Speed transducer of SPEED2100(Navman), Marine instrument!!!
 

Can anyone please tell me how did the speed transducer of SPEED2100 measure the speed of the boat?
I try to design my own display unit for this speed tranduscer. However, i dont know the operation of the speed transducer, such as how i calculate and measure the speed through the paddle wheel of the transducer. When the paddle wheel is moving, how i going to know the speed of the boat?
If anyone know, please tell me.
Thanks a lot!!!