????????????书??????
???????????й?????繦??????????????????????????????????????????????
??????????????
????о??????????????????????????????
1????????????????????????????????????
??1?????????????Q??d???????????????????????????????????????????????????????????????????????????????У???????????????????V?????????????h????????
Q(d)=180???sin-1[sin(v/2)??sin(h/2)]
??У?V??h???λ??????????Q??d?????????
??2????????????Q(??)????????????????????????????0????????????????????????????????????????Q(??)????????????????????????????????????Σ???????
20 lgQ(??)=L(??)-l(a),????Q(??)=100.5[L(??)-L(a)]
??У?L(??)????????????0????????????????L??a????????????????????????
?????????????????????????????????????????????????н?????????н?????Ч??????????????????
???????1???????????????0???B?????????Q(??)??????
?????????????Ч?????????????B????A????????????????????B???????C???????????B???6dB??????B????????L(??)-0dB????C????????L??a??=+6dB??
??20lgQ(??)=L(??)-L(a)=-6dB??????Q(??)=0.5
??3??????????Ls????????1W????繦???????￡????????????????????????1m?????????????????λ???dB spl.
????????????????????Ls??????????????????????r??m??????90dB???????Lr?????????????????繦??We??????Lr?????????1m?????????Lr'???????????????????????????????????????У?Lr'-Lr+20lgr),??????Lr'??Ls????????????????繦??We??????繦???1w)?????????????ó?We??????????????Lr'??Ls??????We????????????????繦???????????????????????????????????????????????????μ??????????Lr'-Ls=10 lg(We/1w)
??10 lgWe=Lr'-Ls????We=100.1(Lr'-Ls)
??????????????????????????????????????????We?????????Q(d)??Q(??)?????漴?????????????????????й????????????????We?????????????????
2???????????????????
??1???????????Lp??????????????Ч??????????????????????λ?dB SPL??
???????￡????????????????????????????????Ч????????????δ????????????????????8-18dB??????????????????????????????Ч???12dB?????????????????Ч???10-18dB??????????????????????Ч????????????????繦????????????????????????????????????3dB??????繦????????????????18dB??????ζ??繦???????Ч??????????????64???????????????100W?繦?????????????????6400W??????????????????????????????????????????????y???????Щ?????????????ò?????????????????????????????????????????У????????????????????????????????????????С?
??2??????????R????????????????????????????
??У?S????????????????a???????????????????????ai?????????Si??????????????
3???????Lr??
???????????????????????r?????????Lr??????Q??d????q(??)??Ls??Lp??R???????????繦??We???????????????We?????????????????????????Lr???????
???????????????????????????????????????????????????????????????????????????????????????????沨??????????????????????We??????????????4??r2??????Wa?r????????I????????
I=Wa/4??r2
??????????????????з??????????????Q??d??????У?
I=Wa??Q??d??/4??r2
????????????????????????????????Q(??)?????
I=Wa??Q??d????Q2(??)/4??r2
[???????Q(??)?????????????????????????????????????????????Q(??)??????????????]??
????????????з??????????????????????????????????????????????????????????????4Wa/R????????
I=Wa{[Q??d????Q2(??)/4??r2]+4/R}
?????????????????????????????????????????????????????L?????????Lo=10 lg/1??10-12,????????У?
Lr=Lw+10 lg{[Q(d)??Q2(??)/4??r2]+4/R}
???У?La??????????La=10 lg Wa+120
?????????????????????????????ж??????????????????????????????????????r?????????????????????????????????н??????????????????Q(??)?????????????У?
Lr=Lwi+10 lg{[Q(d)??Q2(0i)/4??r2+??+Q(d)??Q2??0n))/4??r2]+4/R}
??У?Lwi??????????????????????Q??0n??????????n????????????????????????????rn??????n??????????
???????????????????????￡?????????????????????????
????????繦??????
?????????????繦?????????????μ????????е???????????????????????????????????ж????????????????趨???????????????????????????????????????????85dB???????????10dB????????????????????С???????????????????????н???????????????????????????????????????Щ?????????????????????????繦??????
????????????????????ü??з????????????????????????????????????????????????繦?????????????????????????????????????????????????????? We?????????????繦?????????仰??????????????????????????????????????Lr??????????3dB????????We?????????????????е?繦??????????????????????3dB???繦??????????????????????????????????????????????????????????????????????
Lr=Lw+10 lg{[Q(d)??Q2(??)/4??r2]+4/R}
???????????????????
1???????Lr=Lw+10 lg{[Q(d)??Q2(??)/4??r2]+4/R}????????????r(m)???????????(??)????????????????????Lr????????????????1m????????????????μ??????LR':
Lr'-Lr=10 lg{[Q(d)??q2(??)/4??]+4/4}-10 lg{[Q(d)??Q2(??)/4??r2]+4/R}
??У?Q2(??)??20lgQ(??)=10lgQ2(??)=L(??)-L(a)?????????????????ó???
2???????????????????????????Lr'????????????1m?????????Li??
Li=Lr'+[-20 lg Q(??)]
3????????????Lp????????????????1m??????????Li'??
Li'=Li+Lp
4???????10lgWe=Li'-Ls
????????????????
???????????????????????????????????????????????????????????h??v????90???85??????????83dB??????????????????0.2?????????800m2?????????????????30???????????10m???3KHz??????Ч???????86dB????????????10dB????????3KHz???????????????2????????????繦???
1???????????????????????????????????
R=S??a/1-a=800??0.2/(1-0.2)=200(m2)
Q(d)=180???sin-1[sin(v/2)??sin(h/s)]=180???sin-1[sin(90??/2)??sin(85??/2)??6.3
2)????????????????????????????????86DB?????????????????????????Lr=83dB?????0=30??????????10m??Lr???????????1m????????????????Lr'S??
Lr'=10lg{[Q(d)??Q2(??)/4??]+4/R}-10lg{[Q(d)??Q2(??)/4??r2]+4/R}+Lr=10lg{[6.3??Q2(??)/4??]+4/200}-10lg{[6.3??Q2(??)/4??102]+4/200}+83
???У?Q2(??)???10 lgQ2(??)=L(??)-L(a)????????????????
10lgQ2(??)=L(??)-L(a)=0-6=-6??Q2(??)=0.25
??????Lr'??92dB
3)????????????30???Lr'???????1m????LI??
?????????????Li=Lr'+6=98dB
4????????????????????1m?????????Li'??
Li'=Li+lP=98+10=108dB
5????????????????繦??We??
??10lgWe=Li'-Ls=108-83=25dB
??We??320(w).
???????
