Low Cost ADS-B Transceivers

On Mar 16, 4:51*pm, Mike Schumann
wrote:
The FAA in coordination with the SSA is doing a major test of low cost
ADS-B transceivers this summer in the Washington DC area. *As part of
this effort, MIT is doing a survey of pilots' perception of the value of
ADS-B technology in their environments.

Please take 10 minutes and provide your input:

http://agena.mit.edu/ADSBsurvey

We are finally making some serious progress within the FAA to get them
to take a hard look at commercializing the low cost ADS-B technology
that has been developed by MITRE. *If this effort is successful, we
should see fully functional ADS-B equipment available in the US at FLARM
price points (~$1K). *Please make your voices heard in support of this
effort.

--
Mike Schumann

Some very cool ideas for use of ADS-B in soaring.

I would like to see support for common hardware interfaces and public
APIs so that third-party developers could easily integrate ADS-B
output into existing software and/or make it easy to integrate the
display software into a few common platforms (Windows Mobile PDA/PNA,
iPhone, etc). No one wants to carry around another display unit and
switching between a flight computer app and a situational awareness
app is awkward given how frequently a pilot would need to refer to
both.

Hopefully the commercial unit would be more compact and/or allow the
antennas to be mounted remote from the unit. The prototype is pretty
bulky and appears to have the ADS-B antenna built in.

I'd buy one, especially if I didn't have to buy a transponder too.

Of course I may be retired from the sport by the time all that
infrastructure gets deployed.

9B

On 3/17/2010 4:35 AM, Andy wrote:

The MITRE prototype is actually a very compact unit, approximately the
size of a cigarette pack. It has an interface so that it can be
connected to a wide variety of external display devices. While the
prototype is a portable device, many of us are advocating that there
should be a permanent installation option, so that it does not use up
precious panel space and so that you can have an external antenna option
to maximize performance.

MITRE demonstrated the unit at the AOPA Expo last year using an iPhone
as the graphical display device. The intent is to also interface it to
a variety of glide computers and aviation GPS moving map display
devices. This is not too difficult, technically, by emulating the same
interfaces that currently exist to support FLARM and TIS.

Please take the survey and add your comments. We need to demonstrate to
the FAA that there is widespread enthusiasm for this type of device, so
the certification process will be put on the fast track.

--
Mike Schumann

On Mar 16, 4:51 pm, Mike
wrote:
The FAA in coordination with the SSA is doing a major test of low cost
ADS-B transceivers this summer in the Washington DC area. As part of
this effort, MIT is doing a survey of pilots' perception of the value of
ADS-B technology in their environments.

Please take 10 minutes and provide your input:

http://agena.mit.edu/ADSBsurvey

We are finally making some serious progress within the FAA to get them
to take a hard look at commercializing the low cost ADS-B technology
that has been developed by MITRE. If this effort is successful, we
should see fully functional ADS-B equipment available in the US at FLARM
price points (~$1K). Please make your voices heard in support of this
effort.

--
Mike Schumann

Some very cool ideas for use of ADS-B in soaring.

I would like to see support for common hardware interfaces and public
APIs so that third-party developers could easily integrate ADS-B
output into existing software and/or make it easy to integrate the
display software into a few common platforms (Windows Mobile PDA/PNA,
iPhone, etc). No one wants to carry around another display unit and
switching between a flight computer app and a situational awareness
app is awkward given how frequently a pilot would need to refer to
both.

Hopefully the commercial unit would be more compact and/or allow the
antennas to be mounted remote from the unit. The prototype is pretty
bulky and appears to have the ADS-B antenna built in.

I'd buy one, especially if I didn't have to buy a transponder too.

Of course I may be retired from the sport by the time all that
infrastructure gets deployed.

9B

On Mar 17, 6:19*am, Mike Schumann
wrote:
On 3/17/2010 4:35 AM, Andy wrote:

The MITRE prototype is actually a very compact unit, approximately the
size of a cigarette pack. *It has an interface so that it can be
connected to a wide variety of external display devices. *While the
prototype is a portable device, many of us are advocating that there
should be a permanent installation option, so that it does not use up
precious panel space and so that you can have an external antenna option
to maximize performance.

