option but to rebroadcast emitters which also have CAP1391 fitted.
It may be possible to use the profiling information in our VECTOR database to determine what looks like a good or bad installation, and use that to estimate the likelihood of CAP1391 detection

[Straight Level]

I think we no longer have an option but to rebroadcast emitters which also have CAP1391 fitted.

Problem with that is, ATOM stations won't be able to rebroadcast those poor performing installations because the ATOM station won't be able to detect them either

[Rjk983]

So to state the obvious again “unless you transmit ADS-B OUT not everyone will seen you” and even if its only 1/2 mile before it’s picked up, it may save your life!

This is not correct, Classic Flarm (of which there are many) does not see ADS-B, it only sees Flarm

However, as mentioned in previous posts there appears to be a huge difference in performance, from some CAP1391 devices being tracked very well to others that are effectively useless. Why is unknown, possibly simply poor positioning ?

This is now much more concerning because even those "effectively useless (CAP1391)" as you phrase it, will still have intermittent detection via the ATOM/GRID big HI-Gain antenna located in free space on a pole, this same detection is almost certainly not going to be reproduced using a standard 6.7cm 1090/ADS-B TED Antenna

In this bizarre scenario, the CAP1391 is now masking the detection of the other EC technologies normally provided via uplink, under the assumption that direct detection will be achieved, can this assumption be relied upon? it would appear not.
I think we no longer have an option but to rebroadcast emitters which also have CAP1391 fitted.
It may be possible to use the profiling information in our VECTOR database to determine what looks like a good or bad installation, and use that to estimate the likelihood of CAP1391 detection

Apologies for the interruption of a Luddite…

If I’m reading the problem correctly your ground stations are picking up signals but then not rebroadcasting them as the original airborne transmission is in a format that “should” be detectable by an airborne PAW receiver? And this a deliberate choice you have made presumably because you assume the airborne receiver would also detect the original transmission.

If my understanding is correct I presume this is to prevent two signals from the same transmitter being received by the PAW box. Would this lead to confusion in the box as there would presumably be a short time difference between the signals and therefore the position reports would be out?

Would this cause ghosting and duplicate aircraft warnings or would it mean rewriting the firmware in the on board PAW box so that it discounts the rebro signal if it detects an airborne position report that is similar to the rebro position?

[leemoore1966]

I think we no longer have an option but to rebroadcast emitters which also have CAP1391 fitted.

Problem with that is, ATOM stations won't be able to rebroadcast those poor performing installations because the ATOM station won't be able to detect them either

I am more concerned at the moment that we preclude the rebroadcast of MLAT and FLARM, when we detect the airframe is also emitting CAP1391

On a secondary note we have much better chance of CAP1391 ground detection with those big antenna.

Thx
Lee

[leemoore1966]

@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

[Rjk983]

@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?