21. Which of the following can determine the maximum frequency that can be converted?
A. sample frequency
B. sample rate
C. sample size
D. sample nature
Answer: B
The sample rate can determine the maximum frequency that can be converted as per the Nyquist theorem. The theorem states that the minimum sampling rate frequency should be twice the maximum frequency of the analog signal.
22. Which term determines the random timing error?
A. jitter
B. quantization error
C. sample error
D. delay
Answer: A
Jitter is a random timing error. Jitter can cause irregular sampling errors.
23. Which of the following introduces a phase error?
A. conversion time
B. sampling rate
C. sample size
D. sample nature
Answer: A
The conversion time always introduces a phase error. The conversion time will delay the digital output and hence introduce a phase error.
24. Which of the following can generate an interrupt?
A. timer
B. trigger
C. delay
D. counter
Answer: A
The timer can generate an interrupt to the processor at the rate of sampling frequency.
25. Which filter is used for filtering out the high-frequency components?
A. bandpass filter
B. band-reject filter
C. analog filter
D. digital filter
Answer: C
The higher frequency components can be filtered out by using an analog filter after sampling.
26. Which theorem describes the sampling rate with the frequency of the analog signal?
A. Nyquist theorem
B. Bayes theorem
C. Sampling theorem
D. Parseval’s theorem
Answer: A
The Nyquist theorem states that the minimum sampling rate frequency should be twice the maximum frequency of the analog signal.
27. From which of the following words does codecs is derived?
A. coder
B. decoder
C. coder-decoder
D. coder-encoder
Answer: C
The codec is derived from the coder-decoder and is coupled to perform the coding. It can support both analogs to digital conversion and digital to analog conversion.
28. Which codec is used in digital audio?
A. A-law
B. µ-law
C. linear
D. PCM
Answer: C
In the linear codec, the relationship between the analog and digital values is linear. This method is commonly used in digital audio communication.
29. Which of the following have the same quantization step throughout the range?
A. linear
B. PCM
C. DPCM
D. ADPCM
Answer: A
The quantization step is the same throughout the dynamic range in the linear codec and thus any increase in the analog value increases the digital value, that is, the overall performance is linear.
30. Which is used in telecommunication applications that have a limited bandwidth of 300 to 3100 HZ?
A. linear codec
B. logarithmic codec
C. PCM
D. DPCM
Answer: B
The logarithmic codec is frequently used in the telecommunication system which has a limited bandwidth of 300 to 3100 Hz. this can provide an 8-bit sample at 8 kHz, which is used in the telephones. The commonly used are A-law and µ-law.