MITRE demonstrated the unit at the AOPA Expo last year using an iPhone
as the graphical display device. *The intent is to also interface it to
a variety of glide computers and aviation GPS moving map display
devices. *This is not too difficult, technically, by emulating the same
interfaces that currently exist to support FLARM and TIS.

Please take the survey and add your comments. *We need to demonstrate to
the FAA that there is widespread enthusiasm for this type of device, so
the certification process will be put on the fast track.

--
Mike Schumann

On Mar 16, 4:51 pm, Mike
wrote:
The FAA in coordination with the SSA is doing a major test of low cost
ADS-B transceivers this summer in the Washington DC area. *As part of
this effort, MIT is doing a survey of pilots' perception of the value of
ADS-B technology in their environments.

Please take 10 minutes and provide your input:

http://agena.mit.edu/ADSBsurvey

We are finally making some serious progress within the FAA to get them
to take a hard look at commercializing the low cost ADS-B technology
that has been developed by MITRE. *If this effort is successful, we
should see fully functional ADS-B equipment available in the US at FLARM
price points (~$1K). *Please make your voices heard in support of this
effort.

--
Mike Schumann

Some very cool ideas for use of ADS-B in soaring.

I would like to see support for common hardware interfaces and public
APIs so that third-party developers could easily integrate ADS-B
output into existing software and/or make it easy to integrate the
display software into a few common platforms (Windows Mobile PDA/PNA,
iPhone, etc). *No one wants to carry around another display unit and
switching between a flight computer app and a situational awareness
app is awkward given how frequently a pilot would need to refer to
both.

Hopefully the commercial unit would be more compact and/or allow the
antennas to be mounted remote from the unit. The prototype is pretty
bulky and appears to have the ADS-B antenna built in.

I'd buy one, especially if I didn't have to buy a transponder too.

Of course I may be retired from the sport by the time all that
infrastructure gets deployed.

9B

Have any of you considered this device?

http://www.powerflarm.aero/

It seems to have a lot more capability than just ADS-B

Bob

I did some study on the Power Flarm and set in on the presentation at
the Little Rock Convention. It is interesting, but doesn't provide the
capabilities of ADS-B UAT. The plus is that it contains an IGC flight
recorder. It provides very good traffic location for Flarm and ADS-B
1090ES equipped aircraft. It works similar to a PCAS for mode C and S
transponder targets and receives their altitude reports and senses
distance. The traffic location is a good guess and alerts to get your
head up. I'm not sure what it would report if the transponders
altitude reporting was missing as you would have froma mode A
trasnponder. You do not have any of the ADS-B FIS (Flight Information
Services) such as Nexrad weather radar, TFR's, METARs, SIGMETs, etc.
Most importantly, only other aircraft equipped with Flarm would see
you! You would not be visible to ATC or aircraft equipped with TCAS,
PCS, etc.

In addition to all the FIS information that you can receive over ADS-B
UAT, you are visible to ATC. You are also visible directly visible to
other ADS-B UAT equipped aircraft. ADSB ground stations relay your UAT
position information to aircraft equipped with ADSB 1090ES. Those same
ground station also transmit all traffic ATC is following (primary
radar, Mode A/C/S transponder, ADSB 1090ES, ADSB UAT). Now you have a
much more complete picture of traffic, expect for Flarm only equipped
aircraft, and ATC and many other aircraft can see you!

I have nothing against Flarm and think it was a great technology.
However, it hasn't been adopted in the US. Why not go with with the
newer technology and receive the additional benefits along with the
safety of visibility to ATC and others? The pricing ranges for power
Flarm that ware discussed at the convention, would be similar to the
total cost of a Flight Recorder and the anticipated cost of the ADS-B
UAT.

