Unused bits in the last byte should be set to zero in order to preserve byte boundary. Generic example for a message table: 17 Parameter Symbol Number of bits Description P1 T 6 Parameter 1 P2 D 1 Parameter 2 P3 I 1 Parameter 3 P4 M 27 Parameter 4 P5 N 2 Parameter 5 Unused 0 3 Unused bits Logical view of data as described in § 3.3.7: Bit order M----L-- M------- -------- -------- --LML000 Symbol TTTTTTDI MMMMMMMM MMMMMMMM MMMMMMMM MMMNN000 Byte order 1 2 3 4 5 Output order to VHF data link (bit-stuffing is disregarded in the example): Bit order --L----M -------M -------- -------- 000LML-- Symbol IDTTTTTT MMMMMMMM MMMMMMMM MMMMMMMM 000NNMMM Byte order 1 2 3 4 5 3.3.7.1 Message identification The message ID should be 6 bits long and should range between 0 and 63. The message ID should identify the message type. 3.3.7.2 Self-organizing time division multiple access message structure The SOTDMA message structure should supply the necessary information in order to operate in accordance with § 3.3.4.4. The message structure is shown in Fig. 17. 17 3.3.7.2.1 User identification The user identification (User ID) should be the MMSI (see § 3, 1). The MMSI is 30 bits long. The first 9 digits (most significant digits) should be used only. 3.3.7.2.2 Self-organizing time division multiple access communication The communication state provides the following functions: it contains information used by the slot allocation algorithm in the SOTDMA concept; –
Unused bits in the last byte should be set to zero in order to preserve byte boundary. Generic example for a message table: 17 Parameter Symbol Number of bits Description P1 T 6 Parameter 1 P2 D 1 Parameter 2 P3 I 1 Parameter 3 P4 M 27 Parameter 4 P5 N 2 Parameter 5 Unused 0 3 Unused bits Logical view of data as described in § 3.3.7: Bit order M----L-- M------- -------- -------- --LML000 Symbol TTTTTTDI MMMMMMMM MMMMMMMM MMMMMMMM MMMNN000 Byte order 1 2 3 4 5 Output order to VHF data link (bit-stuffing is disregarded in the example): Bit order --L----M -------M -------- -------- 000LML-- Symbol IDTTTTTT MMMMMMMM MMMMMMMM MMMMMMMM 000NNMMM Byte order 1 2 3 4 5 3.3.7.1 Message identification The message ID should be 6 bits long and should range between 0 and 63. The message ID should identify the message type. 3.3.7.2 Self-organizing time division multiple access message structure The SOTDMA message structure should supply the necessary information in order to operate in accordance with § 3.3.4.4. The message structure is shown in Fig. 17. 17 3.3.7.2.1 User identification The user identification (User ID) should be the MMSI (see § 3, 1). The MMSI is 30 bits long. The first 9 digits (most significant digits) should be used only. 3.3.7.2.2 Self-organizing time division multiple access communication The communication state provides the following functions: – it contains information used by the slot allocation algorithm in the SOTDMA concept;
R-REC-M.1371-5-201402-I!!MSW-E.docx