🔍 Key Concepts

• ITU-R and FCC emission standards for marine VHF/UHF voice channels • Difference between channel spacing (e.g., 25 kHz, 12.5 kHz) and frequency deviation • Typical deviation used for wideband FM vs narrowband FM in marine/land mobile services

💭 Think About

• Think about what deviation value is commonly associated with a traditional 25 kHz wideband FM channel used in marine and land mobile radios. • Which of the listed values is usually connected with narrowband operation, and which one(s) are too large for modern regulated communications channels? • Consider that the maximum deviation must stay comfortably within the channel spacing so that adjacent channels are not interfered with.

✅ Before You Answer

• Identify which answer choice matches the standard deviation for 25 kHz wideband FM voice channels. • Eliminate any values that would clearly overrun a 25 kHz channel when you consider peak-to-peak swing (±deviation). • Check that the remaining value is one you’ve seen associated with marine VHF radiotelephone equipment specifications.