1. EMLAB Modeling of Digital Communication Systems using Simulink Chap.13 Simulink Examples 13.3 Spread Spectrum 13.4 Antenna Nulling

2. EMLAB 1 간섭이 없는 AWGN 환경에서 spread spectrum 을 이용한 BPSK 13.3 Spread Spectrum 13.3.1 Spread Spectrum Simulink Model without In-Band Interference BPSK signal; sampling time: 1s Spread spectrum; sampling time: 0.1s

3. EMLAB 2 13.3.1 Spread Spectrum Simulink Model without In-Band Interference (cont’d) Received signal – BPSK Demodulated signal Transmitted signal Transmitted signal – BPSK Modulated signal Transmitted signal – BPSK Spread Spectrum signal AWGN 에서 BPSK 의 이론적 에러율을 계산해보면 (E b /N 0 =3dB 일 때 ) 에러 개수를 100 개로 제한하고, E b /N 0 =3dB 일 때 시뮬레이션 한 결과는 0.02097 → 차이가 거의 없음 → spreading 이 BER 특성에 미 치는 영향이 없음.

4. EMLAB 3 대역 내 간섭이 있는 경우 13.3.2 Spread Spectrum Simulink Model with In-Band Interference 1kHz, 1V p_p, 30V p_p 비교 Spread spectrum; sampling time: 0.01s, 0.001s 비교

5. EMLAB 4 Spectrum Analyzer 결과 13.3.2 Spread Spectrum Simulink Model with In-Band Interference (cont’d) Spread Spectrum BPSK 잡음 진폭 : 1V p_p

6. EMLAB 5 13.3.2 Spread Spectrum Simulink Model with In-Band Interference (cont’d) Transmitted Signal: 100 chips/bit Despread Signal: 100 chips/bit 잡음 진폭 : 1V p_p

7. EMLAB 6 13.3.2 Spread Spectrum Simulink Model with In-Band Interference (cont’d) Transmitted Signal: 1000 chips/bit Despread Signal: 1000 chips/bit

8. EMLAB 7 13.3.2 Spread Spectrum Simulink Model with In-Band Interference (cont’d) Transmitted Signal: 1000 chips/bit Despread Signal: 1000 chips/bit BPSK Spread Spectrum signal Spread Spectrum signalTransmitted Signal – Before BPSK Modulated Received Signal – BPSK Despread

9. EMLAB 8 13.3.2 Spread Spectrum Simulink Model with In-Band Interference (cont’d) 잡음 진폭 : 60V p_p Transmitted Signal: 100 chips/bit Received Signal: 100 chips/bit

10. EMLAB 9 RLS 필터를 사용하여 간섭을 상쇄시킴. 13.3.3 Spread Spectrum Simulink Model with In-Band Interference and Excision filter length=32, forgetting factor=1, initial input variance=0.1

11. EMLAB 10 잡음 진폭 : 60V p_p, RLS filter 적용 13.3.3 Spread Spectrum Simulink Model with In-Band Interference and Excision (cont’d) Received Signal: 100 chips/bit RLS 에러 진폭

12. EMLAB 11 13.4 Antenna Nulling

13. EMLAB 12 13.4 Antenna Nulling (cont’d)

14. EMLAB 13 앞의 관계식을 이용하면 13.4 Antenna Nulling (cont’d)

15. EMLAB 13.4 Antenna Nulling (cont’d) 14 S/I = 0dB 일 때 송신 신호 잡음 신호 잡음 신호 위상차 복조

16. EMLAB 15 가중치 계산 부 13.4 Antenna Nulling (cont’d)

17. EMLAB 16 S/I = 0dB, 10dB 일 때 – 모두 에러가 없음을 확인. 13.4 Antenna Nulling (cont’d)