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dBm – Conversion Table dBm Watts x x Volts

The dBm sometimes called dBmW or Decibel-miliwatts is an abbreviation for the power ratio in decibels (dB) the measured power referenced to one milliwatt (mW) ( see Conversion Table below ). It is used in RF and fiber optic, as a convenient measure of absolute power because of its ability to express very large or very small values ​​in a short form. By comparison, the decibels ( dB ) is a dimensionless unit , used to quantify the relationship between two values, such as the ratio Signal to Noise. Audio and telephony, dBm is typically referenced relative to an impedance of 600 ohm, while in dBm RF is usually referenced to an impedance of relatively 50 ohms.

 

Tabela de Conversão  dBm x Watts x Volts
photo: flickr

 

What is the difference between “dB”, “dBi” and “dBm”

The DB, dBi e dBm are not synonymous, they mean things quite different.

What is dB

O dB ( decibels ) is a relative measure two different power levels, is used to declare the gain or loss of a device relative to another device. In other words, dB is a logarithmic unit used to express the ratio of two values ​​of a physical quantity, often a power or intensity. This is the basis of dBx.

What is dBi

O dBi (dB isotrópico) – Shows the gain of an antenna relative to an isotropic antenna hypothetical , that evenly distributes energy in all directions (flat land).

What is dBm

O dBm (dB mW) is power in relation to 1 milliwatt widely used in RF, audio and telephony ( and we are seeing this Article).

Examples of the Extremes dBm

-120,0 dBm The signal strength received at the ground from a satélite GPS
+ 80 dBm The power 100 kW broadcast of a commercial radio

 

A convenient form, no dimension is to measure the power:

The exact formula : P (dBm) = 10 log10 · (P (In) / 1 mW)

where
P (dBm) = Power expressed in dBm
P (In) = Absolute power measured in Watts
mW = miliWatts
log10 = log base 10

From this formula, power in dBm 1 Watt é de 30 dBm. As the calculation is logarithmic, each increase of 3dBm is roughly equivalent to twice the actual power of a signal.

In the table below:

+30 dBm
1.00 In
7.08 In

 

Conversion Table dBm Watts x (50 Ohms) x Volts (RMS)

 

