Which of the following types of modulation is common for data emissions below 30 MHz?

  1. DTMF tones modulating an FM signal
  2. FSK
  3. Pulse modulation
  4. Spread spectrum


What do the letters FEC mean as they relate to digital operation?

  1. Forward Error Correction
  2. First Error Correction
  3. Fatal Error Correction
  4. Final Error Correction


How is the timing of FT4 contacts organized?

  1. By exchanging ACK/NAK packets
  2. Stations take turns on alternate days
  3. Alternating transmissions at 7.5 second intervals
  4. It depends on the lunar phase


What is indicated when one of the ellipses in an FSK crossed-ellipse display suddenly disappears?

  1. Selective fading has occurred
  2. One of the signal filters is saturated
  3. The receiver has drifted 5 kHz from the desired receive frequency
  4. The mark and space signal have been inverted


Which of these digital modes does not support keyboard-to-keyboard operation?

  2. RTTY
  3. PSK31
  4. MFSK


What is the most common data rate used for HF packet?

  1. 48 baud
  2. 110 baud
  3. 300 baud
  4. 1200 baud


Which of the following is a possible reason that attempts to initiate contact with a digital station on a clear frequency are unsuccessful?

  1. Your transmit frequency is incorrect
  2. The protocol version you are using is not supported by the digital station
  3. Another station you are unable to hear is using the frequency
  4. All these choices are correct


Which of the following HF digital modes can be used to transfer binary files?

  1. Hellschreiber
  3. RTTY
  4. AMTOR


Which of the following HF digital modes uses variable-length coding for bandwidth efficiency?

  1. RTTY
  3. MT63
  4. PSK31


Which of these digital modes has the narrowest bandwidth?

  1. MFSK16
  2. 170 Hz shift, 45-baud RTTY
  3. PSK31
  4. 300-baud packet


What is the difference between direct FSK and audio FSK?

  1. Direct FSK applies the data signal to the transmitter VFO, while AFSK transmits tones via phone
  2. Direct FSK occupies less bandwidth
  3. Direct FSK can transmit faster baud rates
  4. Only direct FSK can be decoded by computer


How do ALE stations establish contact?

  1. ALE constantly scans a list of frequencies, activating the radio when the designated call sign is received
  2. ALE radios monitor an internet site for the frequency they are being paged on
  3. ALE radios send a constant tone code to establish a frequency for future use
  4. ALE radios activate when they hear their signal echoed by back scatter


Which of these digital modes has the fastest data throughput under clear communication conditions?

  1. AMTOR
  2. 170 Hz shift, 45 baud RTTY
  3. PSK31
  4. 300 baud packet