Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Rich V
FLYER Club Member  FLYER Club Member
#1874914
xtophe wrote:Have you been able to contact the SE2 manufacturer and TIS-B trial people ? Conveniently, it is the same company.


No. uAvionix have still not bothered to acknowledge receipt of the emails I have sent, let alone come back with an informative reply as I requested.

I remain very unimpressed.
#1875081
Well that didn’t take me very long. I dropped the UK’s uAvionix man a line via text and got the following explanation within 30 minutes of asking. :roll:

This is an abridged version of what was explained to me:

There is a TIS-B trial ongoing with the full backing of the CAA. The ADS-B settings were contributed to the briefing note as an AIC could not be fitted in to the AIRAC cycle before transmission started. The trial started late and so has been extended to Dec 21. As with transmission of ownship from an SE2 or an ADS-B transponder, ghosting would be eliminated by turning on the ADS-B Filter (aka ‘Ownship Filter’) in the SkyEcho 2 (SE2) settings but users should also set their own HEX code in the aircraft library of SkyDemon. Users will ONLY see TIS-B if they have selected the second receiver to UAT AND ADS-B In it set to UAT (most people normally ignore this setting so some are seeing it and some are not). This was explained for the AIC but that hasn’t come out yet.

The trial is pushing out MLAT data on Mode S transponders and FLARM rebroadcast (as you have to select UAT not FLARM) to see the TIS-B. It is intended as an enhancement of situational awareness to demonstrate the value of TIS-B in the UK. It allows users to see every common form of EC broadcast except PAW. The ownship filter equally applies to any SE2 user who transmits ADS-B either from their transponder or their SE2. The main lesson is that they also need to set their HEX code in SkyDemon to guarantee the filter as if they fly multiple ac and have the wrong one set in Sky Demon it can cause ghosting in a TIS-B environment. So they need to make sure correct aircraft selected in SkyDemon and they have correctly populated each aircraft’s HEX in the library.


It seems that incorrect settings by the individual can cause the issue. There should have been detail of this in the AIC, but the clunkiness of the 28-day AIRAC cycle meant it was missed. The ownship filter HEX for ADS-B transmissions by SE2 or transponders should work but incorrectly set SkyDemon libraries can over ride this.

I hope folks find that useful? Cheers, Gaz (who doesn’t work for uAvionix)

PS. The bits in blue are the bits for the SkyEcho 2:

https://i.ibb.co/27X9s34/3-B43-DB15-EB0 ... FA2851.jpg

Image

BUT YOU MUST ALSO CONFIGURE YOUR SKYDEMON LIBRARY PROPERLY TOO

Every day is a school day…
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By seanxair
FLYER Club Member  FLYER Club Member
#1875102
Rich V wrote:
xtophe wrote:Have you been able to contact the SE2 manufacturer and TIS-B trial people ? Conveniently, it is the same company.


No. uAvionix have still not bothered to acknowledge receipt of the emails I have sent, let alone come back with an informative reply as I requested.

I remain very unimpressed.


See above. You need to text them apparently.
#1875133
@gaznav
Thanks for elaborating on the TIS-B implementation, could you try and get further clarification on the other points

1. What is the expected positional error for ModeS capture, calculation and internet transmission latency, prior to rebroadcast ?

2. How is the position error from (1) communicated / represented to the user ?

3. If the position error in the rebroadcast, has the potential to overlap the position of the receiver, how is that communicated / represented ?

4. Is the FLARM data captured and rebroadcast at the local Antenna receiver, or via the internet?

5. If (4) is via the internet, then I presume the data is
- captured by OGN/ATOM stations
- relayed to glidernet
- relayed to planefinder (via APRS)
- relayed to the trial UAT for broadcast
If so this data will be delayed significantly, what are the expectations?

6. You mention that PAW data is not included. That is probably a good thing, glidernet was never intended for situational awareness, and the latency and frequency of position updates is kept as a minimum,, if I recall only 1 in every 5 position reports is relayed
If planefinder (glidernet/APRS) is the source of data, how is it ensured that the PAW position reports are discarded ?

I am sure you agree, as this data is available to all CAP1391 users, it is important to understand the potential errors and impacts of this data.

Thx
Lee
#1875276
Dear all,

Mea Culpa on this - the Goodwood@uavionix.com email address was misrouted and the relevant team was not seeing your comments. We have rectified this but are sadly unable to see comments sent before today. Can I please ask all those who have raised a comment to bear with us and resend them and we will take a look at them ASAP.

To close off the ownship ghosting issue; we have checked all our broadcasts and the data we are sending out is correct. The most likely reason for ghosting is a misconfigured combination of the Sky Echo itself and the interaction with Sky Demon.

