Double mode surveillance system based on remote audio/video signals acquisition

At present, remote human signature detection plays an increasingly important role in the field of anti-terrorism and security defense all around the world. In order to acquire remote, non-cooperative human signature signals, a double mode (audio/video) surveillance system is developed. The system mainly consists of a Laser Doppler Vibrometer (LDV), a pan-tilt-zoom (PTZ) camera and a theodolite. The LDV is used to acquire remote audio by detecting the vibration of the object (caused by the acoustic pressure). The PTZ camera is used to capture the video of the human body, and track the body when he/she moves, then analyze the image to select a proper vibrating target for LDV measurements. The theodolite is applied to control the orientation of the LDV. For the reason that many noise sources disturb the LDV-measured signals, such as laser speckle noises, environmental noises and the noises caused by sensor moving, a kind of speech enhancement technology (OM-LSA algorithm) is used to improve the intelligibility of the noisy voice signals detected by the LDV system. Experiments results indicated that the SNR and MOS of the LDV speech signal (the range is 150 m) can be increased by 135% and 26% respectively by using the speech enhancement technology, and the remote speech and video signals (the range is 30 m) can be obtained by the double-mode surveillance system.