AIS units use the following:

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🔍 Key Concepts

• Know which specific VHF channels are internationally allocated for AIS (Automatic Identification System) traffic. • Recall the typical frequencies (in MHz) used for AIS-1 and AIS-2, and that they are in the marine mobile VHF band but not the distress/safety channels. • Remember the usual data rate and modulation used by AIS (GMSK and its standard bit rate).

💭 Think About

• Which of these options lists the pair of channels that are internationally reserved for AIS, rather than for voice, DSC, or general working traffic? • Look at the frequencies: which pair is closest to the well-known AIS-1 and AIS-2 frequencies around 162 MHz? • Compare the data rate (9.6 kbps vs 4.8 kbps): which matches what you’ve studied for AIS messages on GMSK modulation?

✅ Before You Answer

• Eliminate any choice that uses Channel 16 or 70, since those are reserved for distress/safety and DSC, not AIS. • Confirm which frequencies are officially designated AIS channels (often referred to as AIS 1 and AIS 2 in textbooks or ITU references). • Verify that the AIS system uses GMSK modulation at 9.6 kbps, and discard any options that do not match both the modulation type and bit rate.

🔍 Key Concepts

💭 Think About

✅ Before You Answer