Avionics MCQs – Data Conversion – 1
1 - Question
What is the main role of an ADC?
a) Amplify
b) Convert analog to digital
c) Reduce noise
d) Increase range
View Answer
Explanation: ADC corresponds to Analog to Digital Converter which is used to convert an analog signal into a digital. Digital signal can be processed and manipulated.
2 - Question
The process of converting a continuous analog signal to a discrete digital signal is called?
a) Discretisation
b) Sampling
c) Preemphasis
d) Reduction
View Answer
Explanation: An analog signal is continuous and hence contains an infinite number of points. The process in which this continuous signal is discretized is called as sampling. The sampling period determines the accuracy of conversion.
3 - Question
What is the minimum frequency of sampling so that the analog waveform is adequately expressed?
a) Minimum sampling rate
b) Minimum sampling frequency
c) Nyquist frequency
d) Conversion rate
View Answer
Explanation: The minimum frequency at which an analog wave should be sampled is given by Nyquist frequency. If the sampling frequency is below this limit then the analog waveform is not fully represented and leads to data loss.
4 - Question
What is the minimum rate at which an analog signal of frequency 6000Hz is sampled?
a) 6000Hz
b) 60Hz
c) 120Hz
d) 12000Hz
View Answer
Explanation: Minimum sampling frequency= Nyquist frequency = 2x(frequency of analog waveform) = 2x 6000Hz = 12000Hz.
5 - Question
What is the number of voltage increments that can be represented in an 8-bit system?
a) 255
b) 256
c) 215
d) 126
View Answer
Explanation: The number of voltage increments that can be in an N bit system is given by 2N-1 = 28-1 =255.
6 - Question
What is the error that occurs when the number of bits is not sufficient enough to represent the analog voltages?
a) Data error
b) Sampling error
c) Acquisition error
d) Quantization error
View Answer
Explanation: When the number of bits is not sufficient enough to represent the analog voltage levels, quantization error occurs. The greater the number of bits, the greater the number of increments over the analog range and the smaller the quantizing error.
7 - Question
What is the maximum amount of quantization error that can occur in a 10bit system in the input analog voltage is from 0V to 6V?
a) 10mV
b) 6mV
c) 0.5mV
d) 1mV
View Answer
Explanation: The minimum voltage step input is 6/(2N-1) = 6/1023 =5.865mV ≈6mV. This is the maximum error that can occur during the conversion process.
8 - Question
What is the rms noise voltage if the weight of the LSB is 0.005865?
a) 5mV b) 1mV c) 1.7mV d) 0.7mV
View Answer
Answer: c
Explanation:
9 - Question
What is the signal frequency if the rectangular digital wave has a time period of 71.4μs?
a) 14,006Hz
b) 15,036Hz
c) 14Hz
d) 21,436Hz
View Answer
Explanation: Signal frequency = 1/ time period of the wave = 1/71.4μs = 14,006Hz.
10 - Question
What is the 5th harmonic of the rectangular digital wave if the frequency is 14kHz?
a) 21kHz
b) 45kHz
c) 25kHz
d) 70kHz
View Answer
Explanation: Fifth harmonic = 5 x signal frequency = 5 x 14kHz = 70kHz
11 - Question
What is the output of a digital to analog converter?
a) Smooth continuous wave
b) Stairstep wave
c) Triangular waves
d) Circular waves
View Answer
Explanation: The Digital to analog converter takes the binary number as an input and produces the analog voltage proportional to the binary number. These analog voltages represent specific analog voltage levels and have stairstep characters.