Charlie


Have any of you considered this device?

http://www.powerflarm.aero/

It seems to have a lot more capability than just ADS-B

Bob- Hide quoted text -

- Show quoted text -

On Mar 17, 8:12*am, cfinn wrote:
I did some study on the Power Flarm and set in on the presentation at
the Little Rock Convention. It is interesting, but doesn't provide the
capabilities of ADS-B UAT. The plus is that it contains an IGC flight
recorder. It provides very good traffic location for Flarm and ADS-B
1090ES equipped aircraft. It works similar to a PCAS for mode C and S
transponder targets and receives their altitude reports and senses
distance. The traffic location is a good guess and alerts to get your
head up. I'm not sure what it would report if the transponders
altitude reporting was missing as you would have froma mode A
trasnponder. You do not have any of the ADS-B FIS (Flight Information
Services) such as Nexrad weather radar, TFR's, METARs, SIGMETs, etc.
Most importantly, only other aircraft equipped with Flarm would see
you! You would not be visible to ATC or aircraft equipped with TCAS,
PCS, etc.

A UAT does not really make you "visible" to TCAS either.


In addition to all the FIS information that you can receive over ADS-B
UAT, you are visible to ATC.

That depends if the UAT device is a receiver or tramismitter (or
both). Yes I know the "T" in UAT stands for transceiver, so in a sane
world you would think that.... sigh.

Just like with 1090ES there are devices in UAT land that are only
receivers.


You are also visible directly visible to
other ADS-B UAT equipped aircraft. ADSB ground stations relay your UAT
position information to aircraft equipped with ADSB 1090ES. Those same
ground station also transmit all traffic ATC is following (primary
radar, Mode A/C/S transponder, ADSB 1090ES, ADSB UAT). Now you have a
much more complete picture of traffic, expect for Flarm only equipped
aircraft, and ATC and many other aircraft can see you!

But a 1090ES (e.g. PowerFLARM) or UAT receiver gives you that same
"complete picture".

TIS-B is the part that resends what ATC is seeing and it relies on
position ATC position data that requires aircraft to have a Mode-C or
Mode-S transponders. A primary radar target is never retransmitted
over TIS-B. Obviously you need to be within ATC radar coverage for
this to work.

ADS-R is the retramsission by a ground station of UAT to 1090ES and
1090ES to UAT. Since it's bidirectinal a Power-Flarm sees UAT (as well
as it's native 1090ES) traffic as long as it is within range of a ADS-
B ground station.

PowerFlarm (with 1090ES) is clearly intended to be installed along
with a transponder, and I hope people get that. Using it for Flarm
only really does not make much sense in the USA. If you have something
like a Trig TT-21 then that does basic mode-S and is also 1090ES ADS-B
capable so in future you hook up a GPS source to that and be good to
go. Many manufactures (inc. Garmin) are taking this two box approach
to 1090ES, where you add a separate receiver to the aircraft to
complement the Mode-S/1090ES transponder. You will see new products
coming out that do that. Given Europe has gone Mode S, the European
soaring manufacteurs are goign to be focusing on 1090ES based
products.

Be careful in general what you think you are getting with any ADS-B
box. Just being "ADS-B" does not tell you much as to what it does at a
user level. Is it a receiver only, a transmitter only, or both. What
communication protocol does it support to a PDA display? What do I
need to do to get it to display say FIS-B data? If it is a receiver
does it display traffic information? Does it issue traffic alerts? Can
it connect to my PDA to issue pop-up traffic warnings/alarms through
the PDA? Can it display a traffic map on the PDA? BTW most people will
want the box to use the Flarm serial protocol to the PDA (yes Flarm
protocol for ADS-B/TIS-B/ADS-R traffic) since soaring software on PDAs
speak that protocol and we don't have a spare second serial port to
run the Garmin TIS protocol.


The main benefit of a 1090ES transmitter ove a UAT is that since it is
transponder based airborne TCAS systems see it. Even if the aircraft
has ADS-B receivers the TCAS systems do not issue resolution
advisories based on ADS-B. That requires a transponder in the glider.
In high traffic areas where we fly amongst fast jets/airliners I would
rather see people thinking about using transponder/1090ES and add-on
ADS-B receivers (either 1090ES or UAT). The powerFlarm looks like an
excellent add-on for a transponder in that scenario.

