Amateur Extra E2E: HF digital modes
These are the 13 official questions in group E2E of the 2024–2028 Amateur Extra question pool, with the correct answer marked and a plain-English explanation of why it's right. The real exam asks one question from this group.
- E2E01Question 1
Which of the following types of modulation is used for data emissions below 30 MHz?
- ADTMF tones modulating an FM signal
- BFSK Correct
- CPulse modulation
- DSpread spectrum
Why: Data below 30 MHz commonly uses FSK.
- E2E02Question 2
Which of the following synchronizes WSJT-X digital mode transmit/receive timing?
- AAlignment of frequency shifts
- BSynchronization of computer clocks Correct
- CSync-field transmission
- DSync-pulse timing
Why: WSJT-X modes depend on synchronized computer clocks.
- E2E03Question 3
To what does the "4" in FT4 refer?
- AMultiples of 4 bits of user information
- BFour-tone continuous-phase frequency shift keying Correct
- CFour transmit/receive cycles per minute
- DAll these choices are correct
Why: FT4 uses four-tone continuous-phase FSK.
- E2E04Question 4
Which of the following is characteristic of the FST4 mode?
- AFour-tone Gaussian frequency shift keying
- BVariable transmit/receive periods
- CSeven different tone spacings
- DAll these choices are correct Correct
Why: All the listed FST4 traits are correct.
- E2E05Question 5
Which of these digital modes does not support keyboard-to-keyboard operation?
- AWSPR Correct
- BRTTY
- CPSK31
- DMFSK16
Why: WSPR is a beacon mode, not for keyboard-to-keyboard chat.
- E2E06Question 6
What is the length of an FT8 transmission cycle?
- AIt varies with the amount of data
- B8 seconds
- C15 seconds Correct
- D30 seconds
Why: An FT8 cycle is 15 seconds.
- E2E07Question 7
How does Q65 differ from JT65?
- AKeyboard-to keyboard operation is supported
- BQuadrature modulation is used
- CMultiple receive cycles are averaged Correct
- DAll these choices are correct
Why: Q65 averages multiple receive cycles.
- E2E08Question 8
Which of the following HF digital modes can be used to transfer binary files?
- APSK31
- BPACTOR Correct
- CRTTY
- DAMTOR
Why: PACTOR can transfer binary files.
- E2E09Question 9
Which of the following HF digital modes uses variable-length character coding?
- ARTTY
- BPACTOR
- CMT63
- DPSK31 Correct
Why: PSK31 uses variable-length (Varicode) characters.
- E2E10Question 10
Which of these digital modes has the narrowest bandwidth?
- AMFSK16
- B170 Hz shift, 45-baud RTTY
- CFT8 Correct
- DPACTOR IV
Why: FT8 has the narrowest bandwidth of these modes.
- E2E11Question 11
What is the difference between direct FSK and audio FSK?
- ADirect FSK modulates the transmitter VFO Correct
- BDirect FSK occupies less bandwidth
- CDirect FSK can transmit higher baud rates
- DAll these choices are correct
Why: Direct FSK shifts the transmitter's VFO; audio FSK feeds tones into the audio input.
- E2E12Question 12
How do ALE stations establish contact?
- AALE constantly scans a list of frequencies, activating the radio when the designated call sign is received Correct
- BALE radios monitor an internet site for the frequency they are being paged on
- CALE radios send a constant tone code to establish a frequency for future use
- DALE radios activate when they hear their signal echoed by back scatter
Why: ALE scans a list of frequencies and activates when it hears its call sign.
- E2E13Question 13
Which of these digital modes has the highest data throughput under clear communication conditions?
- AMFSK16
- B170 Hz shift, 45 baud RTTY
- CFT8
- DPACTOR IV Correct
Why: PACTOR IV has the highest throughput in clear conditions.