Author Topic: Not seeing OGN-R MLAT traffic on PAW via ATOM  (Read 263 times)


Not seeing OGN-R MLAT traffic on PAW via ATOM
« on: February 06, 2021, 02:26:04 pm »

Hi Lee,

I'm trying to get MLAT traffic to appear on a new PAW Rosetta. I'm running the Rosetta temporarily as a ground station co-located with OGN-R PWRadley.

PWRadley is showing MLAT traffic in the traffic list.

The PAW is connecting to the ATOM, receiving airfield information and METARS - all very good but no MLAT traffic visible on Rosetta.

As an example M-ETAL came overhead at low level and I was able to watch it on the OGN-R radar all the way to landing in the west - but no visibility of it at all on PAW radar.

Do I need to register either the PAW or the OGN-R to see MLAT aircraft.

Best regards


Re: Not seeing OGN-R MLAT traffic on PAW via ATOM
« Reply #1 on: February 06, 2021, 04:40:01 pm »

Probably obvious, but I take it you have Mode-S/3D enabled (and saved) in the Rosetta Config?

Less obvious - do you have Mode-C/S enabled? I could be wrong, but IIRC the Ground Station will only uplink MLAT positions if they are requested by the ‘Airborne’ PilotAware (i.e. your Rosetta), which requires the Rosetta to be directly receiving the Mode-S signal before it will request the MLAT Uplink from the Ground Station.

Edited to remove the third option - I obviously didn’t take in the first time I read it that the airfield info and METARS are uplinking. (I had suggested that the Rosetta might not have been transmitting - i.e. set to Rx Only or no GPS Fix - and therefore wouldn’t trigger the MLAT Uplinks. Sorry!


« Last Edit: February 06, 2021, 05:06:43 pm by exfirepro »


Re: Not seeing OGN-R MLAT traffic on PAW via ATOM
« Reply #2 on: February 06, 2021, 06:28:23 pm »
Thanks Lee,

That helps.

Yes, both options are set as described. So to understand this better; the PAW detects a Mode C/S bearingless target and send the ICAO ID via the link (when established) to the OGN-R station to request the MLAT position of that target from 360Radar. The response is returned via the OGN-R station to the PAW and displayed. I'll check that the PAW is picking up all the mode C/S it should be (as the two units are using different aerials and not necessarily reporting visibility of the same aircraft). I'll split the external 1090 feed to both and I suspect that may resolve it.

Best regards