On Jul 12, 10:44*pm, WaltWX wrote:
On Jun 29, 12:17*am, ursus wrote:



On Jun 22, 6:42*am, Mike Schumann
wrote:

There is no inherent reason that ADS-B UAT transceivers using consumer
grade GPS and RF components can't be built for the same general price
point as FLARM units. *The only difference in the hardware is frequency
and transmit power.

The FLARM RF transceiver costs about $5 in parts. The ADS-B UAT
transceiver is how much ???
Most glider pilots are in complete denial about the commercial
realities of the gliding business:
Selling and supporting an *empty* box, with no production costs, to
glider pilots could not be done below USD 600 per unit.
It is not pretty, but that's the reality if your business intends to
still be around in a few years, while supporting and innovating for
the customers...

The MITRE unit
transmits "unknown" for integrity, as that information is not available
from a consumer grade GPS chipset.

The 'consumer grade' GPS chipset in FLARM provides all the information
you ever need:
DOP, accuracy estimates, pseudorange errors, satellite health and
whatever comes in through WAAS / EGNOS...
Some of that information is also transmitted in the FLARM signal and
used for alarm evaluation.
Just because a device is FAA certified does not mean it is better, it
just means it is outdated ;-)

Another note: *FLARM and ADS-B units are not a cure alls for collision
avoidance in competition flying. *The accuracy of the GPS fixes and the
update rates (even for units meeting the FAA's latest approved specs)
are not high enough to provide collision warnings for gliders that are
sharing a thermal in a gagle. *

The update rate and relative (!) precision of the GPS used in FLARM is
by far sufficient to do collision avoidance in glider competitions.
Other factors are more limiting.
However, if you stick various FAA approved GPS's into gliders your
relative position and velocity information will not be nearly as
good...

My dear US friends; we do agree that 'classic' FLARM is not the best
solution for the US. This is why we never launched it there.
Stay tuned for PowerFLARM; it will deliver all you need, soon.www.powerflarm.com

Urs - FLARM

Urs,

QUESTION: Will PowerFLARM only be monitoring ADB-B data from 1090ES
equipped aircraft? That's my understanding after listening to Daryl
Ramm's reply. Will I be able to monitor the lat/lon and altitude of
transponder equipped aircraft from the ADB-B ground stations
rebroadcasting that information (ADS-R or ... Relay feature of the ADB-
B program). If the ADB-B ground stations relay data from both UAT
equipped aircraft and transponder aircraft, then... will I be able to
get collision advisories from the same algorithm used with FLARM to
FLARM equipped gliders?

FYI... I have ordered one of the early delivery PowerFLARMs based on
the assumption that I can hear all the ADS-B and transponder equipped
aircraft.. either directly air-to-air with the 1090ES aircraft over
through the ADS-B ground stations. Is this a correct assumption? It's
really confusing ... all this ADS-B program stuff with dual
frequencies in the U.S.

Urs, my motivation for purchasing PowerFLARM was a near mid-air I had
at the Parowan 2010 Sports Nationals. If you go to the DAY6 IGC files
and look for these logs: 06LC4541.IGC (my log - Walter Rogers : WX a
Discus 2A) and 06LC4131.IGC (Richard Pfiffner: SD a Ventus) you will
see another near mid air coming out of the first turn. *Our paths
intersected with about 15 feet vertical separation. Fortunately, I saw
the converging glider at the last moment and made a severe pitch down
to miss him. Richard never saw me... Ironically (or maybe... using
good sense) I decided to purchase my PowerFLARM from Richard.

Urs, we met briefly for dinner with Dave Nadler and Lee Kuhkle at the
SSA convention in Littlerock.

Looking forward to PowerFLARM and any future software upgrades that
will help with ADS-B...

Walt Rogers, WX

Walt

I'm nor sure you meant to broadcast this but I'll try to answer
(reconfirm what I think you already know?) on the more generic ADS-B
and PCAS part of your question. [And standard apology for the length
of my posts...]

PowerFLARM to the extent it has PCAS capabilities can see other
transponders being interrogated by ground (SSR Radar and in some
places multilateration systems) and airborne interrogators (TCAS, TCAD
etc). This would give you no direction information for that traffic.

PowerFLARM has a 1090ES receiver so can "see" with high accuracy
aircraft with 1090ES ADS-B data-out. That will over time include all
the airliners, fast jets, any traffic flying over FL 180, and I expect
it to include many GA aircraft who I expect will go with 1090ES data
out and not UAT to meet the ADS-B carriage requirement. Since there is
nothing else involved the line of sight range on this may be quite
significant, well beyond PCAS and FLARM (and ADS-R and TIS-B).

