Merge pull request #148 from thombles/clarify-bit-order
Clarify bit order in various binary structure definitionspull/151/head
Wojciech Kaczmarski
GitHub
commit
7b1a7f15be
152
M17_spec.tex
152
M17_spec.tex
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@ -10,6 +10,8 @@
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\usepackage{tabularray}
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\usepackage{multirow}
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\usepackage{float}
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\usepackage{nicematrix}
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\NiceMatrixOptions{cell-space-top-limit=4pt, cell-space-bottom-limit=4pt}
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\usepackage{tikz}
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\usetikzlibrary{shapes.geometric, arrows.meta}
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\tikzstyle{textonly} = [rectangle,
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@ -487,28 +489,32 @@ Total: 240 Type 1 bits
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Destination and source addresses may be encoded amateur radio callsigns, or special numbers. See the Address Encoding Appendix for details.
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\subsection{LSF TYPE}
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\subsection{LSF TYPE} \label{lsftype}
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The TYPE field contains information about the frames to follow LSF. The Packet/Stream indicator bit determines which mode (Packet or Stream) will be used during the transmission. The remaining field meanings are defined by the specific mode and application.
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\begin{table}[H]
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\centering
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\begin{tblr}{
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colspec={lX},
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}
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\small
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\begin{NiceTabular}{|W{c}{4em}|[tikz=very thick]W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|}
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\hline
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Bits & Content \\
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\diagbox{Byte}{Bit} & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0 \\
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\Hline[tikz=very thick]
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0 &
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\multicolumn{4}{c}{\textit{Reserved}} &
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\parbox{3em}{\centering Signed Stream} &
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\multicolumn{3}{c}{Channel Access Number\ldots} \\
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\hline
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0 & Packet/Stream indicator \\
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1..2 & Data type indicator \\
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3..4 & Encryption type \\
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5..6 & Encryption subtype \\
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7..10 & Channel Access Number (CAN) \\
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11 & Stream signature available \\
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12..15 & Reserved (don't care) \\
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\hline[2px]
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\end{tblr}
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\caption{LSF TYPE definition}
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1 &
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\ldots &
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\multicolumn{2}{c}{\parbox{6em}{\centering Encryption Subtype}} &
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\multicolumn{2}{c}{\parbox{6em}{\centering Encryption Type}} &
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\multicolumn{2}{c}{\parbox{6em}{\centering Data Type}} &
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\parbox{3em}{\centering Packet/ Stream} \\
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\hline
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\end{NiceTabular}
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\normalsize
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\caption{LSF TYPE layout}
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\end{table}
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\begin{table}[H]
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@ -685,23 +691,22 @@ Each Stream Frame contains a 48-bit Link Information Channel (LICH). Each LICH w
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\begin{table}[H]
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\centering
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\begin{tblr}{
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colspec={lX},
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}
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\hline
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Bits & Content \\
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\hline
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0..39 & 40-bit chunk of full LSF Contents (Type 1 bits) \\
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40..42 & LICH\_CNT \\
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43..47 & Reserved \\
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\hline[2px]
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\end{tblr}
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\small
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\begin{NiceTabular}{|W{c}{4em}|[tikz=very thick]W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|}[hvlines]
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\diagbox{Byte}{Bit} & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0 \\
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\Hline[tikz=very thick]
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0 & \Block{3-8}{40-bit chunk of full LSF Contents (Type 1 bits)} \\
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\ldots & \\
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4 & \\
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5 & \multicolumn{3}{c}{LICH\_CNT} & \multicolumn{5}{c}{\textit{Reserved}} \\
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\end{NiceTabular}
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\normalsize
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\caption{Link Information Channel Contents}
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\end{table}
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Total: 48 bits
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The 40-bit chunks start with the most significant byte of the LSF.
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The 40-bit chunks start from the beginning of the LSF.
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\begin{table}[H]
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\centering
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@ -711,12 +716,12 @@ The 40-bit chunks start with the most significant byte of the LSF.
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\hline
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LICH\_CNT & LSF bits \\
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\hline
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0 & 239:200 \\
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1 & 199:160 \\
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2 & 159:120 \\
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3 & 119:80 \\
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4 & 79:40 \\
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5 & 39:0 \\
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0 & 0:39 \\
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1 & 40:79 \\
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2 & 80:119 \\
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3 & 120:159 \\
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4 & 160:199 \\
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5 & 200:239 \\
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\hline[2px]
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\end{tblr}
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\caption{LICH\_CNT and LSF bits}
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@ -899,15 +904,19 @@ Packet Frames contain Packet Contents after ECC/FEC is applied.
