Sonar signals

Medical Ultrasound Many of us have first seen our unborn children or grandchildren thanks to medical ultrasound technology. This application is somewhat related to sonar in that both use pulse echo methods to send and receive signals. However, in this short-range application, transducer arraj can be designed to form images. 

D. J. Daniels, Resolution of ultra wide-band radar signals , Proc. Inst. Elec. Eng.-Radar, Sonar Navig., vol. 146, no. 4, pp. 189-194, Aug 1999. 

Dipping sonar devices equip manned antisubmarine helicopters and fixed-wing aircraft the aircraft flies low and suspends a sonar device at the end of a wire-link which is held just below the surface of the w. The sonar technique is also used in sonabuoys, which use active or passive sonar to detect and locate submarines. Sonabuoys provide anti-submarine warfare data to aircraft which cannot dip sonar devices while hovering overhead, the data being transmitted by coded radio signals... 

Victory, 1993] Victory, C. (1993). Comparison of signal processing methods for passive sonar data. Master s thesis, Department of Electrical Engineering and Computer Science, Naval Post Graduate School. 

During the Titanic mission, the French researchers used a new kind of sonar known as side-scanning sonar. Ordinary sonar surveys a narrow field that must be carefully mapped out in advance. Side-scanning sonar eliminates this drawback, by picking up signals at a diagonal. 

The figure of merit for a sonic system of measurement that utilizes the generation, transmission, and reception of sound is defined as the maximum allowable transmission loss. This loss is derived from the sonar equation, which simply states that the received signal is equal to the background noise plus a measurement requirement, where the measurement requirement is set by the particular measurement under consideration. This method is not unique to sonics and may be applied to radar, astronomy, and communication theory. The advantage of the sonar equation that underlies the figure-of-merit computation is the fact that it permits quantitative comparison of various measurement schemes... 

Typically, each term in the sonar equation is given in decibels per unit bandwidth (1 Hz). A representation of a sonic flowmeter is presented in Fig. 5-1. The processed signal level (PSL) of a one-way transmission system, as shown in Fig. 5-1, may be defined by the equations... 

Sub-Bottom-Profiler This system is another multi-frequency acoustic system which is comparable to a seismic monitoring system of low seabed penetration capability. The acoustic emissions are frequency-modulated and the pulse rate is adjustable to suit the local requirements. The echoed signal can be recorded and processed into a display-form similar to the side-scan-sonar. It produces information about the thickness of sedimentation and can plot the contour of the seabed below the sedimentation layer. 

FIGURE 17.42 Generic active sonar system. (Source Adapted from Knight, W., Pridham, R.G., and Kay, S.M. 1981. Digital signal processing for sonar. Proceedings of the IEEE 69( 11) 1454. IEEE 1981.)... 

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