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On 1/6/2012 1:30 PM, Daron Wilson wrote:
<blockquote
cite="mid:05D86CDC2CB746978241AAC124820BF5@oregonelectric.local"
type="cite">
<pre wrap="">
</pre>
<blockquote type="cite">
<pre wrap="">While the protocol is open, the CODEC is not.
</pre>
</blockquote>
<pre wrap="">
Just for the sake of discussion, is there a P25 hardware codec available for
free? (since P25 is an open non-proprietary protocol by definition)</pre>
</blockquote>
<br>
NO! <br>
<br>
Only part of P25 protocol is open. The over-the-air digital
transport of the data stream, error correction, selective calls to
other station(s), group calls addressed to multiple other stations ,
setup & handshaking for trunking modes, console-to-transmit-site
interfaces, etc are open standards. <br>
<br>
However, the "secret sauce" AMBE (Advanced Multi-Band Excitation)
codec used for voice coding/decoding (that compresses analog voice
to a 4.8 or 2.4 kilobits/sec data stream in P25 systems) is NOT!
It is the proprietary intellectual property of DVSI (Digital
Voice Systems Inc) who collects a royalty of anywhere from $20 to
$100 PER RADIO. <br>
<br>
Further, manufacturers are completely free to add all sorts of
proprietary bells and whistles extensions to the basic P25 standard
for things like vehicle tracking, messaging, etc. I.e. the
error-free transport and delivery of data packets may be open, but
the contents of the packets can be locked up in intellectual
property patents. <br>
<br>
<br>
This is a somewhat similar situation to the $40 to $100 per unit
"Microsoft Tax" that every computer buyer pays if Windows is
preloaded on a PC. The computer hardware is essentially an open
commodity standard (that can be built by anyone from piece parts if
desired), but you are most likely going to be stuck paying the
Microsoft tax to make it useable. <br>
<br>
Or the way HTML is an "open standard" on the Internet, but Microsoft
then uses the strategy of "embrace and extend" to add all sorts of
proprietary extensions to HTML that only work with the Internet
Explorer browser. <br>
<br>
<blockquote
cite="mid:05D86CDC2CB746978241AAC124820BF5@oregonelectric.local"
type="cite">
<pre wrap="">
And...
Is there any thing about the JARL Dstar protocol that prevents someone from
developing their own CODEC solution?</pre>
</blockquote>
<br>
It also uses the AMBE codec. In principle, one could
reverse-engineer the codec and homebrew a compatible piece of
software. However this is criminalized in the US by the vile DCMA
(Digital Millenium Copyright Act) that makes it a Federal Crime to
reverse-engineer proprietary software. Even if you create
completely new code to duplicate the same function. <br>
<br>
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--<br>
<br>
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Skype: WA8LMF<br>
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