Which type 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 JT65 contacts organized?

  1. By exchanging ACK/NAK packets
  2. Stations take turns on alternate days
  3. Alternating transmissions at 1 minute 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 type of digital mode does not support keyboard-to-keyboard operation?

  1. Winlink
  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


What is the typical bandwidth of a properly modulated MFSK16 signal?

  1. 31 Hz
  2. 316 Hz
  3. 550 Hz
  4. 2.16 kHz


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
  2. Audio FSK has a superior frequency response
  3. Direct FSK uses a DC-coupled data connection
  4. Audio FSK can be performed anywhere in the transmit chain


Which type of control is used by stations using the Automatic Link Enable (ALE) protocol?

  1. Local
  2. Remote
  3. Automatic
  4. ALE can use any type of control


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 of these choices are correct