Question

What should be the value of |ak| to ensure that a stable filter is transformed into another stable filter?

(a) < 1

(b) =1

(c) > 1

(d) 0

This question was addressed to me at a job interview.

Query is from Frequency Transformations in the Digital Domain in chapter Digital Filters Design of Digital Signal Processing

Answer 1

Right answer is (a) < 1

For explanation I would say: The value of |ak| < 1 to ensure that a stable filter is transformed into another stable filter to satisfy the condition to satisfy the condition 1.