二零二三年 优质公开课NBDPCOMMUNICATIONPROCEDURES.pptx

GMDSS COMMUNICATION SERVICESCHAPTER 5 TERRESTRIAL RADIO COMMUNICATION Section 4 NBDP Communication Procedures CONTENTS01 Telex and NBDP02 Two Modes in Telex Operation03 High Frequency (HF) MSI04 General Procedures for NBDP Service Telex and NBDP01To understand the role of Telex and NBDP TelexAvailable both in satellite communications and terrestrial system An international, dial-up data communications serviceThe terrestrial radio telex services in the MF and HF marine bands01 Telex and NBDP NBDPSubstituting the Morse code signals Marine telex——Narrow Band Direct Printing01 Telex and NBDPTransmitted by keyboards and automatically received Two Modes in Telex Operation02To master the characteristic of ARQ and FEC Automatic Repetition reQuest ——ARQ Forward Error Correction ——FEC02 Two Modes in Telex Operation Both stations are synchronized to each others signalsIn groups of 3 characters, 7 bitsACK (acknowledge) for proper receipt or NAK (Negative acknowledge)02 Two Modes in Telex OperationARQ Send each character twicePhasing pairsSELFEC——transmission for ships to receive telex messages whilst in a port02 Two Modes in Telex OperationFEC High Frequency (HF) MSI03To understand the characteristic of HF MSI A similar mode to NAVTEX transmitted03 High Frequency (HF) MSITransmitting scheduled, times and allocated frequencies4,209.5 KHz Automatic operation on HF requires receipt of all MSI traffic without the ability to designate stations or types of information03 High Frequency (HF) MSI General Procedures for NBDP Service04To take note of the operation of NBDP The procedures specified in this section employedThe operators exchanging traffic by NBDP equipment04 General Procedures for NBDP Service The traffic may be exchanged with or without the use of error-correcting equipment04 General Procedures for NBDP Service For communication between two stations the ARQ mode should be used when available For transmissions from one coast or ship station to two or more oth