A robust baud rate estimator for noncooperative demodulation

This article describes a robust baud rate estimator for the noncooperative demodulation of digitally modulated communication signals. The described algorithm is carried out in three stages. Starting with a coarse estimate in the first stage, this is refined in the following stages resulting in a very accurate estimate of the unknown band rate. Further an estimate of the symbol phase to initialize a digital phase locked loop is obtained. These signal parameters are used to obtain a control signal which drives an interpolator. Special care has been taken to cope with the time variant and frequency selective distortions expected in the HF-band