PowerFlarm with FlarmView, I have a question.

[[email protected]]

Here at Chicago Glider Club we have the dubious distinction of flying right under the approach path into Midway airport. I have looked at SouthWest planes coming through from all angles, including head-on. Flying with a C-mode transponder helps a lot, Approach will guide the big iron around us although I'm sometimes wondering about the spacing.
My PFlarm will indicate through the FlarmView display a blue dot around my position that is blinking ONLY when a SW or bigger commercial plane (equipped with TCAS?) is coming through. Could there be a connection such that the transponder when interrogated by a TCAS responds in a way that is picked up by PFlarm? What else might the blue blinking dot mean?
Please enlighten me.
Herb, J7

[Richard[_9_]]

On Thursday, May 5, 2016 at 11:17:11 AM UTC-7, wrote:
> Here at Chicago Glider Club we have the dubious distinction of flying right under the approach path into Midway airport. I have looked at SouthWest planes coming through from all angles, including head-on. Flying with a C-mode transponder helps a lot, Approach will guide the big iron around us although I'm sometimes wondering about the spacing.
> My PFlarm will indicate through the FlarmView display a blue dot around my position that is blinking ONLY when a SW or bigger commercial plane (equipped with TCAS?) is coming through. Could there be a connection such that the transponder when interrogated by a TCAS responds in a way that is picked up by PFlarm? What else might the blue blinking dot mean?
> Please enlighten me.
> Herb, J7

that is a mode C or mode S transponder it is non directional and as it gets closer the circle should get smaller. Blue means it is above you.

Richard
www.craggyaero.com

[Ramy[_2_]]

It means you should zoom in to be able to tell how far the target is more or less.

Ramy

[Darryl Ramm]

On Thursday, May 5, 2016 at 11:17:11 AM UTC-7, wrote:
> Here at Chicago Glider Club we have the dubious distinction of flying right under the approach path into Midway airport. I have looked at SouthWest planes coming through from all angles, including head-on. Flying with a C-mode transponder helps a lot, Approach will guide the big iron around us although I'm sometimes wondering about the spacing.
> My PFlarm will indicate through the FlarmView display a blue dot around my position that is blinking ONLY when a SW or bigger commercial plane (equipped with TCAS?) is coming through. Could there be a connection such that the transponder when interrogated by a TCAS responds in a way that is picked up by PFlarm? What else might the blue blinking dot mean?
> Please enlighten me.
> Herb, J7

You've already got the answer, but a bit more detail...

TCAS is a transponder interrogator and receiver, it interrogates on 1030MHz similar to SSR radar and listens for transponder replies on 1090MHz. TCAS is all about that aircraft being able to see transponder equipped aircraft (with typical ranges of several tens of miles). That all those TCAS aircraft also have their own transponders lets them be seen by other aircraft with TCAS and your PowerFLARM's PCAS.

PowerFLARM only receives the 1090 MHz transponder replies, it cannot see the 1030 MHz interrogation signals (and they are not that interesting anyhow).. The combination of airborne TCAS interrogators and ground based SSR interrogators is what causes transponders to reply so a PCAS can see them at all. You won't see a lone TCAS equipped aircraft on your PowerFLARM via PCAS unless there is something else around to interrogate its transponder (and in your environment you have an SSR interrogator so you would see a lone TCAS equipped aircraft).

As airliners equip with ADS-B/1090ES Out heading into 2020 your PowerFLARM will see them directly via that and suppress the PCAS alert. And that happens without any interrogators being needed.

In this environment it is good to see you have a transponder in your glider, hopefully all the gliders in your club do. TCAS can't see your glider, or issue a TA or RA without that. ATC likely can't see gliders at all that are not equipped with transponders, not even as primary radar targets. Visiting FAA folks at the Chicago TRACON or the airport tower and talking with them may be a great thing to do, and maybe you folks already have done that.

