Parameter Estimation of Frequency-Hopping (FH-SS) Signals Using Modified Autocorrelation Techniques

Abstract

The paper deals with the estimation of two main parameters of frequency-hopping spread spectrum (FH-SS) signals': hop rate and epoch time. Hop rate is the number of frequency changes per second and it is equivalent to the code clock rate. Epoch time is the timing offset between the first hop and the receiver's clock when the transmitter and the receiver are not synchronized. Multiple-hop autocorrelation (MHAC) processor is used for estimating the hop rate of FH signals in the presence of broadband thermal noise. During the hopping time, the single-hop autocorrelation (SHAC) processor can be also used to estimate the epoch time. Previous work on both estimators assumes precise knowledge of the signal power, which in practical applications is usually not available apriori. Therefore modified MHAC and SHAC estimators are proposed here, which do not require prior knowledge of signal power. However, the signal power is estimated first and then utilized in the hop rate or epoch time estimation .The performance of the proposed estimators has been tested using extensive computational experiments. The estimators of hop rate for known and unknown signal power approach the same value for signal-to-noise ratio (SNR) ges 0 dB and the error in the estimation < 10% and similar results were obtained for epoch time, while the error in the estimation of signal power < 5% for SNR ges 0 dB.