dBW meaning

In legal and regulatory practice, dBW (decibels relative to one watt) is a logarithmic unit used to state radiofrequency power levels in spectrum licences, equipment approvals, planning conditions for radio sites, and telecoms and satellite contracts. It expresses transmitter power with reference to 1 watt, and is commonly applied to limits on e.i.r.p. or e.r.p. for compliance and interference control. dBW is a technical measure rather than a statutory concept. It is widely used in Ofcom and ComReg licences and schedules, and by reference to ITU/ETSI standards, and may appear in court evidence or contractual specifications. Usage and meaning are consistent across England and Wales, Scotland, Northern Ireland and Ireland. Formulae: - dBW = 10 × log10(power in watts) - Power (watts) = 10^(dBW/10) Values below 1 watt are negative (for example, 0.1 W ≈ −10 dBW). Accurate conversion and rounding matter for demonstrating regulatory compliance and avoiding enforcement action or breach. Practitioners should note whether limits apply to conducted power or to e.i.r.p./e.r.p., and any bandwidth or averaging assumptions stated in the relevant licence or standard.