/
Flashcards from Upload
Save to my account
Sign up
Flashcards from Upload
Digital Modulation and Transmission Basics
Study
1
Question
What is Electronic Communications as defined in the document?
Answer
Transmission, reception, and processing of information with electronic circuits
2
Question
What is Information as defined in the document?
Answer
Knowledge or intelligence communicated between two or more points
3
Question
What is Digital Communications?
Answer
Transmission of digital pulses between two or more points in a system
4
Question
What are two broad fields of Digital Communications?
Answer
Digital Modulation and Digital Transmission
5
Question
What does Digital Modulation study/cover?
Answer
Transmittal of digitally modulated analog signals (carriers)
6
Question
What does Digital Transmission study/cover?
Answer
Systems transporting information in digital form via physical facilities
7
Question
What is another name for Digital Modulation sometimes?
Answer
Digital Radio
8
Question
What is the simplified block diagram of a digital radio system primarily describing?
Answer
Process from transmitter precoding to receiver demodulation/decoding
9
Question
What does the precoder in the transmitter do?
Answer
Performs level conversion and encodes data into bit groups for modulation
10
Question
What is the role of the transmission medium?
Answer
Carries modulated carrier signals from transmitter to receiver
11
Question
What do clock and carrier recovery circuits do?
Answer
Recover analog carrier and timing signals for demodulation
12
Question
List four applications of Digital Modulation Communication mentioned in the text.
Answer
Low-speed voice-band modems, broadband DSL, digital microwave/satellite, cellular PCS, digital TV broadcasting
13
Question
Into how many categories do most communications systems fall?
Answer
Three
14
Question
What are the three categories of communications systems?
Answer
Bandwidth efficient, Power efficient, Cost efficient
15
Question
What is bandwidth efficiency?
Answer
Ability to convey data within a limited bandwidth
16
Question
What is power efficiency?
Answer
Ability to reliably send information at the lowest practical power level
17
Question
What is cost efficiency?
Answer
Low-cost system priority to encourage more users
18
Question
Why is bandwidth efficiency prioritized for digital terrestrial microwave radios?
Answer
To achieve good bandwidth efficiency with low bit-error-rate
19
Question
Why is power efficiency prioritized for handheld cellular phones?
Answer
Because they run on a battery
20
Question
What constraint do developers face when designing digital modulation systems?
Answer
Available bandwidth, permissible power, inherent noise level
21
Question
What are the four forms of Digital Modulation listed?
Answer
ASK, FSK, PSK, QAM
22
Question
What does ASK stand for?
Answer
Amplitude Shift Keying
23
Question
What does FSK stand for?
Answer
Frequency Shift Keying
24
Question
What does PSK stand for?
Answer
Phase Shift Keying
25
Question
What does QAM stand for?
Answer
Quadrature Amplitude Modulation
26
Question
What are the two principal types of multiplexing mentioned?
Answer
TDMA and CDMA
27
Question
What does TDMA stand for?
Answer
Time Division Multiple Access
28
Question
What does CDMA stand for?
Answer
Code Division Multiple Access
29
Question
What is the purpose of multiplexing in communications?
Answer
Add diversity to signals so they can be separated later
30
Question
What does the “Why Digital Modulation?” section list as benefits?
Answer
More information capacity, digital data compatibility, higher security, better quality, quicker availability