[David Kinsell[_2_]]

On Thu, 05 May 2016 11:50:39 -0700, Richard wrote:

> On Thursday, May 5, 2016 at 11:17:11 AM UTC-7, wrote:
>> Here at Chicago Glider Club we have the dubious distinction of flying
>> right under the approach path into Midway airport. I have looked at
>> SouthWest planes coming through from all angles, including head-on.
>> Flying with a C-mode transponder helps a lot, Approach will guide the
>> big iron around us although I'm sometimes wondering about the spacing.
>> My PFlarm will indicate through the FlarmView display a blue dot around
>> my position that is blinking ONLY when a SW or bigger commercial plane
>> (equipped with TCAS?) is coming through. Could there be a connection
>> such that the transponder when interrogated by a TCAS responds in a way
>> that is picked up by PFlarm? What else might the blue blinking dot
>> mean?
>> Please enlighten me.
>> Herb, J7
>
> that is a mode C or mode S transponder it is non directional and as it
> gets closer the circle should get smaller. Blue means it is above you.
>
> Richard www.craggyaero.com

I've been bench testing 6.06 firmware, and see what I believe Herb is
seeing. A small flashing dot right at current position, but it's short
lived and never gets bigger. It's like the range for mode c/mode s
targets is terrible. I see lots of ADS-B targets at distances greater
than 12 miles, but hardly any mode c/mode s. Maybe they gave up trying
to estimate distance for those targets?

[[email protected]]

I fly near a busy airport (KPRC) with several flight schools and lots of targets for my PF with butterfly rectangle display. I get alot of both Adsb and mode c/s targets the mode c consistently show up as rings and seem to jump from 6 miles to 3 miles then 2 and then 1 with a small altitude display above or below to nearest 100' seems pretty straight forward and I don't see any reason to change displays. I also like the dedicated and front and center of where I located the butterfly right on the front lip of my glare shield. Only disadvantage for me is the volume of the alerts could be louder, but I am getting hard of hearing now too :)

[Darryl Ramm]

And what are your PowerFLARM's PCAS range and altitude settings set to?

On Saturday, May 7, 2016 at 7:11:29 AM UTC-7, David Kinsell wrote:
> On Thu, 05 May 2016 11:50:39 -0700, Richard wrote:
>
> > On Thursday, May 5, 2016 at 11:17:11 AM UTC-7, wrote:
> >> Here at Chicago Glider Club we have the dubious distinction of flying
> >> right under the approach path into Midway airport. I have looked at
> >> SouthWest planes coming through from all angles, including head-on.
> >> Flying with a C-mode transponder helps a lot, Approach will guide the
> >> big iron around us although I'm sometimes wondering about the spacing.
> >> My PFlarm will indicate through the FlarmView display a blue dot around
> >> my position that is blinking ONLY when a SW or bigger commercial plane
> >> (equipped with TCAS?) is coming through. Could there be a connection
> >> such that the transponder when interrogated by a TCAS responds in a way
> >> that is picked up by PFlarm? What else might the blue blinking dot
> >> mean?
> >> Please enlighten me.
> >> Herb, J7
> >
> > that is a mode C or mode S transponder it is non directional and as it
> > gets closer the circle should get smaller. Blue means it is above you.
> >
> > Richard www.craggyaero.com
>
> I've been bench testing 6.06 firmware, and see what I believe Herb is
> seeing. A small flashing dot right at current position, but it's short
> lived and never gets bigger. It's like the range for mode c/mode s
> targets is terrible. I see lots of ADS-B targets at distances greater
> than 12 miles, but hardly any mode c/mode s. Maybe they gave up trying
> to estimate distance for those targets?

[David Kinsell[_2_]]

Currently using the default flarmcfg.txt file, so 7000 and 600.


