| 摘要 |
A shopping cart receiver alarm system includes an RF transmitter for transmitting an RF signal having at least a minimum signal strength within a boundary that is generally defined by the outermost contours of a store parking lot . A receiver assembly responsive to the RF signal is housed within the handle of a shopping cart. The receiver assembly includes a self-contained power supply, an RF receiver for receiving the RF signal and for providing an output signal indicating a loss of RF signal strength. The receiver assembly further includes a timing circuit and an audible alarm responsive to an alarm signal generated by the timing circuit. The alarm signal controls the audible alarm according to a selectable alarm timing sequence that is initiated by the output signal of the RF receiver. According to the alarm timing sequence, the timing circuit activates the audible alarm for a first period of time, inactivates the audible alarm for a selectable grace period of time to encourage return of the shopping cart, and, if the shopping cart is not returned, the audible alarm is thereafter continuously activated. The audible alarm is immediately inactivated at any time during the alarm timing sequence if the shopping cart is returned within the boundary. 22
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