At most how many extremal frequencies can be there in the error function of ideal low pass filter?
A. L+1
B. L+2
C. L+3
D. L
Answer:A
At most how many extremal frequencies can be there in the error function of ideal low pass filter?
A. L+1 B. L+2 C. L+3 D. L
Explanation: We know that we can have at most L-1 local maxima and minima in the open interval 0<ω<π. In addition, ω=0 and π are also usually extrema. It is also maximum at ω for pass band and stop band frequencies. Thus the error function of a low pass filter has at most L+3 extremal frequencies.