On Friday, September 29, 2017 at 4:45:24 PM UTC-7, Darryl Ramm wrote:

Looking for the usage split with a dual-link receiver would be interesting... Andy Blackburn you got any observations for GA?

My observations are anecdotal and based on living 15 miles from SFO. I need to take my rig out away from a major airport to where it's mostly GA. With that disclaimer, here's what I saw sitting near the San Carlos, CA airport..

The targets shown on linked screenshots (link below) are from a version of Stratux that shows the type of ADS-B traffic by appending two characters to the beginning of the aircraft ID - e=1090ES, u=UAT for the link frequency; a=ADS-B direct, t=TIS-B, r=ADS-R. The screenshots are from earlier in the summer.

Observations:
1) Most of the ADS-B direct traffic is 1090ES, even for non-airline traffic.. I haven't done a lot of looking up of aircraft IDs to sort out type of aircraft. I'm presuming a bias towards high-end aircraft based on my location..
2) There is some UAT traffic, because something is asking for ADS-R and TIS-B over UAT and it's not me.
3) There seems to still a lot of transponder-only traffic as evidenced by all the TIS-B traffic. I am assuming that if this traffic had an ADS-B direct signal it would take display precedence over TIS-B.
4) A lot of aircraft appear to not have their ADS-B aircraft type set properly as jets seem to pretty regularly show up as pistons. Still trying to figure that one out.
5) Lots of traffic flips between ADS-B direct and ADS-R. I'm assuming this is based on whichever signal is stronger or some de-duplicating logic in Stratux.

https://drive.google.com/open?id=0Bw...Eg5ME8zZmNJWGs

Andy Blackburn
9B