Primarily for general aviation discussion, but other aviation topics are also welcome.
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#1803690
The problem with most ADS-B Out systems is that, contrary to what many people believe, they are not allowed to be shown by certified ADS-B In systems (the SIL and SDA values have to be above certain limits). In addition, there are very few ATC providers that can see ADS-B Out aircraft


This is from that website.

After all the negativity about SE2’s reliability, the fact that nobody seems to know what’s best to get, and the draconian implications these days for busts (not that I’ve ever had one), I’ve decided to cancel my order for an SE2 until the whole process settles down, companies stop bickering here like little kids, and the hardware works as it should.

Back to stealth mode.... :batman:
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By gaznav
#1803691
PaulisHome wrote:If the choice of 12 Jun 06 is relevant to the discussion, I note it wasn't a good gliding day, at least in East Anglia. My club just launched its training fleet and didn't do any soaring. No cross country at all. So the GA model may not be particularly good.

More generally, having spent most of my career in a technical consultancy, I know that it is possible for such consultancies, including QinetiQ, to write things that are wrong, not well thought through, or address a different question from the one now being asked. I have no idea whether that happened here, but an appeal to authority ["It's QinetiQ, they are big, therefore they must be right"] isn't particularly compelling. (It's not necessary to assume nefarious practices, though consultancies delivering the answer a client wants are not unknown). Better I think to actually look at what they did, and what the basis of their conclusions are.

It's a fairly complicated problem. It's not as simple as less power = less range. At these frequencies, range can be up to line of sight (we know we can pick up Flarm signals from gliders > 100km away with a suitable antenna, and Flarm is the lowest power of the systems we're discussing). Often the driver of whether you can see a signal at a receiver in a congested network, is the signal to noise - and the noise is the contribution from everything that's emitting in line of sight).

And then what's the question? Is it "Is System X suitable for GA Air to Air traffic detection, at least most of the time" Or is it, "Is System X suitable for CAT separation all of the time?"

So I think we need to be quite specific about the question we're trying to answer, and look closely at the modelling which is used to answer it. Do we have these?

Paul


Paul

I think the really key piece here is this:

Their model simulated the effects of introducing 828 Low Power ADS-B Transceivers (LPATs) prototypes into the operating environment at any one time.


So they created a model with airliners, biz jets, helicopters and GA aircraft seen on that date in the summer - using their positions for the model. They then added 828 LPATs to their model emitting 20W to see if interference was an issue - according to them, it wasn’t.

Then your point on making errors - yes, I agree they can be made. But there were more than one report and they created several models that we know of (2012, 2014 and 2015). I think it is highly unlikely such an error is made at least 3 times, don’t you?

Also, if this error was so bad, how about all the Class 1 and Class 2 transponders that are now emitting ADS-B on GA aircraft at 10-20 times the power of a CAP1391 device. Do we not think this so-called issue would not have started manifesting itself by now?

Finally, power is most definitely linked to range in the most simplest of equations - free space path loss. Yes, antennae design can also assist with this so-called problem (which can also be fed into the free space path loss equation if required). Further, receiver design can also improve things. Technology shifts on this all of the time (normally incremental gains) and certainly filters for noise on 1090Mhz have come a long with digital processing. So it may be that in the 6-8 years that this study was completed that matters have improved over what the study reported. Further, the removal of more of the non-selective Mode A transponders since will most certainly have cleaned up 1090Mhz.

I’m sorry, but I again believe that there are too many competent organisations that have looked at this to poo-poo it. There is also another big country (Australia) that have also agreed that low-power ADS-B on 1090Mhz works. Don’t you think that’s a little bit of an indicator (exaggeration!) of this solution being the way ahead?
User avatar
By gaznav
#1803692
TheFarmer wrote:
The problem with most ADS-B Out systems is that, contrary to what many people believe, they are not allowed to be shown by certified ADS-B In systems (the SIL and SDA values have to be above certain limits). In addition, there are very few ATC providers that can see ADS-B Out aircraft


This is from that website.

After all the negativity about SE2’s reliability, the fact that nobody seems to know what’s best to get, and the draconian implications these days for busts (not that I’ve ever had one), I’ve decided to cancel my order for an SE2 until the whole process settles down, companies stop bickering here like little kids, and the hardware works as it should.

