Abstract:
A signal transmitter system for an animal training system including an electrical impedance loop, a signal generator and a power supply. The signal generator is connected to the electrical impedance loop. The signal generator provides a current signal to the electrical impedance loop. The power supply provides a voltage level to the signal generator. The voltage level is dependent upon a measured characteristic of a voltage signal that results from an interaction of the current signal with the electrical impedance loop.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a signal transmitter system, and, more particularly, to a signal transmitter system for an animal containment system. 
         [0003]    2. Description of the Related Art 
         [0004]    Conventional and electrical fencing is commonly used to control the location of animals. Barrier fencing, which physically blocks the movement of the animal, is frequently used to confine both domestic pets and farm animals. Physical electrical fencing, which uses an electrical shock to discourage contact with the fence, is typically used to confine commercial livestock. The purpose of an electric fence is to keep farm animals within an area, or to prevent undesired animals from entering the property. High voltage electrical impulses are applied to the fence wire by an energizer. This impulse lasts only thousandths of a second but is repeated every second or so. An animal, which strays into contact with the wire, completes the circuit between the live wire and the soil. The result is an electrical shock sufficiently unpleasant to cause the animal to move rapidly away from the fence before the next electrical impulse. After a few encounters, animals learn not to touch the live wire or approach the fence too closely. 
         [0005]    Electronic animal control systems are known in which a radio frequency receiver collar is attached to the animal to limit the movement of the animal to a predetermined area of confinement. The predetermined area is configured through the physical arrangement of a subterranean transmission antenna, which transmits a unique electromagnetic signal produced by an operably linked transmitting device. The transmission pattern of the subterranean antenna creates zones of transmission or area boundaries in which the attached animal receiver collar is responsive to the uniquely transmitted electromagnetic signal. Upon entering a predetermined limit area, the receiver collar detects the unique electromagnetic signal and in response, delivers a correction stimulus, such as a mild shock or audible signal to the animal. The effect of the repeated stimulus teaches the animal, such as a dog, to avoid the limit area thus confining the animal without use of physical fences or barriers. 
         [0006]    The signal transmitters that send the signal through the subterranean antenna are sufficiently sized to power the antenna regardless of the geometry or the length of the antenna that is installed for the confinement of the animal. This leads to inefficient production of the unique electromagnetic signal. 
         [0007]    What is needed in the art is an efficient adaptive transmitter system. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a signal transmitter system that adapts to the impedance load of the subterranean antenna. 
         [0009]    The invention comprises, in one form thereof, a signal transmitter system for an animal training system including an electrical impedance loop, a signal generator and a power supply. The signal generator is connected to the electrical impedance loop. The signal generator provides a current signal to the electrical impedance loop. The power supply provides a voltage level to the signal generator. The voltage level is dependent upon a measured characteristic of a voltage signal that results from an interaction of the current signal with the electrical impedance loop. 
         [0010]    An advantage of the present invention is that the transmitter system produces less heat than a conventional system. 
         [0011]    Another advantage of the present invention is that an adjustable level of power is supplied to the signal generator to better match the signal generator to the attached impedance loop. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0013]      FIG. 1  is a schematical representation of a confinement system utilizing transmitter system of the present invention; and 
           [0014]      FIG. 2  is a schematical representation of elements of transmitter system of  FIG. 1 . 
       
    
    
       [0015]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a signal transmitter system  10  including an impedance loop  12  and a signal transmitter  14 . Signal transmitter  14  interacts with receiver collar  16  that is positioned around the neck of dog  18 . If dog  18  approaches a boundary defined by the location of impedance loop  12  a signal that is being transmitted over impedance loop  12  is detected by receiver collar  16  causing a corrective stimulus to be applied to dog  18 , to thereby confine dog  18  in the area defined by the geometry of impedance loop  12 . Signal transmitter  14  sends a unique current signal through impedance loop  12 , which is hereinafter referred to as a current signal. It is known that a current signal sent through an inductive component creates a voltage signal as a result of the interaction of the current signal with the inductance of the inductive component, such as impedance loop  12 . 
