Performance of VHF FH-radios with different bit-synchronization mechanisms in a multipath environment

The performance of VHF frequency hopping (FH) radios with different synchronization philosophies is investigated, based on a synthesized channel model which takes into account the spatially inhomogeneous distribution of partial waves. The channel parameters are gained from VHF wideband channel measurements in hilly and mountainous terrain. For the simulation we use a binary phase shift keying (BFSK) modulation and a non-coherent matched filter receiver with a maximum likelihood decision. To keep computation time low, all functional blocks in the communication system are represented in the baseband where the dependence on the carrier frequency is included in the channel model. Due to the multipath propagation, the optimum sampling point at the output of the receiver's matched filter changes for each carrier frequency and for different receiver positions. The simulation results show the difference in the bit error rate (BER) of a slow FH radio system with and without synchronizing each hop.