🔍 Key Concepts

• Typical operating characteristics of echo sounders (depth finders), especially short pulse lengths for better depth resolution • Relationship between pulse width and ability to distinguish between bottom and closely spaced objects • Approximate time scale (microseconds vs milliseconds) used in marine depth-finding sonar

💭 Think About

• Think about how fine the depth resolution needs to be in normal shipboard echo sounders and whether that suggests very short or relatively long pulses • Consider whether depth sounders are designed more like radar (very short pulses) or like long-range communication (longer pulses) • Compare the time units: which choices represent very short bursts suitable for measuring the brief travel time of sound in water?

✅ Before You Answer

• Convert mentally between microseconds (µs) and milliseconds (ms) to see the size difference in each option • Ask yourself which options would allow enough range resolution to detect small depth changes (shorter pulses = better resolution) • Eliminate any ranges that look more appropriate for long-range sonar sweeps rather than typical shipboard depth sounders