A transceiver preferably embedded within a wearable security watch, PDA, or other device which achieves a variety of wireless ultrasonic and/or radio-frequency based functions, including digital identification and proximity and sensation monitoring of assets, individuals, pets, and the like. The portable or wearable device realizes these functions by periodically polling and receiving information tags within the transmitting distance of the device. The invention can help reduce the likelihood of the theft, loss, or misplacement by detecting that a tag associated with or attached to an entity has left an individual's proximity and sounding an alarm. The device can also assist individuals with sensory impairments, including persons who are deaf, diabetic, and the like, by detecting a tagged entity as it enters the space around an individual, or by detecting environmental stimuli, such as excessive heat in an individual's proximity or vital sign changes, and sounding an alarm.