CLOVER is the name of a series or class of modem modulation techniques (“waveforms”) specifically designed for use over high frequency (HF) radio systems.

• CLOVER-II was the first CLOVER waveform sold commercially, developed by Ray Petit and HAL Communications in 1990-92.
• CLOVER-2000 is a higher-rate and wider bandwidth version of CLOVER developed in 1995.
• CLOVER-400 is a special 400 Hz wide waveform that was developed for Globe Wireless.

In ARQ mode, all CCB’s (CLOVER Control Blocks) use BPSM modulation
and data blocks may be sent using BSPM, QPSM, 8PSM, 8P2A, or 16P4A modulation.