Sat Sep 18, 2021 12:11 pm
#1871193
I think its potentially good news that this trial has started, it has the possibility of improving safety for all, as it will be emitting Pilotaware, FLARM and MLAT
I have been reading through the UAT data specification, and I cannot find anywhere that details the system information for
- traffic uplink latency
- traffic uplink accuracy
@Cub @gaznav do you know how this information is relayed over this system ?
This is a crucial element of rebroadcast of traffic information which could be inaccurate
During the (private) trial conducted for ATOM/GRID testing of ModeS/3D we were very careful to only allow the data to be visible to the trial members, not wanting to scare the pants off unwitting users. For our system the only latency is in the MLAT datapath, in the case of FLARM, Fanet, Fanet+ is detected locally, negating all latency issues.
So for MLAT we were careful to calculate that latency/accuracy information and emit as part of the position report to airborne devices. This allows an easy distinction between strategic and tactical data, so whenever the position reported is such that the aircraft could potentially overlap your own position - the target is downgraded to bearingless - reporting relative height, but no bearing, this instructs the Pilot not to focus attention in what is most likely the wrong location
I think the partner for data provision is Planefinder ?
in which case the system data path is probably as follows:-
ATOM/OGN ->(internet)-> Glidernet ->(internet)-> Planefinder->(internet)-> Goodwood/Lasham
So I presume as this data contains latency in all of its data (as it is all provided remotely), that the accuracy information is provided over the link so the decoder and display system can handle this accordingly ?
Is this a GDL90 user extension interface on the SkyEcho providing bearingless target over the GDL90 interface?
How will this work for the non-SkyEcho UAT receivers ?
This is a clearly a critical part of the system integrity which needs to be determined, especially if existing decoders have no way of discriminating this information before passing it to the Pilot for evaluation
During the ModeS/3D trial, we used aircraft fitted with both Mode-S transponders and PilotAware, this was a crucial combination, it meant we could very accurately measure the position error due to the latency, by comparison of the GPS report from the PilotAware system (from the nationwide GRID), and measure against the MLAT calculated report from the Mode-S (courtesy 360Radar)
This allowed us to determine the system parameters when emitting the Mode-S/3D position reports. We plotted some very pretty graphs that were shown on this forum to show the fidelity of the overall system, and this same data is provided as part of the position report uplink
Thx
Lee