<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Hi Matt,<br>
<blockquote cite="mid:51E0613E.6000701@nycap.rr.com" type="cite">
<div id="ygrp-mlmsg" style="position: relative;">
<div id="ygrp-msg" style="z-index: 1;">
<div id="ygrp-text">
<p>
I am trying to get a handle on the data in the Link
Control Word. The<br>
LCW is 72 bits right? On transmission the 72 bit LCW is
serialized into<br>
12 hex bits. And then it is encoded with a (24,12,13) RS
code to yield<br>
24 hex bits. The 24 hex bits are then encoded with a
(10,6,3) shortened<br>
Hamming code to yield 240 bits total.<br>
<br>
Is it known how the bits are serialized? Or better yet is
there an<br>
existing function for unserializing/serializing that will
work here?<br>
</p>
</div>
</div>
</div>
</blockquote>
The Common Air Interface specification defines the bit interleaving.
We typically use a static const array identifying the indices of the
bits that make up a given logical field.<br>
<br>
<blockquote cite="mid:51E0613E.6000701@nycap.rr.com" type="cite">
<div id="ygrp-mlmsg" style="position:relative;">
<div id="ygrp-msg" style="z-index: 1;">
<div id="ygrp-text">
<p>
And the Hamming and RS codes: does anyone have functions
for decoding<br>
(10,6,3) Hamming and (24,12,13) RS code?.</p>
</div>
</div>
</div>
<img moz-do-not-send="true"
src="mailbox:///home/stevie/.icedove/vhc5zpy5.default/Mail/Local%20Folders/Drafts?number=5075972&s=97359714/grpId=22084582/grpspId=1705644089/msgId=956/stime=1373659456"
height="1" width="1"> <br>
<div style="color: #fff; height: 0;"></div>
<!-- end group email -->
</blockquote>
<br>
An RS implementation is included in GNURadio and/or ET++. A
generalized hamming code is also available in ET++. In the latter
case you'll find its parameterized by the number of bits input,
number of bits added during encoding and the distance (which is
2*no-of-bits-it-can-fix - 1). I attach a specific hamming code we
use in op25 but make no warranties as to its suitability for LCW.<br>
<br>
Regards<br>
<br>
Stevie<br>
</body>
</html>