A wireless charging in-band communication system includes a channel encoding for message error correction and detection. A modulation module performs biphase modulation for DC balanced signals and impedance switching to change reflected impedance seen by the source. A synchronization module prepends the message with a synchronization sequence having Golay complementary codes. A receiver module receives the message from the transmitter module. A preamble detection block has a Golay complementary code correlator used for message detection, synchronization, and equalization coefficient estimation and selection. A decoding module that performs biphase demodulation with error correction with a DC offset being estimated as the average value of the signal over the length of the message before channel decoding. The decoding module performs equalization, error correction and detection channel decoding.