This document describes an Ethernet-based intelligent security system that uses both PIR (pyroelectric infrared) sensors and ultrasonic sensors for intruder detection. The system architecture includes indoor and outdoor sensor groups that detect intruders and trigger a majority voting mechanism (MVM). The MVM then activates indoor PIR and ultrasonic sensors. If the MVM detects an intruder, it triggers an embedded board to power a webcam for capturing images. The document discusses the working of the PIR sensors, ultrasonic sensors, and GSM modem used for remote monitoring and alarm functions. It also provides circuit diagrams and explains the working of the sensor processing, alarm, and GSM interfacing segments of the security system.