-2dbm是多少
2\u6beb\u74e6\u7b49\u4e8e\u591a\u5c11dbm2\u6beb\u74e6\u7b49\u4e8e3dbm.
http://wenku.baidu.com/view/d6406d02b52acfc789ebc98f.html
\u5c06dBm\u8f6c\u6362\u4e3aW\u7684\u53e3\u7b97\u65b9\u6cd5
dBm\u662f\u4e00\u4e2a\u8868\u793a\u529f\u7387\u7edd\u5bf9\u503c\u7684\u503c\uff08\u4e5f\u53ef\u4ee5\u8ba4\u4e3a\u662f\u4ee51mW\u529f\u7387\u4e3a\u57fa\u51c6\u7684\u4e00\u4e2a\u6bd4\u503c\uff09\uff0c\u8ba1\u7b97\u516c\u5f0f\u4e3a\uff1a10log\uff08\u529f\u7387\u503c/1mw\uff09\u3002
\u3000\u3000\u8fd9\u91cc\u5c06dBm\u8f6c\u6362\u4e3aW\u7684\u53e3\u7b97\u89c4\u5f8b\u662f\u8981\u5148\u8bb0\u4f4f\u201c1\u4e2a\u57fa\u51c6\u201d\u548c\u201c2\u4e2a\u539f\u5219\u201d\uff1a
\u3000\u3000\u201c1\u4e2a\u57fa\u51c6\u201d\uff1a
\u3000\u300030dBm\uff1d1W
\u3000\u3000\u201c2\u4e2a\u539f\u5219\u201d\uff1a
\u3000\u30001)\uff0b3dBm\uff0c\u529f\u7387\u4e582\u500d\uff1b\uff0d3dBm\uff0c\u529f\u7387\u4e581/2
\u3000\u3000\u4e3e\u4f8b\uff1a33dBm\uff1d30dBm+3dBm\uff1d1W\u00d72=2W
\u3000\u3000\u3000\u3000\u300027dBm\uff1d30dBm\uff0d3dBm\uff1d1W\u00d71/2=0.5W
\u3000\u30002)\uff0b10dBm\uff0c\u529f\u7387\u4e5810\u500d\uff1b\uff0d10dBm\uff0c\u529f\u7387\u4e581/10
\u3000\u3000\u4e3e\u4f8b\uff1a40dBm\uff1d30dBm+10dBm\uff1d1W\u00d710=10W
\u3000\u3000\u3000\u3000\u300020dBm\uff1d30dBm\uff0d10dBm\uff1d1W\u00d70.1=0.1W
\u3000\u3000\u4ee5\u4e0a\u53ef\u4ee5\u7b80\u5355\u7684\u8bb0\u4f5c\uff1a30\u662f\u57fa\u51c6\uff0c\u7b49\u4e8e1W\u6574\uff0c\u4e92\u6362\u4e0d\u7b97\u96be\uff0c\u53e3\u7b97\u53ef\u5b8c\u6210\u3002\u52a03\u4e58\u4ee52\uff0c\u52a010\u4e58\u4ee510\uff1b\u51cf3\u9664\u4ee52\uff0c\u51cf10\u9664\u4ee510\u3002
\u3000\u3000\u51e0\u4e4e\u6240\u6709\u6574\u6570\u7684dBm\u90fd\u53ef\u7528\u4ee5\u4e0a\u7684\u201c1\u4e2a\u57fa\u51c6\u201d\u548c\u201c2\u4e2a\u539f\u5219\u201d\u8f6c\u6362\u4e3aW\u3002
\u3000\u3000\u4f8b1\uff1a44dBm=?W
\u3000\u3000\u3000\u3000 44dBm=30dBm+10dBm+10dBm\uff0d3dBm\uff0d3dBm
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=1W\u00d710\u00d710\u00d71/2\u00d71/2
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=25W
\u3000\u3000\u4f8b2\uff1a32dBm=?W
\u3000\u3000\u3000\u3000 32dBm=30dBm+3dBm+3dBm+3dBm+3dBm\uff0d10dBm
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=1W\u00d72\u00d72\u00d72\u00d72\u00d70.1
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=1.6W
\u3000\u3000\u8ba1\u7b97\u6280\u5de7\uff1a
\u3000\u3000+1dBm\u548c+2dBm\u7684\u8ba1\u7b97\u6280\u5de7
\u3000\u3000+1dBm=+10dBm\uff0d3dBm\uff0d3dBm\uff0d3dBm
\u3000\u3000\u3000\u3000\u3000=X\u00d710\u00d71/2\u00d71/2\u00d71/2
\u3000\u3000\u3000\u3000\u3000=X\u00d71.25
\u3000\u3000+2dBm=\uff0d10dBm+3dBm+3dBm+3dBm+3dBm
\u3000\u3000\u3000\u3000\u3000=X\u00d70.1\u00d72\u00d72\u00d72\u00d72
\u3000\u3000\u3000\u3000\u3000=X\u00d71.6
\u3000\u3000\u5728\u8ba1\u7b97\u4e2d\uff0c\u6709\u65f6\u5019\u4e5f\u53ef\u4ee5\u6839\u636e\u4e0a\u9762\u7684\u89c4\u5f8b\u53d8\u6362\u4e3a\uff0d1dBm\u548c\uff0d2dBm\uff0c\u8fbe\u5230\u5feb\u901f\u53e3\u901f\u7684\u76ee\u7684\uff0c\u5373\uff1a
