PdBm

PdBm is a notation sometimes used to denote the power level expressed in decibels relative to one milliwatt. In practice, the quantity is the same as the standard dBm unit, which is defined as P(dBm) = 10 log10(P / 1 mW). The use of PdBm is not universal, and many sources simply use dBm; when encountered, it should be understood as representing the power in dBm, with the same logarithmic scale.

Converting between watts and PdBm (dBm): P(W) can be converted to dBm with P(dBm) = 10 log10(P(W) × 1000). Conversely, P(W) = 10^{(P(dBm) − 30)/10}. Examples: 1 mW equals 0 dBm; 10 mW equals 10 dBm; 1 W equals 30 dBm. The relationship to dBW is dBm = dBW + 30.

Caution is warranted in pulsed or wideband applications. For such signals, rms or average power differs from peak power, and some contexts may use PdBm to denote peak power (P_peak) rather than average power (P_avg). If peak versus average is relevant, the specific definition should be stated to avoid ambiguity.

Typical usage areas include wireless communications, RF transmitters, antenna link budgets, and received signal strength indicators, where power levels are conveniently expressed in dBm. The underlying meaning remains a logarithmic measure of power relative to 1 mW, with the unit symbol often written as dBm, while PdBm may appear in some datasheets or texts as an alternate notation.