A method for transmitting wireless power to a wireless power receiver , the method performed by a wireless power transmitter and comprising: initiating a digital ping to solicit a response from the wireless power receiver ; receiving, from the wireless power receiver , the response; receiving, from the wireless power receiver in a first operating mode, a first received power packet related to power calibration, wherein a mode value included in the first received power packet is 1, receiving after the first received power packet, from the wireless power receiver in the first operating mode, a second received power packet related to power calibration, wherein a mode value included in the second received power packet is 2, constructing a first power calibration curve based on a received power value included in the first received power packet as a first calibration data point of the first power calibration curve and a received power value included in the second received power packet as an additional calibration data point of the first power calibration curve, receiving after the second received power packet, from the wireless power receiver in a second operating mode, a third received power packet related to power calibration, wherein a mode value included in the third received power packet is 1, receiving after the third received power packet, from the wireless power receiver in the second operating mode, a fourth received power packet related to power calibration, wherein a mode value included in the fourth received power packet is 2, and constructing a second power calibration curve based on a received power value included in the third received power packet as a first calibration data point of the second power calibration curve and a received power value included in the fourth received power packet as an additional calibration data point of the second power calibration curve. initiating a digital ping to solicit a response from the wireless power receiver ; receiving, from the wireless power receiver , the response; receiving, from the wireless power receiver in a first operating mode, a first received power packet related to power calibration, wherein a mode value included in the first received power packet is 1, receiving after the first received power packet, from the wireless power receiver in the first operating mode, a second received power packet related to power calibration, wherein a mode value included in the second received power packet is 2, constructing a first power calibration curve based on a received power value included in the first received power packet as a first calibration data point of the first power calibration curve and a received power value included in the second received power packet as an additional calibration data point of the first power calibration curve, receiving after the second received power packet, from the wireless power receiver in a second operating mode, a third received power packet related to power calibration, wherein a mode value included in the third received power packet is 1, receiving after the third received power packet, from the wireless power receiver in the second operating mode, a fourth received power packet related to power calibration, wherein a mode value included in the fourth received power packet is 2, and constructing a second power calibration curve based on a received power value included in the third received power packet as a first calibration data point of the second power calibration curve and a received power value included in the fourth received power packet as an additional calibration data point of the second power calibration curve. <EOS>