# Fast Fourier Transform (FFT) - Electronic Engineering (MCQ) questions & answers

1)   Discrete cosine transforms (DCTs) express a function or a signal in terms of

a. Sum of cosine functions oscillating at different frequencies
b. Sum of cosine functions oscillating at same frequencies
c. Sum of cosine functions at different sampling intervals
d. Sum of cosine functions oscillating at same sampling intervals
 Answer  Explanation ANSWER: Sum of cosine functions oscillating at different frequencies Explanation: No explanation is available for this question!

2)   In Overlap-Add Method with linear convolution of a discrete-time signal of length L and a discrete-time signal of length M, for a length N, zero padding should be of length

a. L, M > N
b. L, M = N
c. L, M < N
d. L, M < N2
 Answer  Explanation ANSWER: L, M < N Explanation: No explanation is available for this question!

3)   Overlap-Add Method Deals with principles that

a. The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length L + M - 1
b. The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length L + M
c. The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length 2L + M - 1
d. The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length 2L + 2M - 1
 Answer  Explanation ANSWER: The linear convolution of a discrete-time signal of length L and a discrete-time signal of length M produces a discrete-time convolved result of length L + M - 1 Explanation: No explanation is available for this question!

4)   The overlap save method is used to calculate

a. The discrete convolution between a sampled signal and a finite impulse response (FIR) filter
b. The discrete convolution between a sampled signal and an infinite impulse response (IIR) filter
c. The discrete convolution between a very long signal and a finite impulse response (FIR) filter
d. The discrete convolution between a very long signal and a infinite impulse response (IIR) filter
 Answer  Explanation ANSWER: The discrete convolution between a very long signal and a finite impulse response (FIR) filter Explanation: No explanation is available for this question!

5)   Radix - 2 FFT algorithm performs the computation of DFT in

a. N/2Log2 N multiplications and 2Log2 N additions
b. N/2Log2 N multiplications and NLog2 N additions
c. Log2 N multiplications and N/2Log2 N additions
d. NLog2 N multiplications and N/2Log2 N additions
 Answer  Explanation ANSWER: N/2Log2 N multiplications and NLog2 N additions Explanation: No explanation is available for this question!

6)   For the calculation of N- point DFT, Radix -2 FFT algorithm repeats

a. 2(N Log2 N) stages
b. (N Log2 N)2/2 stages
c. (N Log2 N)/2 stages
d. (N Log2(2 N))/2 stages
 Answer  Explanation ANSWER: (N Log2 N)/2 stages Explanation: No explanation is available for this question!

7)   The computational procedure for Decimation in frequency algorithm takes

a. Log2 N stages
b. 2Log2 N stages
c. Log2 N2 stages
d. Log2 N/2 stages
 Answer  Explanation ANSWER: Log2 N stages Explanation: No explanation is available for this question!

8)   DIT algorithm divides the sequence into

a. Positive and negative values
b. Even and odd samples
c. Upper higher and lower spectrum
d. Small and large samples
 Answer  Explanation ANSWER: Even and odd samples Explanation: No explanation is available for this question!

9)   FFT may be used to calculate

1) DFT
2) IDFT
3) Direct Z transform
4) In direct Z transform

a. 1, 2 and 3 are correct
b. 1 and 2 are correct
c. 1 and 3 are correct
d. All the four are correct
 Answer  Explanation ANSWER: 1 and 2 are correct Explanation: No explanation is available for this question!

10)   The Cooley–Tukey algorithm of FFT is a

a. Divide and conquer algorithm
b. Divide and rule algorithm
c. Split and rule algorithm
d. Split and combine algorithm
 Answer  Explanation ANSWER: Divide and conquer algorithm Explanation: No explanation is available for this question!