DETERMINATION OF SPIN PARAMETERS OF A SPORTS BALL
First Claim
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1. A method of estimating a spin frequency of an unmarked rotating sports ball in flight, the method comprising:
- receiving, using a receiver of a radar arrangement, electromagnetic waves reflected from the unmarked rotating sports ball;
deriving from said received electromagnetic waves, via the radar arrangement, a signal having a first frequency corresponding to a velocity of the unmarked rotating sports ball, the signal being amplitude modulated by a modulation frequency; and
estimating, via the radar arrangement, at at least a single point in time, the spin frequency of the unmarked rotating sports ball based on at least one frequency distance between a harmonic of the modulation frequency and one or more of;
in a first case, the first frequency and, in a second case, an additional harmonic of the modulation frequency.
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Abstract
A method of determining spin parameters of a sports ball, such as spin axis and rotation velocity of a golf ball. The spin axis is determined solely from the trajectory of the flying ball, and the rotational velocity is determined from a frequency analysis of a signal provided by a radar, which signal comprises spectrum traces positioned equidistantly in frequency, which frequency distance relates to the spin velocity.
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Citations
20 Claims
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1. A method of estimating a spin frequency of an unmarked rotating sports ball in flight, the method comprising:
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receiving, using a receiver of a radar arrangement, electromagnetic waves reflected from the unmarked rotating sports ball; deriving from said received electromagnetic waves, via the radar arrangement, a signal having a first frequency corresponding to a velocity of the unmarked rotating sports ball, the signal being amplitude modulated by a modulation frequency; and estimating, via the radar arrangement, at at least a single point in time, the spin frequency of the unmarked rotating sports ball based on at least one frequency distance between a harmonic of the modulation frequency and one or more of;
in a first case, the first frequency and, in a second case, an additional harmonic of the modulation frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for estimating a spin frequency of an unmarked rotating sports ball in flight, the system comprising:
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a receiver of a radar arrangement configured to, at at least a single point in time, receive electromagnetic waves reflected from the unmarked rotating sports ball and provide a corresponding signal, which is amplitude modulated by a modulation frequency, wherein the radar arrangement is configured to perform a frequency analysis of the amplitude modulated signal and detect at least one harmonic of the modulation frequency, the radar arrangement being further configured to estimate the spin frequency from a frequency distance between said at least one harmonic and one or more of;
in a first case, a first frequency corresponding to a velocity of the unmarked rotating sports ball and, in a second case, an additional harmonic of the modulation frequency. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A system for estimating a spin frequency of an unmarked rotating sports ball in flight, the system comprising:
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a receiver of a radar arrangement; and a computer-readable medium storing instructions which, when executed on the receiver, cause the receiver to perform operations comprising; receiving electromagnetic wave reflected from the unmarked rotating sports ball; deriving, from the electromagnetic waves, a signal having a first frequency corresponding to a velocity of the unmarked rotating sports ball, the signal being amplitude modulated by a modulation frequency; and estimating, at a point in time, the spin frequency of the unmarked rotating sports ball based on a frequency distance between a harmonic of the modulation frequency and one of the first frequency and an additional harmonic of the modulation frequency. - View Dependent Claims (19, 20)
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Specification