Over the last few months a series of unidentified Mode-s plots have been appearing across the country
They are being picked up by the multilateration service offered by PlanePlotter.
Whilst appearing to be valid flights , the concensus of opinion is that they are being "generated " to test a network of some type
Initial observations point to the signals eminating from antenna mounted on cell phone masts and possibly on wind turbines.
In the animation below the generated signals start in the Race Bank windfarm and end outside Leeds.
All traffic has been filtered out apart from selected Mode-S idents
http://i54.tinypic.com/120pmrl.gif
Similar tracks have appeared in the Wellingborough area and also across the Manchester zone. They end as abruptly as they start.
Is the UK testing a wide area multilateration system which will use the cell phone mast infrastructure as ground stations ?