On Mon, 30 Aug 2004 10:28:59 -0400, Michael Graves wrote:
>On Mon, 30 Aug 2004 16:21:04 +0100, Kevin Walsh wrote:
>
>>Rich Adamson [EMAIL PROTECTED] wrote:
>>> > 3. If impendance mismatch is the (or a major contributing) factor, can
>>> > we not devise some interface circuit which will allow a variable rate
>>> > on the impedance so we can "dial out" the echo based on individual line
>>> > conditions?
>>> >
>>> That would be called the TDM card. It has a chipset that was designed
>>> to match telco standards in many (if not all) countries. In Canada,
>>> if you have x100p echo problems, you'll have them with the tdm card
>>> as well.
>>>
>>> You'll find plenty of discussion in the archives relative to x100p/tdm
>>> echo problems unrelated to impedence mismatches. Seems there is an issue
>>> with interrupt latency, pci controller, or something like that associated
>>> with some motherboards that "is" impacting echo (as well as other things).
>>>
>>> Multiple individuals have found that replacing their motherboards fixed
>>> the echo problem with these cards, but no one (as yet) as put their
>>> finger on why with any degree of accuracy. Lots of opinions, but no
>>> real facts to date.
>>>
>>> [snip]
>>>
>>> There is a high probability (but this is a wild guess) the echo issue
>>> has something to do with the specific chipset used by the motherboard
>>> manufacturer, and if that guess is correct, probably something to do
>>> with how interrupts are handled or pci controller issues, etc.
>>> Something on certain motherboards seem to be delaying the transfer of
>>> data to/from x100p/tdm cards, and that delay is sufficient enough to
>>> fall outside the limits of the echo cancellation software within *.
>>>
>>You could go to a lot of time, effort and expense buying a TDM card,
>>fitting a new motherboard (PCI 2.2), fiddling with gains and trying
>>all of the other suggestions that have been posted, or you could just
>>buy an external FXO device, such as a Sipura SPA-3000, and expect it
>>to just work.
>>
>>External devices are not sensitive to PCI latency and are not
>>concerned with the brand of motherboard you use. All facilities,
>>such as echo cancellation, are provided onboard rather than via a
>>software driver.
>>
>>I don't have echo problems on my X100P (at home) but that won't stop
>>me from dumping it in favour of a Sipura SPA-3000 next month, once it
>>gets full UK support in firmware (caller ID etc.).
>>
>
>Bear in mind that many of us who have been using the SPA-3000 in the US
>have also been experiencing echo related problems. I'm trying the
>latest firmware which is only a few days old, but I'm pretty close to
>chucking it in favor of something else.
>
After a day and a half of using the SPA-3000 with v2.1.0 firmware I can
say that they echo problem is much better. Not wholly resolved, but
better. I still have to jack up the PSTN>VOIP gain setting a lot in
order to hear the incomming caller.
Michael
--
Michael Graves [EMAIL PROTECTED]
Sr. Product Specialist www.pixelpower.com
Pixel Power Inc. [EMAIL PROTECTED]
o713-861-4005
o800-905-6412
c713-201-1262
"The greatest dangers to liberty lurk in insidious encroachments
by men of zeal, well-meaning but without understanding."
- U.S. Supreme Court Justice Louis Brandeis, 1928
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