What does the scanning function of an FM transceiver do?
The correct answer is C: Tunes through a range of frequencies to check for activity. The scanning function of an FM transceiver tunes through a range of frequencies (or memory channels) to check for activity. When it detects a signal (opens squelch), it stops so you can listen.
Scanning is a useful feature for finding active frequencies. The transceiver automatically tunes through a preset range of frequencies or through memory channels, stopping when it detects a signal. This allows you to monitor multiple frequencies without manually tuning. You can typically set scan limits, choose which memory channels to scan, and adjust how long the scanner pauses on active frequencies. This is a standard feature on most modern FM transceivers.
Exam Tip
Scanning = Tunes through frequencies. Remember: The scanning function automatically tunes through a range of frequencies to check for activity, stopping when it finds a signal.
Memory Aid
"**S**canning = **S**earching **F**requencies (think 'S = SF' = Searching Frequencies)"
Real-World Application
You enable scanning on your 2-meter transceiver, and it automatically tunes through the 2-meter band (144-148 MHz). When it detects a signal (squelch opens), it stops and you can listen. After a few seconds of no activity, it continues scanning. This lets you monitor the entire band and find active frequencies without manually tuning. You can also scan just your memory channels if you prefer.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Scanning doesn't check signal deviation. Deviation is a modulation parameter, not what scanning does.
Option B: Incorrect. Scanning doesn't prevent interference to repeaters. It's a receive function for finding active frequencies.
Option D: Incorrect. Scanning doesn't check for messages on digital bulletin boards. It scans frequencies for any activity, not specifically digital messages.
题目解析
The correct answer is C: Tunes through a range of frequencies to check for activity. The scanning function of an FM transceiver tunes through a range of frequencies (or memory channels) to check for activity. When it detects a signal (opens squelch), it stops so you can listen. Scanning is a useful feature for finding active frequencies. The transceiver automatically tunes through a preset range of frequencies or through memory channels, stopping when it detects a signal. This allows you to monitor multiple frequencies without manually tuning. You can typically set scan limits, choose which memory channels to scan, and adjust how long the scanner pauses on active frequencies. This is a standard feature on most modern FM transceivers.
考试技巧
Scanning = Tunes through frequencies. Remember: The scanning function automatically tunes through a range of frequencies to check for activity, stopping when it finds a signal.
记忆口诀
**S**canning = **S**earching **F**requencies (think 'S = SF' = Searching Frequencies)
实际应用示例
You enable scanning on your 2-meter transceiver, and it automatically tunes through the 2-meter band (144-148 MHz). When it detects a signal (squelch opens), it stops and you can listen. After a few seconds of no activity, it continues scanning. This lets you monitor the entire band and find active frequencies without manually tuning. You can also scan just your memory channels if you prefer.
错误选项分析
Option A: Incorrect. Scanning doesn't check signal deviation. Deviation is a modulation parameter, not what scanning does. Option B: Incorrect. Scanning doesn't prevent interference to repeaters. It's a receive function for finding active frequencies. Option D: Incorrect. Scanning doesn't check for messages on digital bulletin boards. It scans frequencies for any activity, not specifically digital messages.
知识点
Scanning, Frequency scanning, Activity detection, Transceiver features
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.