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\begin{table}[H]
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\centering
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\begin{tblr}{ll}
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\hline
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Bits & Meaning \\
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\hline
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0..199 & 200-bit chunk of Single Packet \\
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200 & End of Frame (EOF) indicator \\
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201..205 & Packet Frame/Byte Counter \\
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\hline[2px]
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\end{tblr}
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\small
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\begin{NiceTabular}{|W{c}{4em}|[tikz=very thick]W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|}[hvlines]
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\diagbox{Byte}{Bit} & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0 \\
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\Hline[tikz=very thick]
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0 & \Block{3-8}{200-bit chunk of Single Packet} \\
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\ldots & \\
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24 & \\
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25 &
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\parbox{3em}{\centering End of Frame} &
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\multicolumn{5}{c}{Packet Frame/Byte Counter} &
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\Block[fill=gray]{1-2}{} & \\
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\end{NiceTabular}
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\normalsize
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\caption{Packet Contents}
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\end{table}
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@ -923,31 +932,31 @@ When there are no bytes remaining in the Packet Data after removing a 25-byte (o
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\begin{table}[H]
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\centering
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\begin{tblr}{
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colspec={lX},
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}
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\hline
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Bits & Meaning \\
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\hline
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0..4 & Frame number, 0..31 \\
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5 & Set to 0, Not end of frame \\
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\hline[2px]
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\end{tblr}
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\small
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\begin{NiceTabular}{|W{c}{4em}|[tikz=very thick]W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|}[hvlines]
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\diagbox{Byte}{Bit} & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0 \\
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\Hline[tikz=very thick]
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0 &
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0 &
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\multicolumn{5}{c}{Frame number, 0..31} &
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\Block[fill=gray]{1-2}{} & \\
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\end{NiceTabular}
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\normalsize
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\caption{Packet Metadata Field with EOF = 0}
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\end{table}
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\begin{table}[H]
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\centering
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\begin{tblr}{
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colspec={lX},
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}
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\hline
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Bits & Meaning \\
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\hline
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0..4 & Number of bytes in frame, 1..25 \\
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5 & Set to 1, End of frame \\
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\hline[2px]
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\end{tblr}
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\small
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\begin{NiceTabular}{|W{c}{4em}|[tikz=very thick]W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|W{c}{3em}|}[hvlines]
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\diagbox{Byte}{Bit} & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0 \\
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\Hline[tikz=very thick]
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0 &
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1 &
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\multicolumn{5}{c}{Number of bytes in frame, 1..25} &
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\Block[fill=gray]{1-2}{} & \\
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\end{NiceTabular}
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\normalsize
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\caption{Packet Metadata Field with EOF = 1}
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\end{table}
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@ -1133,30 +1142,23 @@ The destination address used by a client may simply be a callsign or reflector d
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\paragraph{TYPE field}
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The TYPE field contains information about the frames to follow LSF.
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The TYPE field contains information about the frames to follow LSF. For full definition see Section \ref{lsftype}.
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\begin{table}[H]
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\centering
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\begin{tblr}{ll}
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\hline
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Bits & Meaning \\
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Packet/Stream & 1 = Stream Mode \\
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\hline
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0 & Packet/Stream indicator \\
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& 1 = Stream Mode \\
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Data Type & $10_2$ = Voice only (3200 bps) \\
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\hline
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1..2 & Data type indicator \\
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& $10_2$ = Voice only (3200 bps) \\
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\hline
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3..4 & Encryption type \\
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& $00_2$ = None \\
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Encryption Type & $00_2$ = None \\
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& $01_2$ = Scrambling \\
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& $10_2$ = AES \\
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\hline
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5..6 & Encryption subtype \\
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Encryption Subtype & Depends on Encryption Type \\
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\hline
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7..10 & Channel Access Number (CAN) \\
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\hline
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11..15 & Reserved (don't care) \\
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Channel Access Number (CAN) & 0..15 \\
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\hline[2px]
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\end{tblr}
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\caption{M17 Voice LSF TYPE definition}
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