Hi, just a little update on observations re region-5 MLAT. Just an observation from a long term ADSBX feeder, a little feedback, if you like, and some silly questions, maybe. No pressure. MLAT display for north-east Germany (region 5) on the public adsbx-VRS Global Radar page seems to have become somewhat unstable in the last few months. When the regions where last split, things seemed to work well, MLAT display improved, in terms of reliability of meta MODE S display (speed, altitude etc), as well as in general coverage. However, it gradually decayed for the above mentioned part of the world: A lot of aircraft appear with no speed, no altitude (many have GND), no call sign - in all possible variations. Additionally, MLAT display seems to "blink" or "jump" back and forth with different views of aircraft. What I mean by that is that the VRS display of Global Radar page jumps from displaying a few aircraft at some positions for a few seconds then jumps to a complete different set of aircraft at different positions in the next seconds. Then it jumps back to the previous "set" of aircraft - and so on. In addition, flight trails disappear that way, there is almost not long term flight trailing possible any more. With a few "jumps" back and forth between the above mentioned VRS view states, the trails will disappear. Aircraft constantly appear with short trails again. This had been much better in the past, meaning long term trail observation was possible without problems. Load issue? The above mentioned area coincides with the EU´s largest and most unique extreme military air training zone, ED-R 401 of MVPA type. Initially, MODE S observation of military aircraft was ok through ADSBX. Over the years, it went through a few ups and downs. Whenever MLAT would decay, ADSBX would change it to the better again. And currently we seem to be at down again. Military aircraft seem to disappear, a huge portion not showing at all (this has been verified on the spot by volunteers, comparing whats visible on ADBSX / FR24 / FA MLAT and what´s actually going on in the sky: often there are huge military air warfare sessions ongoing (with up to four fighter jets at once), while ADSBX shows a blank sky for that area, sometimes with a fraction of the fighter jets becoming visible on MLAT for a few seconds, then disappearing again, trails a complete garbled mess (used to be different). The above "jumps" or the the "blinking" between different states of the VRS view seem to briefly show military aircraft, then hiding them. The "bigger picture" is lost, as at any time, only a fraction of aircraft seem to be visible in a given view of VRS Global Radar for the above area. Military aircraft can sometimes be seen (MLAT) at takeoff, then disappearing mid flight. All military trails are messed up, too. No long term trails any more. Trails have become increasingly edgy in the past few months. They used to be smooth. They used to be observable for hours uninterrupted. There seem to be huge discrepancies somewhere in the feeder network covering that area, maybe in lat/long settings or time sync? Or could it be intentional active jamming/obfuscation of military traffic and exercises? When I look at the coverage map display for region 5 and there for north east Germany, MLAT coverage shows identical MLAT trails for many receivers, just in some instances with a offset of a couple dozen Kilometers. That seemed to be different in the past. You would have identical MLAT trails, geographically identical, for all receivers that covered them. They wouldn´t jump all over the place. Example: I run a few receivers. All show identical portions of MLAT trails, geographically identical. When I click on other receivers, they may show the very same MLAT pattern, just with a pretty stark offset from mine. While others show identical positioned trails to my receivers. These identical patterns, with a large offset is something that I never saw a few months ago. Can it lead to trashing MLAT so much that coverage shows the above signs in the VRS Global Radar page (blinking/jumping)? MODE 5: a standard that NATO wants to deploy for all military aircraft by 2025. A parliamentary question in Germany´s Bundestag revealed that, according to the fed govt, all military aircraft constantly (!) have "transponders" activ (!) that german air traffic control (apparently DFS can use MODE 5) uses, in order to ensure air traffic in civil/military mixed zones like MVPA NE will be safe (unless fighterjets crash amidst packed tourist hubs - like this summer). Since most fighter jets never show on MODE S MLAT, what transponders do they have activated then? MODE 5 seems to be an encrypted version of MODE S, as far as I understand. Does MODES 5 encrypt all data or is it actually still sending clear data? Would MODE 5 go unnoticed for MODE S MLAT as it is done here at ADSBX? Thanks for your insights!
