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Men and women who turn their lives over to God will discover that He can make a lot more out of their lives than they can. He will: deepen their joys, expand their vision, quicken their minds, strengthen their muscles, lift their spirits, multiply their blessings,
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Men and women who turn their lives over to God will discover that He can make a lot more out of their lives than they can. He will: • deepen their joys, • expand their vision, • quicken their minds, • strengthen their muscles, • lift their spirits, • multiply their blessings, • increase their opportunities, • comfort their souls, • raise up friends, • and pour out peace. • Whosoever will lose his life in the service of God will find he has eternal life. • - Pres. Ezra Taft Benson Thought of the Day IT 327 - Schweber Chap 3
Schweber, Chap 3: DeciBels and Noise IT 327 - Schweber Chap 3
1 Just a littletickler IT 327 - Schweber Chap 3
DeciBels • Origin of the unit? • Why? For Power: dB = 10 log10 (P2/P1) For Voltage: dB = 20 log10(V2/V1) OR: For Power: dB = 10 log10 (Pout/Pin) For Voltage: dB = 20 log10 (VMeas/VRef) Example 1: Perfectwire (R = 0Ω; L = 0H; C = 0F) P1 = 1W; P2 = 1W. Find dB. IT 327 - Schweber Chap 3
DeciBels: More Examples P1= 1W; P2 = 0.5W. Find dB. V1= 10V; V2= 5W. Find dB. P1 = 50W; P2 = 0.1aW. Find dB. Voyager 1 & 2 P1 = 1W; P2 = 1000W. Find dB. Commercialpoweramplifier P1= 50kW; P2 = 10µW. Find dB. Commercial AM radio (KSL 1160) IT 327 - Schweber Chap 3
DeciBels: Standard References dBW = 1 W Howmuchis 20 dBW? dBm = 1 mWHowmuchis -30 dBmW? dBV = 1 V Howmuchis 40 dBV? dBmV = 1 mVHowmuchis -120 dBmV? dBc = ideal carrier dBi = isotropic (omnidirectional) dB (audio) = ? Howmuchis 30 dB? 70 dB? 100 dB? 120 dB? IT 327 - Schweber Chap 3
Noise in Systems IT 327 - Schweber Chap 3
Definition of BW IT 327 - Schweber Chap 3
Definition of BW IT 327 - Schweber Chap 3
Acceptible SNR • Audio: 90 dB (Classical); 40 dB (other) • Video: 60 dB • Digital: 20 dB • Space: -60 dB IT 327 - Schweber Chap 3