Sat, 07 May 2016 10:13:05 -0700, Darryl Ramm wrote:

> And what are your PowerFLARM's PCAS range and altitude settings set to?
>
> On Saturday, May 7, 2016 at 7:11:29 AM UTC-7, David Kinsell wrote:
>> On Thu, 05 May 2016 11:50:39 -0700, Richard wrote:
>>
>> > On Thursday, May 5, 2016 at 11:17:11 AM UTC-7,
>> > wrote:
>> >> Here at Chicago Glider Club we have the dubious distinction of
>> >> flying right under the approach path into Midway airport. I have
>> >> looked at SouthWest planes coming through from all angles, including
>> >> head-on. Flying with a C-mode transponder helps a lot, Approach will
>> >> guide the big iron around us although I'm sometimes wondering about
>> >> the spacing. My PFlarm will indicate through the FlarmView display a
>> >> blue dot around my position that is blinking ONLY when a SW or
>> >> bigger commercial plane (equipped with TCAS?) is coming through.
>> >> Could there be a connection such that the transponder when
>> >> interrogated by a TCAS responds in a way that is picked up by
>> >> PFlarm? What else might the blue blinking dot mean?
>> >> Please enlighten me.
>> >> Herb, J7
>> >
>> > that is a mode C or mode S transponder it is non directional and as
>> > it gets closer the circle should get smaller. Blue means it is above
>> > you.
>> >
>> > Richard www.craggyaero.com
>>
>> I've been bench testing 6.06 firmware, and see what I believe Herb is
>> seeing. A small flashing dot right at current position, but it's short
>> lived and never gets bigger. It's like the range for mode c/mode s
>> targets is terrible. I see lots of ADS-B targets at distances greater
>> than 12 miles, but hardly any mode c/mode s. Maybe they gave up trying
>> to estimate distance for those targets?

[Darryl Ramm]

So do you have much traffic below ~2,000' AGL where you are? That are also in SSR interrogator coverage? (although TCAS should fill in as an interrogator). Why not try setting everything unlimited and see what happens.

Partial obstructions, local reflections etc. can severely screw with PCAS's estimation of range. Testing that on the ground may be a waste of time.

On Saturday, May 7, 2016 at 11:44:51 AM UTC-7, David Kinsell wrote:
> Currently using the default flarmcfg.txt file, so 7000 and 600.
>
>
> Sat, 07 May 2016 10:13:05 -0700, Darryl Ramm wrote:
>
> > And what are your PowerFLARM's PCAS range and altitude settings set to?
> >
> > On Saturday, May 7, 2016 at 7:11:29 AM UTC-7, David Kinsell wrote:
> >> On Thu, 05 May 2016 11:50:39 -0700, Richard wrote:
> >>
> >> > On Thursday, May 5, 2016 at 11:17:11 AM UTC-7,
> >> > wrote:
> >> >> Here at Chicago Glider Club we have the dubious distinction of
> >> >> flying right under the approach path into Midway airport. I have
> >> >> looked at SouthWest planes coming through from all angles, including
> >> >> head-on. Flying with a C-mode transponder helps a lot, Approach will
> >> >> guide the big iron around us although I'm sometimes wondering about
> >> >> the spacing. My PFlarm will indicate through the FlarmView display a
> >> >> blue dot around my position that is blinking ONLY when a SW or
> >> >> bigger commercial plane (equipped with TCAS?) is coming through.
> >> >> Could there be a connection such that the transponder when
> >> >> interrogated by a TCAS responds in a way that is picked up by
> >> >> PFlarm? What else might the blue blinking dot mean?
> >> >> Please enlighten me.
> >> >> Herb, J7
> >> >
> >> > that is a mode C or mode S transponder it is non directional and as
> >> > it gets closer the circle should get smaller. Blue means it is above
> >> > you.
> >> >
> >> > Richard www.craggyaero.com
> >>
> >> I've been bench testing 6.06 firmware, and see what I believe Herb is
> >> seeing. A small flashing dot right at current position, but it's short
> >> lived and never gets bigger. It's like the range for mode c/mode s
> >> targets is terrible. I see lots of ADS-B targets at distances greater
> >> than 12 miles, but hardly any mode c/mode s. Maybe they gave up trying
> >> to estimate distance for those targets?

[David Kinsell[_2_]]

There's some low level traffic around, from local airports. It's
frequently interrogated, I have a separate ADS-B receiver that also shows
mode s targets, and it shows a lot of stuff buzzing around during the
day. Increasing the altitude limits of course adds more. PCAS target
range can only be increased to 10K meters, so that's a limiting factor in
how much you'll ever see with PF.