I worry about how well we will have ADS-B ground station coverage
along busy low-level routs like major ridge soaring locations, the
white mountains etc. Without that, gliders with UATs and 1090ES will
not see each other. The low-level ground station coverage test maps
I've see are very impressive but still in mountainous terrain we are
goign to have holes. There probably needs to be attention paid to what
the actual coverage is in areas. Look at adopting dual 1090ES/UAT
receivers (some vendors appear to be working on those) or try to
standardize on one standard in an area (driven by clubs or FBOS?).
Since the PowerFLarm is a packaged unit that is available and works
today I think we will start to see some clubs standardizing around
that already for all the PCAS/ADS-B goodness and the proven Flarm
capability in situations like glider-on glider traffic on mountain
ridges. (but still I am really worried that people don't adopt Flarm
alone in the USA where they really need to be moving to ADS-B).


Darryl



I have nothing against Flarm and think it was a great technology.
However, it hasn't been adopted in the US. Why not go with with the
newer technology and receive the additional benefits along with the
safety of visibility to ATC and others? The pricing ranges for power
Flarm that ware discussed at the convention, would be similar to the
total cost of a Flight Recorder and the anticipated cost of the ADS-B
UAT.

Charlie



Have any of you considered this device?

http://www.powerflarm.aero/

It seems to have a lot more capability than just ADS-B

Bob- Hide quoted text -

- Show quoted text -

People need to be very wary about buying ADS-B UAT receive only devices.
The ITT ADS-B ground stations only transmit TIS-B information in
response to an ADS-B interrogation. If you only have an ADS-B receiver,
and there is no other ADS-B equipped aircraft in your vicinity, you will
not see any ground station relayed traffic.

In the long term, once we get widespread deployment of ADS-B systems,
there will be a serious push to get TCAS systems to directly respond to
ADS-B equipped aircraft, with the eventual goal of phasing out Mode C
transponders completely. This, however, is many years off.

As far as mountain flying goes, ADS-B ground station coverage should be
significantly better than radar coverage. The original FAA plan was
that all general aviation aircraft in the US would use ADS-B UAT, and
1090 Extended Squitter would be reserved for commercial aircraft. In
this kind of environment, gliders would still be protected from each
other while ridge soaring out of range of a ground station, as they
could see each other.

The recent availability of ADS-B compatible Mode S transponders for the
soaring market complicates maters significantly, as we may now may see a
mixed environment of ADS-B UAT and 1090ES based systems at low
altitudes, which would require ground station coverage to work properly.
This complexity could have been avoided if the FAA had focused on low
cost ADS-B UAT equipment from the get go, so that it wouldn't have been
unduly burdensome on foreign air carriers to standardize on ADS-B UAT as
the single technology platform in the US.

Mike Schumann

On 3/17/2010 12:22 PM, Darryl Ramm wrote:
On Mar 17, 8:12 am, wrote:
I did some study on the Power Flarm and set in on the presentation at
the Little Rock Convention. It is interesting, but doesn't provide the
capabilities of ADS-B UAT. The plus is that it contains an IGC flight
recorder. It provides very good traffic location for Flarm and ADS-B
1090ES equipped aircraft. It works similar to a PCAS for mode C and S
transponder targets and receives their altitude reports and senses
distance. The traffic location is a good guess and alerts to get your
head up. I'm not sure what it would report if the transponders
altitude reporting was missing as you would have froma mode A
trasnponder. You do not have any of the ADS-B FIS (Flight Information
Services) such as Nexrad weather radar, TFR's, METARs, SIGMETs, etc.
Most importantly, only other aircraft equipped with Flarm would see
you! You would not be visible to ATC or aircraft equipped with TCAS,
PCS, etc.

A UAT does not really make you "visible" to TCAS either.


In addition to all the FIS information that you can receive over ADS-B
UAT, you are visible to ATC.

That depends if the UAT device is a receiver or tramismitter (or
both). Yes I know the "T" in UAT stands for transceiver, so in a sane
world you would think that.... sigh.

Just like with 1090ES there are devices in UAT land that are only
receivers.