Potência Rel.
@ 50 Ohms
Abs Power.
Tension (RMS)
Potência Rel.
@ 50 Ohms
Potência Abs.
Tenare (RMS)
-150 dBm
1.00 aW
7.08 nV
-50 dBm
10.00 nW
708.35 uV
-149 dBm
1.26 aW
7.95 nV
-49 dBm
12.59 nW
794.78 uV
-148 dBm
1.58 aW
8.92 nV
-48 dBm
15.85 nW
891.76 uV
-147 dBm
2.00 aW
10.01 nV
-47 dBm
19.95 nW
1.00 mV
-146 dBm
2.51 aW
11.23 nV
-46 dBm
25.12 nW
1.12 mV
-145 dBm
3.16 aW
12.60 nV
-45 dBm
31.62 nW
1.26 mV
-144 dBm
3.98 aW
14.13 nV
-44 dBm
39.81 nW
1.41 mV
-143 dBm
5.01 aW
15.86 nV
-43 dBm
50.12 nW
1.59 mV
-142 dBm
6.31 aW
17.79 nV
-42 dBm
63.10 nW
1.78 mV
-141 dBm
7.94 aW
19.96 nV
-41 dBm
79.43 nW
2.00 mV
-140 dBm
10.00 aW
22.40 nV
-40 dBm
100.00 nW
2.24 mV
-139 dBm
12.59 aW
25.13 nV
-39 dBm
125.89 nW
2.51 mV
-138 dBm
15.85 aW
28.20 nV
-38 dBm
158.49 nW
2.82 mV
-137 dBm
19.95 aW
31.64 nV
-37 dBm
199.53 nW
3.16 mV
-136 dBm
25.12 aW
35.50 nV
-36 dBm
251.19 nW
3.55 mV
-135 dBm
31.62 aW
39.83 nV
-35 dBm
316.23 nW
3.98 mV
-134 dBm
39.81 aW
44.69 nV
-34 dBm
398.11 nW
4.47 mV
-133 dBm
50.12 aW
50.15 nV
-33 dBm
501.19 nW
5.01 mV
-132 dBm
63.10 aW
56.27 nV
-32 dBm
630.96 nW
5.63 mV
-131 dBm
79.43 aW
63.13 nV
-31 dBm
794.33 nW
6.31 mV
-130 dBm
100.00 aW
70.84 nV
-30 dBm
1.00 uW
7.08 mV
-129 dBm
125.89 aW
79.48 nV
-29 dBm
1.26 uW
7.95 mV
-128 dBm
158.49 aW
89.18 nV
-28 dBm
1.58 uW
8.92 mV
-127 dBm
199.53 aW
100.06 nV
-27 dBm
2.00 uW
10.01 mV
-126 dBm
251.19 aW
112.27 nV
-26 dBm
2.51 uW
11.23 mV
-125 dBm
316.23 aW
125.96 nV
-25 dBm
3.16 uW
12.60 mV
-124 dBm
398.11 aW
141.33 nV
-24 dBm
3.98 uW
14.13 mV
-123 dBm
501.19 aW
158.58 nV
-23 dBm
5.01 uW
15.86 mV
-122 dBm
630.96 aW
177.93 nV
-22 dBm
6.31 uW
17.79 mV
-121 dBm
794.33 aW
199.64 nV
-21 dBm
7.94 uW
19.96 mV
-120 dBm
1.00 fW
224.00 nV
-20 dBm
10.00 uW
22.40 mV
-119 dBm
1.26 fW
251.33 nV
-19 dBm
12.59 uW
25.13 mV
-118 dBm
1.58 fW
282.00 nV
-18 dBm
15.85 uW
28.20 mV
-117 dBm
2.00 fW
316.41 nV
-17 dBm
19.95 uW
31.64 mV
-116 dBm
2.51 fW
355.02 nV
-16 dBm
25.12 uW
35.50 mV
-115 dBm
3.16 fW
398.33 nV
-15 dBm
31.62 uW
39.83 mV
-114 dBm
3.98 fW
446.94 nV
-14 dBm
39.81 uW
44.69 mV
-113 dBm
5.01 fW
501.47 nV
-13 dBm
50.12 uW
50.15 mV
-112 dBm
6.31 fW
562.66 nV
-12 dBm
63.10 uW
56.27 mV
-111 dBm
7.94 fW
631.32 nV
-11 dBm
79.43 uW
63.13 mV
-110 dBm
10.00 fW
708.35 nV
-10 dBm
100.00 uW
70.84 mV
-109 dBm
12.59 fW
794.78 nV
-9 dBm
125.89 uW
79.48 mV
-108 dBm
15.85 fW
891.76 nV
-8 dBm
158.49 uW
89.18 mV
-107 dBm
19.95 fW
1.00 uV
-7 dBm
199.53 uW
100.06 mV
-106 dBm
25.12 fW
1.12 uV
-6 dBm
251.19 uW
112.27 mV
-105 dBm
31.62 fW
1.26 uV
-5 dBm
316.23 uW
125.96 mV
-104 dBm
39.81 fW
1.41 uV
-4 dBm
398.11 uW
141.33 mV
-103 dBm
50.12 fW
1.59 uV
-3 dBm
501.19 uW
158.58 mV
-102 dBm
63.10 fW
1.78 uV
-2 dBm
630.96 uW
177.93 mV
-101 dBm
