This set of Avionics Multiple Choice Questions & Answers (MCQs) focuses on “Digital Signal Processing”.
1. Any digital computer can be used for DSP.
Explanation: DSP is the use of a fast digital computer or digital circuitry to perform processing on digital signals. Any digital computer with sufficient speed and memory can be used for DSP.
2. What happens after the signal is passed through the analog to digital converter in a DSP?
a) Changed back to analog
b) Stored in a RAM
Explanation: When the signal is converted from analog to digital it is a sequence of binary numbers which is stored in the RAM. A user defined code that is usually stored in the ROM performs mathematical and other manipulations after which it is converted back into analog signals.
3. Who is credited with creating the stored program concept?
a) John Von Neumann
b) Larry Page
c) Alan Turing
d) Ken Thompson
Explanation: Physicist John Von Neumann is generally credited with creating the stored program concept that is the basis of operation of all digital computers. Binary words representing computer instructions are stored sequentially in a memory to form a program. The instructions are fetched and executed one at a time at high speed.
4. What is the accessibility limitation of only one data or instruction set at a time from the memory called?
a) Von Neumann limitation
b) Von Neumann limit
c) Von Neumann speed
d) Von Neumann bottleneck
Explanation: The accessibility limitation of only one data or instruction set at a time from the memory is called as Von Neumann bottleneck. This has the effect of greatly limiting the execution speed.
5. Which type of architecture uses different storage space for program code and the data?
a) Von Neumann architecture
b) Harvard architecture
c) Fragmented architecture
d) Split cell architecture
Explanation: In a Harvard architecture microprocessor, there are two memories, a program or instruction memory, usually a ROM, and a data memory, which is a RAM. Also, there are two data paths into and out of the CPU between the memories. Because both instructions and data can be accessed simultaneously, very high-speed operation is possible.
6. What is the reason for the need of high speed DSP?
a) Less power consumption at higher speeds
b) Better processing capabilities
c) High sampling frequency
d) Easily programmable
Explanation: The time taken for input/output and the processing time together must be smaller than the sampling period to ensure the continuous flow of data. Since high sampling frequencies are needed for accurately converting the analog signal to digital, high speed DSP is a must.
7. Selectivity in a DSP is better than its analog equivalent.
Explanation: With DSP, the filters can have characteristics far superior to those of equivalent analog filters. Selectivity can be better because of the ease of controlling binary numbers, and the passband or reject band can be customized to the application.
8. Reduction in the number of binary words required to represent an analog signal is called ________
c) Data compression
d) Data minimization
Explanation: Data compression is a process that reduces the number of binary words needed to represent a given analog signal. Since analog to digital conversion produces a huge amount of data, for transmission it is a necessity that data is compressed.
9. What is the process of examining the frequency content of a signal?
a) Signal decoding
b) Spectrum analysis
c) Signal analysis
d) Data analysis
Explanation: Spectrum analysis is the process of examining a signal to determine its frequency content. Algorithms such as discrete Fourier transform (DFT) and FPGA is used to analyze the frequency content of an input signal.
10. What is the program that is used to speed the spectrum analysis process?
d) Fast Fourier transforms
Explanation: The DFT is a complex program that is long and time-consuming to run. In general, computers are not fast enough to perform DFT in real time as the signal occurs. Therefore, a special version of the algorithm has been developed to speed up the calculation. Known as the fast Fourier transform (FFT), it permits real-time signal spectrum analysis.
11. Which of the following is not possible when the signal is analog?
a) Phase shifting
d) Data compression
Explanation: Data compression is done by checking redundancy in data. Data redundancy checking is only possible when the data is in digital form and hence data compression cannot be done in analog signals.
Sanfoundry Global Education & Learning Series – Avionics.
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