Comment by alnwlsn

I have dealt with such a system. I'm not sure it was GPS based but one of the options you could get was a radio system so that additional vehicles that arrived on scene would automatically sync their lights and sirens to match the ones already there. The lights and sirens themselves are CAN modules and run off a custom CAN bus. It was pretty interesting to go through the configuration software and see the literally hundreds of preset flash patterns for different regions of the world.