Admissible pole locations for tracking random references

Admissible pole locations for tracking step inputs are well known and widely used for designing tracking controllers. In some applications, however, references are random signals rather than steps. What are admissible pole locations for tracking such references? This is the question addressed in this note. Specifically, a method for constructing admissible domains, which lead to the desired closed loop behavior, is developed and illustrated by a hard disk drive controller design.