New CAA low power portable ADS-B device spec

[SteveHutt]

FYI,

http://fasvig.org/new-easy-process-to-enable-electronic-identification-of-light-aircraft-announced

Steve

[AlanG]

Hi

Having read through the document linked to above and then the further reading document that it links to and then ploughed my way through the CAP 1391 document i am not a lot wiser as to how this effects the PAW Project.   My initial reaction is that the CAA are trying to encourage established manufactures to produce a device operating on the 1090 Mhz frequency for Tx/Rx for around a similar cost to PAW and that this would be the only system they would recognise or authorise.

I have to admit that most of the jargon and technical references in these documents are way over my head so if there is anyone out there who can translate it into "Dummies" speak for those of us without a degree in Avionics.
As far as I can deduce, PAW hit the target in that it can receive and alert us to other ADS-B and Mode S traffic in our vicinity but due to the proposed new RF Bridge being on *** Mhz it will only render us visible to other PAW equipped aircraft and not the ADS-B In equipped aircraft and therefore lacks the compatibility that they seem to be squawking about. (Pardon the Pun).

I look forward to others comments on this and hopefully to to be proved wrong that this is a deliberate attempt to thwart the initiative which has been demonstrated by this project.

Regards
Alan

[SteveHutt]

Hi Alan,

You say you are "not a lot wiser as to how this effects the PAW project?" Well in my mind it is pretty obvious. The CAA want to increase the number of GA a/c flying with ADS-B Out and if you have a PAW then that is a good thing for your flying safety as you would then be able to detect them.

The CAP 1391 document lays out a spec for anyone that wishes to develop a portable low power electronic conspicuity device that provides ADS-B Out (and In, if desired) on the 1090MHz frequency.

Another key thing is that they are proposing to reduce the regulatory burden for the manufacturer. They say:

"As part of the planned introduction of the proposal we are consulting with manufacturers on a new process that aims to remove regulatory barriers, making it easier for manufacturers to build a range of devices.  Once the process is up and running manufacturers will be required to make a declaration to the CAA that their device complies with the relevant approval.  This will ensure that all EC devices, that have an acknowledged declaration, meet the standard set out for it to be used legally on board an aircraft.  The administration charge for declaration has been waived for the first year of the scheme."

So... The proposed process is along the lines of the CE verification that PilotAware have undertaken for the new Bridge.

This CAP 1391 proposal has been a long time in the making and follows on from work on electronic conspicuity dating back several years. 1090MHz ADS-B is the international standard for electronic conspicuity and the certified EC world by definition must support it so the CAA have to as well. I applaud the work the CAA have done. My only sadness is the time it has taken.

Talk of "thwarting" PAW is just plain silly. If PilotAware so chose they could set about adding 1090MHz ADS-B Out capability into PAW by taking advantage of the simpler regulations the CAA are proposing. Personally, I think it would be great if PilotAware were to do this and I would encourage them to do so. As a PAW user you would be safer if PAW output 1090MHz ADS-B Out as it would be helping to make you seeable by more aircraft that you are sharing airspace with.

Steve

[SteveN]

Talk of "thwarting" PAW is just plain silly. If PilotAware so chose they could set about adding 1090MHz ADS-B Out capability into PAW by taking advantage of the simpler regulations the CAA are proposing. Personally, I think it would be great if PilotAware were to do this and I would encourage them to do so. As a PAW user you would be safer if PAW output 1090MHz ADS-B Out as it would be helping to make you seeable by more aircraft that you are sharing airspace with.

Great idea Steve but  we still seem to have the restriction that 2 devices cannot emit 1090Mhz from the same aircraft meaning PAW's ADS-B out would have to be switched off in a transponder equipped aircraft.  Same issue with LPAT. No one want's pilots to turn off their transponders.

I had hoped the trials would have been testing this in the air to see if it actually mattered.

