This paper describes a new patent-pending digital-ultrasonic sensor network technology, which provides a “security protection sphere” around the authorized user(s) and the infrastructure system or system(s) to achieve C3I in Homeland Security and Law Enforcement Applications. If the system device, such as a firearm, a secure computer, PDA, or vehicle is misplaced, stolen or removed from the security protective sphere, an alarm is activated. A digital-ultrasonic sensor/tag utilizes the system’s physical structure to form a 2 to 20 Meter programmable protection sphere around the device and the authorized user. In addition, the system allows only authorized users to utilize the system, thereby creating personalized weapons, secure vehicle access or secure computer hardware. If an unauthorized individual accesses the system device, the system becomes inoperative and an alarm is activated. As the command and control, the authorized individual is provided a secure wristwatch/PDA. Access control is provided by "touch" and is controlled through the wristwatch/PDA/smartcard with a unique digital-ultrasonic coding and matching protocol that provides a very high level of security for each wireless sensor.