Total least squares and constrained least squares applied to frequency domain system identification

Total-least-squares and constrained-least-squares methods are applied to the Transfer Function Determination Code (TFDC). TFDC is a frequency domain system identification code for determining the SISO input-output transfer function of a system from experimentally derived frequency response data. TFDC is modified to implement a total-least-squares solution, to employ a solution to the combined least-squares/total-least-squares problem, and to apply constrained least squares to ensure quadrantal symmetry of the poles and zeros. Results of applying each method to an example system are presented and compared.