Noise Sources: Target Radiated Noise• Target radiated noise can interfere with activereception. Is often the means of detecting atarget passively• Noise varies widely in strength with source type• Noise can have a wide variety of spectral shapes• Noise varies as 20*log(r) + ar18Applied Research LaboratoryTarget Echo• The target reflects a replica of the transmittedsignal• The echo level is proportional to the transmittedsource level.• The proportionality “constant” is target strength(TS), a complex measure of the sound reflectingattributes of the target.• Target echo varies as 40*log(r) + 2ar• Target echo spectrum of a moving target isdoppler shifted relative to transmitted signal 19Applied Research LaboratorySonar System Block Diagram20Applied Research LaboratorySonar System• A sonar system may be part of a largersystem, say an autonomous vehicle, withother subsystems (autopilot, propulsion,etc.)• Sonar systems can contain both atransmitter and receiver, sometimes usingthe same transducer hardware.• Often broken down into units of the sonarhardware itself, and a signal processing unit(SPU).

Target Radiated Noise
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