dB related parameters - moerjielovecookie

1 dB: Decibel#

dB is a unit of power gain, an abbreviation for Decibel, representing a logarithmic unit of the ratio of two values with the same unit. The calculation formula is:

dB=10\times log_{10}\frac{P2}{P1}

where P1 and P2 represent two different power values or signal strength values. When P2 is greater than P1, dB is positive, indicating that the signal has been amplified; conversely, when dB is negative, it indicates that the signal has been attenuated.

2 dBm: Decibel-milliwatt#

dBm is the abbreviation for decibel-milliwatt (Decibels relative to one milliwatt), a unit that represents the absolute value of power. Its definition is the decibel value relative to 1 milliwatt (mW), meaning that 0 dBm equals 1 milliwatt. The calculation formula for dBm is:

dBm=10\times \log_{10}\frac{P}{1mW}

where P represents the power value to be measured; the larger the dBm, the greater the power.
dBm is commonly used to describe parameters such as transmission power, reception power, and antenna gain.

3 dBc: Decibels relative to carrier#

dBc is the abbreviation for decibels relative to carrier (Decibels relative to carrier), used to describe the ratio of signal power to carrier power within a specific frequency range. Its calculation formula is:

dBc=10\times \lg\frac{P_{sideband}}{P_{carrier}}

where $P_{sideband}$ represents the sideband power and $P_{carrier}$ represents the carrier power. dBc reflects the strength of the sideband signal relative to the carrier signal, helping to assess the purity of the signal, interference conditions, and spectral efficiency.

4 dBuV#

According to $V^2=P\times R$, it can be derived:

dBuV=90+dBm+10\lg R

When the impedance is 50Ω, the conversion relationship is: $$
dBm=dBuV-107

# Relationships dB is a relative unit, while dBm and dBc are absolute units.

1W=30dBm

Add 3 multiply by 2, add 10 multiply by 10, subtract 3 divide by 2, subtract 10 divide by 10.