79.43 fW
2.00 uV
-1 dBm
794.33 uW
199.64 mV
-100 dBm
100.00 fW
2.24 uV
+0 dBm
1.00 mW
224.00 mV
-99 dBm
125.89 fW
2.51 uV
+1 dBm
1.26 mW
251.33 mV
-98 dBm
158.49 fW
2.82 uV
+2 dBm
1.58 mW
282.00 mV
-97 dBm
199.53 fW
3.16 uV
+3 dBm
2.00 mW
316.41 mV
-96 dBm
251.19 fW
3.55 uV
+4 dBm
2.51 mW
355.02 mV
-95 dBm
316.23 fW
3.98 uV
+5 dBm
3.16 mW
398.33 mV
-94 dBm
398.11 fW
4.47 uV
+6 dBm
3.98 mW
446.94 mV
-93 dBm
501.19 fW
5.01 uV
+7 dBm
5.01 mW
501.47 mV
-92 dBm
630.96 fW
5.63 uV
+8 dBm
6.31 mW
562.66 mV
-91 dBm
794.33 fW
6.31 uV
+9 dBm
7.94 mW
631.32 mV
-90 dBm
1.00 pW
7.08 uV
+10 dBm
10.00 mW
708.35 mV
-89 dBm
1.26 pW
7.95 uV
+11 dBm
12.59 mW
794.78 mV
-88 dBm
1.58 pW
8.92 uV
+12 dBm
15.85 mW
891.76 mV
-87 dBm
2.00 pW
10.01 uV
+13 dBm
19.95 mW
1.00 In
-86 dBm
2.51 pW
11.23 uV
+14 dBm
25.12 mW
1.12 In
-85 dBm
3.16 pW
12.60 uV
+15 dBm
31.62 mW
1.26 In
-84 dBm
3.98 pW
14.13 uV
+16 dBm
39.81 mW
1.41 In
-83 dBm
5.01 pW
15.86 uV
+17 dBm
50.12 mW
1.59 In
-82 dBm
6.31 pW
17.79 uV
+18 dBm
63.10 mW
1.78 In
-81 dBm
7.94 pW
19.96 uV
+19 dBm
79.43 mW
2.00 In
-80 dBm
10.00 pW
22.40 uV
+20 dBm
100.00 mW
2.24 In
-79 dBm
12.59 pW
25.13 uV
+21 dBm
125.89 mW
2.51 In
-78 dBm
15.85 pW
28.20 uV
+22 dBm
158.49 mW
2.82 In
-77 dBm
19.95 pW
31.64 uV
+23 dBm
199.53 mW
3.16 In
-76 dBm
25.12 pW
35.50 uV
+24 dBm
251.19 mW
3.55 In
-75 dBm
31.62 pW
39.83 uV
+25 dBm
316.23 mW
3.98 In
-74 dBm
39.81 pW
44.69 uV
+26 dBm
398.11 mW
4.47 In
-73 dBm
50.12 pW
50.15 uV
+27 dBm
501.19 mW
5.01 In
-72 dBm
63.10 pW
56.27 uV
+28 dBm
630.96 mW
5.63 In
-71 dBm
79.43 pW
63.13 uV
+29 dBm
794.33 mW
6.31 In
-70 dBm
100.00 pW
70.84 uV
+30 dBm
1.00 In
7.08 In
-69 dBm
125.89 pW
79.48 uV
+31 dBm
1.26 In
7.95 In
-68 dBm
158.49 pW
89.18 uV
+32 dBm
1.58 In
8.92 In
-67 dBm
199.53 pW
100.06 uV
+33 dBm
2.00 In
10.01 In
-66 dBm
251.19 pW
112.27 uV
+34 dBm
2.51 In
11.23 In
-65 dBm
316.23 pW
125.96 uV
+35 dBm
3.16 In
12.60 In
-64 dBm
398.11 pW
141.33 uV
+36 dBm
3.98 In
14.13 In
-63 dBm
501.19 pW
158.58 uV
+37 dBm
5.01 In
15.86 In
-62 dBm
630.96 pW
177.93 uV
+38 dBm
6.31 In
17.79 In
-61 dBm
794.33 pW
199.64 uV
+39 dBm
7.94 In
19.96 In
-60 dBm
1.00 nW
224.00 uV
+40 dBm
10.00 In
22.40 In
-59 dBm
1.26 nW
251.33 uV
+41 dBm
12.59 In
25.13 In
-58 dBm
1.58 nW
282.00 uV
+42 dBm
15.85 In
28.20 In
-57 dBm
2.00 nW
316.41 uV
+43 dBm
19.95 In
31.64 In
-56 dBm
2.51 nW
355.02 uV
+44 dBm
25.12 In
35.50 In
-55 dBm
3.16 nW
398.33 uV
+45 dBm
31.62 In
39.83 In
-54 dBm
3.98 nW
446.94 uV
+46 dBm
39.81 In
44.69 In
-53 dBm
5.01 nW
501.47 uV
+47 dBm
50.12 In
50.15 In
-52 dBm
6.31 nW
562.66 uV
+48 dBm
63.10 In
56.27 In
-51 dBm
7.94 nW
631.32 uV
+49 dBm
79.43 In
63.13 In
+50 dBm
100.00 In
70.84 In
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