On Tue, 11 Jul 2006 06:55:58 -0700, jmk wrote:

It's why one should select non-overlapping channels for neighboring
clouds.

I wish the FAA would show the same sense. But they are bound and
determined to fit the entire ADS-B thing into MODE-S, in spite of existing
MODE-S congestion in many areas already. And in spite of the known fact
that MODE-S can't handle the MANY other potential benefits of ADS-B, like
weather uplink, etc. I hope they don't force it,

I don't quite follow your point here. But that exposes another aspect of
ADS-B that's confusing to me.

I don't understand the relationship between VDL, Mode S squitter, and
UAT. My cursory reading tells me that these are three different
communication technologies, any of which can be used to carry ADS-B data.
However, that would appear to defeat a major benefit of ADS-B: if two
aircraft are out of RADAR coverage, they're still supposed to "talk" to
each other. But if one is carrying a UAT and another a Mode S squitter,
how could that communication occur?

[...]

Instead, take the estimated
$1 Billion savings from eliminating the present VOR system (except for a
small backup infrastructure) and just BUY every plane out there an ADS-B
system.

I like having a good mix of ground and satellite stations. I'd like to
see, in fact, GPS units which include NAV radios (ie. the Garmin 430/530
line) feed the VOR NAV data into the location computation as well. It
would provide an additional check against satellite signal loss. It would
be less precise (esp. when compared to WAAS), but there's no reason that
satellite "backup" needs to be twisting needles and catching CDIs.


No, I'd thought that this was all already defined. How else could
these services be running in Alaska and part of the US East Coast?

You'd think so, wouldn't you.

Well, sure, before this conversation.

But no, it's not already defined.
Even
the frequency (MODE-S vs. VHF) are still up for grabs. All those
systems currently running are "test systems" only.

Which means I could buy the Garmin GDL-90 and find it useless? That's not
something Garmin is advertising.


BTW, the latest edition of AVIONICS Magazine had some pretty good
articles in it on ADS-B.

Is that:

http://www.avionicsmagazine.com/

? Is the article there? I'm not seeing it (at least in the June edition,
which is the latest I see online).

Thanks...

- Andrew