radar modeling

I work on a PC combat flight simulation of the F/A-18E and it seems in it that is the speed wich induce the range detection of the SAM radar : more the speed is slow , more the detection range is far .
It is not the contrary more you are quick more you are detect far for doppler radar ( I presume SAM like SA-10D/E SA-11 or 12 get Doppler radar ) ?

so now what believe , apparently it is the comportmentof the plane wich induce the apparition of the symbol so I believe that the EW page only watch radar contacts which have detect you but ???

Does a RWR must to watch both the radar contact wich have not detect you and the radar contact which have detect you in reality ?