Method and apparatus for digitally determining the speed of a target vehicle while the radar platform vehicle is in motion

A doppler radar device for determining the speed of a target vehicle when the radar platform vehicle is moving, said device comprising:

• a means for receiving a composite doppler signal having frequency components relating to the speed of said target vehicle and the speed of said radar platform vehicle;
• means for frequency translating the received doppler signal so as to lock the frequency translated component resulting from the platform vehicle speed to a preselected reference frequency;
• means for separating the frequency translated doppler signal into a first frequency translated component and a second frequency translated component;
• means for frequency translating said first frequency translated component to provide a first speed component;
• means for converting said first speed component into speed information;
• and
• means for displaying said speed information of said first speed component.

A method for separating the doppler signal received from a target vehicle by a moving platform having a doppler radar transceiver thereon into composite frequencies, said step comprising the steps of:

• frequency translating the received doppler signal so as to lock a frequency translated component thereof to a preselected reference frequency;
• filtering the received doppler signal into a first frequency translated component and a second frequency translated component;
• and
• frequency translating said first frequency translated component to provide a first signal suitable for displaying speed information.