I wonder if anybody has any ideas on something which I’m quite curious about…
I have been feeding the FR24 and Planefinder sites for the past 9 years. Recently I started to feed flightaware and have been looking at the ‘Nearby Sites’ section of my Flightaware stats. I would say I average around 1650 aircraft per day at this time of year. This puts me in the top half of the nearby feeders, probably only because I’m fortunate to live at quite a reasonable high elevation.
However, there is one feeder who stands out from the rest, and consistently picks up more than 1000 aircraft per day than any other nearby sites. The coordinates that are listed for them are not particularly in a place with higher elevations than where I’m located. It’s listed as being 6 miles away from me. I know the coordinates that are on the Flightaware site are only approximate, but it gives you a rough idea where the receiver is. The same feeder looks to be listed in the top 10 feeders in the UK on the FR24 website.
Something else that puzzles me is that their MLAT count of aircraft per day is quite low relative to the the overall aircraft they are seeing. In fact, a lot of nearby sites have better MLAT figures per day.
Not being that technically minded about ADS B, I was wondering how they could be achieving these sorts of figures. Is there a way they could have combined receivers in different parts of the country and their MLAT figures are tied to just one location, hence why their the MLAT figures are relatively so low?
Could well be one of the cases for why FR recently asked multi site feeders to turn off MLAT.
Get your flows wrong, you can erroneously send more than ‘real’ data back and boost your stats artificially.
FA and others try to account for it by using different ports. But you can still muck it up with the wrong NETCAT command
I can’t think of a location in this area that would have that sort of coverage and receiving so many positions over 250 miles. You would also think their MLAT numbers would be a lot higher than they are if they are seeing so much traffic from one receiver in one location. I have been looking on heywhatsthat.com and can’t find a location around this area that would produce anything like that sort of coverage.
I don’t know very much about linux, but I’m assuming using a NETCAT command allows you to feed multiple receivers into one feed. Perhaps that’s what’s happening and they have receivers in different geographical locations and their stats are aggregated on Flightaware. It’s the only way this novice can see them getting the figures that they are. It would sort of explain why there MLAT figures don’t reflect their overall figures and why they seem to be achieving a consistently high number of positions of over 250 miles.
I assumed (probably wrongly) each individual registered feeder would have to be tied to one geographical location and you would have to register any others not at that location separately under different usernames.
Netcat is not the only was to collect data from multiple feeds. There are other tools like Virtual Radar Server, ModesMixer2 etc.
If you have doubts that these recievers are violating the FA TOS, you should report it to FA
Friend of mine is operating one receivery, but with two sticks and two antennas in a church tower.
Reason is a concrete block in between. Operating only one of them would be half blind on one or the other side.
I used to think that about a feeder that’s only 6 miles from me, constantly pulling in big numbers, but I just put it down to them having a tuned setup that’s better than mine.
I have always wondered how people get even consistent position on the coloured bars, majority of mine is in the <50mi on both of my feeders
Leeds is pretty flat, a receiver mounted for example on any of the larger structures in the city … maybe even on a private radio tower in a garden with maybe 10m of height.
This is completely achievable.
Combining feeds usually looks very different.
Also MLAT wouldn’t work AT all when combining feeds.
Geograph is the most important factor for getting long range / good reception.
After that comes receive hardware. Spending a couple hundreds on hardware can make quite the difference compared to a cheaper setup.
That’s especially true when there is interference in the area.
The lower numbers for MLAT … might be that the MLAT isn’t working all the time for example due to a sloppily entered location or undervoltage now and then causing MLAT to desync.
The 2 setups you linked are perfectly achievable with good gear and a good view of the horizon.
The antenna having a phenomenal view in all directions is the basis for exceptional range.
Thanks for pointing out reasons why the MLAT figure and peers could be lower.
I’m still curious why in an area which isn’t very elevated and wouldn’t have good view of the horizon, what sort of set up you would need to achieve these kind of results. I’m at a elevation of about 173m. How would someone with a receiver at an elevation of around 100m be performing so well, even if they mounted the antenna on a 10m mast.?
Using heywhatsthat.com, which seems pretty accurate at predicting the maximum distance you would be able to see aircraft (depending on their altitude) from a particular location, I can’t find any locations in this area that would perform that well. Perhaps I’m missing something though?
Consider that “above sea level” (elevation) and and “above ground level” (height) are related, but separate things. And HeyWhat’sThat considers geographic obstructions but doesn’t know anything about buildings and trees at your location.
So if you have your antenna mounted at your roof peak, and it’s 8 meters off of the ground, but you are surrounded by multi-story buildings or trees, then your next door neighbor who has their antenna mounted on a 20 meter pole is likely to see significantly better results.
Remember that this hobby is primarily limited by line of sight.
