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G8MNY > TECH 14.07.03 15:12l 49 Lines 2516 Bytes #999 (0) @ WW
BID : 5566_GB7CIP
Read: DB0FHN GUEST OE7FMI
Subj: dBW & dB Levels
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<WB0TAX<IK1ZNW<GB7CRV<GB7CIP
Sent: 030713/2209Z @:GB7CIP.#32.GBR.EU #:5566 [Caterham] $:5566_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
dBWs
The Formulae for POWER is 10log POut/1WATT, which gives this easy to remember
1dB step table based only on +/- 3, 6 & 10dB.
Note, dBW is "0" referenced to 1W.
+3dB is doubling the power, -3dB is only a half.
+6dB is Quadrupling power, -6dB is only a quarter.
+10dB is 10 fold the power, -10dB is only a tenth.
mW dBW Watts dBW Watts dBW Watts dBW Watts dBW
10 -20 0.1 -10 1 0 10 10 100 20
12.5 -19 0.125 -9 1.25 1 12.5 11 125 21
15.65 -18 0.1565 -8 1.565 2 15.65 12 156.5 22
20 -17 0.2 -7 2 3 20 13 200 23
25 -16 0.25 -6 2.5 4 25 14 250 24
31.25 -15 0.3125 -5 3.125 5 31.25 15 312.5 25
40 -14 0.4 -4 4 6 40 16 400 26
50 -13 0.5 -3 5 7 50 17 500 27
62.5 -13 0.625 -2 6.25 8 62.5 18 625 28
80 -11 0.8 -1 8 9 80 19 800 29
For Voltage and Currents the formulae is 20log in/out, which gives this easy to
remember 2dB step table based only on +/- 6, 12 & 20dB.
+6dB is doubling the level, -6dB is only a half.
+12dB is Quadrupling level, -12dB is only a quarter.
+20dB is 10 fold the level, -20dB is only a tenth.
NB +1dB is about +11% (111%), & -1dB is about -9% (91%) of level.
Ratio dB Ratio dB Ratio dB Ratio dB Ratio dB
0.01 -40 0.1 -20 1 +0 10 +20 100 +40
0.0125 -38 0.125 -18 1.25 +2 12.5 +22 125 +42
0.01565 -36 0.1565 -16 1.565 +4 15.65 +24 156.5 +44
0.02 -34 0.2 -14 2 +6 20 +26 200 +46
0.025 -32 0.25 -12 2.5 +8 25 +28 250 +48
0.03125 -20 0.3125 -10 3.125 +10 31.25 +30 312.5 +50
0.04 -28 0.4 -8 4 +12 40 +32 400 +52
0.05 -26 0.5 -6 5 +14 50 +34 500 +54
0.0625 -24 0.625 -4 6.25 +16 62.5 +36 625 +56
0.08 -22 0.8 -2 8 +18 80 +38 800 +58
/QSL
73 De John, G8MNY @ GB7CIP
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