Which of the following is a form of amplitude modulation?
AnswerSingle sideband
Single sideband is derived from amplitude modulation by suppressing the carrier and one sideband, leaving only one sideband to carry the information.
RF PREP // FCC AMATEUR RADIO
T8 · Signals and Emissions
Technician · correct answers only, in question-pool order.
What type of modulation is commonly used for VHF packet radio transmissions?
AnswerFM or PM
VHF packet radio commonly carries its digital audio tones using frequency or phase modulation on the RF carrier.
Which type of voice mode is often used for long-distance (weak signal) contacts on the VHF and UHF bands?
AnswerSSB
SSB uses less bandwidth and transmitter power than FM for a comparable voice contact, which makes it well suited to weak-signal VHF and UHF work.
Which type of modulation is commonly used for VHF and UHF voice repeaters?
AnswerFM or PM
Most VHF and UHF voice repeater systems use frequency modulation or the closely related phase modulation.
Which of the following signal types has the narrowest bandwidth?
AnswerCW
CW occupies very little spectrum because the transmitted information is carried by keying a single carrier on and off.
Which sideband is normally used for 10-meter HF, VHF, and UHF single-sideband communications?
AnswerUpper sideband
The usual convention is upper sideband on 10 meters and on VHF and UHF SSB.
What is one characteristic of single sideband (SSB) compared to FM?
AnswerSSB signals have narrower bandwidth
SSB voice occupies less spectrum than FM voice, allowing more signals to fit into the same amount of band space.
What is the approximate bandwidth of a typical single sideband (SSB) voice signal?
Answer3 kHz
A typical amateur SSB voice signal occupies roughly 3 kHz of spectrum.
What is the approximate bandwidth of an FM voice signal on VHF repeaters?
AnswerBetween 10 and 15 kHz
A typical VHF FM repeater voice signal occupies roughly 10 to 15 kHz, considerably wider than an SSB voice signal.
What is the approximate bandwidth of AM fast-scan TV transmissions?
AnswerAbout 6 MHz
Analog AM fast-scan television uses a video channel roughly 6 MHz wide, far broader than ordinary voice or data modes.
What is the approximate bandwidth required to transmit a CW signal?
Answer150 Hz
A properly keyed CW signal is extremely narrow. The Technician pool uses approximately 150 Hz as its required bandwidth.
Which of the following is a disadvantage of FM compared with single sideband?
AnswerOnly one signal can be received at a time
FM receivers exhibit a capture effect: when two signals arrive on the same frequency, the stronger one tends to dominate instead of both being heard clearly.
What telemetry information is typically transmitted by satellite beacons?
AnswerHealth and status of the satellite
Satellite beacons commonly transmit telemetry describing the spacecraft's operating health and status.
What is the impact of using excessive effective radiated power on a satellite uplink?
AnswerBlocking access by other users
Using more uplink power than necessary can overpower other stations sharing the satellite transponder and make it difficult for them to gain access.
Which of the following are provided by satellite tracking programs?
AnswerSatellite tracking programs provide real-time ground-track maps, pass times and pointing angles, and apparent frequency including Doppler shift.
Satellite tracking software can show the spacecraft's ground track, predict pass times and pointing angles, and account for apparent frequency changes caused by Doppler shift.
What mode of transmission is commonly used by amateur radio satellites?
AnswerSSB, FM, and CW/data.
Amateur satellites may carry SSB, FM, CW, and data systems depending on the spacecraft and transponder design.
What is a satellite beacon?
AnswerA transmission from a satellite that contains status information
A satellite beacon is a regular transmission from the spacecraft containing identification, telemetry, or other status information.
Which of the following are inputs to a satellite tracking program?
AnswerThe Keplerian elements
Keplerian elements describe a satellite's orbit mathematically. Tracking software uses them to calculate where and when the satellite will be visible.
What is Doppler shift in reference to satellite communications?
AnswerAn observed change in signal frequency caused by relative motion between the satellite and Earth station
Relative motion between the satellite and ground station changes the apparent received frequency. The frequency is shifted one way while approaching and the other while receding.
What does it mean if a satellite is operating in U/V mode?
AnswerThe satellite uplink is in the 70-centimeter band and the downlink is in the 2-meter band
In the U/V naming convention, U means the UHF 70-centimeter uplink and V means the VHF 2-meter downlink.
What causes spin fading of satellite signals?
AnswerRotation of the satellite and its antennas
As a satellite rotates, the orientation of its antennas changes relative to the ground station. The received signal can rise and fall as a result.
What does the term LEO mean in reference to communication satellites?
AnswerLow Earth Orbit, which has a period of around 100 minutes
LEO means Low Earth Orbit. Many amateur satellites in LEO circle Earth in roughly 100 minutes.
Who is permitted to receive telemetry from an amateur radio satellite?
AnswerAnyone
Amateur satellite telemetry is intended to be openly receivable; no amateur license is required merely to listen to it.
Which of the following is a way to determine whether your satellite uplink power into a linear transponder satellite is neither too low nor too high?