Doing more experiments, looks like the defaults aren't good at all for
the FlarmViews that Herb and I are using. In particular the protocol for
the RJ45 and d-sub gets set to 'default', much better results with
version 7. From their description, they ought to default to ver 4.
ADS-B vertical range is set for unlimited, a bizarre choice if you're
actually flying. "Process Mode C Targets" is shut off by default.

Not sure how Herb has his configured, but after setting the protocol to
7, I saw an ADS-B target show up with a plane symbol and a flashing ring,
and got the flashing blue dot when the target was right overhead. So it
seems to be a collision alert. A PCAS target showed up as just a
flashing ring, so it's working as expected now. Max range was about 6
miles in both cases.

These results were with latest firmware on PF and FlarmView, ymmv.

-Dave

On Sat, 07 May 2016 12:07:19 -0700, Darryl Ramm wrote:

> So do you have much traffic below ~2,000' AGL where you are? That are
> also in SSR interrogator coverage? (although TCAS should fill in as an
> interrogator). Why not try setting everything unlimited and see what
> happens.
>
> Partial obstructions, local reflections etc. can severely screw with
> PCAS's estimation of range. Testing that on the ground may be a waste of
> time.
>
> On Saturday, May 7, 2016 at 11:44:51 AM UTC-7, David Kinsell wrote:
>> Currently using the default flarmcfg.txt file, so 7000 and 600.
>>
>>
>> Sat, 07 May 2016 10:13:05 -0700, Darryl Ramm wrote:
>>
>> > And what are your PowerFLARM's PCAS range and altitude settings set
>> > to?
>> >
>> > On Saturday, May 7, 2016 at 7:11:29 AM UTC-7, David Kinsell wrote:
>> >> On Thu, 05 May 2016 11:50:39 -0700, Richard wrote:
>> >>
>> >> > On Thursday, May 5, 2016 at 11:17:11 AM UTC-7,
>> >> > wrote:
>> >> >> Here at Chicago Glider Club we have the dubious distinction of
>> >> >> flying right under the approach path into Midway airport. I have
>> >> >> looked at SouthWest planes coming through from all angles,
>> >> >> including head-on. Flying with a C-mode transponder helps a lot,
>> >> >> Approach will guide the big iron around us although I'm sometimes
>> >> >> wondering about the spacing. My PFlarm will indicate through the
>> >> >> FlarmView display a blue dot around my position that is blinking
>> >> >> ONLY when a SW or bigger commercial plane (equipped with TCAS?)
>> >> >> is coming through. Could there be a connection such that the
>> >> >> transponder when interrogated by a TCAS responds in a way that is
>> >> >> picked up by PFlarm? What else might the blue blinking dot mean?
>> >> >> Please enlighten me.
>> >> >> Herb, J7
>> >> >
>> >> > that is a mode C or mode S transponder it is non directional and
>> >> > as it gets closer the circle should get smaller. Blue means it is
>> >> > above you.
>> >> >
>> >> > Richard www.craggyaero.com
>> >>
>> >> I've been bench testing 6.06 firmware, and see what I believe Herb
>> >> is seeing. A small flashing dot right at current position, but it's
>> >> short lived and never gets bigger. It's like the range for mode
>> >> c/mode s targets is terrible. I see lots of ADS-B targets at
>> >> distances greater than 12 miles, but hardly any mode c/mode s.
>> >> Maybe they gave up trying to estimate distance for those targets?

[Hartley Falbaum[_2_]]

On Thursday, May 5, 2016 at 2:17:11 PM UTC-4, wrote:
> Here at Chicago Glider Club we have the dubious distinction of flying right under the approach path into Midway airport. I have looked at SouthWest planes coming through from all angles, including head-on. Flying with a C-mode transponder helps a lot, Approach will guide the big iron around us although I'm sometimes wondering about the spacing.
> My PFlarm will indicate through the FlarmView display a blue dot around my position that is blinking ONLY when a SW or bigger commercial plane (equipped with TCAS?) is coming through. Could there be a connection such that the transponder when interrogated by a TCAS responds in a way that is picked up by PFlarm? What else might the blue blinking dot mean?
> Please enlighten me.
> Herb, J7

So--did you have "Process Mode C targets" shut off, or on?