Allowing two devices  (same hex code) would accelerate adoption not least amongst Garmin transponder owners.  My guess is greater that 50% of the aircraft flying have Garmin transponders that will cost £1200 to upgrade or in the case of the GTX328 never be upgradable. That could be a huge jump in take up.

[AlanG]

Hi Steve

Call me an old cynic but i was a little suspicious of your initial involvement in this forum  but had come to accept that you had a genuine interest in the efforts of Lee and the team to succeed.  Even making requests and suggestions to make the software useful for users to obtain the verification required to connect the non-certified GPS unit to their Xponders.
My comment of  "not a lot wiser as to how this effects the PAW project?" was somewhat tongue in cheek as it is fairly obvious that as PAW is not using 1090 mhz it would not apparently be supported in the newly announced process.  The dialog in all of the linked articles constantly  refers to "manufactures" and is obviously prioritised toward them.

If you consider my "Talk of "thwarting" PAW is just plain silly" then why do you believe there is a sudden rush to take this forward after all of the dalliance of the intervening years since first mooted.  I believe that the PAW project has given the "manufactures" & the CAA the boot up the proverbial that they required as they saw  a potentially lucrative market being snatched from under their noses
Your suggestion that PAW should adopt the 1090 Mhz route is as far as I can establish going to fly in the face of producing a low cost, self build unit that uses off the shelf available parts as I'm not aware of any readily available 1090 Mhz transceivers in this category.  I'm sure these will be far more available to the established manufactures & probably cheaper.
I now feel vindicated in my initial suspicion of your motives for being involved in this forum as I cannot believe that you did not know what was going to be contained in the CAA announcement.
That is not meant to be a condemnation or criticism of anything you have said or done by being involved in the forum but just my personal observation that  it was less than honest.

Having reviewed some of your posts Steve, I see the following from a post in another thread which i suppose demonstrated your thinking and I think was what alerted me subliminally to the fact that you were not totally on board with PAW but maybe I have to consider that you were more honest than I've given you credit for.

"I am a supporter of PilotAware but I view ADS-B Out as a much more valuable thing to broadcast than P3i.
Everyone with ADS-B In (including PilotAware) will see ADS-B broadcasts.
Only PilotAware users will see P3i Broadcasts.
ADS-B Out (i.e. transponder) antennas will be fixed externally installed therefore offer more reliable transmissions that P3i
ADS-B Out transmissions are more powerful
As has been said, things are still developing. ADS-B is not going to go away but how it is going to be used may well adapt with time.
And the usage of ADS-B may well have an influence on other things, airspace being an obvious candidate.

Steve"


Regards
Alan

[SteveHutt]

Great idea Steve but  we still seem to have the restriction that 2 devices cannot emit 1090Mhz from the same aircraft meaning PAW's ADS-B out would have to be switched off in a transponder equipped aircraft.  Same issue with LPAT. No one want's pilots to turn off their transponders.

I had hoped the trials would have been testing this in the air to see if it actually mattered.

Allowing two devices  (same hex code) would accelerate adoption not least amongst Garmin transponder owners.  My guess is greater that 50% of the aircraft flying have Garmin transponders that will cost £1200 to upgrade or in the case of the GTX328 never be upgradable. That could be a huge jump in take up.

I very much agree with you Steve, and have been saying so for a very long time. If two devices in the same a/c both broadcast the same Hex code and one does the non-ES bits while the other does ONLY the ES bits then in theory I see no reason why this ought not work and is worthy of investigation.

I gather there is a flag in the broadcast data that indicates whether a device can respond to being interrogated by SSR. Mode S transponder set this flag to "yes". The problem would be if two devices sharing the workload on a single Hex code set this flag different to each other as it may confuse SSR ground stations. The simple idea that comes to my mind is that a portable ADS-B device operating on its own would have the respond to interrogations flag set to "no", but if paired with a device on the same Hex code that can respond then the portable ADS-B device would flag "yes" as its 'partner' device will do the responding. (There is no response mechanism in the pure ES part of the system). That is all a bit of a pfaff but it hangs together in my mind.

