Signal generation model considerations for time varying delayed signals

In their paper "Correlator Compensation Requirements for Passive Time Delay Estimation with Moving Source or Receivers," Adams et al. discuss the problem of estimating the time varying delay between two separately time varying delayed sensor signals. This correspondence gives a more exact derivation of the time varying delay at the input of the estimator. The investigations are given with the intention of facilitating the synthesis of signal generation models with several time varying delay elements.