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On 2011-02-25 11:02, Paul Nijjar wrote:
<blockquote cite="mid:20110225160215.GD1774@pirg.uwaterloo.ca"
type="cite">
<pre wrap="">On Thu, Feb 24, 2011 at 10:21:52PM -0500, Insurance Squared Inc. wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Here's where I'm puzzled. Seems like plenty of people using Voip on the
list. Am I the only one experiencing this problem repeatedly? Or does
everyone else's calls degrade as soon as the kids get home from school?
</pre>
</blockquote>
<pre wrap="">
I have mentioned this before, but our Sympatico routers are
configurable so that our ATAs get priority bandwidth. I don't remember
how I did this; it may have been through IP address. So if you could
prioritize your Asterisk box's IP, you might win.
I agree with John that the "A" in ADSL is a big pain. Fortunately we
have not experienced much degradation, but I worry about it a fair
amount.
- Paul</pre>
</blockquote>
Execulink (in my case Golden.net) resells Bell's DSL and they tell me
that the service is ADSL2+.<br>
<br>
see: various wikipedia hits on ADSL and ADSL2+ and <b>ITU G.992.x</b> <br>
<br>
<a href="http://whirlpool.net.au/wiki/ADSL_Theory">http://whirlpool.net.au/wiki/ADSL_Theory</a>
and<br>
<a
href="http://www.ee.kth.se/php/modules/publications/reports/2005/IR-SB-EX-0509.pdf">http://www.ee.kth.se/php/modules/publications/reports/2005/IR-SB-EX-0509.pdf</a><br>
<br>
"Under good conditions the newest ADSL technology (ADSL2+) can offer
downloads at 25<br>
Mbit/s, which is more than sufficient for most “in home”-applications
today and should be<br>
compared to a V.90 modem’s top bit rate at 56 kBit/s (0,056 Mbit/s)."<br>
<br>
Whether ADSL or ADSL2+ , the signal format uses multiple frequencies,
above the voice band, as carriers each modulated with a combination of
phase shift and amplitude signal changes to encode as few as one or two
bits. Each of the multiple carriers is not unlike one of the two
carriers used in the 56 kBits/s modem mentioned above, one used for
upstream, one for downstream.<br>
<br>
IMO: The DSL signal between the DSLAM has about as digital content as
an AM or FM radio signal, one carrier with amplitude or frequency shift
keying. Many forget that the transmission media whether RF or CAT5
cable all live in an analog world. And the signals pumped over the
media are usually, except in the flat ribbon cables in one's PC are
analog signals. (The SATA standards, too, take the analog environment
into account.)<br>
<br>
Fibre?: The days of binary on/off are long gone. Here too, wavelength
modulation (aka frequency modulation) comes into play. And the big boys
use multiple wavelengths on one fibre cable.<br>
<br>
As for the OP's original question: I dunno. The issue may be solved
with a better downstream protocol, e.g. ADSL2+.<br>
<br>
JohnJ<br>
<br>
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