The procedure of phase vector measurement using the least square algorithm is briefly described and an optimized minimum square filter is given. The influence of temperature on the algorithm is analyzed and simulated calculation is made of the relationship between temperature-shift and AC measuring errors. An analysis is also made of the temperature-shift on communication. It is proposed that the degree of temperature-shift be obtained using the baud-rate-self-adaptive algorithm. The sampling period is calibrated so as to ensure the error-free phase measuring method and procedure.