This set of Software Defined Radio Multiple Choice Questions & Answers (MCQs) focuses on “Hardware Architecture – 1”.
1. Which among the following is not a part of RF front-end section in receive mode?
a) Antenna-matching unit
b) Low-noise amplifier
c) Power amplifier
d) ADC
View Answer
Explanation: The RF front-end section in receive mode consists of antenna-matching unit, low noise amplifiers, filters, local oscillators, and analog to digital converters. The power amplifier is a part of RF front-end section in transmit mode.
2. The circuits of transmit mode in RF front end _____ RF signal.
a) suppresses
b) synthesizes
c) boosts
d) modulates
View Answer
Explanation: The circuits of transmit mode in RF front end synthesizes RF signal. The generated signal must not introduce disturbance at any other frequencies and affect other users of the spectrum.
3. ____ time aligns a signal and fits it into the information bandwidth.
a) AGC
b) Channel equalizer
c) Modem
d) Tracking loop
View Answer
Explanation: The modem generates the signal to be transmitted and processes the signal received in case of a full duplex radio. It also time aligns, de-spreads a signal and fits it into the information bandwidth.
4. The number of times an electronic signal changes its state is measured by ____
a) word rate
b) signal rate
c) bit rate
d) baud rate
View Answer
Explanation: Baud rate gives the rate at which information is sent in a communication channel. The number of times an electronic signal changes state is measured by baud rate.
5. The modem may include ____ to correct channel multipath artifacts.
a) equalizer
b) frequency offset
c) AGC
d) interference suppressor
View Answer
Explanation: The modem may include equalizer to correct channel multipath artifacts and for filtering and delay distortions. Equalization is carried out after the modem time aligns a signal according to baud time.
6. ____ can be used to correct encoded symbols received in error.
a) Fine filter
b) Structured redundancy
c) Tracking loop
d) De-spreading
View Answer
Explanation: If the waveform were to include error detection and correction technique such as FEC coding, structured redundancy would be introduced in the coding process. The structured redundancy is exploited to detect and correct encoded sequences that were received in error.
7. The modem groups the bits to be transmitted into ____
a) packet
b) symbol
c) frame
d) segment
View Answer
Explanation: The procedure performed for transmission at the modem is the inverse of the procedure performed for reception. The modem groups the bits to be transmitted into packet, and then structured redundancy is introduced for error correction at the receiver.
8. A ____ is used to represent a symbol.
a) scale
b) number
c) figure
d) waveform shape
View Answer
Explanation: Each symbol is represented by a waveform. The modem synthesizes the waveform and filters it to fit within the desired bandwidth.
9. ____ depends on the amount of redundancy in a data stream.
a) Encryption
b) Data compression
c) Encoding
d) Grouping of data
View Answer
Explanation: Data coding has different types of redundancies within a message or between messages. Data compression ranges from 10% to 50% depending on the amount of redundancy present in original information data stream.
10. The modem must control ____ to produce the desired carrier frequency.
a) filter
b) low noise amplifier
c) power amplifier
d) antenna-matching unit
View Answer
Explanation: The modem controls external RF elements, including transmit and receive mode, carrier frequency and smart antenna. The modem controls power amplifier and local oscillators to produce the desire carrier frequency.
11. Speech application typically runs on ____ processor.
a) DSP
b) GPP
c) FPGA
d) ASIC
View Answer
Explanation: The application processer usually runs voice coder, video coder, data coder, and web browser functions. Speech and video applications run on DSP processor. Text and web browsing run on GPP processor.
12. Which of the following is not a characteristic of cryptographic security?
a) Confidentiality
b) Authentication
c) Authorization
d) Latency
View Answer
Explanation: The cryptographic security function must encrypt any information to be transmitted. Confidentiality, data integrity, authentication, source authentication, authorization and non-repudiation are the characteristics of cryptographic security as defined by US National Institute of Science and Technology (NIST).
13. ____ is used to identify the creator of information.
a) Integrity authentication
b) Source authentication
c) Integrity authorization
d) Source authorization
View Answer
Explanation: Integrity authentication verifies the reliability of data. Source authentication is used to identify the creator of information. Digital signature and key agreement techniques are examples of authentication services.
14. Encryption is a generalized process.
a) True
b) False
View Answer
Explanation: Each application has a distinctive encryption process, and encryption cannot be generalized. The Digital Encryption Standard (DES) and Advanced Encryption Standard (AES) from US National Institute of Technology (NIST) monitor the standard for cryptographic process.
15. The modem controls the antenna matching unit to maximize voltage standing wave ratio.
a) True
b) False
View Answer
Explanation: Antenna matching unit is a part of RF front end section in transmit mode and in receive mode. In transmit mode, the modem controls the antenna matching unit to minimize voltage standing wave ratio.
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