Anti Collision Device

i have been working on the simulation of a driver assist system namely,Anti collision device.using the principles of radar,the system will try to warn the driver in case of a possible head on collision with the car in front,the system will act as the helpline for the driver in windy,fogy or inclement weather. i have used simulink to circumvent the situation but i`m stuck as the minimum detectable distance of the system is 5m and max distance is 100m,resulting in the pulse repetition frequency of 1.5Mhz with 5% duty cycle. pls..advise

[Walter Roberson]

Okay, so the pulse repetition frequency is 1.5 MHz with 5% duty cycle. Why is that more or less of a problem than other frequencies or other duty cycles?