<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt">Joel,<br><br>Conventional VoIP probably doesn't, but D-Star and other similar systems don't follow those rules; the FEC is actually handled by the AMBE Vocoder chips through firmware programming.<br><br>Matthew Pitts<br>N8OHU<br><div><span><br></span></div><div><br></div> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div dir="ltr"> <hr size="1"> <font face="Arial" size="2"> <b><span style="font-weight:bold;">From:</span></b> Joel Black <w4jbb@charter.net><br> <b><span style="font-weight: bold;">To:</span></b> Discussion of D-RATS <drats_users@intrepid.danplanet.com> <br> <b><span style="font-weight: bold;">Sent:</span></b> Friday, September 20, 2013 6:23 PM<br> <b><span style="font-weight:
bold;">Subject:</span></b> Re: [drats_users] ERROR Correction in slow speed data<br> </font> </div> <div class="y_msg_container"><br><div id="yiv5858165617">
<div>
Okay, this goes against what little I have learned about VoIP
traffic.<br>
<br>
I didn't think there was any FEC with voice. That's why voice has
priority on data networks that use VoIP. Otherwise, if a data
packet has priority, it would bump a voice packet. When a voice
packet is bumped, you lose bits of it resulting in choppy audio.<br>
<br>
I have experienced this when some of our first quasi VoIP locations
came online. Voice is live traffic. Once it is said, it goes.
There's nothing to re-transmit.<br>
<br>
Without getting into the engineering (which will leave me drooling
and nodding off to sleep), how does D-STAR use FEC on voice?<br>
<br>
73,<br>
Joel - W4JBB<br>
<br>
<div class="yiv5858165617moz-cite-prefix">On 9/20/13 3:57 PM, John Davis wrote:<br>
</div>
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<div class="yiv5858165617MsoNormal"><span style="font-size:11.0pt;color:#1F497D;">That
is true. The FEC is on the voice with 2400 bits for voice
and 1200 for FEC.</span></div>
<div class="yiv5858165617MsoNormal"><span style="font-size:11.0pt;color:#1F497D;"> </span></div>
<div class="yiv5858165617MsoNormal"><span style="font-size:11.0pt;color:#1F497D;">John
WB4QDX</span></div>
<div class="yiv5858165617MsoNormal"><span style="font-size:11.0pt;color:#1F497D;"> </span></div>
<div class="yiv5858165617MsoNormal"><b><span style="font-size:11.0pt;">From:</span></b><span style="font-size:11.0pt;">
<a rel="nofollow" class="yiv5858165617moz-txt-link-abbreviated" ymailto="mailto:drats_users-bounces@intrepid.danplanet.com" target="_blank" href="mailto:drats_users-bounces@intrepid.danplanet.com">drats_users-bounces@intrepid.danplanet.com</a>
[<a rel="nofollow" class="yiv5858165617moz-txt-link-freetext" ymailto="mailto:drats_users-bounces@intrepid.danplanet.com" target="_blank" href="mailto:drats_users-bounces@intrepid.danplanet.com">mailto:drats_users-bounces@intrepid.danplanet.com</a>]
<b>On Behalf Of </b>Daniel Metcalf<br>
<b>Sent:</b> Friday, September 20, 2013 4:55 PM<br>
<b>To:</b> Discussion of D-RATS<br>
<b>Subject:</b> Re: [drats_users] ERROR Correction in slow
speed data</span></div>
<div class="yiv5858165617MsoNormal"> </div>
<div>Agreed. From what I have read d-star is a lot like the UDP
network protocol where it is transmit and forget there is no
handshaking / error correction built in. It is up to the
application developer to handle error correction and the
d-rats package does perform some level of error correction.</div>
<div>Dan Metcalf - KB3UUN.</div>
<div>
<div class="yiv5858165617MsoNormal">On Sep 20, 2013 3:54 PM, "John Davis"
<<a rel="nofollow" ymailto="mailto:jdavis@gtworks.com" target="_blank" href="mailto:jdavis@gtworks.com">jdavis@gtworks.com</a>>
wrote:</div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in;">
<div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="font-size:11.0pt;color:#1F497D;">My
understanding is that the low speed data channel
does NOT have error correction, however, D-RATS
offers Error correction in Message and File Transfer
modes where it is most important.</span></div>