PowerFLARM has a 1090ES receiver so *if* you also have an ADS-B
transmitter properly configured to transmit your GPS position and ADS-
B receiver capability codes (i.e. set to show your aircraft receives
1090ES) then the ADS-B ground infrastructure will rebroadcast UAT data-
out equipped traffic over 1090ES that it is aware of within a cylinder
around your aircraft. The size of this cylinder is significantly less
than the ultimate range of UAT or 1090ES direct transmissions so this
one damper on anybody thinking they can track their glider buddies
over very long ranges in the air if there is mixed UAT and 1090ES
involved. The ADS-B data-out/transmitter you need for this would
typically be something like the Trig TT21 Mode S/1090ES transponder
but could be a UAT transmitter (or transceiver).

For the PowerFLARM or any other ADS-B receiver to see SSR radar
targets via TIS-B again the ADS-B ground infrastructure needs to know
where you are so it can broadcast possible threats in a cylinder
around you. But it will only broadcast traffic that the SSR radar
system (or multilateration in some areas - like the newly announced
Alaska deployment) can "see". There seems to be a common misconception
that ADS-B TIS-B will show transponder equipped threats over vast
areas, but it cannot show any TIS-B threats near you if you are flying
outside of traditional SSR radar (or multilateration) coverage. Again
the ADS-B data-out needed to tell the ground infrastructure where you
are would today normally be a Mode S /1090ES transponder.

One point of confusion with ADS-B traffic is some people talk about
TIS-B as if it means any traffic you see on ADS-B, it specifically
means just the SSR radar (or multilateration) traffic information
retransmitted on ADS-B. Traffic information via UAT or 1090ES data-out
direct and ADS-R is not "TIS-B" traffic.

I am concerned that in many cases pilots will not be able to tell ADS-
B receivers are not working correctly when they do not also have an
ADS-B transmitter. Gosh they will see ADS-B direct and ADS-R and TIS-B
traffic but the later two will only be traffic around other aircraft,
not necessarily yours. Unfortunately there are ADS-B receiver vendors,
especially USA based UAT receiver manufactures, who are not making
this requirement extremely clear. Some of those vendors seem to have
only woken up to this recently and are repositioning their UAT
receiver only "traffic systems" as "weather receivers" -- wanna guess
why? :-( I hope PowerFLARM in the USA makes very clear the need for an
ADS-B transmitter to enable full ADS-B traffic data-in. In Europe
today this is irrelevant so not surprising it is not called out in
European marketing material. Of course the PowerFLARM should work as a
FLARM-FLARM detector, PCAS detector and 1090ES direct traffic receiver
without any separate ADS-B transmitter.

There are large areas of the USA airspace we use where there is no SSR
coverage to enable ADS-R but even there you may get a PCAS alert
because of airborne interrogators. As more aircraft equip with ADS-B
(and I expect many will be 1090ES) you will see 1090ES targets replace
those directionless PCAS threats and unlike with PCAS you don't need
an external interrogator to see those 1090ES threats (because they
"squitter" their position ever second). It's trivial to deduplicate a
Mode S and 1090ES threat so something like PowerFLARM should be able
to suppress the PCAS warning for those 1090ES equipped threats. Even
as we pass the ADS-B carriage mandate there will be some aircraft that
stay equipped with say Mode C transponders and don't equip with ADS-B
anything, in which case there are times when you won't receive any
warnings from those aircraft. That's a scenario worth remembering with
some gliders equipped with Mode C transponders where there is no ADS-B
carriage mandate. If the transponders are not being interrogated a
PowerFLARM can't do anything for you -- you need those other gliders
to have a PowerFLARM (for FLARM-FLARM) or ADS-B data-out capability.

Maybe with the collision at Parowan, and at the World contest, and
other near misses (like yours) at both contests it may well be time to
start mandating FLARM/PowerFLARM in Contests to deal with this glider-
on-glider threat. In my mind that is a problem Flarm addresses just
about as good as it ever can be done. ADS-B futureware is really about
interacting with ATC and other traffic, and hopefully useful for long
distance tracking/SAR etc.

And we are focused on glider-on-glider issues here. Remember if the
issue is airliners and fast-jets the only thing that works properly
against those aircraft TCAS systems is a transponder (which could be a
Mode S/1090ES unit). The TCAS in those fast jets and airliners and
military transports etc. will not issue an resolution advisory (RA)
against a UAT equipped aircraft that does not also have a transponder.
The place where ATC bureaucracy and ADS-B technology meet seems to
have missed us, it really assumes your ADS-B transmitter is a
transponder or you have a separate transponder if UAT equipped.


Darryl