Research On Low-complexity Narrow-band Interference Suppression In DSSS System

Spread spectrum communication system has found wide application in bothmilitary and civilian areas for its various advantages such as strong anti-jammingcapability, excellent security. However, additional anti-jamming methods must be takenwhen jamming intensity exceeds the intrinsic jamming margin of the system. This thesismainly focuses on the pre-processing of narrow band interference in DSSS systemespecially under the circumstances of fast changing jamming and limited systemresources. The main contributions are as follows:1. Some common anti-jamming algorithms are analyzed systematically, among whichCME algorithm in frequency domain and LMS algorithm in time domain arespecially researched and compared in performance and implementation complexity.2. Two frequency tracking algorithms are researched. One is PLL, which is a Costasloop; and the other is Goertzel algorithm. An improved jamming frequencylocation algorithm is proposed based on these two algorithms and verified toguarantee its validity.3. A low-complexity anti-jamming system is designed and simulated. PLL is used forjamming tracking and IIR filter whose coefficients are controlled by the outputfrequency deviation of PLL is used for jamming cancellation in the systemrespectively.