H2.1a Piezoelectric principles Analyze the effect of transducer design on Transducers and Transducer arrays beam design, characteristics and performance. generation of beam-forming, side lobes. acoustic waves Transducer Quality factor Describe the design and use of and spherical waves in wide-bandwidth and terms of wavelength, parametric transducers. (I) amplitude and frequency. Absorption, spherical Differentiate between chirp and CW spreading transmission, and characterize their Frequency, attenuation relative performance. relationship to range Acoustic units, intensities and Determine source level from typically sound levels available sonar specification. Signal to noise ratio H2.1b Explain how properties of the acoustic Active Sonar Equation Propagation of medium and source frequency affect the including sound source, causes acoustic waves propagation of acoustic of propagation loss in relation to water properties together Calculate propagation loss in practical (A) with characteristics of the sea situations, using medium property floor and targets, acoustic observations and available tables. noise level and directivity H2.1c Acoustic Identify the sources of noise and describe Continuous Wavelength (CW), noise the effect of noise on echo sounding. Chirp transmission Define the directivity index. System parameters including (I) bandwidth, pulse length, pulse Calculate the effect on sonar range of a repetition rate, gain, detection variety of noise conditions and sonar threshold. directivity circumstances. Range resolution and spatial H2.1d Define the characteristic impedance of an resolution. Reflection, acoustic medium. Dynamic range, clipping and scattering and saturation system Assess the effects of varying seafloor Sound speed profile and performance. composition, texture, and slope on echo gradient strength.
H2.1a Transducers and generation of acoustic waves (I) Piezoelectric principles Transducer arrays design, beam-forming, side lobes. Transducer Quality factor and spherical waves in terms of wavelength, amplitude and frequency. Absorption, spherical spreading Frequency, attenuation relationship to range Acoustic units, intensities and sound levels Signal to noise ratio Active Sonar Equation including sound source, causes of propagation loss in relation to water properties together with characteristics of the sea floor and targets, acoustic noise level and directivity Continuous Wavelength (CW), Chirp transmission System parameters including bandwidth, pulse length, pulse repetition rate, gain, detection threshold. Range resolution and spatial resolution. Dynamic range, clipping and saturation Sound speed profile and gradient Analyze the effect of transducer design on beam characteristics and performance. Describe the design and use of wide-bandwidth and parametric transducers. Differentiate between chirp and CW transmission, and characterize their relative performance. Determine source level from typically available sonar specification. H2.1b Propagation of acoustic waves (A) Explain how properties of the acoustic medium and source frequency affect the propagation of acoustic Calculate propagation loss in practical situations, using medium property observations and available tables. H2.1c Acoustic noise (I) Identify the sources of noise and describe the effect of noise on echo sounding. Define the directivity index. Calculate the effect on sonar range of a variety of noise conditions and sonar directivity circumstances. H2.1d Reflection, scattering and system performance. Define the characteristic impedance of an acoustic medium. Assess the effects of varying seafloor composition, texture, and slope on echo strength.
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