The position accuracy based on Decawave Ultra-Wideband (UWB) is affectedmainly by three factors: hardware delays, clock drift, and signal power. Thisarticle discusses the last two factors. The general approach to clock drift correc-tion uses the phase-locked loop (PLL) integrator, which we show is subject tosignal power variations, and therefore, is less suitable for clock drift correction.The general approach to the estimation of signal power correction curves re-quires additional measurement equipment. This article presents a new methodfor obtaining the curve without additional hardware and clock drift correctionwithout the PLL integrator. Both correction methods were fused together toimprove two-way ranging (TWR).