Golf ball location system

Abstract

A golf ball and golf ball search receiver is described. The golf ball includes a transmitter and the search receiver includes a receiver. The golf ball may be activated by an accelerometer that causes the transmitter to produce an RF signal across a predetermined frequency band for a duration of time, which may be determined by a timer. The transmitter modulates an audio signal and transmits the modulated signal within an output band of the transmitter. The receiver tunes to a narrower band thereby receiving and demodulating a fraction of the transmitted signal. The receiver's input band halves an input bandwidth set to coincide with a fraction of the output band, thereby alleviating adverse effects due to variations in transmitter and receiver components, as well as adverse effects due to localized noise within the output band. Additionally, relative positioning of the receiver's input band may cycle across the transmitter's output band to further mitigate the adverse effects of localized noise.

1 . A system for locating a golf ball, the system comprising: 
 the golf ball having an encapsulated transmitter that modulates an audible signal to an output band, wherein the output band defines an output bandwidth; and    a receiver having an input band defining an input bandwidth wherein a center frequency of the input band of the receiver is variable;    wherein the input bandwidth is smaller than the output bandwidth.    
   
   
       2 . The system of  claim 1 , wherein the audible signal comprises a saw-tooth wave.  
   
   
       3 . The system of  claim 1 , wherein the audible signal has a period defining a frequency between about 20 Hz and about 20 kHz.  
   
   
       4 . The system of  claim 1 , wherein the audible signal has a period defining a frequency between about 60 Hz and about 2 kHz.  
   
   
       5 . The system of  claim 1 , wherein the audible signal has a period defining a frequency between about 2 kHz and about 6 kHz.  
   
   
       6 . The system of  claim 1 , wherein the audible signal comprises a sequence of audible tones.  
   
   
       7 . The system of  claim 1 , wherein the audible signal comprises a sequence of audible tones and pauses between the tones.  
   
   
       8 . The system of  claim 1 , wherein the transmitter further includes a battery and the audible signal indicates a condition of the battery.  
   
   
       9 . The system of  claim 1 , wherein the transmitter includes a free running oscillator.  
   
   
       10 . The system of  claim 9 , wherein the free running oscillator includes an LC tank circuit having an inductor and a capacitor.  
   
   
       11 . The system of  claim 10 , wherein the inductor comprises an antenna.  
   
   
       12 . The system of  claim 1 , wherein the transmitter further includes a variable capacitance.  
   
   
       13 . The system of  claim 12 , wherein the variable capacitance is provided by a bank of switched capacitors.  
   
   
       14 . The system of  claim 13 , wherein the bank of switched capacitors is controlled by an output of a counter.  
   
   
       15 . The system of  claim 1 , wherein the center frequency of the input band cycles across a range of the output band at a sub-audible rate.  
   
   
       16 . The system of  claim 15 , wherein the sub-audible rate is between about 0 Hz and about 10 Hz.  
   
   
       17 . The system of  claim 15 , wherein the sub-audible rate is between about 1 Hz and about 2 Hz.  
   
   
       18 . The system of  claim 15 , wherein the input band cycles across the output band following a saw-tooth wave having a period defined by the sub-audible rate.  
   
   
       19 . The system of  claim 15 , wherein the input band cycles across only a sub-portion of the output band thereby defining a guard band at each end of the output band.  
   
   
       20 . The system of  claim 19 , wherein the guard band is at least as wide as the input bandwidth.  
   
   
       21 . The system of  claim 1 , wherein an output bandwidth of the output band is between about 4 MHz and about 5 MHz.  
   
   
       22 . The system of  claim 1 , wherein the input bandwidth is between about 0.1 MHz and about 0.3 MHz.  
   
   
       23 . The system of  claim 1 , wherein an output bandwidth of the output band is between about 4 MHz and about 5 MHz and the input bandwidth is between about 0.1 MHz and about 0.3 MHz.  
   
   
       24 . The system of  claim 1 , wherein the input bandwidth represents less than 50. % of an output bandwidth of the output band.  
   
   
       25 . The system of  claim 1 , wherein the input bandwidth represents between about 5% and about 50% of an output bandwidth of the output band.  
   
   
       26 . The system of  claim 1 , wherein the input bandwidth represents between about 2% and about 8% of an output bandwidth of the output band.  
   
   
       27 . The system of  claim 1 , wherein the receiver includes a detector.  
   
   
       28 . The system of  claim 27 , wherein the detector comprises an AM detector.  
   
   
       29 . The system of  claim 1 , wherein the receiver includes an extendable antenna.  
   
   
       30 . A golf ball comprising: 
 an encapsulated transmitter that modulates an audible signal to an output band;    wherein the output band defines an output bandwidth and the transmitter includes a free running oscillator having an inductor and a capacitor.    
   
   
       31 . The golf ball  claim 30 , wherein the free running oscillator further has a variable capacitance.  
   
   
       32 . The golf ball  claim 31 , wherein the variable capacitance is provided by a bank of switched capacitors.  
   
   
       33 . The golf ball  claim 32 , wherein the bank of switched capacitors is controlled by an output of a counter.  
   
   
       34 . A method to locate a golf ball using a golf ball location system having a transmitter encapsulated in a golf ball and a receiver, the method comprising: 
 modulating an audible signal with the transmitter;    transmitting the modulated signal to an output band;    providing a receiver with an input band, wherein the input band is narrower and within the output band;    receiving an input signal residing within the input band; and    varying a center frequency of the input band to traverse the output band.    
   
   
       35 . The method of  claim 34 , wherein the act of varying the center frequency comprises modulating the input band across the output band at a sub-audible rate.  
   
   
       36 . The method of  claim 34 , further comprising: 
 extending an antenna on the receiver to increase an input signal gain;    moving the receiver closer to the transmitter; and    retracting the antenna to decrease the input signal gain.    
   
   
       37 . The method of  claim 34 , wherein the act of modulating the audible signal comprises cycling a center frequency of the transmitted signal across the output band at the audible rate.