At 12:05 PM 24/05/05 +1000, you wrote:
>As an outsiders quick & admittedly largely uninformed view... But an
>opinion from the chattering masses none the less and readily intended to
>be torn to shreds ;-)
>
>The primary difference between ADSB & FLARM with respect to sports
>aviation seems to be the potentially massive difference in cost unless
>the Govt subsidises ADSB to get it in use. The system is as it is being
>applied intended for everything from a hang glider to a 747 in order to
>maintain standardisation at all cost. Regardless, that is, of the actual
>requirements of the different levels of operation within aviation as a
>whole, or their capacity to carry & operate the equipment.
Don,
I wouldn't get too excited about the gliding movement being able to
organise anything let alone a technology development program.
I gather the main feature of FLARM is that it _actually works_ and is in a
lot of gliders and being tested and gaining operational experience every day.
Is the use of an unlicensed band such a risk?
If an ADSB GPS/transmitter outputs GPS data for use by FLARM then the FLARM
might still be the way to go on its unlicensed band as the software is
optimised to prevent glider to glider collisions. Alternatively the FLARM
rf section might be the ADSB section for both transmitter and receiver and
FLARM software could be used in your receiver warning device.
ADSB isn't going to be cheap at all. They are insisting on a TSO'd GPS card
and the whole thing will have to be TSO'd. Read expensive.
A fancy GPS receiver is necessary if you want absolute positions for ATC
purposes. For aircraft to aircraft collision avoidance only relative
positions are necessary. It doesn't matter that the absolute positions are
out by some amount. Well mounted antennas feeding the same model GPS
receivers running the same software and with the same setups are all that
is required.
ADSB also transmits the data twice a second. So how far can a bugsmasher or
glider go in 0.5 seconds?
ADSB will need the transmitter power to get back to the ADSB receiver on
the ground. FLARM or any aircraft to aircraft anti collision device only
needs to reach as far as you want warning time for - around 5-10nm will do
fine. This also means the target discrimination processing is a lot
easier.(In Australia, for light aircraft discriminating 1 out of 1 targets
should be easy - for the 1% of the time there is anyone near).
We're now talking a much higher duty cycle on the ADSB transmitter than on
a transponder at frequencies that are of concern for health effects. No
problem in a metal aircraft.
We live in interesting times. The fine detail of ADSB implementation will
indeed be fascinating.(code for GA and sport aviation gets screwed - again)
Mike
Borgelt Instruments - manufacturers of quality soaring instruments
phone Int'l + 61 746 355784
fax Int'l + 61 746 358796
cellphone Int'l + 61 428 355784
Int'l + 61 429 355784
email: [EMAIL PROTECTED]
website: www.borgeltinstruments.com
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