Which of these digital modes has the highest data throughput under clear communication conditions?

PACTOR IV is a proprietary digital mode designed specifically for high-speed data transfer over HF frequencies. Under clear conditions, it uses advanced Quadrature Amplitude Modulation (QAM) and adaptive equalization to achieve uncompressed data throughputs exceeding 5,500 bits per second. In contrast, FT8 is designed for extremely weak-signal communication, not speed. It takes 15 seconds to transmit a tiny payload of data (just a few characters). Therefore, its data throughput is extremely low. Traditional modes like 45 baud RTTY and MFSK16 are robust and excellent for live keyboard-to-keyboard chat, but they operate at speeds well under 100 bits per second. When the channel is clear, PACTOR IV vastly outperforms all of these alternatives in terms of throughput.