You are also visible directly visible to
other ADS-B UAT equipped aircraft. ADSB ground stations relay your UAT
position information to aircraft equipped with ADSB 1090ES. Those same
ground station also transmit all traffic ATC is following (primary
radar, Mode A/C/S transponder, ADSB 1090ES, ADSB UAT). Now you have a
much more complete picture of traffic, expect for Flarm only equipped
aircraft, and ATC and many other aircraft can see you!

But a 1090ES (e.g. PowerFLARM) or UAT receiver gives you that same
"complete picture".

TIS-B is the part that resends what ATC is seeing and it relies on
position ATC position data that requires aircraft to have a Mode-C or
Mode-S transponders. A primary radar target is never retransmitted
over TIS-B. Obviously you need to be within ATC radar coverage for
this to work.

ADS-R is the retramsission by a ground station of UAT to 1090ES and
1090ES to UAT. Since it's bidirectinal a Power-Flarm sees UAT (as well
as it's native 1090ES) traffic as long as it is within range of a ADS-
B ground station.

PowerFlarm (with 1090ES) is clearly intended to be installed along
with a transponder, and I hope people get that. Using it for Flarm
only really does not make much sense in the USA. If you have something
like a Trig TT-21 then that does basic mode-S and is also 1090ES ADS-B
capable so in future you hook up a GPS source to that and be good to
go. Many manufactures (inc. Garmin) are taking this two box approach
to 1090ES, where you add a separate receiver to the aircraft to
complement the Mode-S/1090ES transponder. You will see new products
coming out that do that. Given Europe has gone Mode S, the European
soaring manufacteurs are goign to be focusing on 1090ES based
products.

Be careful in general what you think you are getting with any ADS-B
box. Just being "ADS-B" does not tell you much as to what it does at a
user level. Is it a receiver only, a transmitter only, or both. What
communication protocol does it support to a PDA display? What do I
need to do to get it to display say FIS-B data? If it is a receiver
does it display traffic information? Does it issue traffic alerts? Can
it connect to my PDA to issue pop-up traffic warnings/alarms through
the PDA? Can it display a traffic map on the PDA? BTW most people will
want the box to use the Flarm serial protocol to the PDA (yes Flarm
protocol for ADS-B/TIS-B/ADS-R traffic) since soaring software on PDAs
speak that protocol and we don't have a spare second serial port to
run the Garmin TIS protocol.


The main benefit of a 1090ES transmitter ove a UAT is that since it is
transponder based airborne TCAS systems see it. Even if the aircraft
has ADS-B receivers the TCAS systems do not issue resolution
advisories based on ADS-B. That requires a transponder in the glider.
In high traffic areas where we fly amongst fast jets/airliners I would
rather see people thinking about using transponder/1090ES and add-on
ADS-B receivers (either 1090ES or UAT). The powerFlarm looks like an
excellent add-on for a transponder in that scenario.

I worry about how well we will have ADS-B ground station coverage
along busy low-level routs like major ridge soaring locations, the
white mountains etc. Without that, gliders with UATs and 1090ES will
not see each other. The low-level ground station coverage test maps
I've see are very impressive but still in mountainous terrain we are
goign to have holes. There probably needs to be attention paid to what
the actual coverage is in areas. Look at adopting dual 1090ES/UAT
receivers (some vendors appear to be working on those) or try to
standardize on one standard in an area (driven by clubs or FBOS?).
Since the PowerFLarm is a packaged unit that is available and works
today I think we will start to see some clubs standardizing around
that already for all the PCAS/ADS-B goodness and the proven Flarm
capability in situations like glider-on glider traffic on mountain
ridges. (but still I am really worried that people don't adopt Flarm
alone in the USA where they really need to be moving to ADS-B).


Darryl



I have nothing against Flarm and think it was a great technology.
However, it hasn't been adopted in the US. Why not go with with the
newer technology and receive the additional benefits along with the
safety of visibility to ATC and others? The pricing ranges for power
Flarm that ware discussed at the convention, would be similar to the
total cost of a Flight Recorder and the anticipated cost of the ADS-B
UAT.

