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Unformatted text preview: sical Channel shall be
determined based on the mission requirements for data quality and the selected
options for the underlying Channel Coding Sublayer. This field may be mandatory
depending on the selected options for the Channel Coding Sublayer. 4.1.6.2 Frame Error Control Field Encoding Procedure 4.1.6.2.1 The Encoding Procedure shall accept an (n–16)bit Transfer Frame, excluding the
Frame Error Control Field, and generate a systematic binary (n,n–16) block code by
appending a 16bit Frame Error Control Field as the final 16 bits of the codeblock, where n is
the length of the Transfer Frame.
4.1.6.2.2 The equation for the contents of the Frame Error Control Field is: FECF = [(X16 ⋅ M(X)) + (X(n–16) ⋅ L(X))] modulo G(X)
where
– all arithmetic is modulo 2; – n is the number of bits in the encoded message; – M(X) is the (n–16)bit message to be encoded expressed as a polynomial with binary
coefficients; – L(X) is the presetting polynomial given by
15 L(X) = ∑ Xi ;
i=0 G(X) is the generating polynomial given by
G(X) = X16 + X12 + X5 + 1.
NOTE – The X(n–16) ⋅ L(X) term has the effect of presetting the shift register to all ‘1’ state
prior to encoding. CCSDS 132.0B1 Page 413 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL 4.1.6.3 Frame Error Control Field Decoding Procedure The error detection syndrome, S(X), is given by
S(X) = [(X16 ⋅ C*(X)) + (Xn ⋅ L(X))] modulo G(X)
where
– C*(X) is the received block, including the Frame Error Control Field, in polynomial
form; and
– S(X) is the syndrome polynomial which will be zero if no error is detected and nonzero if an error is detected.
4.2 PROTOCOL PROCEDURES AT THE SENDING END 4.2.1 OVERVIEW
This subsection describes procedures at the sending end associated with each of the functions
shown in figure 45. Data flow from the top to the bottom of the figure. This figure
identifies datahandling functions performed by the protocol entity at the sending end and
shows logical relationships among these functions. Th...
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This document was uploaded on 03/06/2014.
 Spring '14

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