Author Topic: Filter different signals transmitting from same aircraft  (Read 3146 times)

Gary Nelson

Filter different signals transmitting from same aircraft
« on: November 06, 2017, 08:36:59 am »
If a single plane is transmitting (1) Pi3 (2) Mode S and (3) ADS-B (likely uncertified ads-b)   then what would another Pilot Aware user see on their screen - presumably not 2 aircraft (pi3 + ads-b) and a proximity alert (mode s)

I couldn’t find this topic elsewhere and apologies if already covered
« Last Edit: November 06, 2017, 08:39:31 am by Gaz »

Keithvinning

Re: Filter different signals transmitting from same aircraft
« Reply #1 on: November 06, 2017, 08:41:31 am »
Hi Gaz

You will only see 1 aircraft. The 3 transmissions that you have noted will all be associated with a unique ICAO number. All will be detected only 1 will be shown. Probably in this instance the ADSB as it will be the strongest, then the PAW. Obviously you will see that ADSB PAW and FLARM are superior as they will have an associated GPS position.

Admin

Re: Filter different signals transmitting from same aircraft
« Reply #2 on: November 06, 2017, 08:59:24 am »
To add to Keiths posting.

This assumes that PilotAware and ADSB/Mode-S have been setup to use the same ICAO number, this is what PilotAware uses to determine it is from a common source.

For the Mode-S transmission, as Keith says - this will NOT generate a proximity warning as it is superceded by the PilotAware/ADS-B Positioned Data.

Having said the above, there is a slight potential gotcha, Mode-S transponders are configured to respond to all interrogations, so if interrogated by a Mode-C interrogation, it will elicit a Mode-C response.

If the receiving PilotAware is also setup to receive Mode-C, then there is the potential to report the Mode-C as a Proximity warning - this is because Mode-C transmissions do not contain the ICAO code, so cannot be associated with the ModeS/ADS-B/PilotAware.
The software in PilotAware has been written in such a way to try to mitigate the above dis-association between Mode-C & Mode-S/ES, we call this 'coalescing', and it works very well using a number of techniques to omit the Mode-C Proximity data, by determining that it has eminated from the same source as the Mode-S/ES transponder.

We have spent a lot of time refining these algorithms to help present multiple data sources in the most efficient and non conflicting manner.

Thx
Lee

Gary Nelson

Re: Filter different signals transmitting from same aircraft
« Reply #3 on: November 06, 2017, 04:12:34 pm »
Thank both - very helpful