Charlie



Have any of you considered this device?

http://www.powerflarm.aero/

It seems to have a lot more capability than just ADS-B

Bob- Hide quoted text -

- Show quoted text -





--
Mike Schumann

On Mar 17, 9:22*am, Darryl Ramm wrote:

I worry about how well we will have ADS-B ground station coverage
along busy low-level routs like major ridge soaring locations, the
white mountains etc. Without that, gliders with UATs and 1090ES will
not see each other.

Darryl,

Was I mistaken in taking from the survey that ADS-B supports aircraft-
to-aircraft position reporting without a ground station repeater? I
figured that would allow two gliders in any remote location to see
each other if they both had ADS-B transceivers (like the Mitre unit).
With ground stations you then should get position reporting between
transponder and ADS-B.

I figured any collision avoidance advice would be a function of on-
board software capability, not constrained by the means of position
reporting - as long as you know your position and track and a target's
position and track, shouldn't you be able to figure out the collision
avoidance part?

It seems to me that you should be able to design ADS-B such that you
no longer need transponders. What did I miss?

9B

On 3/18/2010 2:32 AM, Andy wrote:
On Mar 17, 9:22 am, Darryl wrote:

I worry about how well we will have ADS-B ground station coverage
along busy low-level routs like major ridge soaring locations, the
white mountains etc. Without that, gliders with UATs and 1090ES will
not see each other.

Darryl,

Was I mistaken in taking from the survey that ADS-B supports aircraft-
to-aircraft position reporting without a ground station repeater? I
figured that would allow two gliders in any remote location to see
each other if they both had ADS-B transceivers (like the Mitre unit).
With ground stations you then should get position reporting between
transponder and ADS-B.

I figured any collision avoidance advice would be a function of on-
board software capability, not constrained by the means of position
reporting - as long as you know your position and track and a target's
position and track, shouldn't you be able to figure out the collision
avoidance part?

It seems to me that you should be able to design ADS-B such that you
no longer need transponders. What did I miss?

9B
If both gliders have ADS-B UAT transceivers they will be able to see
each other without a ground station, just like FLARM. The same is the
case if both gliders use 1090ES transceivers. The problem is if one
glider has ADS-B UAT and the other uses 1090ES, then they can't see each
other unless they are within range of a ground station.

In addition, the ground station will transmit the position of any Mode
C/S transponder equipped aircraft to an ADS-B equipped aircraft. As a
result, if you are within range of a ground station, an ADS-B equipped
aircraft will see all other ADS-B or conventional transponder equipped
aircraft in its vicinity.

If you have a MITRE transceiver connected to a PDA or a device like an
iPhone, there is nothing stopping someone from implementing a poor man's
TCAS in addition to showing other aircraft on a moving map display. The
new iPhone is a particularly intriguing device, as it has a built in
sensor that permits you to display a compass bearing. As a result, you
could implement a voice warning system that could actually tell you the
bearing, distance, and relative altitude of a collision threat based on
your current heading. This could be very useful in a glider that is in
a thermal, where the heading is constantly changing.

--
Mike Schumann

Andy

On Mar 17, 11:32 pm, Andy wrote:
On Mar 17, 9:22 am, Darryl Ramm wrote:



I worry about how well we will have ADS-B ground station coverage
along busy low-level routs like major ridge soaring locations, the
white mountains etc. Without that, gliders with UATs and 1090ES will
not see each other.

Darryl,

Was I mistaken in taking from the survey that ADS-B supports aircraft-
to-aircraft position reporting without a ground station repeater? I
figured that would allow two gliders in any remote location to see
each other if they both had ADS-B transceivers (like the Mitre unit).
With ground stations you then should get position reporting between
transponder and ADS-B.

That is TIS-B and that only happens if the transponder equipped
aircraft is within range of ATC radar. The ATC radar data is processed
by back-end systems and then relayed through an ADS-B ground station.
Just being within range of an ADS-B groudn station does *not* mean you
see nearby transponder equipped aircraft. The ADS-B ground statiosn
are going to provide coverage over vast areas where there is no ATC
radar coverage. I think some people might be confused about this,
thinking maybe the ADS-B ground stations have radar or multilateration
etc. can can locate transponder equipped aircraft. They cannot. That
data that is delivered as TIS-B (SSR radar/transponder derived data)
comes from existing ATC radar systems.