[David Kinsell[_2_]]

On Thu, 05 May 2016 11:17:09 -0700, herbkilian wrote:

> Here at Chicago Glider Club we have the dubious distinction of flying
> right under the approach path into Midway airport. I have looked at
> SouthWest planes coming through from all angles, including head-on.
> Flying with a C-mode transponder helps a lot, Approach will guide the
> big iron around us although I'm sometimes wondering about the spacing.
> My PFlarm will indicate through the FlarmView display a blue dot around
> my position that is blinking ONLY when a SW or bigger commercial plane
> (equipped with TCAS?) is coming through. Could there be a connection
> such that the transponder when interrogated by a TCAS responds in a way
> that is picked up by PFlarm? What else might the blue blinking dot
> mean?
> Please enlighten me.
> Herb, J7

In bench testing, I've seen PCAS targets create flashing blue rings,
decreasing in diameter as the target approaches, and then the small blue
ring is replaced with the blue blinking dot as the target is overhead.
The dot is bigger than a small blue ring, so I assume that's just to make
it more visible. The beeper is not going off, so PF doesn't think
there's an imminent collision threat. Are you not seeing the blue rings
before the blue dot? If you're not, then there's some configuration
issue that needs to be fixed.

The bigger question is how well your PF is handling your Mode C
transponder? It has trouble filtering out your own transmissions, may
want to consider upgrading to Mode S for best results. I assume you have
Aggressive filtering selected, and you are receiving Mode C?

[JS]

On Monday, May 9, 2016 at 8:16:44 AM UTC-7, David Kinsell wrote:
> The bigger question is how well your PF is handling your Mode C
> transponder? It has trouble filtering out your own transmissions, may
> want to consider upgrading to Mode S for best results. I assume you have
> Aggressive filtering selected, and you are receiving Mode C?

Using aggressive filtering and a Trig TT22 that's being interrogated by Mode C. The flashing blue dot is boring.
Until checking the "use TXP altitude" box, every pull-up brought a collision warning.
This is my second PowerFLARM used in conjunction with Mode S. The previous installation of PF with Trig TT21 wasn't a problem. But that might have been using better FLARM firmware?
Jim

[David Kinsell[_2_]]

On Mon, 09 May 2016 08:32:58 -0700, JS wrote:

> On Monday, May 9, 2016 at 8:16:44 AM UTC-7, David Kinsell wrote:
>> The bigger question is how well your PF is handling your Mode C
>> transponder? It has trouble filtering out your own transmissions, may
>> want to consider upgrading to Mode S for best results. I assume you
>> have Aggressive filtering selected, and you are receiving Mode C?
>
> Using aggressive filtering and a Trig TT22 that's being interrogated by
> Mode C. The flashing blue dot is boring.
> Until checking the "use TXP altitude" box, every pull-up brought a
> collision warning.
> This is my second PowerFLARM used in conjunction with Mode S. The
> previous installation of PF with Trig TT21 wasn't a problem. But that
> might have been using better FLARM firmware?
> Jim

Mode C doesn't interrogate anything, it responds to ground radar or TCAS.
With no Mode C in your ship, can't imagine Aggressive filtering would be
needed. Probably best not to use it.

-Dave

[Darryl Ramm]

Jim is fairly correct in the terminology he is using.

There are Mode A and Mode C and Mode S interrogations and what a transponder replies with depends on that interrogations (and if it support that type of interrogation, a "Mode S Transponder" Supports Mode A, C, and S interrogations. A "Mode C" transponder supports Mode A and C interrogations)

Lots of people use "Mode C" or "Mode C interrogation" to mean any altitude interrogation even though most Mode S transponders will usually be interrogated via Mode S type interrogation to return altitude data. They'll respond perfectly like a Mode C transponder for legacy Mode C interrogators.

Legacy SSR issues interleaved Mode A and C interrogations, modern SSR adds Mode S. TCAS does Mode C and Mode S only. Sone GA PCAS systems do legacy mode C only.

