Principles and Equations for PDA

Mathematically, the phase of a Doppler burst received at detector i can be expressed as 

Note in eq. (4-37) that the refractive index of the particle, ti2, does not appear. Hence, in practice this means that the reflection mode is a useful scattering mode to employ in situations where the exact value of the refractive index is not known. 

For second-order refraction, P, cannot be given as a closed-form solution but must be solved for numerically by an iterative pr(x ess. In this mode, small inaccuracies in the value of the refractive index of the particle may result to large errors in its diameter estimation hence care should be used when employing this scattering mode. 

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