Patent ID: 8510869

Claim:
A method used for warning a skier/snowboarder of an approaching skier/snowboarder from the side or behind, comprising: a. A transmitter portion of a rear looking radar system module mounted within the skier's/snowboarder's helmet using: 2 MHz bandwidth, 5.8 MHz center frequency, 2 mW transmit power, direct sequence spread spectrum with binary phase shift key modulation and 1024 chip Hadamard code symbols and a radar range gate timer set to 4.5 s at transmission; b. A two element antenna array mounted within or on a rear surface of the skier's/snowboarder's helmet used in conjunction with transmit and receive beamformers to form ±30° beams; c. A receiver portion of said rear looking radar system module (mounted within the skier's/snowboarder's helmet) using: said radar range gate with 10 m maximum range, clutter processing to remove returns from stationary targets, a correlator matched to the 1024 chip Hadamard code, a threshold monitoring mechanism to declare a valid radar detection and turn off the radar range gate timer, and a range determination algorithm; d. A timing and control portion of said rear looking radar system module that includes a sequencing and alerting algorithm to control radar ping sequencing and user alerts; e. Right and left earphones mounted inside the skier's/snowboarder's helmet to which range proportional, variable frequency audio alerts are directed indicating range and direction to a detected target; f. A rechargeable battery mounted within said rear looking radar system module with a recharging interface mounted on a surface of the helmet; and g. A large ski glove friendly ON/OFF switch mounted on a surface of the skier's/snowboarder's helmet for easy access when transitioning to high false alarm rate areas.