This is one reason it's nice to have say PCAS in the PowerFLARM so you
can get some warning of nearby transponder equipped aircraft even
outside radar coverage (in the case of PCAS outside of ATC radar
coverage this assumes some other interrogator like TCAS in overflying
aircraft).

BTW one of the interesting problems with the whole alphabet soup of
ADS-B/TIS-B/ADS-R/FLARM/PCAS/TCAD/TCAS etc. is threat deduplication.
There are many problems that can cause a threat to appear duplicated
if detected via different technologies or you can even see a ghost of
yourself. I expect this to be an interesting problem with many of
these systems, and we'll need to see how well they work in practice.


ATC radar coverage is not

I figured any collision avoidance advice would be a function of on-
board software capability, not constrained by the means of position
reporting - as long as you know your position and track and a target's
position and track, shouldn't you be able to figure out the collision
avoidance part?

It seems to me that you should be able to design ADS-B such that you
no longer need transponders. What did I miss?

9B


TCAS uses transponders, that's how it works. We can't change that just
becasue it seems antiquated (which it does). TCAS "sees" other
aircraft based on Mode C or Mode S interrogations. TCAS-II is deeply
integrated with Mode S and uses Mode S data links between different
TCAS-II equipped aircraft to coordinate resolution advisories.

If you even want to think about using ADS-B for collision avoidance
you need everybody carrying ADS-B data-out. That won't happen in the
USA for another 10 years. The only technology designed to be used in
cockpits that issues an RA that pilots are supposed to follow is TCAS.
Today in areas like around Reno/Minden (where Andy flys), TCAS is the
last fallback for avoiding a collision between a glider and a fast jet
or airliner. For other folks flying out in the boondocks, I don't
care, but around dense airline and jet traffic we need to make sure we
have compatibility with TCAS. Collision avoidance (vs. traffic
awareness) is complex, TCAS is a RTCA standard, there is no equivalent
standard developed for collision avoidance using ADS-B. Without that
manufactures cannot make something, regulatory agencies cannot require
it, etc. It just does not exist.

As ADS-B technologies roll out we also need a back-up in the national
airspace system, and ATC radar and transponders will be that backup so
I just don't see them going away in our lifetimes.

The FAA has been struggling to just get mandatory ADS-B data-out
carriage by ~2020. The motivations for getting that adopted in GA has
been muddled, which is a pitty I think this could have been marketed
much better to owner/pilots. But without wide option of ADS-B data-
out, let alone data-in doing TCAS style collision avoidance based on
ADS-B makes no sense. But I don't really blame the FAA, they've been
trying to work all this and Nextgen out, with a awful lack of overall
funding.

Long long terms (==decades) ADS-B based systems could offer more than
TCAS or could work better with it. Today TCAS-II version 7 can use
ADS-B to reduce the transponder pinging between aircraft but it never
issues an RA based on ADS-B position data. It would be great to see a
system that offers the capabilities of TCAS-III like horizontal RA
maneuvers, and maybe better range than TCAS in crowded airspace
environments. TCAS-III became so complex it never got to market.

And again just be careful exactly what you are getting in any
scenario. ADS-B data-out just sends your position, and you have to add
a GPS source (which today if you wanted to fully comply with future
carriage requirements (which don't apply to gliders) is expensive).
You can have a box that does ADS-B data-in but how is traffic
displayed? Just having an "ADS-B receiver" does not mean you will get
traffic warnings. The box might well happily watch the treat aircraft
as you both collide. That traffic display/warning happens at an
application layer above ADS-B. There are standards for symbology etc.
to display in aircraft for ADS-B data but much of that is not that
relevant to us. Some new traffic awareness system from vendors like
Garmin will mix active transponder interrogation (TCAS-I like) with
ADS-B 1090ES data-in derived traffic. But those systems never issues
RAs anyhow.

