Almost. As I understand it, most 802.11 hardware works by creating a baseband I/Q signal with the center frequency at 0 Hz using a pair of DACs and then upconve

Almost. As I understand it, most 802.11 hardware works by creating a baseband I/Q signal with the center frequency at 0 Hz using a pair of DACs and then upconverting it to the final transmission frequency by multiplying it with a seperately-generated carrier frequency. (The idea of negative frequencies may seem a bit strange, but because there are seperate in-phase and quadrature components the math works out.) If you decrease the DAC clock but keep the carrier the same this is what happens.