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PACTOR
CLOVER 2
CLOVER2000

CLOVER2

Parameter	Value
System	Half-duplex ARQ
Center frequency	In the range (−3750,+ 3750) Hz; automatic frequency control (AFC): +/−50 Hz
Speed	31.25 Baud
Modulation	PSK2A, PSK4A, PSK8A, PSK16A, ASK2PSK8, ASK4PSK16, 2DPSK2A; 4 tones
Additional Info	ITA-5

CLOVER-2 is an adaptive modulation system with ARQ that uses Reed-Solomon (RS) coding to achieve a remarkable performance even under the worst HF propagation conditions. Data modulated onto four tones spaced 125 Hz. The modulation rate of each tone is 31.25 Baud. The supported modulation techniques include binary phase-shift keying (PSK2A), quaternary PSK (PSK4A), 8-PSK (PSK8A), 16-PSK (PSK16A), binary amplitude-shift keying combined with 8-PSK (ASK2PSK8), quaternary ASK combined with 16-PSK (ASK4PSK16), and two-channel diversity binary PSK (2DPSK2A).

RS coding is utilized to correct transmission errors. Four coding levels (called RS Efficiency) are specified, which allow for more or less error correction within a block.
The level of RS Efficiency is automatically detected by the demodulator. After successful synchronization, it may take several tens of seconds before any text is output in the GUI.

The percentages in the following list of coding levels, relate the number of information symbols (user data) to the block length, a block comprises user data and parity check symbols:

ROBUST: 60%
NORMAL: 75%
FAST: 90%
OFF: 100% (i.e., no error correction)