the company I work for make the displays. The factory is in Ireland, we do mainly sale/support and design in the UK office. Occasionally I fly to Southern Ireland to test my design on the hardware. This sign below is about 10 meters long and 3 meters. Dot resolution of 378x88 pixels in Yellow and While
This is the controller behind it all. It takes in a LVDS or DVI signal. Cuts out the top left hand corner of the display and generate LED data. This is done across 4 FPGA's so we had enough pins. Many ribbons cables here. The controller also detect is 1 LED has failed too, and can report back to the head office.