supplement Number 1

The Supplementary Material is organized as follows: Section S1 derives the ESB-PDH modulation spectrum; Section S2 characterizes the RF output of the S-DDS-HS system, including modulation bandwidth, linearity, phase noise, and phase-truncation spur analysis; Section S3 provides a comprehensive hardware implementation guide covering platform selection, PLL configuration, reference clock requirements, PCB layout, and GTX IP core setup.