Transmission Power

The RF power level used by tags and anchors when transmitting, measured in milliwatts or dBm. Higher power increases range but consumes more battery. Regulatory limits restrict maximum allowed power. Systems balance power to achieve required range while maximizing battery life.

Transmission power in industrial RTLS refers to the radio frequency energy level at which tags transmit signals, measured in decibels relative to one milliwatt (dBm) or absolute power (milliwatts). UWB RTLS tags typically operate at transmission power levels from -10 to +10 dBm (0.1 to 10 milliwatts), while BLE tags might operate from -20 to +4 dBm. Active RFID systems may use higher power up to +20 dBm or more. UWB regulations generally limit equivalent isotropic radiated power (EIRP) to -41.3 dBm/MHz average power density, achieved through spreading energy across wide bandwidth rather than high absolute power. The relationship between transmission power and range follows inverse square law for free space propagation: doubling distance requires quadrupling power (6 dB increase) to maintain equivalent received signal strength. Link budget analysis determines required transmission power: accounting for free space path loss (increasing with distance and frequency), antenna gains (transmit and receive antennas amplifying signal), cable and connector losses (typically 1-3 dB in practical installations), implementation margins (10-15 dB typically included for reliability), environmental attenuation (penetration through walls, absorption by materials, additional loss from non-line-of-sight conditions), and receiver sensitivity (minimum received signal strength for reliable detection). Industrial RTLS tag configurations typically allow: factory-default power settings optimized for typical deployments, field-adjustable power enabling optimization for specific environments (lower power in dense anchor deployments with short ranges, higher power in sparse deployments or large open areas), and application-specific power tuning balancing battery life, range, and capacity requirements.