A new bit synchronization method for a GPS receiver

We develop a maximum-likelihood bit synchronization algorithm. This algorithm computes an estimate of the bit energy for all possible bit boundary candidates and chooses that candidate which maximizes the energy. Means to estimate whether the received signal contains enough bit value changes are also presented. The effect of frequency error is analyzed. It is shown that small frequency errors can be tolerated. Furthermore, a way to deal with larger errors is developed. Computer simulations show that the new algorithm is efficient in handling a very weak received signal.