Golf course range finder

• US 5,311,271 A
• Filed: 07/28/1993
• Issued: 05/10/1994
• Est. Priority Date: 01/21/1992
• Status: Expired due to Fees

• Current Assignee: Dme/Golf Incorporated
• Original Assignee: Dme/Golf Incorporated
• Inventors: Hurt, David B., Neal, Gregory R.
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/099,052
• Time in Patent Office: 286 Days
• Field of Search: 356/4, 356/5, 342/118, 342/125
• US Class Current: 356/5.1
• CPC Class Codes: G01C 15/02 Means for marking measuring points
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal

Abstract

A range finder for use on a golf course comprising a transceiver and a target. The transceiver emits a transmit beam along a transmission axis which is received by the target, and the target returns a return beam to the transceiver. A lens on the transceiver surrounds the transmission axis and focuses the return beam on a detector. Preferably, the lens has a dimension which is about twice the diameter of a retro-reflector mounted on the target.

Claims

1. A gold course range finding apparatus for determining the distance between a golfer on a fairway and a topological feature of the golf course, said range finding apparatus comprising:

a target having a signal returner which receives an electromagnetic transmit signal incident thereon and responsively returns an electromagnetic return signal;

a transceiver comprising a return signal focuser comprising an optical lens, said transceiver further comprising a transmitter and a receiver, said transmitter transmitting said electromagnetic transmit signal along a transmission axis, said return signal focuser surrounding said transmission axis; and

wherein said transmitter further comprises a tubular shield, said shield passing through said lens and having a longitudinal axis coincident with said transmission axis and perpendicular to a latitudinal plane of said lens.

2. A golf course range finding apparatus for determining the distance between a golfer on a fairway and a topological feature of the golf course, said range finding apparatus comprising:

a target having a signal returner which receives an electromagnetic transmit signal incident thereon and responsively returns an electromagnetic return signal;

a transceiver comprising a return signal focuser, a transmitter and a receiver, said transmitter transmitting said electromagnetic transmit signal along a transmission axis, said return signal focuser surrounding said transmission axis;

wherein said receiver converts said return signal to an electrical signal, said transducer further comprising a signal processing circuit utilizing said electrical signal to determine the distance between said target and said transceiver;

wherein said signal processing circuit comprises;

an amplitude modulator electrically coupled to said transmitter;

a phase detector having a first input and a second input, said phase detector electrically coupled at said first input to said amplitude modulator and said phase detector coupled at said second input to said return signal receiver, said phase detector providing information indicative of the phase difference between said electromagnetic transmit signal and said electromagnetic return signal;

a return signal amplitude detector electrically coupled to said receiver, said amplitude detector providing information indicative of the amplitude of said electromagnetic return signal; and

a distance measuring circuit comprising an analog-to-digital converter, a microprocessor and memory.

3. The apparatus of claim 2, wherein said distance measuring circuit further comprises:

a digitization unit which digitizes said electrical amplitude signal and said electrical phase signal, said digitization unit providing a digital amplitude signal and a digital phase signal, respectively; and

a digital signal processor which filters said digital amplitude signal and said digital phase signal to suppress spurious noise in said digital amplitude signal and said digital phase signal.

4. The apparatus of claim 3, wherein said digital signal processor comprises a low pass filter which filters said digital signals.

5. The apparatus of claim 3, wherein said digital signal processor comprises a steady state detector, said steady state detector sensing said signals to identify per of stability in said signals.

6. The apparatus of claim 3, wherein said distance measuring circuit further comprises means for comparing said digital amplitude signal with an expected amplitude corresponding to the distance measured by said distance measuring circuit to determine whether the measured distance is valid.

7. The apparatus of claim 3, wherein said distance measuring circuit further comprises means for correcting said digital phase signal by subtracting a phase shift amount, the magnitude of said phase shift amount being dependent upon the magnitude of said digital amplitude signal.

8. A golf course range finding apparatus for determining the distance between a golfer on a fairway and a topological feature of the golf course, said range finding apparatus comprising:

a target having a signal returner which receives on electromagnetic transmit signal incident thereon and responsively returns an electromagnetic return signal;

a transceiver comprising a return signal focuser, a transmitter and a receiver, said transmitter transmitting said electromagnetic transmit signal along a transmission axis, said return signal focuser surrounding said transmission axis, said receiver converting said return signal to an electrical signal, said transceiver further comprising a signal processing circuit connected to said receiver, said signal processing circuit utilizing said electrical signal to determine the distance between said target and said transceiver, said signal processing circuit comprising a return signal amplitude detector electrically coupled to said receiver, said amplitude detector providing information indicative of the amplitude of said electromagnetic return signal, said signal processing circuit comparing said amplitude with a reference value to determine if the amplitude of said electromagnetic return signal is within a range of amplitudes.