Detection and Estimation

The concepts of echo detection and parameter estimation are introduced in this chapter by considering point scattering which is the simplest scattering model. It results from signal propagation in a homogeneous non-dispersive medium and reflection from a single distant point that may be moving at constant speed with a velocity component along the line of sight. The resulting echo is a Doppler dilated and delayed signal with the same fundamental form as the transmitted waveform (2.26). An understanding of approaches to its detection and the estimation of its constituent parameters is fundamental to an understanding of the signal processing required for the more complex echos treated in later chapters. Common examples are those that are delay and/or Doppler spread because of multiple propagation paths (multipath) especially in shallow water, boundary reverberation, and scattering from fish schools.