As many of you will know Sky Demon will compare the aircraft you select to fly from its library and the data in your Sky Echo. If they are different it will offer to reconfigure the Sky Echo. If you perhaps fly in a Club environment and you make an error in aircraft selection you can overwrite the Sky Echo so that it sends out the wrong Hex ID with its ADS-B broadcast, ie it is different from the Hex code being sent out by the Mode S transponder of the aircraft you fly that day. The Sky Echo will filter ADS-B input for the Hex code you have set and so, even making this error, in a non-TIS-B setting you do not self alarm (Ghost).

However, in a TIS-B environment this error is compounded because you are receiving on the UAT frequency, into which we are sending you traffic from MLAT sources based on Mode S outputs. Because your Sky Echo is filtering the wrong Hex, the output from the transponder in the aircraft you are flying is seen as a conflict - the Sky Echo does not know that is you and so lets it through to Sky Demon, which also does not realise it is you, and so displays in your Deep 6. This will only happen under TIS-B.

The message is as Gaznav says. Fully configure your Sky Echo as he indicated. Make sure any aircraft you fly stored in your Sky Demon library are fully populated INCLUDING Hex code (and make sure it is the correct Hex code as we see some finger trouble errors here). If told by Sky Demon that the aircraft you have selected to fly is not the same as the one stored in your Sky Echo - Do you Want to Change It? Think carefully before responding as this is where the error can creep in. You would not normally be aware of it (though your Club will not be pleased), but under TIS-B you will see a ghost if you get it wrong.

I hope that makes sense.

Again I am sorry for the admin error that caused us to miss your comments - we really do want to see them so please resubmit any issues you have.

Thanks for your patience - we are adding some enhancements to the TIS-B service as I write and I think you will find them very useful. We'll update you on that in due course.
Last edited by uAvionixUK on Thu Oct 07, 2021 6:21 pm, edited 1 time in total.
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By Rich V
FLYER Club Member  FLYER Club Member
#1875281
Thank you for replying. I am a bit tied up just now, but my initial response is that I only fly one aeroplane, my own, and both my SE2 and my SD are correctly set up, with accurate and matching hex codes. I will, again, check this when I can, but I still think there is a fundamental flaw somewhere in your trial data configuration. I cannot believe there are so many if us that have got it wrong.

But as I said, thank you for your reply here. That is very welcome.

Rich V
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#1875289
Hi @leemoore1966

I would be well outside my ‘swim lane’ to answer your questions, but I would expect most of these will be swept up in the trial report. As this is expected to be a potential national solution, just like CAP1391 and the use of uncertified GPS on Mode S ES transponders was, then I would hope that trial data will be released in formal reports like the ones here:

https://airspace4all.org/wp-content/doc ... e-V1.0.pdf

Or

https://nats.aero/blog/wp-content/uploa ... report.pdf

Obviously PAW users can benefit if they configure for receiving UAT output as I understand it, so it should be a good win for all if this trial is successful and leads to nationally provided TIS-B and FIS-B service for the benefit of all.

You never know, it might even stop me whining and moaning on here about ADS-B - surely a win-win scenario! :lol:

Cheers, Gaz
#1875363
gaznav wrote:…Obviously PAW users can benefit if they configure for receiving UAT output as I understand it, so it should be a good win for all if this trial is successful and leads to nationally provided TIS-B and FIS-B service for the benefit of all.


To be honest Gaz, it would not be a good idea to invest any time and effort in this right now for the following reasons:

In 2017 (4 years ago) this attempt began in an earlier format that grew to 3 stations in the South of England
https://uavionix.com/uat-in-the-uk-part-i/
We invested time and effort to support a team of PAW evaluators, and it ended in a whimper, not a bang - I presume due to lack of funding, but I did not see any results or findings of that previous trial published

I see no difference here right now, its a trial with no funding plan for a national rollout, unless I missed something?

Further to this there is scant information anywhere regarding the quality or content of the data being broadcast, or how it is to be interpreted by the receivers.

Best of luck in the endeavours, but I can tell you from experience, getting a national system such as this up and running, is much much more than simply installing a couple of transmitters

Thx
Lee
#1875495
@leemoore1966

The previous trial was just 978 UAT FIS-B weather that you mention. This one is to investigate how ADS-B might be used to integrate autonomous air vehicles into the same airspace through the use of TIS-B and with an offshoot of FIS-B. That’s a totally different trial all together :thumright:

The service is part of a trial that is underway around Goodwood Aerodrome that aims to develop new surveillance technology and operational procedures in support of Beyond Visual Line of Sight (BVLoS) operations.


Cheers, Gaz
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