Codegroup Message Structure

Codegroup messages should have a

-- HEADER
-- BODY
-- FOOTER

each of different formats.

Format notes 

# : Numbers only 
$ : Letters only 

The HEADER format is 

-- H##### 

The BODY format is 

-- $$$$$ (ZZZZZ reserved for 1st codegroup) 

The FOOTER format is

-- F####

The Message Body in the initial version has checksums, but over time this will not do as the message codeing formats become more complex.

Transitioning to CRC32K is important, but the alterations to the message structure format are not clear at this time.

---

Transitioning later on to a Packet & Frame coding infrastructure is important. It is assumed that the the CRC32K cheksums will be kept.

Future Frame coding format notes (provisional)

-- Frame Mode and Frame Version must be declared in the Header. Initially both should be 16 bits.

-- Messages too short for a Frame will not contain a Frame, this should be noted in the Frame Mode in the Header.

-- Frames will not collide with Packets.

-- Frames can only hold groups of Packets.

-- Frames will only hold

1. A standard CCSDS Frame Marker, or Magic Number.
2. A Frame Number, probably 16 bits. Probably incremented using +2 or +4 steps.
3. A checksum or hashsum of the group of preceding Packets.
4. A CRC32K checksum of the Frame.

-- One Frame will equal either 3 Packets or 5 Packets.