Technician exam: signals and emissions
Modulation types, bandwidth, satellites, digital modes and the signals you transmit. 47 questions, 10 at a time, starting with ones you haven't seen.
Rules to remember10 key signals and emissions rulesShow the rules
- VHF and UHF voice repeaters use FM or the closely related PM. (p. 59)
- By convention, upper sideband is used on 10 meters and on VHF and UHF; lower sideband is the custom on the lower HF bands. (p. 60)
- An SSB voice signal occupies about 3 kHz, enough to carry the speech frequencies needed for clear voice. (p. 60)
- A VHF repeater FM voice signal is roughly 10 to 15 kHz wide, which is why repeater channels are spaced that far apart. (p. 60)
- A CW signal needs only around 150 Hz, the narrowest of the common amateur modes. (p. 61)
- Amateur satellites carry SSB, FM, and CW or data, depending on the satellite. (p. 61)
- Amateur satellite telemetry is not encrypted, so anyone may receive and decode it. (p. 63)
- A gateway is a station that connects amateur radio users to the internet. (p. 65)
- Packet radio, IEEE 802.11 Wi-Fi and FT8 all carry information as digital data, so each is a digital mode. (p. 65)
- APRS can carry GPS positions, short text messages and weather station reports. (p. 65)
Taken from the explanations to checked practice questions; page numbers link to the official handbook.
Sample signals and emissions questions
1.Which of the following methods is used to locate sources of noise interference or jamming?
- ARadio direction finding
- BDoppler radar
- CPhase locking
- DEcholocation
Show the answer
✓ A. Radio direction finding
Radio direction finding uses directional antennas and receivers to take bearings and track down where a signal or noise comes from.
2.Which of the following is a disadvantage of FM compared with single sideband?
- AFM signals are more susceptible to high SWR
- BVoice quality is poorer
- COnly one signal can be received at a time
- DFM signals are harder to tune
Show the answer
✓ C. Only one signal can be received at a time
FM receivers lock onto the strongest signal on a channel, so overlapping stations cannot be heard together, while SSB can let weaker signals through.
3.What telemetry information is typically transmitted by satellite beacons?
- AHealth and status of the satellite
- BThe signal strength of received signals
- CTime of day accurate to plus or minus 1/10 second
- DAll these choices are correct
Show the answer
✓ A. Health and status of the satellite
Satellite beacons send telemetry about the satellite's health and status, such as voltages and temperatures.
4.Who is permitted to receive telemetry from an amateur radio satellite?
- AOnly a licensed radio amateur who has received the encryption key from AMSAT
- BAnyone
- COnly the satellite control operator
- DOnly the control operator or a licensed radio amateur who has received the encryption key from the control operator
Show the answer
✓ B. Anyone
Amateur satellite telemetry is not encrypted, so anyone may receive and decode it.