Patent ID: 7595633

Claim:
A method for measuring the velocity of a projectile, the method comprising: providing first and second magnetoresistive sensors that are biased by an applied voltage, wherein the first and second sensors are separated from each other by a distance, D; when a projectile is within a sensing path of the first sensor, communicating a first voltage signal from the first magnetoresistive sensor to a signal processing device and taking a first time measurement, t 1 , to be a signal point crossing of the first voltage signal, wherein at the signal point crossing the first voltage signal has a magnitude of about half the applied voltage; when the projectile is within a sensing path of the second sensor, communicating a second voltage signal from the second magnetoresistive sensor to the signal processing device and taking a second time measurement, t 2 , to be a signal point crossing of the second voltage signal, wherein at the signal point crossing the second voltage signal has a magnitude of about half the applied voltage; and calculating a velocity, v 1 , of the projectile, wherein v 1 =D×(t 2 −t 1 ) −1 .