This correspondence studies robustness properties of the constant modulus (
CM) criterion and the constant modulus algorithm (CMA) to the suboptimal bu
t practical situation where the number of fractionally spaced equalizer coe
fficients is less than what is needed to remove all intersymbol interferenc
e (ISI), Hence, there necessarily exists an error in the equalized signal.
Relationships between Chi and mean squared error cost functions are establi
shed.