Questions - Digital Systems

Question file 30

QUESTIONS WITH ANSWERS    STUDY NOTES 

     
  1. In the block diagram shown, the block designated "modem" is a:
    1. modulator/demodulator
    2. modulation emphasis unit
    3. Morse demodulator
    4. MOSFET de-emphasis unit
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  2. In the block diagram shown, the "modem":
    1. monitors the demodulated signals
    2. de-emphasises the modulated data
    3. translates digital signals to and from audio signals
    4. determines the modulation protocol
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  3. The following can be adapted for use as a modem:
    1. an electronic keyer
    2. a spare transceiver
    3. a spare receiver
    4. a computer sound-card
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  4. The following are three digital communication modes:
    1. DSBSC, PACTOR, NBFM
    2. AGC, FSK, Clover
    3. PSK31, AFC, PSSN
    4. AMTOR, PACTOR, PSK31
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  5. In digital communications, FSK stands for:
    1. phase selection keying
    2. final section keying
    3. frequency shift keying
    4. final signal keying
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  6. In digital communications, BPSK stands for:
    1. binary phase shift keying
    2. baseband polarity shift keying
    3. band pass selective keying
    4. burst pulse signal keying
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  7. When your HF digital transmission is received with errors due to multi-path conditions, you should:
    1. increase transmitter power
    2. reduce transmitted baud rate
    3. reduce transmitter power
    4. change frequency slightly
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  8. The letters BBS stand for:
    1. binary baud system
    2. bulletin board system
    3. basic binary selector
    4. broadcast band stopper
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  9. "ITA2" is:
    1. a 5 bit alphabet used for digital communications
    2. Morse code sent such that the baud speed is equal to the dot speed
    3. a coding system identifying modulation types
    4. an error correction code
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  10. The following communication mode is generally used for connecting to a VHF packet radio bulletin board:
    1. SSB
    2. AM
    3. FM
    4. DSB
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