Patent ID: 8463540

Claim:
A system for use on a shopping cart to enable movement of the shopping cart to be monitored and controlled, the system comprising: a shopping cart wheel; a braking mechanism configured to inhibit movement of the shopping cart; and electronic circuitry coupled to the braking mechanism, said electronic circuitry configured to detect signals that reflect a current location of the shopping cart wheel, and to transmit status messages via a wireless radio frequency (RF) link, including status messages reflective of said signals detected by the electronic circuitry, said electronic circuitry comprising: a Very Low Frequency (VLF) receiver configured to detect VLF signals transmitted by a VLF transmitter; an RF transceiver configured to communicate bi-directionally over the wireless RF link in a frequency band that falls substantially higher than a VLF frequency band; and a controller coupled to the VLF receiver, the RF transceiver, and the braking mechanism, said controller configured to control the braking mechanism; wherein the electronic circuitry is configured to determine, based at least in part on messages received over the RF link with the RF transceiver, whether to respond to detection of a VLF signal by the VLF receiver by activating the braking mechanism.