Mode S interrogators (SSR and TCAS) utilize a trick (using side lobe suppression) to prevent Mode S capable transponders replying to their Mode A or C legacy interrogations.


On Monday, May 9, 2016 at 9:26:43 AM UTC-7, David Kinsell wrote:
> On Mon, 09 May 2016 08:32:58 -0700, JS wrote:
>
> > On Monday, May 9, 2016 at 8:16:44 AM UTC-7, David Kinsell wrote:
> >> The bigger question is how well your PF is handling your Mode C
> >> transponder? It has trouble filtering out your own transmissions, may
> >> want to consider upgrading to Mode S for best results. I assume you
> >> have Aggressive filtering selected, and you are receiving Mode C?
> >
> > Using aggressive filtering and a Trig TT22 that's being interrogated by
> > Mode C. The flashing blue dot is boring.
> > Until checking the "use TXP altitude" box, every pull-up brought a
> > collision warning.
> > This is my second PowerFLARM used in conjunction with Mode S. The
> > previous installation of PF with Trig TT21 wasn't a problem. But that
> > might have been using better FLARM firmware?
> > Jim
>
> Mode C doesn't interrogate anything, it responds to ground radar or TCAS.
> With no Mode C in your ship, can't imagine Aggressive filtering would be
> needed. Probably best not to use it.
>
> -Dave

[Darryl Ramm]

Sorry another r.a.s. typo. " Sone GA PCAS systems do legacy mode C only. " should be "Some GA TCAD systems do legacy mode C interrogations only." An example system is the L-3 SkyWatch, it's a Mode C interrogator only, no Mode S. And obviously PCAS does not do any interrogations, it just listens to responses from transponders to other interrogations.

BTW Those legacy Mode C only interrogators help mess things up for deduplicatiing 1090ES and FLARM signals from traffic. Since the reply to a legacy Mode C interrogation, even from a Mode S transponder, does not include the aircraft's ICAO address a PowerFLARM can't easily know to suppress the PCAS alert for a target it also has via ADS-B/1090ES or FLARM.

[Tango Eight]

On Saturday, May 7, 2016 at 10:11:29 AM UTC-4, David Kinsell wrote:
> On Thu, 05 May 2016 11:50:39 -0700, Richard wrote:
>
> > On Thursday, May 5, 2016 at 11:17:11 AM UTC-7, wrote:
> >> Here at Chicago Glider Club we have the dubious distinction of flying
> >> right under the approach path into Midway airport. I have looked at
> >> SouthWest planes coming through from all angles, including head-on.
> >> Flying with a C-mode transponder helps a lot, Approach will guide the
> >> big iron around us although I'm sometimes wondering about the spacing.
> >> My PFlarm will indicate through the FlarmView display a blue dot around
> >> my position that is blinking ONLY when a SW or bigger commercial plane
> >> (equipped with TCAS?) is coming through. Could there be a connection
> >> such that the transponder when interrogated by a TCAS responds in a way
> >> that is picked up by PFlarm? What else might the blue blinking dot
> >> mean?
> >> Please enlighten me.
> >> Herb, J7
> >
> > that is a mode C or mode S transponder it is non directional and as it
> > gets closer the circle should get smaller. Blue means it is above you.
> >
> > Richard www.craggyaero.com
>
> I've been bench testing 6.06 firmware, and see what I believe Herb is
> seeing. A small flashing dot right at current position, but it's short
> lived and never gets bigger. It's like the range for mode c/mode s
> targets is terrible. I see lots of ADS-B targets at distances greater
> than 12 miles, but hardly any mode c/mode s. Maybe they gave up trying
> to estimate distance for those targets?

IIRC PF's max (software limited) range for non-directional "traffic" is 6 miles. It's in their docs, somewhere.

Why would you want flarm to report non-directional "traffic" beyond even 3 miles? Nice to know your device is working I suppose, but in flight this is just another distraction.

Suggest you set the range of your display to something useful like 2 - 4 miles. Set to 24 miles, which is what I guess is going on here, the important stuff (the close stuff) will not be displayed properly (e.g. blinking dots).

best,
Evan Ludeman