I have not given up hope that this two devices in one aircraft issue will be resolved. I guess that comes after giving a portable ADS-B Out option to those aircraft with no transponder.

There are other issues like currently 'UK only' that are unwelcome and efforts are underway to try to address that.

Regards,

Steve

[SteveHutt]

Hi Alan,

I very much put PilotAware in the category of 'manufacturers'. They have already announced they will be selling complete devices. See here: http://pilotawarehardware.com/product/pilotaware-complete/. And they can provide feedback to the CAA via the manufacturer survey if there are any aspects of the proposal that they feel need improving.

There has not been a sudden rush to produce the CAP 1391 proposal. It has been under development for a significant time and the related Project EVA work has been ongoing for a long time now. Just google LPAT and Project EVA. You can even read about them on this very forum. Nothing has been hidden.

I do take exception to you questioning my honesty. I have never sought to undermine PilotAware. You are free to search my posts here and on the Flyer Forum. I was asked by Lee if I would join the PAW Technical Committee and I politely declined on the basis that I supported a standards-based approach to electronic conspicuity so I have been very straight. I have focussed my involvement in PilotAware on the parts of PAW that support the ADS-B standard. And On that score I am pleased that PilotAware have been able to provide benefit to the GA community.

EDIT
I see you have amended your post Alan, but saying "more honest" is still not saying "honest" so I still take exception I am afraid. I have never acted other than what I see is in the best interests of the GA community.

Regards,
Steve

[thearb]

Hi guys,

As a moderator, I'm a little uncomfortable with the way this thread is heading. So far this forum has avoided the bad feeling that so many others have, and that is due to the underlying sense that we are all on the same side here with a ground breaking project that has come from the grass roots and put the authorities to shame.

Personal attacks will not be tolerated, attack the idea, not the person.
Thanks.

[AlanG]

Hi
No need to worry, there was no personal attack intended, just the thoughts rolling round my head at what seems to me a crucial point in the development of this great project, 
As i said,  I am now more interested in other contributors thoughts on where this goes in the future, especially those of the team who have committed so much time and effort for, so far, so little reward.
I am still 100% behind Lee and the team as even with two or more systems we are still much safer if we in the GA sector can see and be seen by each other.  Much of the research quoted states that the most likely event of a mid air is with like for like type of aircraft so the more PAW units that are out there the safer we will be.
The gliding fraternity have gone their own way with a system incompatible with any other as far as I am aware which I suspect was in response to the same problem. 
Following the trials, we are now able to fit non-certified GPS to our transponders that will allow SSR & PAW equipped aircraft to see them but ACAS/TCAS still can't see them.  ?
Yes, It's always preferable if everyone sings from the same hymn-sheet but that would require legislation and at what cost?

Alan

[Mig29fuk]

Thank you Moderator for stepping in as you have. I too felt that sentiments were edging towards personal.

[Moffrestorer]

I think we can all agree that PAW is an Electronic Conspicuity (EC) device. However, it is not an ADS-B transmitting device and does not seem to fall within the definition of CAP1391 which only deals with the specification of an EC transmitting ADS-B ES on 1090 MHz.

Although PAW can serve as an uncertified GPS source for a Mode S transponder, as such, it appears to fall within the definition of a Full Category Device (para2.2) and therefore outside the scope of Chapter 6 of CAP1391. It is the Mode S transponder itself that carries the appropriate approvals. Furthermore, while PAW is able to receive ADS-B and ADS-B ES, there is no requirement for approval for receiving on 1090, only recommendations, that are sensible to comply with as far as they impact on PAW as a device. Colour coding of alerts for example will not be a PAW issue but instead fall under the remit of the navigation software provider, such as SD or PocketFMS/Easy VFR.

