<DIV>So are saying that T2240 will gurantee no echo issues? Did you get any echo issues with a different PC with the same cards and Pstn lines?</DIV>
<DIV> </DIV>
<DIV>Taff.<BR><BR><B><I>Steve Underwood <steveu@coppice.org></I></B> wrote:</DIV>
<BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">Rich Adamson wrote:<BR><BR>>>On Fri, 2004-07-16 at 12:07 -0600, Rich Adamson wrote:<BR>>><BR>>> <BR>>><BR>>>>No echo on eMachine T2240 2.2ghz Celery, 360m RAM, with either tdm04b<BR>>>>or x100p running any Head cvs after June 23rd (totally stock install).<BR>>>><BR>>>>Wouldn't necessarily recommend this box for any commercial production<BR>>>>use, but...<BR>>>><BR>>>>What's common and not so common between these _very_ diverse boxes?<BR>>>> <BR>>>><BR>>>My guess would be interrupt and/or PCI latency. Echo is produced by<BR>>>delays in the audio path so if some motherboards are adding delays it's<BR>>>going to make the echo worse. Fiddling with PCI bus settings both in the<BR>>>BIOS and from Linux (using the pci tools) may help in some
cases.<BR>>><BR>>>The unfortunate part about this is that there are SO many variables that<BR>>>can influence latency that you can't really tell if a motherboard is<BR>>>going to work or not until you try it. Even two MBs with the same CPUs<BR>>>and the same north/south bridges could produce different results.<BR>>>Probably the best we can hope for right now is to start building a<BR>>>whitelist of known good motherboards for people to reference when<BR>>>building Asterisk systems.<BR>>> <BR>>><BR>><BR>>I'm kinda thinking you're right in the ball park of where 'at least some'<BR>>of the remaining echo issues might be coming from. We have an entire<BR>>laundry list of what its _not_, but nothing substantial in terms of<BR>>what _might_ be causing it on selected systems and no good way to<BR>>quantify it.<BR>> <BR>><BR>Frame slips could explain some. All the reports of pages getting chopped <BR>while
using the SofFax in spandsp, which I have followed up on, have <BR>been due to frame slips. It seems a lot of people have their clocking <BR>wrong, and those slips willscrew the training of an echo canceller just <BR>as well as they screw up modems.<BR><BR>>Anyone have the knowledge/experience to be able to write "something"<BR>>that might provide all of us with a clue in terms of buss latency<BR>>(or whatever we might want to call this)?<BR>><BR>>I'm not a programmer, but it would seem like this test app would have to<BR>>run in a manner similar to *, interact with digium cards, and return <BR>>some value that would represent overall latency. Don't think its all<BR>>that important whether it returns an accurate number of milliseconds<BR>>or some integer value, as long as the value can be compared from one<BR>>motherboard to another (and from one site to another). Sort of a<BR>>"run this and tell me what value is returned" kind of thing.<BR>>
<BR>><BR>An app that loops back multiple ports and pumps data around in circles <BR>for hours would shake out a lot of flaky systems. I used to use one in <BR>the early days of the Tormenta 1 card, but I probably don't have it any <BR>more.<BR><BR>Regards,<BR>Steve<BR><BR>_______________________________________________<BR>Asterisk-Users mailing list<BR>Asterisk-Users@lists.digium.com<BR>http://lists.digium.com/mailman/listinfo/asterisk-users<BR>To UNSUBSCRIBE or update options visit:<BR>http://lists.digium.com/mailman/listinfo/asterisk-users<BR></BLOCKQUOTE><p>
<hr size=1> <font size="2" face="Verdana, Arial, Helvetica, sans-serif"><a href="http://uk.rd.yahoo.com/evt=21626/*http://uk.messenger.yahoo.com"><strong>ALL-NEW
Yahoo! Messenger</strong></a><strong> - <font color="#FF9900"><em>sooooo many
all-new ways to express yourself</em></font></strong></font>