“…Many efforts have been made to improve these techniques: analyzing their convergence [21], adding mechanisms for online detection of noise frequencies [22], [23], getting better frequency resolution when the frequency separation between two adjacent tones is small [24], correcting the mismatch at those frequencies [25]- [27], or considering non-linearities M. Ferrer, M. De Diego, G. Piñero, A. Gonzalez are with the Institute of Telecommunications and Multimedia Applications (iTEAM), Universitat Politècnica de València (UPV), Spain, e-mail: mferrer, mdediego, gpinyero, agonzal@dcom.upv.es.…”