Back to stealth mode.... :batman:


Surely, if no-one can see your SkyEcho then you don’t need to worry about “draconian implications these days for busts”? :cyclopsani:

That seems to contradict itself, a wee bit?
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By neilmurg
#1803698
Pick an EC SOLUTION, I DON'T CARE WHICH
@Miscellaneous , you keep referencing me, FFS pick an EC system, install it, stop whining from the 'dun nuthin' sidelines
@gaznav and @Cub when you contribute 15 - 30% of the posts on a page, you haven't effectively thought through your point, your just spamming. As 2 leading authorities on this issue, we expect you should at least be able to concisely, accurately and truthfully make your point in a single post. Or you're undermining your own credibility. Be better
Last edited by neilmurg on Sat Oct 17, 2020 11:06 pm, edited 1 time in total.
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By Rob L
#1803700
neilmurg wrote:Pick an EC SOLUTION, I DON'T CARE WHICH
@Miscellaneous , you keep referencing me, FFS pick an EC system, install it, stop whining from the 'dun nuthin' sidelines


Eh? From how many tens of pages ago are you referring? :?:
#1803709
Shoestring Flyer wrote:Seems like drones in Germany and Switzerland are using Flarm not ADSB.
https://flarm.com/droniq-utm-enables-bv ... nflicting/


That is no good in the UK but same difference.
By G-JWTP
#1803722
rjc101 wrote:
Cessna571 wrote:What I don’t understand about all the “congestion naysayers”

The issue isn't ADS-B as such, but the frequency 1090MHz. This is used by Transponders and ADS-B transmissions.

Every time a radar head 'paints' a transponder (Mode A, C, or S), it replies on 1090MHz.
If a TCAS transmitter sends a pulse on 1030MHz, the replies from transponders are all on 1090MHz.
A Mode-S ES enabled transponder will reply to being painted by a radar head, and also regularly transmit data on 1090MHz.


Heres the thing.

Maybe gaznav, Cub or anyone could help me with.

The big 'sell' from the CAA on mode S was that the world was running out of codes and 'bandwidth. ( we'll gloss over the present chaos).

We would go mode S or 'Select.

In other words rather than every transponder responding to a radar sweep, not the correct term but good enough, which is what happens with modes A &C. Only the 'Selected ' transponder would reply. This would free up codes and bandwidth.

Another bright spark also come up with the notion that we could also use the data part of the extended squatter, ES, to send information back down to ATC, ADSB was part of this along with a raft of other stuff, TAS, alt selected in autopilot , heading, being others.

I just don't see how we could clog up the system if there isn't the need for all aircraft to send all of this data all of the time. By definition the system should be selective, which it seems, by reading above, not to be.

G-JWTP
#1803736
Surely, if no-one can see your SkyEcho then you don’t need to worry about “draconian implications these days for busts”? :cyclopsani:

That seems to contradict itself, a wee bit?


So, are you now saying my Mode S Funke doesn’t do anything at all? Ok, I’ll keep that turned off too.

I’m actually totally confused by so much in this discussion.
gaznav liked this
#1803739
TheFarmer wrote:
I’m actually totally confused by so much in this discussion.


Don't be.

There are people on here who think that having Xray vision goggles alone is great for seeing everyone; they omit to mention that if nobody turns on their headlights it will still be like riding bumper cars.

ADSB is the standard; see and be seen.
Nick, gaznav liked this
#1803744
Flyin'Dutch' wrote:
TheFarmer wrote:
I’m actually totally confused by so much in this discussion.


Don't be.

There are people on here who think that having Xray vision goggles alone is great for seeing everyone; they omit to mention that if nobody turns on their headlights it will still be like riding bumper cars.

ADSB is the standard; see and be seen.


..and eventually when the rest of the aircraft out there, the flying schools, the gliders et al have caught up and ditched their Mode C & S , Flarm etc in about 5years time you will be able to see almost all the traffic out there! :wink:
User avatar
By TheFarmer
#1803745
I agree FD, but I’ve decided to wait until there’s a standardised system where the hardware works reliably, and the traffic info is not just a random and minimal selection.
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