21. How many types of logarithmic codecs are used commonly?
A. 2
B. 3
C. 4
D. 5
Answer: A
There are two types of logarithmic codecs that are commonly used. They are a-law which is used in UK and µ-law codec which is used in the US.
22. What does ADPCM stand for?
A. address differential pulse code modulation
B. adaptive differential pulse code modulation
C. address dynamic pulse code machine
D. adaptive dynamic pulse code modulation
Answer: B
The adaptive differential pulse code modulation is used in telecommunications and is based on non-linear quantization values.
Adaptive differential pulse-code modulation (ADPCM) is a variant of differential pulse-code modulation (DPCM) that varies the size of the quantization step, to allow further reduction of the required data bandwidth for a given signal-to-noise ratio.
23. Which of the following uses a non-linear quantization value?
A. PCM
B. DPCM
C. ADPCM
D. linear codec
Answer: C
The adaptive differential pulse code modulation is based on non-linear quantization values. In the ADPCM, instead of using all bits for encoding, only a few bits are used for encoding which makes it nonlinear.
24. Which of the following works by increasing the dynamic range?
A. logarithmic codec
B. linear codec
C. DPCM
D. PCM
Answer: C
The differential pulse code modulation can improve the accuracy and resolution by having a 16-bit dynamic range. It works by the increasing dynamic range.
25. Which device can make the PWM operation easier?
A. timer
B. software
C. hardware
D. transistor
Answer: A
The timer can be used for making up the PWM waveform far more easier and faster and it will free the processor to do other things without affecting the timing.
26. Which of the following can be used for providing high gain?
A. transistor
B. Darlington transistor pair
C. resistor
D. capacitor
Answer: b
The Darlington pair of transistors can provide high gain than a single transistor. This is one of the methods used to avoid voltage mismatches that the system produces. By using high gain transistors the voltage mismatches can be reduced up to a limit.
27. Which devices have high drive capability?
A. transistor
B. fet
C. buffer pack
D. Darlington amplifier
Answer: c
The buffer pack is used to avoid the voltage mismatches which possess a high drive capacity and it can also provide high drive currents than the normal logic outputs.
28. Which of the following is used to switch heavy loads?
A. fet
B. transistor
C. buffer pack
D. Darlington pair
Answer: a
The field-effect transistor can be used to provide a very high effective gain and hence they can be used to switch heavy loads easily from a logic device. These are also voltage-controlled transistors.
29. Which allows the switching of DC motor by using two outputs and four FETs?
A. transistor
B. H bridge
C. Darlington pair
D. buffer pack
Answer: b
The H bridge can be created by using several switches which allows a DC motor to be switched on and reversed in the direction. The switching can be done by using two outputs and four FETs.
30. Which of the following is used to create the H bridge?
A. switches
B. led
C. capacitor
D. inductor
Answer: a
The H bridge can be created by using several switches. This allows a DC motor to be switched on and reversed in the direction and the switching of the DC motor can be done by using two outputs and four FETs.