PowerFlarm v3.40

It would be nice to have the option to include a list of transponder codes that were always suppressed. For example, 1202. One could make the determination if a majority of the local gliders with a transponder also had FLARM. If that was a reasonable assessment for your location, then suppressing all the 1202 hits would potentially reduce the false alarms based on transponders and would rely on the more reliable FLARM data.

On Saturday, April 19, 2014 2:49:22 PM UTC-7, wrote:
It would be nice to have the option to include a list of transponder codes that were always suppressed. For example, 1202. One could make the determination if a majority of the local gliders with a transponder also had FLARM. If that was a reasonable assessment for your location, then suppressing all the 1202 hits would potentially reduce the false alarms based on transponders and would rely on the more reliable FLARM data.

Ah the trouble there is you cannot definitively associate a Mode A squawk reply with the same transponder doing a Mode C reply. And there will be situations where targets are doing Mode C only replies (e.g. any time a target is being interrogated by TCAS I or II but out of range of ground SSR... which I'm guessing happens a fair amount).

The 'best' you could do in that situation is stop all PCAS warnings. That may be/is likely too drastic, you can also so try adjusting the PCAS height/range parameters. Ultimately there is nothing you can do that is goign to work that well with Mode C transponders. Hopefully over time this will go away as an issue as Mode S transponder use keeps growing in the USA glider fleet.

There is no need/strong justification to replace a Mode C today, they work great for letting ATC know where you are and with TCAS, TCAD and PCAS in GA aircraft etc. but on the other hand there is no sane reason to buy a new Mode C transponder today. The possible issues here with PowerFLARM interoperability is just one of those reasons. Over time and as equipment ages and gets expensive to repair and new Mode S transponder technology hopefully keeps falling in cost and size etc. we'll just see the current Mode C usage in the glider fleet migrating over to Mode S. I'm much less worried about Mode C vs. Mode S than I am to encourage *any* transponder use in areas of high airline, fast jet, and even GA traffic.

Anybody who what my opinion on what the FAA should have really done with Mode S vs. Mode C transponders and ADS-B Out carriage mandates, etc. is welcome to buy me a six pack of beer and put up with an hour of whining.

Of course you all know that I'm not a Flarm guy.

Having said that, it strikes me funny that nobody seems to have noticed that
it's the "same altitude" aircraft that's going to hit you. Why would you
want all transponders at co-altitude to be suppressed? And the notion that
you're going to be OK since the Flarm will point out other Flarm traffic.
Listen up, Guys: GA, military, and airlines are NOT using Flarm. Oh, and
we have at least one guy at Moriarty who has a Flarm but not a transponder.
So he and the half dozen or so Flarm equipped gliders can avoid each other
but he's cruising along blissfully unaware that ATC can't see him, nor can
the airliners or military flights that buzz in and out of ABQ daily.

Hopefully Flarm will work this out as Zaon did several years ago.


"darrylr" wrote in message
...
On Saturday, April 19, 2014 2:49:22 PM UTC-7, wrote:
It would be nice to have the option to include a list of transponder codes
that were always suppressed. For example, 1202. One could make the
determination if a majority of the local gliders with a transponder also
had FLARM. If that was a reasonable assessment for your location, then
suppressing all the 1202 hits would potentially reduce the false alarms
based on transponders and would rely on the more reliable FLARM data.

Ah the trouble there is you cannot definitively associate a Mode A squawk
reply with the same transponder doing a Mode C reply. And there will be
situations where targets are doing Mode C only replies (e.g. any time a
target is being interrogated by TCAS I or II but out of range of ground
SSR... which I'm guessing happens a fair amount).

The 'best' you could do in that situation is stop all PCAS warnings. That
may be/is likely too drastic, you can also so try adjusting the PCAS
height/range parameters. Ultimately there is nothing you can do that is
goign to work that well with Mode C transponders. Hopefully over time this
will go away as an issue as Mode S transponder use keeps growing in the USA
glider fleet.

There is no need/strong justification to replace a Mode C today, they work
great for letting ATC know where you are and with TCAS, TCAD and PCAS in GA
aircraft etc. but on the other hand there is no sane reason to buy a new
Mode C transponder today. The possible issues here with PowerFLARM
interoperability is just one of those reasons. Over time and as equipment
ages and gets expensive to repair and new Mode S transponder technology
hopefully keeps falling in cost and size etc. we'll just see the current
Mode C usage in the glider fleet migrating over to Mode S. I'm much less
worried about Mode C vs. Mode S than I am to encourage *any* transponder use
in areas of high airline, fast jet, and even GA traffic.

Anybody who what my opinion on what the FAA should have really done with
Mode S vs. Mode C transponders and ADS-B Out carriage mandates, etc. is
welcome to buy me a six pack of beer and put up with an hour of whining.

I am pretty sure that the suppression is based on power as well, in addition to altitude. So only a strong signal at the same altitude will be suppressed. Which mean you will still get warning for same altitude until the other aircraft is very close, giving you enough warning. I assume this is the same way that Zaon works. But again this is just my guess. Will be nice if Flarm folks will comment on this.

Ramy

That's what I would hope. I recall that, when I installed my Mode S
transponder and had it tested, it was putting out over 175 watts to the test
equipment antenna. Don't we have an inverse cube function of power density
to distance? I think that's right, though I probably didn't say it
correctly. Anyway, an aircraft a couple of hundred feet away would be
received in the milliwatt range, maybe somewhat more, but certainly not at
100+ watts.