Whilst I broadly agree that for the future EC might be better served if all systems standardised on 1090 ES, the fact is that the RF output powers quoted, are much, much higher than likely to be utilised by the new PAW Bridge, and the power drain of a CAP 1391 EC device will hence be more difficult to accommodate in many of the airframes which PAW is aimed at. There is also the considerable disadvantage that a CAP 1391 EC has to be inhibited from transmitting if the airframe is already equipped with a transponder.

PilotAware as a completed product, WILL be a manufactured item and it may be sensible to apply for approval by submitting a Declaration of Conformance, especially as it is likely that fees are to be waived initially, according to Steve Hutt (though I cannot find reference to this in CAP 1391). I feel that it may be important for the future of this project that PilotAware attempts to follow the "spirit" of CAP 1391 with regard, to sections concerned with Testing , Manuals, Receiver characteristics etc. in so far as they apply.

[BobDarby]

There are a lot of ideas being expressed in this thread and a few misconceptions.  As someone who has been involved in ADS-B (on 1090MHz and other frequencies) for a long time, and who also participated in the Electronic Conspicuity Working Group, I have tried to set out the main principles of Electronic Conspicuity, Airborne Collision Avoidance for GA and their relationship to ADS-B, together with a short summary on current activities.

I must also correct the initial statement of the post dated 26.03.16 08.01.21pm, which states "PAW ... is not an ADS-B transmitting device".  It most definitely is an ADS-B transmitting device!!

My main concern is safety and to get the greatest benefit for the widest possible range of GA pilots by promoting mutual interoperability - which leads to the mantra of SEE, BE SEEN, AND AVOID.

[exfirepro]

I must also correct the initial statement of the post dated 26.03.16 08.01.21pm, which states "PAW ... is not an ADS-B transmitting device".  It most definitely is an ADS-B transmitting device!!

Hi Bob,

I was initially confused when I read the above, but having read your summary and given this more thought, you are of course correct that PAW, with its RF Bridge fitted, can be classed as an 'ADS-B' transmitting device as in poor man's speak it is... 'Broadcasting positional information to make the plane more visible,' just not on the normally accepted ADS-B frequency of 1090MHz, ...though I suppose if used as the GPS source for a Mode 'S' transponder, PAW would certainly form a significant component of a 1090MHz ADS-B Out Transmitter.

From personal experience, I am well aware of the effectiveness of such a system as I currently use my PAW to provide the 1090 MHz ADS-B in component of a full 1090MHz ADS-B system and have significant experience of and great confidence in its performance in this area.

I await with interest commercial LPAT developments, though have some concerns that any significant cost (over that of systems like PAW) will inevitably lead to resistance to its broad take-up. I also have concerns that the cost of LPAT may be prohibitive to those like myself, who have already invested in 1090MHz ADS-B out capability via a Transponder, who would be buying yet another transmitter which we would (at least under current rules) be obliged to disable.

Another serious concern is the current position whereby ADS-B generated on 1090MHz through the use of 'non-certified' GPS must transmit an SDA/SIL '0', which I understand makes it effectively invisible to ATC / TCAS - making me suddenly invisible again to everyone except PAW, FLARM and presumably LPAT (oh and of course - very important - FR24). I hope this situation can be improved otherwise why would we bother?

Please don't think I'm being negative - far from it - I have taken on considerable expense (almost £5,000 in the past year) to make my aircraft more conspicuous and will be delighted when everyone else is finally able to see ME (other than via FR24).

Regards

Peter

[bryannortje]

Hi all after reading through the latest developments I want to ask - What is the point of the conspicuity trial of LPAT, PilotAware and FLARM, as it looks as though there is already a decision made on LPAT and 1090 EC equivalent units?

[SteveN]

I must also correct the initial statement of the post dated 26.03.16 08.01.21pm, which states "PAW ... is not an ADS-B transmitting device".  It most definitely is an ADS-B transmitting device!!

How can it be a ADS-B transmitting device when it does not transmit ADS-B messages (PAW=P3i) and it uses a frequency in the public band?