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Class User Id: 016 NATO JANUS reference Implementation

Proposed Application Type specification for Class user i.d.= 016


Please refer to the forum Class User Id: 016 NATO JANUS reference Implementation - Forum

016 - 00


Application Fields

Name
Type
Descriptor
Station IdentifierIntegerAcoustic ID of transmitter
Parameter Set IdentifierIntegerTransmitter capabilities enumeration or bitmask
Payload SizeIntegerSize in bytes of the payload
PayloadText/BinaryMessage content

Note: The Parameter Set Identifier field is yet to be defined.

Application Data Block

Bits
Descriptor
0/1 bit set
Comments
25 - 18Station Identifier00000000 : 11111111Station identifier of sender
17 - 6Parameter Set000000000000 : 111111111111Encoded parameter set
5 - 0Payload Size000000 : 111111Size of Cargo encoded


In order to save bits, and allow for a Cargo size bigger than 64 bits (the 6 bits of the "Payload Size" only provide 2^6=64 combinations), a custom mapping between the Payload Size bit pattern and the actual size of the encoded Cargo was developed. The Payload Size is encoded as:
Payload Size Range Encoded Value Actual Cargo Size
0 ~ 2 Payload Size Payload Size
3 ~ 4 3 4
5 ~ 480 4 + (Payload Size - 1 - mod(Payload Size - 1, 8)) / 8 Payload Size - 1 - mod(Payload Size - 1, 8)+8

The increased range of the Cargo size (0 to 480 bits) comes with a loss of granularity in the available sizes. It allows for the sizes 0,1,2,4, and starting from 8, only multiples of 8 are available. E.g.: 0,1,2,4, 8, 16, 24, 32, 40,...,472,480.


016 - 01


Application Fields

Name
Type
Descriptor
Station_IdentifierIntegerAcoustic ID of transmitter
Destination_IdentifierIntegerAcoustic ID of end receiver
Ack_RequestBooleanRequest of acknowledgement from the end receiver
Payload_SizeintegerSize in bytes of the payload
PayloadText/BinaryMessage content


Application Data Block

Bits
Descriptor
0/1 bit set
Comments
25 - 18Station Identifier00000000: 11111111Station identifier of sender
17 - 10Destination Identifier 00000000: 11111111Station identifier of selected receiver
9Ack_Request 0= No Req, 1= Ack ReqRequest of acknowledgement from the end receiver
8 - 0Payload Size000000000: 111111111Size of the cargo: payload size plus 2 Bytes for the CRC16

Cargo will be composed by the payload followed by a 2 bytes CRC16 (X^16 + X^15 + X^2 + 1) Full description of CRC16