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146 lines
2.1 KiB
Plaintext
146 lines
2.1 KiB
Plaintext
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% FILENAME N30.TXT
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% Digital Systems
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% Release version 3, October 2001
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% Q 9 modified 6 Mar 2012
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%QUESTION: 1
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#30.1 <img src = "digista.gif" align = right width = 352 height = 93>
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<extralines = 1 totallines = 6 >
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In the block diagram shown, the block designated "modem" is a:
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modulator/demodulator
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modulation emphasis unit
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Morse demodulator
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MOSFET de-emphasis unit
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% ans 1
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%QUESTION: 2
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#30.2 <img src = "digista.gif" align = right width = 352 height = 93>
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<extralines = 1 totallines = 6 >
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In the block diagram shown, the "modem":
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monitors the demodulated signals
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de-emphasises the modulated data
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translates digital signals to and from audio signals
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determines the modulation protocol
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% ans 3
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%QUESTION: 3
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#30.3 The following can be adapted for use as a modem:
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an electronic keyer
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a spare transceiver
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a spare receiver
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a computer sound-card
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% ans 4
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%QUESTION: 4
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#30.4 The following are three digital communication modes:
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DSBSC, PACTOR, NBFM
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AGC, FSK, Clover
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PSK31, AFC, PSSN
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AMTOR, PACTOR, PSK31
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% ans 4
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%QUESTION: 5
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#30.5 In digital communications, FSK stands for:
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phase selection keying
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final section keying
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frequency shift keying
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final signal keying
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% ans 3
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%QUESTION: 6
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#30.6 In digital communications, BPSK stands for:
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binary phase shift keying
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baseband polarity shift keying
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band pass selective keying
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burst pulse signal keying
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% ans 1
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%QUESTION: 7
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#30.7 When your HF digital transmission is received with errors due to multi-path
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conditions, you should:
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increase transmitter power
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reduce transmitted baud rate
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reduce transmitter power
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change frequency slightly
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% ans 2
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%QUESTION: 8
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#30.8 The letters BBS stand for:
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binary baud system
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bulletin board system
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basic binary selector
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broadcast band stopper
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% ans 2
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%QUESTION: 9
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#30.9 APRS is an adaptation of packet radio. APRS stands for
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Automatic Packet Reporting System
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Amateur Position Reporting System
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Automatic Packet Relay System
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Amateur Position Relay System
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% ans 1
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%QUESTION: 10
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#30.10 The following communication mode is generally used for connecting to a
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VHF packet radio bulletin board:
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SSB
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AM
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FM
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DSB
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% ans 3
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