The map located here
https://radar.lowflyingwales.co.uk/pilotaware-contributors/ is an internal tool that we use to keep an eye on the PilotAware groundstations that connect to 360Radar to either contribute to our MLAT coverage or pull from it. It was primarily put together to show where it was likely that an aircraft would pick up transmissions from a PAW groundstation. It was based on code used to create other maps and as a result also happens to show the status of any receiver whose name starts with PW.
On the map, blue pins are PAW ground stations contributing to MLAT positions because they have a
second 1090 MHz SDR whilst red ones are either offline OR are simply pulling MLAT positions and are not contributing to them OR are sending data to our European server.
Receivers that show as red can do so for several reasons - often users will name a station whilst setting it up and then will rename it again. A good example is PWPWThame which was correctly renamed to PWThame in November 2019. PWThame has uploaded recently but was last seen yesterday (July 19th) as indicated by the Last Seen time. PWPWThame last uploaded, according to the Last Seen time, back in November 2019 presumably when it was correctly renamed. With nearly 1,200 360Radar contributors there's a fair amount of churn where users install a system and then reinstall it at some point later choosing a different name or spelling it differently.
In an ideal world the system would track these automatically but it doesn't and I then end up having to manually investigate why a station appears to be offline. I am currently in the process of cleaning the database of receiver names so that an automated email alert can be sent when a receiver hasn't uploaded for a period of time. This will contain the receiver name, latitude, longitude and altitude so that should the user need to re-install they can use the same values.
The Last Seen time is based on when the receiver last contributed to an MLAT calculation and to work that out we need access to the relevant server log files. Since this is an internal tool that was quickly thrown together for a specific purpose it doesn't access the data from our European server which is why all European stations are showing in red so in the case of European PAW ground stations this map can be ignored.
The Last Seen time will vary according to the receiver location so those receivers in more remote areas where there is less Mode S traffic may have Last Seen time several hours old. Since the demise of regional airline FlyBe (who had quite a large Mode S equipped fleet) the 360Radar network spends most of its time tracking mostly GA and military Mode S aircraft so once GA aircraft stop flying most groundstations will not contribute to an MLAT position until either a military aircraft flies over or another Mode S aircraft comes into view.
So does that mean that this map is useless ? No but it could be better.
The map suggests that PWThame last uploaded yesterday morning (July 19th at 09:22) indicating that there probably is a problem with that receiver as there were plenty of Mode S aircraft around to MLAT yesterday but with lots of dead receivers on the page it's misleading which is why I'm working on an email alerting system to notify that PAW groundstation owners that their receiver is down.
