This application relates to signal processing methods and apparatuses. An example method includes generating a physical layer protocol data unit (PPDU) and sending the PPDU. The PPDU includes a first field, and the first field includes M sequences. The M sequences include a first sequence, a second sequence, a third sequence, and a fourth sequence. A partial sequence in the first sequence, a partial sequence in the second sequence, a partial sequence in the third sequence, and a partial sequence in the fourth sequence are determined based on Golay complementary sequences.