Patent ID: 7672797

Claim:
A fluid flow velocity measurement system comprising: an ultrasonic transmitter transmitting a pulsed signal within a body of fluid, said pulsed signal comprising a plurality of pulses, each pulse of said plurality of pulses comprising a group of cycles of discrete frequency, each pulse of said plurality of pulses followed by a period of no transmission, and each pulse of said plurality of pulses having a predetermined pulse length, said predetermined pulse length referring to a time period encompassing said group of cycles of discrete frequency and not including said period of no transmission; an ultrasonic receiver receiving a plurality of Doppler shifted signals from objects flowing with said fluid, said Doppler shifted signals resulting from said pulsed signal reflected from said objects flowing with said fluid; said ultrasonic receiver receiving said Doppler shifted signals during a plurality of receive time intervals, each receive time interval occurring during said period of no transmission following each pulse of said plurality of pulses transmitted by said ultrasonic transmitter; said ultrasonic receiver generating a time domain signal train from said receiving during said plurality of receive time intervals; said ultrasonic receiver receiving a summation of reflections resulting from at least two prior pulses of said pulsed signal during each receive time interval of said plurality of receive time intervals, said reflections resulting from at least two prior pulses being above a noise level, at least one pulse of said at least two prior pulses being transmitted before a receive interval prior to each said receive time interval; a time domain to frequency domain signal convener producing a spectral response of said time domain signal train; a detection means for finding a peak Doppler shift within said spectral response of said time domain signal train, said peak Doppler shift resulting from said Doppler shifted signals reflected from objects flowing with said fluid; and a computation means for finding an average flow velocity based on said peak Doppler shift.