Consistent estimation models for the fine time synchronization of FH systems

Four basic estimation methods are discussed, namely the delay-advance method, the early-late filter method, a modified early-late filter method, and the novel two-tone method. These methods all use noise power estimation in a frequency bin not occupied by a signal; this estimate is then used to reduce the bias and make the estimate of the time error consistent. Simulation results on the performance of these four methods obtained using the bias reduction (BR) technique are given. The simulation results are for AWGN (additive white Gaussian noise) only, which represents system noise and noise jamming across the entire band. The BR technique is shown to reduce the bias and make the estimates consistent for all four basic methods. Although the BR also increases the standard deviation, the decrease in bias more than offsets the effect of increased standard deviation. The best overall performance is achieved with the modified early-late filter method