How are paired SITOR (NBDP) frequencies...

Question 1 / 27070DflKtpvMRMbcjAMc9s2j

Question 1 of 27070DflKtpvMRMbcjAMc9s2j

How are paired SITOR (NBDP) frequencies normally used?

Question 1 of 27070

How are paired SITOR (NBDP) frequencies normally used?

🔍 Key Concepts

• SITOR (NBDP) modes of operation: ARQ vs FEC • Use of paired frequencies in maritime HF/MF data services • Difference between SITOR/NBDP and DSC functions and frequencies

💭 Think About

• Ask yourself: Why would a system need paired frequencies instead of a single working frequency? What does that imply about how it sends and receives data? • Think about ARQ (Automatic Repeat reQuest) versus FEC (Forward Error Correction): which one requires a return path from the receiving station? • Consider what type of digital service normally uses dedicated DSC frequencies—are these the same as SITOR/NBDP paired working channels?

✅ Before You Answer

• Verify which SITOR mode (ARQ or FEC) needs a two‑way exchange during the message transmission itself. • Confirm whether Distress on HF/MF normally uses special DSC channels or regular SITOR paired working frequencies. • Make sure you distinguish DSC calling frequencies from NBDP working channels in the GMDSS HF/MF band.

Question 1 of 27070

How are paired SITOR (NBDP) frequencies normally used?

These are normally used for ARQ communications with coast radio stations.

These are normally used for FEC communications with coast radio stations.

These are normally used only for Distress communications to limit channel interference.

These are normally used for DSC communications with coast radio stations.

Question 1 / 27070DflKtpvMRMbcjAMc9s2j

Question 1 of 27070DflKtpvMRMbcjAMc9s2j

How are paired SITOR (NBDP) frequencies normally used?

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Question 1 of 27070

How are paired SITOR (NBDP) frequencies normally used?

🔍 Key Concepts

• SITOR (NBDP) modes of operation: ARQ vs FEC • Use of paired frequencies in maritime HF/MF data services • Difference between SITOR/NBDP and DSC functions and frequencies