- 1992 IEEE. A common problem in power networks is the estimation of the fundamental frequency of harmonic signals. A group of methods that have attracted significant attention in the literature are based on autoregressive modeling . When they are used, the frequency is found via the estimated autoregressive parameters of the model. In the paper we propose and examine two related methods that use the autoregression as an underlying model, avoid the estimation of its parameters, and determine the fundamental frequency directly. Simulation results are provided that demonstrate the performance of the methods.