Technician T8A: Modulation and bandwidth
These are the 12 official questions in group T8A of the 2026–2030 Technician 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.
- T8A01Question 1
Which of the following is a form of amplitude modulation?
- ASpread spectrum
- BPacket radio
- CSingle sideband Correct
- DPhase shift keying (PSK)
Why: Single sideband is a form of amplitude modulation.
- T8A02Question 2
What type of modulation is commonly used for VHF packet radio transmissions?
- AFM or PM Correct
- BSSB
- CAM
- DPSK
Why: VHF packet radio commonly uses FM or PM.
- T8A03Question 3
Which type of voice mode is often used for long-distance (weak signal) contacts on the VHF and UHF bands?
- AFM
- BDRM
- CSSB Correct
- DPM
Why: SSB is the usual voice mode for weak-signal VHF and UHF contacts.
- T8A04Question 4
Which type of modulation is commonly used for VHF and UHF voice repeaters?
- AAM
- BSSB
- CPSK
- DFM or PM Correct
Why: VHF and UHF voice repeaters use FM or PM.
- T8A05Question 5
Which of the following signal types has the narrowest bandwidth?
- AFM voice
- BSSB voice
- CCW Correct
- DSlow-scan TV
Why: CW is the narrowest of these signals.
- T8A06Question 6
Which sideband is normally used for 10-meter HF, VHF, and UHF single-sideband communications?
- AUpper sideband Correct
- BLower sideband
- CSuppressed sideband
- DInverted sideband
Why: Upper sideband is used on 10 meters, VHF and UHF.
- T8A07Question 7
What is one characteristic of single sideband (SSB) compared to FM?
- ASSB signals are easier to tune in correctly
- BSSB signals are less susceptible to interference
- CSSB signals have narrower bandwidth Correct
- DSSB signals are less susceptible to high SWR
Why: SSB takes up less bandwidth than FM.
- T8A08Question 8
What is the approximate bandwidth of a typical single sideband (SSB) voice signal?
- A1 kHz
- B3 kHz Correct
- C6 kHz
- D15 kHz
Why: An SSB voice signal is about 3 kHz wide.
- T8A09Question 9
What is the approximate bandwidth of an FM voice signal on VHF repeaters?
- ALess than 500 Hz
- BAbout 150 kHz
- CBetween 10 and 15 kHz Correct
- DBetween 50 and 125 kHz
Why: An FM voice signal on a repeater is about 10 to 15 kHz wide.
- T8A10Question 10
What is the approximate bandwidth of AM fast-scan TV transmissions?
- AMore than 10 MHz
- BAbout 6 MHz Correct
- CAbout 3 MHz
- DAbout 1 MHz
Why: AM fast-scan TV is about 6 MHz wide.
- T8A11Question 11
What is the approximate bandwidth required to transmit a CW signal?
- A2.4 kHz
- B150 Hz Correct
- C1000 Hz
- D15 kHz
Why: A CW signal needs about 150 Hz.
- T8A12Question 12
Which of the following is a disadvantage of FM compared with single sideband?
- AVoice quality is poorer
- BOnly one signal can be received at a time Correct
- CFM signals are harder to tune
- DFM signals are more susceptible to high SWR
Why: With FM the strongest signal wins, so you can only receive one at a time.