Sat Jan 12, 2019 11:32 am #1664843
leemoore1966 wrote:I have been told if the ADSB is broadcasting a SIL=0. Then the NACp should not be used
In which case it is indeed a receiver problem, as the receiver is passing NACp over the GDL90 interface for an ADSB source providing SIL=0
Thanks Lee, that is also interesting. I would have thought that knowing if NACp is low whether it is SIL=0 or SIL=1 is useful either way. As @neilmurg states. NACp is related to the number of satellites locked on and the resultant quality of the position report. So surely, this goes back to our debate about SIL=0 and SIL>=1 in that maybe we should have an ability to display the various levels of confidence in the reported position? I’m thinking colours, shades or shapes though and not whopping great rings of uncertainty for those with poor GPS/GNSS fixes for the reasons I stated before!
This is a good journey that we are all going through here and it was made poignant again yesterday when I overflew the area just south of WCO where the tragic mid-air occurred just over 2 years ago. These devices are now starting to see each other much better and flying with a PowerFLARM Portable and a SkyEcho 2 yesterday made me realise that these are great for spotting traffic that I may have missed before. Pretty much all EC devices on the market now (PAW, SE and PFLARM) can either see or be seen by the other, which is really great. I do think we are getting there with GA Electronic Conspicuity and that the convergence is happening - I’m definitely seeing much more GA ADS-B in the UK than I saw even just a year ago. Now with FLARM detection I will see even more. I’m still confident we’ll get over the ‘hump’ of concurrent Mode S use as well - I know this is being discussed at various levels in various organisations to agree the way ahead.
Here’s hoping 2019 sees further significant advances for the good of all.