[LEAPSECS] ADS-B, was: Some personal notes on the Torino meeting

From: Ed Davies <ls_at_edavies.nildram.co.uk>
Date: Wed, 04 Jun 2003 00:05:43 +0100

First of all, thanks Markus for your report.

One borderline off-topic clarification:

> He took the
> ADS-B (Automatic Dependent Surveilance Broadcast) system as an example,

Use of the word "the" here is a bit of a problem. ADS-B is a generic
term, a bit like GNSS vs GPS, Glonass, etc. There are three ADS-B systems
which I know of being trialed in various parts of the world. One is
UAT, being developed by the US parcel carriers (UPS is the "ring-leader"
I think) which works on a discrete frequency (980 MHz, if I recall
correctly). Another is an extension of GPS-squitter which puts a GPS
position and other information on the end of the normal mode S response
from a standard modern aircraft transponder (1060 MHz, again IIRC).
This is being pushed by the US FAA. The third is VDL (VHF data link)
mode 4 which was being trialed in Europe by the Swedish civil aviation
authority, Swedish airlines, Lufthansa, gliders in Sweden, etc. VDL
mode 4 has been adopted legally in the Russian federation though I've
no idea of the implementation state.

Some airliners on long oceanic routes call in their positions
automatically via satellite. This also comes under the ADS-B banner
and is in pretty widespread use, particularly over the Pacific.

Regretably, Eurocontrol is pushing for mode S transponders in all
aircraft, rather than ADS-B which is, in my humble opinion, a complete
disaster for all of general aviation and the military and anybody else
who makes a habit of flying around without full air traffic control
but that's a rant for another list, I'm just not sure which :-).

Anyway, all I'm trying to say is that any discussion about what
"ADS-B" does or doesn't do with time had better be clear about which
system they are talking about.

Of course, if different systems coexist but choose different time
scales it's likely that the areas where they try to interoperate
will be where the real leap second problems happen.

Ed.
Received on Tue Jun 03 2003 - 16:06:49 PDT