"Ramy" wrote in message
...
I am pretty sure that the suppression is based on power as well, in addition
to altitude. So only a strong signal at the same altitude will be
suppressed. Which mean you will still get warning for same altitude until
the other aircraft is very close, giving you enough warning. I assume this
is the same way that Zaon works. But again this is just my guess. Will be
nice if Flarm folks will comment on this.

Ramy

On Sunday, April 20, 2014 9:17:30 PM UTC-5, Dan Marotta wrote:
That's what I would hope. I recall that, when I installed my Mode S

transponder and had it tested, it was putting out over 175 watts to the test

equipment antenna. Don't we have an inverse cube function of power density

to distance? I think that's right, though I probably didn't say it

correctly. Anyway, an aircraft a couple of hundred feet away would be

received in the milliwatt range, maybe somewhat more, but certainly not at

100+ watts.





"Ramy" wrote in message

...

I am pretty sure that the suppression is based on power as well, in addition

to altitude. So only a strong signal at the same altitude will be

suppressed. Which mean you will still get warning for same altitude until

the other aircraft is very close, giving you enough warning. I assume this

is the same way that Zaon works. But again this is just my guess. Will be

nice if Flarm folks will comment on this.



Ramy

Dan, radiation diminishes according to the inverse square law, just as gravitational forces or sound:
http://en.wikipedia.org/wiki/Inverse-square_law
If you double the distances, intensity falls to a quarter.

OK, I was picturing the power as on the surface of an expanding sphere from
the point of transmission (4/3 * pi * r **3) but, as I said, I wasn't sure.


wrote in message
...
On Sunday, April 20, 2014 9:17:30 PM UTC-5, Dan Marotta wrote:
That's what I would hope. I recall that, when I installed my Mode S

transponder and had it tested, it was putting out over 175 watts to the
test

equipment antenna. Don't we have an inverse cube function of power
density

to distance? I think that's right, though I probably didn't say it

correctly. Anyway, an aircraft a couple of hundred feet away would be

received in the milliwatt range, maybe somewhat more, but certainly not
at

100+ watts.





"Ramy" wrote in message

...

I am pretty sure that the suppression is based on power as well, in
addition

to altitude. So only a strong signal at the same altitude will be

suppressed. Which mean you will still get warning for same altitude until

the other aircraft is very close, giving you enough warning. I assume
this

is the same way that Zaon works. But again this is just my guess. Will be

nice if Flarm folks will comment on this.



Ramy

Dan, radiation diminishes according to the inverse square law, just as
gravitational forces or sound:
http://en.wikipedia.org/wiki/Inverse-square_law
If you double the distances, intensity falls to a quarter.

Dan -

The statistics show over and over that glider-to-glider collisions are more of a threat than glider-to-GA/Miliatry. FLARM isn't intended to be a perfect solution; it's intended to provide a very reliable, medium-cost, low-power solution for the biggest collision threat: other maneuvering gliders.

Mode C and even Mode S systems are not well-suited for combating glider-on-glider carnage when the craft are in close proximity and maneuvering.

There simply is no perfect solution; but I for one will take the single solution that reasonably covers the broadest range of targets and situations - and right now that's a PowerFLARM.

--Noel

"noel.wade" wrote:
Dan -

The statistics show over and over that glider-to-glider collisions are
more of a threat than glider-to-GA/Miliatry. FLARM isn't intended to be a
perfect solution; it's intended to provide a very reliable, medium-cost,
low-power solution for the biggest collision threat: other maneuvering gliders.

Mode C and even Mode S systems are not well-suited for combating
glider-on-glider carnage when the craft are in close proximity and maneuvering.

There simply is no perfect solution; but I for one will take the single
solution that reasonably covers the broadest range of targets and
situations - and right now that's a PowerFLARM.

--Noel

Hopefully that decision gets made by each pilot for the conditions they fly
in. And it's not necessarily a choice between a transponder or PowerFLARM.
And the decision should not always come down to PowerFLARM being the first
choice for all pilots. And having both provides very broad technology
assistance. And if in busy airspace areas establishing local procedures,
radio contact with ATC etc. with or without a transponder may be
appropriate.

Around busy airspace with lots of airliners and fast jet traffic the
PowerFLARM is just not going to be of much use. Except maybe highlighting
how much airline etc. traffic is around to be worried about as you see them
via 1090ES (around 1/3rd of airliners are currently 1090ES Out? I am not
sure).

Worrisome areas include those with lots of fast aircraft, all of who are
are in touch with ATC and everybody expects TCAS to just work because
'everybody else has a transponder'. The consequence of being the invisible
glider without a transponder that gets run into by an airliner is not going
to be pretty, so hopefully there is a local flying situation risk x
consequence part of any decision of what to equip with.

But yes clearly for glider-glider collision risks PowerFLARM is by far the
best choice. PCAS in PowerFLARM gives you useful help around GA traffic,
but for the big/fast conflicts you want to be seen by ATC and the TCAS
aboard those aircraft. Which means you need a transponder. ADS-B remains
largely a complex mess/futureware.

Darryl

Good points, Noel.


"noel.wade" wrote in message
...
Dan -

The statistics show over and over that glider-to-glider collisions are more
of a threat than glider-to-GA/Miliatry. FLARM isn't intended to be a perfect
solution; it's intended to provide a very reliable, medium-cost, low-power
solution for the biggest collision threat: other maneuvering gliders.

Mode C and even Mode S systems are not well-suited for combating
glider-on-glider carnage when the craft are in close proximity and
maneuvering.

There simply is no perfect solution; but I for one will take the single
solution that reasonably covers the broadest range of targets and
situations - and right now that's a PowerFLARM.

--Noel