Simulated Assessment of Interference Effects in Direct Sequence Spread Spectrum (DSSS) QPSK Receiver
AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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This research developed and validated a generic simulation for a direct sequence spread spectrum DSSS, using di erential phase shift keying DPSK and phase shift keying PSK modulations, providing the exibility for assessing intentional interference e ect using DSSS quadrature phase shift keying receiver QPSK with matched ltering as a reference. The evaluation compares a comprehensive pool of jamming waveforms at pass-band that include continuous wave CW interference, broad-band jamming, partial-band interference and pulsed interference. The methodology for jamming assessment included comparing the bit error rate BER versus required jamming to signal ratio JSR for di erent interferers using the Monte Carlo approach. This thesis also analyzes the e ect of varying the jammer bandwidth for broad-band jammers including broad-band noise BBN, frequency hopping interference FHI, comb- spectrum interference CSI, multi-tone jamming MTJ, random frequency modulated interference RFMI and linear frequency modulated interference LFMI. Also, the e ect of changing the duty cycle for pulsed CW waveforms is compared with the worst case pulsed jamming equation. After the evaluation of di erent interferers, the research concludes that pulsed binary phase shift keying BPSK jamming is the most e ective technique, whereas the CW tone jamming and CW BPSK interference result are least e ective. It is also concluded that by nding an optimum bandwidth, FHI and BBN improves the required JSR by approximately 2.1 dB, RFMI and LFMI interference by 0.9 and 1.5 dB respectively. Alternately, MTJ and CSI improves their e ectiveness in 4.1 dB and 3.6 dB respectively, matching the performance of the pulsed BPSK jammer.
- Electrical and Electronic Equipment
- Radio Communications