TopTekninen sanakirjadBm - tehonmittauksen logarytmiyksikkö

dBm - tehonmittauksen logarytmiyksikkö

dBm – a unit of absolute level of reference to the power of 1 mW (milliwatt); a dBmW expression ought to be used according to the rule but the expression of dBm is exceptionally used here.

 

This unit is commonly used in telecommunications (e.g. an output power of an access point is provided) or it is used in designing WLAN network. A unit expressed in dB informs us how much this power is lower than power expressed in 1 mW. The level 0 dB corresponds to 1 mW (milliwatt).

 

A commonly used power formula is used in converting mW into dBm.

 

P(ref) – a referential value, which is a reference measure, which in this case is 1 mW (milliwatt)

 

A power formula in dBm which is more straightforward visually:

 

Example
Let us convert 10 mW into dBm:

 

If we want to convert dBm into mW, we use the following formula:

 

Example
Let us convert 20 dBm into mW (milliwatts).

 

Tab. 1. Conversion of dBm into mW - wide range 

-30 dBm 0,001 mW
-20 dBm 0,01 mW
-10 dBm 0,1 mW
0 dBm 1 mW
10 dBm 10 mW
20 dBm 100 mW
30 dBm 1000 mW
40 dBm 10000 mW
50 dBm 100000 mW
60 dBm 1000000 mW
70 dBm 10000000 mW
80 dBm 100000000 mW

Tab. 2. Conversion of dBm into mW - detailed range 

14 dBm 25,119 mW
16 dBm 39,811 mW
18 dBm 63,096 mW
20 dBm 100,000 mW
22 dBm 158,489 mW
24 dBm 251,189 mW
26 dBm 398,107 mW
28 dBm 630,957 mW
30 dBm 1000,000 mW

We can also convert power to voltage very easily: dBm into dBµV and dBmV. In order to convert voltage from power we have to know internal impedance. In terrestrial, cable and industrial television systems, impedance of 75 ohm is used. In radio systems it is 50 ohm. 

The formulas for these two environments are provided below: 

dBmV = 46,9897 + dBm (@ 50 ohm)
dBmV = 48,7506 + dBm (@ 75 ohm) 

Example
We convert 15 dBm into dBmV (for impedance of 50 ohm) 

dBmV = 46,9897 + 15 = 61,9897 dBmV 

dBµV = 60 + dBmV 

dBµV = 106,98 + dBm (@ 50 ohm)
dBµV = 108,75 + dBm (@ 75 ohm) 

Example
We convert 20 dBm into dBµV (for impedance of 50 ohm) 

dBµV = 106,98 + 20 = 126,98 dBµV 


Netto:0.00 USD
Brutto:0.00 USD
Paino:0.00 kg
Erityisesti suositellaan
HAKKURITEHOLÄHDE 12V/10A/P
12V/10A/P

Netto: 11.24 USD

LUKKOKIVEN LIITIN FX-F1
FX-F1

Netto: 0.69 USD

KYTKENTÄKENTTÄ KEYSTONE PP-24/FX/C
PP-24/FX/C

Netto: 15.34 USD

VIRTALÄHDE 12V/5A/5.5
12V/5A/5.5

Netto: 10.37 USD

VIRTALÄHDE 12V/5A/5.5*P50
12V/5A/5.5*P50

Netto: 503.08 USD

VIRTALÄHDE 12V/5A/5.5*P50
12V/5A/5.5*P50

Netto: 503.08 USD

AHD, HD-CVI, HD-TVI, PAL-KAMERA APTI-H14MP-37 PINHOLE - 720p, 3.7 mm
APTI-H14MP-37

Netto: 46.24 USD

ETÄISYYSPURISTIN OZP-50
OZP-50

Netto: 1.80 USD

JATKOHIHNA HDMI-EX-120-V3
HDMI-EX-120-V3

Netto: 121.55 USD

 
60-713 Poznań, Graniczna 10
puh.: +(48) 61 864 69 66
e-mail: shop@delta.poznan.pl
Työtunnit
Maan.-Perj: 8.00 - 19.00
Lauant.: 8.00 - 14.00
Myyntiosasto, Toimitukset
puh.: +(48) 61 864 69 66
e-mail: shop@delta.poznan.pl
Tekninen tuki
puh.: +(48) 61 864 69 98
e-mail: support@delta.poznan.pl
(c) 2001-2019 DELTA