Which modes could be selected to receive vessel traffic lists from high seas shore stations?

Which modes could be selected to receive vessel traffic lists from high seas shore stations?

• A. SSB and FEC
• B. AM and FM
• C. CW and RTTY
• D. USB and LSB

Answer: (A)

The essential idea is that vessel traffic lists are sent over HF by shore stations using a data-friendly, long-range method. SSB provides efficient long-distance transmission on HF, and Forward Error Correction is used to protect the data against the errors that can occur over open ocean radio paths. Together, SSB and FEC let you reliably receive these lists from distant shore stations, even in noisy conditions. The other choices don’t fit because AM and FM aren’t the typical long-range HF modes for this service; CW and RTTY are older, slower methods not used for transmitting these lists; and USB/LSB are only options for selecting a sideband within SSB, not the complete mode and data-coding combination used for vessel traffic lists.

The essential idea is that vessel traffic lists are sent over HF by shore stations using a data-friendly, long-range method. SSB provides efficient long-distance transmission on HF, and Forward Error Correction is used to protect the data against the errors that can occur over open ocean radio paths. Together, SSB and FEC let you reliably receive these lists from distant shore stations, even in noisy conditions.

The other choices don’t fit because AM and FM aren’t the typical long-range HF modes for this service; CW and RTTY are older, slower methods not used for transmitting these lists; and USB/LSB are only options for selecting a sideband within SSB, not the complete mode and data-coding combination used for vessel traffic lists.