Ham Radio General Class Test Digital Modes and Data Communications 1 — Questions and Answers
Question 1: Which digital mode uses 15-second structured time slots and is most widely used for weak-signal HF communication?
- FT8 (Correct answer)
- PSK31
- RTTY
- Olivia
Correct answer: FT8
FT8 uses 15-second transmission and receive windows and can decode signals well below the audible noise floor, making it the dominant weak-signal HF mode.
Question 2: What is the standard frequency shift used for RTTY operation on HF bands?
- 170 Hz (Correct answer)
- 500 Hz
- 1000 Hz
- 3000 Hz
Correct answer: 170 Hz
The standard frequency shift for HF RTTY is 170 Hz between the mark and space frequencies, which fits within the passband of an SSB transceiver.
Question 3: What is the approximate bandwidth occupied by a PSK31 signal?
- 31 Hz (Correct answer)
- 500 Hz
- 2.4 kHz
- 6 kHz
Correct answer: 31 Hz
PSK31 uses a symbol rate of 31.25 baud, resulting in a signal bandwidth of approximately 31 Hz — extremely narrow for HF digital communication.
Question 4: At what standard data rate is packet radio typically operated on HF bands?
- 300 baud (Correct answer)
- 1200 baud
- 9600 baud
- 56000 baud
Correct answer: 300 baud
HF packet radio is standardized at 300 baud due to the narrower bandwidth constraints and propagation characteristics of HF frequencies.
Question 5: What does APRS stand for?
- Automatic Packet Reporting System (Correct answer)
- Amateur Position Relay Station
- Automatic Propagation Relay System
- Amateur Packet Radio Service
Correct answer: Automatic Packet Reporting System
APRS stands for Automatic Packet Reporting System, used to automatically transmit position, weather, and status information over amateur radio.
Question 6: What type of modulation does PSK31 use?
- Phase shift keying (Correct answer)
- Frequency shift keying
- Amplitude shift keying
- Single sideband suppressed carrier
Correct answer: Phase shift keying
PSK stands for Phase Shift Keying — PSK31 shifts the phase of the carrier to encode data, making it highly efficient in narrow bandwidth.
Question 7: Which digital mode is designed for propagation testing using extremely low power and automatically uploads reception reports to an internet database?
- WSPR (Correct answer)
- FT8
- RTTY
- PSK63
Correct answer: WSPR
WSPR (Weak Signal Propagation Reporter) transmits very low power beacons and reports reception spots to wsprnet.org, enabling global propagation analysis.
Ham Radio General Class Test Digital Modes and Data Communications 1
Which digital mode uses 15-second structured time slots and is most widely used for weak-signal HF communication?