Frequency error measurement in GMSK signals in a multipath propagation environment

The paper presents an efficient method for evaluating the carrier frequency in GMSK communication systems. This method operates in a non-intrusive way. It utilizes the Learning Vector Quantisation neural network based demodulator for reconstructing the transmitted phases. From these and the expected phases is estimated the carrier frequency error. The method is able to operate both in static and multi-path propagation cases and it does not require a high frequency sampling rate because the base-band signal is processed. In order to apply the method two procedures, PSP (Procedure for Static Propagation) and PMP (Procedure for Multi-path Propagation), are set-up. Tests performed on GMSK signals show that the method is quite attractive, fast and more accurate if compared with other approaches.