---

Like Mike says. UAT will see UAT directly, 1090ES will see 1090ES
directly. We are going to have both in the USA glider fleet and need
to start realizing that. The FAA thought that UAT would be popular in
the GA/low-end market etc. but they never really produced a convincing
driver for adoption of ADS-B in general or of UATs over 1090ES. Way
way back when this started transponders looked expensive and complex
but market dynamics produce things like the Garmin GTX 330 in GA and
the Trig TT21 well suited for gliders. If you are engineering a modern
Mode S transponder it is not much to add the capability to do 1090ES
data-out and add a small box to do 1090ES data-in. In the GA market
that makes sense since most aircraft are required to have a
transponder anyhow so you might as well do ADS-B over 1090ES.

Europe has mandated Mode S transponder usage so we are seeing lots of
Mode S innovation driven by that, that's why we have the Trig TT21.
And that is why European glider related avionics companies like
Butterfly/PowerFLARM and Garrecht have 1090ES based products. UAT
should have benefits, like lower power consumption (but the TT-21 has
pretty low power consumption), maybe FIS-B (needs a way to display the
data), maybe lower cost - but we've got to see actual products in
market to be sure about the cost. Current UAT transceivers are not
really low cost/suitable for gliders, hopefully this will change. The
marketing guy in me thinks the time to market will have a big impact
on adoption of 1090ES vs UAT in gliders, and right now 1090ES based
devices from Europe like the TT21 and PowerFLARM are becoming
available. For several $k you will soon be able to set up a pretty
impressive Trig TT21+1090ES data-out+PowerFLARM system, not bad for
early adopter costs. For folks with only Mode C transponders or who
fly in areas where there are no need for transponders I would hope low-
cost/low-power UAT transceivers do become available. It is going to be
interesting to see what happens.

How is that for a rambling reply?

Darryl

On Mar 17, 11:12*am, cfinn wrote:
I did some study on the Power Flarm and set in on the presentation at
the Little Rock Convention. It is interesting, but doesn't provide the
capabilities of ADS-B UAT. The plus is that it contains an IGC flight
recorder. It provides very good traffic location for Flarm and ADS-B
1090ES equipped aircraft. It works similar to a PCAS for mode C and S
transponder targets and receives their altitude reports and senses
distance. The traffic location is a good guess and alerts to get your
head up. I'm not sure what it would report if the transponders
altitude reporting was missing as you would have froma mode A
trasnponder. You do not have any of the ADS-B FIS (Flight Information
Services) such as Nexrad weather radar, TFR's, METARs, SIGMETs, etc.
Most importantly, only other aircraft equipped with Flarm would see
you! You would not be visible to ATC or aircraft equipped with TCAS,
PCS, etc.

In addition to all the FIS information that you can receive over ADS-B
UAT, you are visible to ATC. You are also visible directly visible to
other ADS-B UAT equipped aircraft. ADSB ground stations relay your UAT
position information to aircraft equipped with ADSB 1090ES. Those same
ground station also transmit all traffic ATC is following (primary
radar, Mode A/C/S transponder, ADSB 1090ES, ADSB UAT). Now you have a
much more complete picture of traffic, expect for Flarm only equipped
aircraft, and ATC and many other aircraft can see you!

I have nothing against Flarm and think it was a great technology.
However, it hasn't been adopted in the US. Why not go with with the
newer technology and receive the additional benefits along with the
safety of visibility to ATC and others? The pricing ranges for power
Flarm that ware discussed at the convention, would be similar to the
total cost of a Flight Recorder and the anticipated cost of the ADS-B
UAT.

Charlie



Have any of you considered this device?

http://www.powerflarm.aero/

It seems to have a lot more capability than just ADS-B

Bob- Hide quoted text -

- Show quoted text -

I remember when TCAS was showing up in the 80's, and my friend was
complaining
that they should just use GPS location info to resolve conflicts. It
seems that day
is finally here.

The FLARM nmea sentences are designed to add the conflict information
to an
existing GPS datastream. It would make life pretty easy if the ADS-B
conflict
information was forwarded using the same sentences. Most of the PDA
apps already
read the FLARM sentences and integrate them into their display. I
don't know how
you would integrate the weather data into a 4800bps nmea datastream,
though.

-- Matt