Two-level FH acquisition scheme with adaptive threshold

The jamming problem is a major threat for any FH systems especially in acquisition stage. Acquisition stage is a very important task in any FH receiver because without acquisition the FH hopping receiver can´t demodulate his data. To solve the problem of jamming in FH receivers during acquisition stage, a two-level acquisition scheme with adaptive threshold is proposed for a frequency-hopped spread spectrum system. The advantage of this scheme is its threshold is dependent on the number of jammed channels. The performance of this scheme is evaluated for two types of jamming: partial-band noise jamming and partial-band tone jamming. The results show that the proposed adaptive-threshold acquisition scheme achieves higher detection probability and lower false alarm probability than a conventional fixed scheme.