This patented solution offers a compact mobile monitoring device that can monitor location and other information. The device includes a GPS receiver, an auxiliary sensor and a wireless communication module. The device is compact and low-cost because of integrity, such as the wireless communication module and the GPS receiver can be on a single IC. In addition to location monitoring, the device can monitor environmental information, such as temperature. The device can be used to track an animal, such as a dog. Or, the device can be used to track a package and change its environment accordingly.