         [0017]    Since impedance loop  12  can conceivably on any type and form of planar geometrical layout for the confinement of dog  18  the length and shape of impedance loop  12  is not known by the manufacturer and is uniquely laid out to meet the animal owner&#39;s animal confinement needs. The present invention adapts to the impedance encountered by signal transmitter  14  by altering power supplied to the signal generator to more accurately tailor the power consumption of transmitter  14  to that needed to send the unique current signal through impedance loop  12 . 
         [0018]    Now, additionally referring to  FIG. 2  there is shown transmitter  14  powered by a power source  20 . Signal transmitter  14  includes a power supply  22 , a signal generator  24 , an amplifier  26  and a sensor  28 . Power supply  22  receives power from power source  20  and converts it into DC power that is supplied to signal generator  24  and amplifier  26 . Signal generator  24  includes circuitry to create the unique current signal that is to be sent into impedance loop  12 . The signal created in signal generator  24  is amplified by amplifier  26 , which sends the current signal into impedance loop  12 . When amplifier  26  is driving the current signal at a predetermined frequency through impedance loop  12  it may require a relatively high power supply voltage to accomplish this. Controlling circuitry contained in power supply  22  utilizes information from sensor  28  from the reflected voltage signal caused by the current signal being sent through impedance loop  12  to determine if the voltage level from power supply  22  should be altered as it is supplied to signal generator  24  and/or amplifier  26 . For example, a microprocessor may be utilized to monitor the slew or signal clipping that is detected in the voltage signal sensed by sensor  28 . The microprocessor will periodically take a burst of samples of the analog waveform representative of the voltage signal detected by a sensor  28 . If there is a high slew rate or if there is more than a certain number of samples with less than a predetermined amount of change, which is known as signal clipping, the voltage from power supply  22  is increased to reduce or eliminate the clipping. The detection of a high slew rate indicates that more power is needed to properly send the correct current signal through impedance loop  12 . If the slew rate is lower than a predetermined amount then the power supply voltage is decreased, thereby reducing the power dissipated in signal generator  24  and/or amplifier  26 . 
         [0019]    Although the peak voltage levels of the voltage signal could be measured in order to detect the needed power supply adjustment, it has been found that impedance loop  12  may pick up other signals and distort the peak values of the voltage signal that would be detected by sensor  28 . With this in mind the present invention relies upon the rate of change of the voltage signal, also known as the slew rate to determine if the voltage level being supplied by power supply  22  should be adjusted. The slew rate measurements may be averaged over a predetermined period of time, such as ten seconds, to prevent any oscillations that would occur if the reaction time was too fast. 
         [0020]    The adjustment of voltage from power supply  22  may consist of multiple levels that are selected by the microprocessor based upon the slew rates detected in the information from sensor  28 . Alternatively, the voltage adjustment of power supply  22  may be a continuous adjustment between a predetermined high voltage and a minimum voltage. 
         [0021]    To understand the slew rate detection method of the present invention a sinusoidal waveform can be envisioned for the sampling of the voltage. The signal slew rate is of course dependent upon the portions of the signal being measured. If the voltage signal is being clipped then several samples will show minimal changes in the voltage level caused by the clipping. If the slew rate is high during the signal crossing of zero volts, then the voltage signal peak will be high. Conversely, if the slew rate is low during the signal crossing of zero volts, then the voltage signal peak is lower. This correspondence of the slew rate of the signal with the anticipated peak value is used in the present invention to adjust the voltage supplied to the signal generator/amplifier. 
         [0022]    The present invention advantageously reduces the amount of power utilized by the transmitter system, which increases the reliability and longevity of the transmitter system while saving energy. Another advantage of the present system is that the uniform current signal can be efficiently produced, which is then less dependent upon the geometry and length of impedance loop  12 . 
         [0023]    While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.