An algorithm for parameter estimation of frequency hopping emitters and their separation and grouping in unique radio networks

1) Military Technical Institute, (VTI), Ratka Resanovića 1, 11132 Belgrade, SERBIA 2) Faculty of Electrical Engineering, Kralja Aleksandra 73, 11000 Belgrade, SERBIA Introduction ODERN radio surveillance systems have to intercept signals with unknown parameters in very complex multiple incident signal scenario in environments of high noise and interference. Furthermore, surveillance systems are often faced with the low probability-of-intercept (LPI) signals such as spread spectrum signals. Frequency hopping-FH signals are a class of spread spectrum signals. Interception of frequency hopping signals is a very complex and challenging technical problem. In typical tactical situation more classical as well as frequency hopping emitters with unknown signal parameters are active at the same time as a frequency sub-band. These unknown parameters have to be estimated from the radio signal received in the given frequency band and time observation interval. Modern radio surveillance systems have to provide detection of FH signals, estimation of direction-of-arrival (DOA), separation of FH signals from narrowband signals, separation and grouping of FH transmitters in unique radio networks. An algorithm for the estimation of FH signal parameters such as: hop duration, frequency shift and distance between two adjacent frequency channels in case when many of FH signals are more superposed on antenna array, is presented in this paper. The algorithm is based on the spatial-timefrequency signal analysis. An algorithm for separation and grouping of FH transmitters in unique radio networks is proposed and presented as well.