FPGA implementation of rapid PN code acquisition using iterative message passing algorithms

Spread-spectrum (SS) techniques are widely used in many military communication systems because they have many advantages, such as ranging capabilities, antijam protection, low probability of detection or interception, and multiple access capability. There are many forms of SS, such as a direct sequence spread spectrum (DS/SS), frequency hopping (FH), hybrid DS-FH, and ultrawideband (UWB). In all cases, pseudorandom or pseudonoise (PN) sequences play important roles. They are periodic sequences with a long period in practical systems. The long PN sequences are desirable to reduce the probability of detection by an unintended receiver over a short time interval. But it is also a challenge for a receiver to detect and acquire the signal.