Competition topic analysis: 2021 E question “Digital-Analog Signal Hybrid Transmission Transceiver”

“Design and manufacture a wireless transceiver that performs mixed transmission of digital-analog signals on the same channel. Among them, the digital signal is composed of a set of 4 numbers from 0 to 9; the analog signal is a voice signal with a frequency range of 100 Hz to 5 kHz. Using wireless transmission, the carrier frequency range is 20~30MHz, the channel bandwidth is not more than 2...