Pet owners have long struggled with adequate measures of pet containment. Inadequately confined pets run the risk of damaging property and endangering the animal. Physical barriers such as fences can be quite expensive and often not aesthetically pleasing. For over 20 years a number of pet containment systems have been developed to keep animals to predefined areas. Imbedding a wire perimeter and connecting to a transmitter system has been a popular method. The pet wears a collar that has a receiver and a motivation system for providing a stimulus to the pet as it approaches a boundary. Limitations have been the cost associated with the wiring and the fact that the pets are unable to re-enter the boundary area if they escape. There is also the problem that a lawnmower can damage wires not buried properly. To overcome this limitation, wireless systems have also been developed. The receiver only produces a stimulus when there is a loss of signal from the pet.
In radio collars there is a safe area in which the pet can roam without receiving a warning stimulus. When the pet moves away from this area the collar/receiver gives a warning signal (a shock, loud sound, or other stimulation) to the pet. Therefore the pet learns to stay within the safe area. The collar unit comprises a multiplicity of radio signal receivers each having a receiving antenna. The system transmitter continuously transmits a radio frequency (RF) signal and a mobile receiver assembly mounted in the collar unit on the dog. The receiver assembly receives the RF signal and measures the intensity of the received signal.
Early patents for underground pet containment systems were granted in the early 1970s. Documentation as to who the original inventor was is not available but technology from electronic transmission had been in use for Global Positioning System (GPS) since the early 1960s to track animals in the wild. The desire to keep pets safe and away from restricted areas in private homes (such as gardens and children's play areas) moved the technology into the home market.
The materials for the collar range from nylon to leather with a metal buckle and D-ring to hold the collar in place. Suitable wiring and electronic components consist of oscillators, transistors, capacitors, and resistors that are incorporated in the receiver and transmitter devices. Systems using buried wire containment systems use heavy duty 18-gauge wire.
Some radio collars use a wire imbedded in the ground to transmit signals to the receiver. Other forms use only a transmitter box and the collar, avoiding the wire. Depending on the device's strength, it can cover anywhere from 50 to 500 yd (46-457 m). The level of intensity will also vary depending on the size and temperament of the dog. There are separate devices for smaller, larger, or more stubborn dogs.
Skilled technicians at work stations perform calibration tests such as soldering inspection, high and low voltage vibration, and humidity thermal cycling. The receivers are tested to ensure that the correct amount of voltage or level of sound is distributed when activated. The collar is also subjected to tests such as strength and durability.
Waste materials (discarded wire and electrical components) are disposed through industry waste removal. Any plastic that can be reused is melted down and remolded. When the collar material is defective, it is discarded.
Future systems are being designed that use orthogonally positioned antennas to ensure boundary signals are detected. The risk of inadvertent shocks from nonboundary RF signals has been greatly reduced by encoding the transmitter with a preselected signal eliminating errant shocks from abhorrent RF signals. Additionally trapped animals will no longer continue to receive corrections until the battery is drained of power. The shocks are suspended but the circuitry continues to monitor for the boundary signal. Microprocessor circuitry is used to analyze the received signals and to control the annoyance signals. The microprocessor circuitry is also be powered down when not in use and then turned back on when a signal is received to be analyzed to further conserve power. Additionally, the circuitry may include one or more motion sensors that allow the power-draining circuitry to be energized in response to movement of the animal such that when the animal is at rest and not trying to cross the boundary, the battery is not wasted trying to detect a boundary signal that should not be present.
Radio Fence Distributors, Inc. Web Page. December 2001. < http://radiofence.com >.
United States Patent and Trademark Office Web Page. December 2001. < http://www.uspto.gov/patft/index.html >.
Woolf, Norma Bennett. "Hidden Fences, Out of Sight May not Mean Peace of Mind." Dog Owner's Guide December 2001. < http://www.canismajor.com/dog/fencesl.html >.
Bonny P. McClain