FREQUENCY TRACKING USING HIDDEN MARKOV-MODELS WITH AMPLITUDE AND PHASE INFORMATION

This paper demonstrates how the hidden Markov model (HMM) frequency tr acker can be extended by the addition of amplitude and phase informati on. The HMM tracker as originally formulated uses a gate of spectral b ins from FFT processing, and associates each cell with a state of the hidden Markov chain. A measurement sequence based on the output of a s imple threshold detector forms the input to the HMM tracker. Two exten sions to the original tracker are proposed. The first, the HMM/A track er, incorporates the FFT amplitudes in the cells of the measurement se quence. The second, HMM/AP tracker, does not use a measurement sequenc e, but uses instead the FFT amplitude and phase values in all cells wi thin the gate. A comparison of the results obtained in using the three HMM based trackers with simulated data is presented, and reveals that the extended trackers outperform the original HMM tracker. An analysi s of the effect of parameter mismatch for the three HMM based trackers is presented. The use of the three HMM based trackers as detectors is also discussed.