PowerFlarm for ADSB source?

Couple questions, maybe Darryl you could take a shot at these.

Would there be a perceptible position error if one compared the reported position from a PowerFlarm Core with a fully approved ADSB source. Compare it to say the Trig TN70 unit. http://www.trig-avionics.com/tn70.html

If the reported position error is suitably small, what would be required to show that the PowerFlarm Core meets the "performance requirements" to be used as a NMEA source for ADSB out?

With many of us in the US installing PowerFlarm, there is some sense to seeing if this device could get to the point, legally, of being used as a source for a Trig transponder that is capable of ADSB out.


Mark

wrote:
Couple questions, maybe Darryl you could take a shot at these.

Would there be a perceptible position error if one compared the reported
position from a PowerFlarm Core with a fully approved ADSB source.
Compare it to say the Trig TN70 unit. http://www.trig-avionics.com/tn70.html

If the reported position error is suitably small, what would be required
to show that the PowerFlarm Core meets the "performance requirements" to
be used as a NMEA source for ADSB out?

With many of us in the US installing PowerFlarm, there is some sense to
seeing if this device could get to the point, legally, of being used as a
source for a Trig transponder that is capable of ADSB out.


Mark

I already kind of covered this in another thread, there is absolutely no
way any standard consumer type GPS source (like used in PowerFLARM) can
meet the performance requirements of TSO-C145 or similar specs. The hard
part of those requirements is not so much positional accuracy they are
reliability and error detection. You cannot use any NEMA GPS to do this
(meet the 2020 carriage mandate requirements), there is not enough
reliability related data in the NEMA steam, suitable GPS' talk ARINC 429 or
'Aviation' serial format over RS-232.

Again, all this is why TSO-C199 is interesting as it specifically covers
using consumer GPS sources in ADS-B based anti-collision beacons. However
that TSO does not apply to the 2020 ADS-B out carriage mandate (which
gliders are exempt from). Read that TSO to get a flavor of what is
involved, it needs work from a vendor to show a GPS is suitable, not just
an end-user connecting up any old consumer GPS. One of the encouragements
for the FAA doing all this is... the careful and successful use of
consumer GPS technology in FLARM.

I wonder if the reason for requiring high-resolution TSO'd GPSs is that ADS-B will be used for IFR separation and for fast-moving aircraft, so high-resolution position and updates is an absolute requirement, a la fast-scan radar.

i should have also added:

with FLARM, the aircraft move slowly, and they are all VFR, so having relative position and altitude from a non-certified, low-res source is still fundamentally useful for improving see-and-avoid (although not necessarily for IFR separation)

On Tuesday, February 24, 2015 at 10:36:13 AM UTC-5, Bob Pasker wrote:
I wonder if the reason for requiring high-resolution TSO'd GPSs is that ADS-B will be used for IFR separation and for fast-moving aircraft, so high-resolution position and updates is an absolute requirement, a la fast-scan radar.

On Tuesday, February 24, 2015 at 7:40:38 AM UTC-8, Bob Pasker wrote:
i should have also added:

with FLARM, the aircraft move slowly, and they are all VFR, so having relative position and altitude from a non-certified, low-res source is still fundamentally useful for improving see-and-avoid (although not necessarily for IFR separation)

On Tuesday, February 24, 2015 at 10:36:13 AM UTC-5, Bob Pasker wrote:
I wonder if the reason for requiring high-resolution TSO'd GPSs is that ADS-B will be used for IFR separation and for fast-moving aircraft, so high-resolution position and updates is an absolute requirement, a la fast-scan radar.

I believe Darryl. It's not the position resolution that is the issue. My consumer GPSs seem to do a pretty good job of resolution within a few meters. For ATC, when you are doing 5-mile separation, what's a few meters of resolution? It seems the TSO requirements that can't be met by consumer GPS is reliability (as in, is it producing a valid position at all) and error detection/reporting (can you tell when you are not producing a valid position at all and let the rest of us know).

Bob Pasker wrote:
i should have also added:

with FLARM, the aircraft move slowly, and they are all VFR, so having
relative position and altitude from a non-certified, low-res source is
still fundamentally useful for improving see-and-avoid (although not
necessarily for IFR separation)

On Tuesday, February 24, 2015 at 10:36:13 AM UTC-5, Bob Pasker wrote:
I wonder if the reason for requiring high-resolution TSO'd GPSs is that
ADS-B will be used for IFR separation and for fast-moving aircraft, so
high-resolution position and updates is an absolute requirement, a la fast-scan radar.

FLARM GPS *is* high resolution and highly accurate if it was not FLARM
could not possibly work. That separation between gliders in a thermal is
way less than what the FAA cares about using in the NAS. Some of the more
subtle GPS technical challenges were handled because FLARM knew what they
were doing, only worked with specific very well understood (to them) GPS
chipsets etc. Note that you never get to drive a FLARM with any old
external GPS source, but they provide a NEMA output as a convenience...

... and thank the FLARM folks for showing what is possible and helping the
FAA even get to TSO-C199. Now if anything ever comes from that we will have
to wait and see...

thanks for the clarification. regarding "one more time," I had not seen your earlier messages.

Bob Pasker wrote:
I wonder if the reason for requiring high-resolution TSO'd GPSs is that
ADS-B will be used for IFR separation and for fast-moving aircraft, so
high-resolution position and updates is an absolute requirement, a la fast-scan radar.

Let me try to say it one more time, it is *not* about resolution, or even
accuracy (consumer GPS chipsets have no problem doing either) it is about
reliability and failure detection. The FAA is clearly concern that they
need this reliability so ADS-B can be used as the primary means of
controlling aircraft separation in the NAS.