Looking around Winnipeg, there are 2-3 feeders within 250nm of each other. Based on the lack of coloured lines on the Eastern US Coverage map (http://www.adsbexchange.com/coverage-2/), I'm guessing that isn't a quorum to have "participated in a successful MLAT calculation" Assuming well tuned, on time, functioning feeders; What is the minimum number of feeders within what range for them to participate in MLAT calculations? How close it too close? (for example, putting a 2nd feeder 50 feet from the one in my garage probably isn't going to help much, right?) Is there an optimal distance?
As I understand it, the minimum receiver should be a minimum of 2 km (6561 ft) and the receiving stations should be as close to right angles to the transmitter for best results. Further, the optimal distance between receiving stations would be dependent on the altitude of the transmitter. Closer stations are needed for low flying aircraft, while stations farther away will work with aircraft at higher altitudes.
I'm assuming all receivers need to "hear" the Mode-S signals and so of the 2 stations closest to me, one's gone off line ("darethehair" - actually, looks like it's back atm) and the next one is too far away (>200nm). I see on the coverage map buttons for 4+, 5+ and 6+ "station overlap". Does that mean there needs to be a minimum of 4 stations to produce MLAT results? 2 doesn't seem to be enough. What about 3? I might be willing to setup another station, but only if would result in MLAT positions being produced/displayed.
You are right, 4 stations are necessary. Adding another station is a good idea. Somebody else will see more receivers in neighborhood and maybe start to feed ADSBx too. More than 200nm distance is acceptable (your range can cover part of other receiver range).
