Ball location system
First Claim
1. A ball location assessment apparatus for installation beneath a surface of a playing court, said apparatus including at least one transmit coil and at least one receive coil wherein said at least one transmit coil and said at least one receive coil are selectively aligned so as to be in a mutually adjacent and overlapping position to one another beneath a pre-designated portion of said surface, each receive coil being provided for detecting the presence of a magnetically permeable ball, the orientation of said at least one receive coil relative to said at least one transmit coil being such that the at least one receive coil is substantially electrically nulled so that the net induced electro-motive force across the at least one receive coil is substantially zero with respect to alternating magnetic fields emitted from said at least one transmit coil.
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Accused Products
Abstract
An arrangement to determine whether a tennis ball is "in" or "out" on a playing surface, which includes both a transmit coil and a receive coil beneath the playing surface and a modified tennis ball to have a non-zero magnetic permeability, so that an alternating signal can be transmitted from the transmit coil and re-radiated from the tennis ball, which can then be detected by the receive coils, and can be synchronously demodulated and resistive and reactive components of the signal analysed to discriminate the ball from other influences. The receive coils can be wound to avoid electro-magnetic interference from far fields.
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Citations
14 Claims
- 1. A ball location assessment apparatus for installation beneath a surface of a playing court, said apparatus including at least one transmit coil and at least one receive coil wherein said at least one transmit coil and said at least one receive coil are selectively aligned so as to be in a mutually adjacent and overlapping position to one another beneath a pre-designated portion of said surface, each receive coil being provided for detecting the presence of a magnetically permeable ball, the orientation of said at least one receive coil relative to said at least one transmit coil being such that the at least one receive coil is substantially electrically nulled so that the net induced electro-motive force across the at least one receive coil is substantially zero with respect to alternating magnetic fields emitted from said at least one transmit coil.
Specification