\u3000\u3000\uff0d1dBm=\uff0d10dBm+3dBm+3dBm+3dBm
\u3000\u3000\u3000\u3000\u3000=X\u00d70.1\u00d72\u00d72\u00d72
\u3000\u3000\u3000\u3000\u3000=X\u00d70.8
\u3000\u3000\uff0d2dBm=\uff0d3dBm+1dBm
\u3000\u3000\u3000\u3000\u3000=X\u00d71/2\u00d71.25
\u3000\u3000\u3000\u3000\u3000=X\u00d70.625
\u3000\u3000\u4f8b3\uff1a51dBm=30dBm+10dBm+10dBm+1dBm
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=1W\u00d710\u00d710\u00d71.25
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=125W
\u3000\u3000\u4f8b4\uff1a38dBm=30dBm+10dBm\uff0d2dBm
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=1W\u00d710\u00d70.625
\u3000\u3000\u3000\u3000\u3000\u3000\u3000=6.25W
\u3000\u3000\u8fd9\u6837\u90fd\u662f\u53e3\u7b97\uff0c\u662f\u4e0d\u662f\u5f88\u7b80\u5355\u554a\uff1f\u4f60\u8bb0\u4f4f\u4e86\u5417\uff1f
\u3000\u3000\u53e6\uff1adBw\u4e0eW\u7684\u6362\u7b97
\u3000\u3000dBw\u4e0edBm\u4e00\u6837\uff0cdBw\u662f\u4e00\u4e2a\u8868\u793a\u529f\u7387\u7edd\u5bf9\u503c\u7684\u5355\u4f4d\uff08\u4e5f\u53ef\u4ee5\u8ba4\u4e3a\u662f\u4ee51W\u529f\u7387\u4e3a\u57fa\u51c6\u7684\u4e00\u4e2a\u6bd4\u503c\uff09\uff0c\u8ba1\u7b97\u516c\u5f0f\u4e3a\uff1a10log\uff08\u529f\u7387\u503c/1w\uff09\u3002
\u3000\u3000dBw\u4e0edBm\u4e4b\u95f4\u7684\u6362\u7b97\u5173\u7cfb\u4e3a\uff1a0 dBw = 10log1 W = 10log1000 mw = 30 dBm\u3002
\u3000\u3000\u5982\u679c\u529f\u7387P\u4e3a1W\uff0c\u6298\u7b97\u4e3adBw\u540e\u4e3a0dBw\u3002
\u3000\u3000\u603b\u4e4b\uff0cdB\uff0cdBi, dBd, dBc\u662f\u4e24\u4e2a\u91cf\u4e4b\u95f4\u7684\u6bd4\u503c\uff0c\u8868\u793a\u4e24\u4e2a\u91cf\u95f4\u7684\u76f8\u5bf9\u5927\u5c0f\uff0c\u800cdBm\u3001dBw\u5219\u662f\u8868\u793a\u529f\u7387\u7edd\u5bf9\u5927\u5c0f\u7684\u503c\u3002\u5728dB\uff0cdBm\uff0cdBw\u8ba1\u7b97\u4e2d\uff0c\u8981\u6ce8\u610f\u57fa\u672c\u6982\u5ff5\uff0c\u7528\u4e00\u4e2adBm\uff08\u6216dBw\uff09\u51cf\u53e6\u5916\u4e00\u4e2adBm\uff08dBw\uff09\u65f6\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u662fdB\uff0c\u5982\uff1a30dBm - 0dBm = 30dB\u3002
\u3000\u3000\u4e00\u822c\u6765\u8bb2\uff0c\u5728\u5de5\u7a0b\u4e2d\uff0cdBm\u548cdBm\uff08\u6216dBw\u548cdBw\uff09\u4e4b\u95f4\u53ea\u6709\u52a0\u51cf\uff0c\u6ca1\u6709\u4e58\u9664\u3002\u800c\u7528\u5f97\u6700\u591a\u7684\u662f\u51cf\u6cd5\uff1adBm \u51cf dBm \u5b9e\u9645\u4e0a\u662f\u4e24\u4e2a\u529f\u7387\u76f8\u9664\uff0c\u4fe1\u53f7\u529f\u7387\u548c\u566a\u58f0\u529f\u7387\u76f8\u9664\u5c31\u662f\u4fe1\u566a\u6bd4\uff08SNR\uff09\u3002dBm \u52a0 dBm \u5b9e\u9645\u4e0a\u662f\u4e24\u4e2a\u529f\u7387\u76f8\u4e58\u3002
\u8981\u6c42\u91c7\u7eb3
dBm意即分贝毫瓦。 功率单位 与P（瓦特）换算公式：
(10*P)dBm=(10*P)dB-30dB (P:瓦 )
纯计数单位
-2dbm，大约相当于0.63mW，也就是0.63毫瓦。
绛旓細-2dbm鍗-2鍒嗚礉姣摝 dBm鎰忓嵆鍒嗚礉姣摝銆 鍔熺巼鍗曚綅 涓嶱锛堢摝鐗癸級鎹㈢畻鍏紡锛(10*P)dBm=(10*P)dB-30dB (P:鐡 )绾鏁板崟浣 鍙傝冭祫鏂欙細http://baike.baidu.com/view/413258.htm?fr=ala0_1_1
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