🔍 Key Concepts

• SITOR (NBDP) normally operates on MF/HF frequencies, not VHF or UHF. • VHF and UHF are generally limited to line-of-sight range due to how they propagate. • At night, skywave (ionospheric) propagation greatly affects which bands can cover hundreds of miles.

💭 Think About

• Which of the listed bands are typically used for long-range, beyond-line-of-sight maritime communication with coast stations? • How does the ionosphere at night affect MF/HF versus VHF/UHF signals over an 800‑mile path? • If SITOR (NBDP) is used for long-distance telex-like communication, on which band is it normally assigned by regulations and coast station frequency lists?

✅ Before You Answer

• Verify the normal frequency bands allocated for SITOR (NBDP) coast and ship stations in your study material or ITU/USCG tables. • Check the approximate maximum range of VHF-FM and UHF marine communications under standard conditions (without special propagation). • Confirm which band relies on ionospheric reflection to routinely achieve 800‑mile (and greater) communication distances, especially at night.