dBm represents a measure of power in decibels relative to 1 milliwatt (mW), typically across a 50-ohm (Ω) load. A signal with a power level of 0 dBm corresponds to:
- 224 mV RMS
- 316 mV peak
- 633 mV peak-to-peak
for a sine wave.
For any other power level, the dBm value can be calculated using the formula:
dBm = 10 × log(P/1 mW) = 10 × log[(V rms2)/(R × 1 mW)]
Where:
- log10 is the base-10 logarithm
- VRMS is the root mean square voltage
- R is the load resistance, typically 50 Ω