An object detection device which determines an amplitude A.sub.r of an ultrasonic wave received by a receiving unit, detects a frequency f.sub.r of the ultrasonic wave, sweeps a frequency f.sub.p of a pulse signal after a predetermined time has elapsed from start of generation of the pulse signal, and determines that the received ultrasonic wave is a reflected wave of the probe wave when the frequency f.sub.r after the amplitude A.sub.r becomes a predetermined reference value or more from start of transmission of the probe wave makes the same change as the frequency f.sub.p. When an ultrasonic wave received by a receiver is determined to be a reflected wave of the probe wave, the object detection unit calculates a distance to an object based on a time from transmission of the probe wave to reception of the ultrasonic wave.

An object detection device which determines an amplitude A.sub.r of an ultrasonic wave received by a receiving unit, detects a frequency f.sub.r of the ultrasonic wave, sweeps a frequency f.sub.p of a pulse signal after a predetermined time has elapsed from start of generation of the pulse signal, and determines that the received ultrasonic wave is a reflected wave of the probe wave when the frequency f.sub.r after the amplitude A.sub.r becomes a predetermined reference value or more from start of transmission of the probe wave makes the same change as the frequency f.sub.p. When an ultrasonic wave received by a receiver is determined to be a reflected wave of the probe wave, the object detection unit calculates a distance to an object based on a time from transmission of the probe wave to reception of the ultrasonic wave.

An ultrasonic system for determining the location of a driver of a vehicle, includes a hand-held device with at least a first ultrasonic sensor, wherein the first ultrasonic sensor has at least one transmitter, and a motor vehicle having a multiplicity of second ultrasonic sensors, wherein the second ultrasonic sensors each have at least one receiver for receiving signals of the first ultrasonic sensor. A method is disclosed for determining the location of a driver of a vehicle.

An ultrasonic system for determining the location of a driver of a vehicle, includes a hand-held device with at least a first ultrasonic sensor, wherein the first ultrasonic sensor has at least one transmitter, and a motor vehicle having a multiplicity of second ultrasonic sensors, wherein the second ultrasonic sensors each have at least one receiver for receiving signals of the first ultrasonic sensor. A method is disclosed for determining the location of a driver of a vehicle.

A method of determining a measure of wave speed intensity in a fluid conduit uses ultrasound measurements to determine the conduit diameter, as a function of time, at a longitudinal position of the conduit, and to determine a measure of fluid velocity, as a function of time, in a volume element at said longitudinal position of the conduit. The ultrasound measurement to determine the measure of fluid velocity is effected by decorrelation of scattering objects within the fluid flow in successive frames sampling the volume element. A wave speed may be determined from a ratio of the change in fluid velocity at the longitudinal position as a function of time and the change in a logarithmic function of the conduit diameter as a function of time. A measure of wave intensity may be determined as a function of change in determined conduit diameter and corresponding change in fluid velocity.

A method of determining a measure of wave speed intensity in a fluid conduit uses ultrasound measurements to determine the conduit diameter, as a function of time, at a longitudinal position of the conduit, and to determine a measure of fluid velocity, as a function of time, in a volume element at said longitudinal position of the conduit. The ultrasound measurement to determine the measure of fluid velocity is effected by decorrelation of scattering objects within the fluid flow in successive frames sampling the volume element. A wave speed may be determined from a ratio of the change in fluid velocity at the longitudinal position as a function of time and the change in a logarithmic function of the conduit diameter as a function of time. A measure of wave intensity may be determined as a function of change in determined conduit diameter and corresponding change in fluid velocity.

An object detection device comprises a transmission sound pressure adjustment unit adjusting a sound pressure of the search wave so that the sound pressure of the search wave or a reflected wave based on the search wave is within a predetermined transmission target range. The transmission unit transmits, as the search wave, a first search wave with a first frequency changing with time at a first rate and a second search wave with a second frequency changing with time at a second rate that is different from the first rate. The transmission sound pressure adjustment unit is configured to adjust the sound pressure of each of the first and second search waves so that the sound pressure of the corresponding one of the first and second search waves or the reflected wave based on the corresponding one of the first and second search waves is within the transmission target range.

An object detection device comprises a transmission sound pressure adjustment unit adjusting a sound pressure of the search wave so that the sound pressure of the search wave or a reflected wave based on the search wave is within a predetermined transmission target range. The transmission unit transmits, as the search wave, a first search wave with a first frequency changing with time at a first rate and a second search wave with a second frequency changing with time at a second rate that is different from the first rate. The transmission sound pressure adjustment unit is configured to adjust the sound pressure of each of the first and second search waves so that the sound pressure of the corresponding one of the first and second search waves or the reflected wave based on the corresponding one of the first and second search waves is within the transmission target range.

An object detection device which determines an amplitude A.sub.r of an ultrasonic wave received by a receiving unit, detects a frequency f.sub.r of the ultrasonic wave, sweeps a frequency f.sub.p of a pulse signal after a predetermined time has elapsed from start of generation of the pulse signal, and determines that the received ultrasonic wave is a reflected wave of the probe wave when the frequency f.sub.r after the amplitude A.sub.r becomes a predetermined reference value or more from start of transmission of the probe wave makes the same change as the frequency f.sub.p. When an ultrasonic wave received by a receiver is determined to be a reflected wave of the probe wave, the object detection unit calculates a distance to an object based on a time from transmission of the probe wave to reception of the ultrasonic wave.

An object detection device which determines an amplitude A.sub.r of an ultrasonic wave received by a receiving unit, detects a frequency f.sub.r of the ultrasonic wave, sweeps a frequency f.sub.p of a pulse signal after a predetermined time has elapsed from start of generation of the pulse signal, and determines that the received ultrasonic wave is a reflected wave of the probe wave when the frequency f.sub.r after the amplitude A.sub.r becomes a predetermined reference value or more from start of transmission of the probe wave makes the same change as the frequency f.sub.p. When an ultrasonic wave received by a receiver is determined to be a reflected wave of the probe wave, the object detection unit calculates a distance to an object based on a time from transmission of the probe wave to reception of the ultrasonic wave.