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.
If ADSB is not used by EVERYTHING then there are still enormous
opportunities for failure. It will provide coverage for mainstream GA
operating in controlled areas but it will fail when operating in areas
where there are aircraft operating without the equipment in
non-controlled areas. Some of the system configurations suggested only
solve half of the problem i.e. reporting position but not being able to
view others or alternatively detecting others but not reporting position.
Having said this it remains that ADSB will be:
- Analysed & specified to the finest detail
- Tested & tested &...
- Manufactured by companies competent in the Avionics field
- Certified as compliant with the above
The FLARM style of system has great potential for a 2nd layer of
operation but it must be recognised up front that it will meet very few
of the above.
It may however provide an excellent resource for light aircraft with
limited battery capacity. The biggest failing in the FLARM system at
present is it's use of the ISM band. Admittedly if the units functioned
simultaneously on two of the SS bands it may boost the probability of
reliable operation but the risk remains large.
FLARM on a dedicated chunk of spectrum would be an entirely different
matter. Enter FLARM_ver2 for want of a better description.
A system using a dedicated broadband RF slot, DGPS or other secondary
system capable of indicating satellite status, optional 2nd GPS, BSP (
brutally simple protocol ) is not outside the bounds of reality.
Particularly when an Open Source development model is applied to the
project as lots of sets of eyes, many very competant engineers, get to
do code walk throughs. The goal would be a simple, robust, cost
effective system, with a far better suitability to purpose.
Such a project is well within the capabilities of the gliding movement
as an international body, particularly when carried out in conjunction
with some of the major Universities already working in the area, FLARM
being the example. Toss in some Government grants to improve air safety
while allowing the Government to get out of supplying subsidies for the
far more expensive ADSB. Where do we sign...
The system could operate at two levels-
- Level 1: High bit rate, short range, low power, low current,
anti-collision based on single chip freq hopping spread spectrum
devices. Capable of maintaining a rapid update adhoc network with >100
aircraft in close proximity. May have to be country specific due to
available bandwidth but the actual transceiver/antenna/band could still
be same/similar.
- Level 2: Low bit rate, low frequency system, higher power, higher
current. Lower update rate intended to communicate with ATC ground
stations ( say on the existing NAV/COM band somewhere ) to exchange
information for interface to the ADSB system. Exchange is done on a
regular basis from the sailplane, synched by the ground station, with
the ground station only broadcasting ADSB traffic as required by the
light aircraft clients.
The glider pilot gets a reasonably priced system ( the implication being
that if it is reasonably priced then everything that leaves the ground
will have one ). ATC gets to know where we are & we get to know where
the other guys are. Light aviation avionics manufacturers such as Robert
(if he chooses) manufacture systems & contribute a per unit fee to
assist with the running of the standards organisation to further develop
the units.
Because the system is designed for light aviation and it's accompanying
quirks then it would be possible to block coverage of other sailplanes,
in a competition for example, if they are outside a preset radius or
collision model.
FLARM or it's descendants would be difficult to certify as a result of
their origin but the question to be put is this: Is a certified but only
partially implemented ADSB any better, or in fact even far worse, than a
non-certified but FULLY implemented FLARM_ver2 variant.
Cheers
Don
Shred away...
RF Developments Pty Ltd wrote:
Robert,
Australia is going ADS-B which will give the same protection, all you need
is a 1090 receiver and PDA, or possibly by then you might be able to use the
existing moving map glide computers like the B2000 etc, they will receive
the LAT/LON and height, plus aircraft ID so it would be easy to display
these. The glider will still require the ADS-B squitter box, which is
currently being developed, I have just got back from Germany with such a
unit which we will make here in Oz, as well as other products from Filser (
radios and transponders ) under a new company here - Filser
International/Avionics Australasia.
There are a number of the other systems around ( like that in the U.K ),
unfortunately all using non standard design and non certified ( we have VH
registered aircraft ), and rely on everyone buying that brand. ADS-B will be
a universal system allowing all to use the same technology, as well as
providing ATC coverage which should ultimately free up airspace.
Cheers
Nigel
Nigel Andrews
Managing Director
RF Developments Pty Ltd
"A Queensland Company devoted to Research and Development in aviation
electronics"
Email [EMAIL PROTECTED]
Web www.rf-developments.com
Ph: (61) 7 54635670 Fax: (61) 7 54635695
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-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Robert Hart
Sent: Tuesday, May 24, 2005 9:33 AM
To: Soaring in Australia
Subject: [Aus-soaring] FLARM
Hi
I was just looking over the BGA pages and came across a mention of FLARM
(see http://www.flarm.com/index_en.html)
Flarm warns against aircrafts and obstacles.
The small-size, low-cost, low-power device FLARM broadcasts its own
position and speed vector (as obtained with an integrated GPS) over
a license-free ISM band radio transmission. At the same time it
listens to other devices based on the same standard. Intelligent
motion prediction algorithms predict short-term conflicts and warn
the pilot accordingly by acoustical and visual means. FLARM
incorporates a high-precision WAAS 16-channel GPS receiver and an
integrated low-power radio transceiver. Static obstacles are
included in FLARM's database. The collision warning algorithms were
calibrated and optimized using thousands of flight logs. No warning
is given if an aircraft does not pose an immediate threat.
Is this compatible/comparable with the system here in Australia (whose
name currently escapes me)?
I also wonder when exactly a glider in the same thermal as you is deemed
to 'pose an immediate threat'?
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