ADS-B thoughts

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lucaberta
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ADS-B thoughts

Postby lucaberta » Thu Dec 04, 2008 5:08 am

Yesterday I've listened to episode #105 and Amy mentioned the NavWorx UAT product, which I believe is very interesting given also the much more interesting price compared to the full-blown certified UAT from Garmin (which is the only option if you have a certified airplane though).

http://navworx.com/

There is not a whole lot of information about the product and the different devices this might feed the data to yet, but I am sure the website will be updated in the future. One of the cool things of the Internet is that you can find every bit of documentation, including the very detailed installation manuals, of most new products. Infact, having a well-thought website and a user forum today has to be part of a good marketing plan by any newborn company.

One of the things that's there is worth giving a look to:

http://navworx.com/docs/ADSBSlides.pdf

These slides go into some more detail on ADS-B in general, although certain things are a little more complex than how they are portrayed here. I'd like to clarify a point that I believe is not clearly spelled out in slide #8 (apart from the typo in the UAT frequency which is 978 MHz and not 987 MHz!).

Commercial aircraft do have a different radio standard for ADS-B, which is based on mode S and is called 1090ES, and that's not only when they are *above* 24000'! Commercial planes will not have an UAT like light planes, and so effectively ADS-B between a light plane and a commercial plane will only work when under coverage of a GBT. GBTs, the ADS-B radios on the ground, need to do quite a bit of work in order to make commercial traffic appear on our small GPS screen and trigger a "traffic" call, like TIS does today.

At the same time light planes have UATs that talk to one another on the 978 MHz frequency, and thus you might have a mix of "real" traffic coming from UAT broacasts, which are inherently more accurate than TIS since the processing is all done locally on the aircraft avionics, and traffic information which is relayed by TIS-B, and so the position of the actual traffic will be not as accurate as UAT-to-UAT as some processing is done on the ground at the radar facility, and the TIS-B data is compiled and sent over to the GBT.

In a nutshell, you might end up having a mix of more accurate true ADS-B data on the screen, and some TIS-B generated less accurate data at the same time. With the issue that the TIS-B traffic might include both high-speed commercial traffic and non ADS-B light aircraft (like TIS does today). A mix of different data on the same screen.

This might be an issue, this might not be an issue. I don't have a clear thought on this as this is all quite new to the industry. Maybe an indication of this difference is already being implemented on the Garmin screens, I should do some research.

Bottomline, more electronics in the cockpit are not a bad thing, but they just add a lot more complexity in the system, and might make things even more confusing to the pilot under stress.

More information from the FAA on ADS-B are to be found here:
http://www.adsb.gov/

Ciao, Luca (IK2OVV and K2OVV for those who know what this means...)

P.S. In the rest of the world there will only be 1090ES, even for light planes. We are already being forced to install mode S transponders, and there is no advantage to us at this time. Just more money to throw in, and no service coming out anywhere near from mode S, unlike in the USA. Stop bitchin' 'bout ADS-B guys, else you'll need to come here to fly for a while, and all of a sudden the US of A and FAA will look so muuuuch better to your eyes! :D
Luca Bertagnolio, CPL/ASEL/AMEL/ASES/IR

US States I've overflown or flown in:
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lucaberta
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Re: ADS-B thoughts

Postby lucaberta » Thu Dec 04, 2008 5:29 am

Adding to my own message, just found an interesting screenshot of a mix of TIS-B and ADS-B traffic around the Anchorage area:

Image

Note the different depiction of the ADS-B traffic and the TIS-B traffic. Works for me!

This pic was found on the FAA website, reachable by going to:
http://www.adsb.gov

Happy to get a discussion going... let's see what you guys think of all this!

Ciao, Luca
Luca Bertagnolio, CPL/ASEL/AMEL/ASES/IR

US States I've overflown or flown in:
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