<div class="yiv5858165617MsoNormal" style=""><span style="font-size:11.0pt;color:#1F497D;"> </span></div>
<div class="yiv5858165617MsoNormal" style=""><span style="font-size:11.0pt;color:#1F497D;">John
WB4QDX</span></div>
<div class="yiv5858165617MsoNormal" style=""><span style="font-size:11.0pt;color:#1F497D;"> </span></div>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in;">
<div class="yiv5858165617MsoNormal" style=""><b><span style="font-size:11.0pt;">From:</span></b><span style="font-size:11.0pt;">
<a rel="nofollow" ymailto="mailto:drats_users-bounces@intrepid.danplanet.com" target="_blank" href="mailto:drats_users-bounces@intrepid.danplanet.com">drats_users-bounces@intrepid.danplanet.com</a>
[mailto:<a rel="nofollow" ymailto="mailto:drats_users-bounces@intrepid.danplanet.com" target="_blank" href="mailto:drats_users-bounces@intrepid.danplanet.com">drats_users-bounces@intrepid.danplanet.com</a>]
<b>On Behalf Of </b>Dave Welker<br>
<b>Sent:</b> Friday, September 20, 2013 3:19 PM<br>
<b>To:</b> D-Rats Mailing List<br>
<b>Subject:</b> [drats_users] ERROR Correction
in slow speed data</span></div>
</div>
</div>
<div class="yiv5858165617MsoNormal" style=""> </div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">Hello all,</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">Can anyone
confirm if the D-RATS slow speed data has FEC
(Forward Error Correction) built in now or not?</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">I understand
that D-STAR voice does have error correction built
in. I've checked on the D-RATS home
page/documentation</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">which is a
August 2009 reference.</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""> </div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">This is what
I found in this document Under users
manual/files: Is this still current information?</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""> </div>
</div>
<div>
<div style="margin:0in;margin-bottom:.0001pt;background:white;word-spacing:0px;"><b><span style="color:#666666;">Unlike
the D-STAR DV Voice Channel, which has error
correction built into the protocol, the Data
Sub-channel has no error correction. </span></b></div>
<div style="margin:0in;margin-bottom:.0001pt;line-height:11.25pt;background:white;word-spacing:0px;"><span style="font-size:9.0pt;color:#666666;"> </span></div>
<div style="margin:0in;margin-bottom:.0001pt;background:white;word-spacing:0px;"><b><span style="color:#666666;">This
makes the transfer of data across D-STAR a lot
more dependant on a good radio path being
established between the two locations wishing to
</span></b></div>
<div style="margin:0in;margin-bottom:.0001pt;line-height:11.25pt;background:white;word-spacing:0px;"><span style="font-size:9.0pt;color:#666666;"> </span></div>
<div style="margin:0in;margin-bottom:.0001pt;background:white;word-spacing:0px;"><b><span style="color:#666666;">exchange
data. D-RATS includes the ability to test
connectivity between two locations</span></b><b><span style="font-size:9.0pt;color:#666666;">.</span></b></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""> </div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">Thanks in
advance</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">regards</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">Dave</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">W2SRP</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""> </div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""> </div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">Goals are
where we want to be;<br>
Objectives are the steps to get there.</span></div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""> </div>
</div>
<div>
<div class="yiv5858165617MsoNormal" style=""><span style="
">There are 2
rules to success in life:<br>
1. Don't tell people everything you know.</span></div>
</div>
</div>
</div>
<div class="yiv5858165617MsoNormal" style="margin-bottom:12.0pt;"><br>
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