Request for clarification in the paper: stability analysis of GPS carrier tracking loops by phase margin approach

Upon further study of the proposed technique presented in the paper ‘‘Stability analysis of GPS carrier tracking loops by phase margin approach’’ by the authors, Tian Jin and JunXing Ren, we feel that additional clarification is needed. We are offering recommendations for clarification to the authors, but we first preface our recommendations with our proposed GNSS carrier tracking loop model followed by our derivation of the associated transfer function.