AnswerYour signal strength on the downlink should be about the same as the beacon
On a linear transponder, a useful operating guideline is to keep your downlink signal about as strong as the satellite beacon rather than overpowering the transponder.
Which of the following methods is used to locate sources of noise interference or jamming?
AnswerRadio direction finding
Radio direction finding uses directional reception from one or more locations to determine the bearing toward an interfering or jamming signal.
Which of these items would be useful for a hidden transmitter hunt?
AnswerA directional antenna
A directional antenna lets the operator compare signal strength as the antenna is aimed in different directions, helping establish a bearing to the hidden transmitter.
What operating activity involves contacting as many stations as possible during a specified period?
AnswerContesting
A contest challenges operators to make as many qualifying contacts as possible during a defined operating period and under a specific set of rules.
Which of the following is good practice when contacting another station in a contest?
AnswerSending only the minimum information needed for proper identification and the contest exchange
Contest exchanges are intentionally efficient. Send only the information required for station identification and the specific contest exchange.
What is a grid locator?
AnswerA letter-number designator assigned to a geographic location
A grid locator is a standardized letter-and-number code that identifies a geographic area, making station locations easy to exchange compactly.
How is over the air access to Internet Radio Linking Project (IRLP) nodes accomplished?
AnswerBy using Dual-Tone Multi-Frequency (DTMF) signals
IRLP nodes are commonly controlled over the air with DTMF commands sent from the user's radio.
What is Voice Over Internet Protocol (VoIP)?
AnswerA method of delivering voice communications over the internet using digital techniques
Voice over Internet Protocol digitizes voice and transports it over internet networks instead of a traditional analog telephone path.
What is the Internet Radio Linking Project (IRLP)?
AnswerA technique to connect amateur radio systems, such as repeaters, via the internet
IRLP links amateur radio systems such as repeaters through internet connections, allowing RF users at different nodes to communicate.
Which of the following protocols enables an amateur station to transmit through a repeater without using a radio to initiate the transmission?
AnswerEchoLink
EchoLink can let an authenticated amateur operator use a computer or phone client to connect through an EchoLink-enabled repeater or node without originating the connection by radio.
What is required before using the EchoLink system?
AnswerRegister your call sign and provide proof of license
EchoLink requires users to register their amateur call sign and verify that they hold a valid amateur radio license.
What is an amateur radio station that connects other amateur stations to the internet?
AnswerA gateway
A gateway connects amateur radio users or systems to another network, including the internet.
Which of the following is a digital communications mode?
AnswerPacket radio, IEEE 802.11, and FT8.
Packet radio, IEEE 802.11 networking, and FT8 all convey information digitally rather than by ordinary analog voice.
What is FT8?
AnswerA digital mode capable of low signal-to-noise operation
FT8 is designed for reliable communication at very low signal-to-noise ratios, making it effective for weak-signal contacts.
What kind of data can be transmitted by APRS?
AnswerGPS position data, text messages, and weather data.
APRS packets can carry station position, short text messages, weather observations, and other tactical information.
What is meant by the term "NTSC?"
AnswerAn analog fast-scan color TV signal
In the Technician pool, NTSC refers to the traditional analog fast-scan color television signal standard.
Which of the following is an application of APRS?
AnswerProviding real-time tactical digital communications in conjunction with a map showing the locations of stations
APRS combines real-time packet data with map displays, making it useful for tactical communications and tracking station locations.
What does the abbreviation "PSK" mean?
AnswerPhase Shift Keying
PSK stands for Phase Shift Keying, a digital modulation method that conveys data by changing the phase of the carrier.
Which of the following describes DMR?
AnswerA technique for time-multiplexing two digital voice signals on a single 12.5 kHz repeater channel
DMR uses two time slots on one 12.5 kHz radio channel, allowing two separate digital voice conversations to share the same RF channel.
Which of the following is included in packet radio transmissions?
AnswerA checksum for error detection, addressing information, and automatic repeat request when errors occur.
Packet radio frames include addressing information and a checksum for error detection, and protocols can request retransmission when errors are found.
What is CW?
AnswerAnother name for a Morse code transmission
CW means continuous wave in radio terminology and is the traditional emission used for Morse code transmissions.
Which of the following operating activities is supported by digital mode software in the WSJT-X software suite?
AnswerEarth-Moon-Earth, weak-signal propagation beacons, and meteor scatter.
WSJT-X supports specialized weak-signal modes used for Earth-Moon-Earth, propagation beacons, and meteor-scatter work.
What is the role of ARQ in a transmission system?
AnswerAn error correction method in which the receiving station detects errors and sends a request for retransmission
ARQ means Automatic Repeat reQuest. The receiver detects an error and requests that the transmitting station send the affected information again.
Which of the following best describes an amateur radio mesh network?
AnswerAn amateur-radio data network using commercial Wi-Fi equipment with modified firmware
The Technician pool describes an amateur mesh network as a data network built from commercial Wi-Fi hardware running modified firmware for amateur-radio networking.