On Mon, 17 May 2004 17:30:13 GMT, "Caroline"
put finger to keyboard and
composed:
Responses to Frank and Asimov follow, along with a few more general
observations.
"Franc Zabkar" wrote
Caroline wrote
I did a modem noise check of my phone lines (in my new home) several months
ago.
What did this involve?
From an Earthlink technician, September, 2003:
--------
1. Go to Control Panel
2. Double click Dial-Up Networking icon.
3. Click the Connection icon. Right click to display "Properties." Choose
"Properties."
4. Click through General, Configure, Connection, Advanced.
5. Uncheck the box next to "Use Error Control." Click OK
6. Click "Options."
7. Click "Bring up terminal window after dialing. Click OK. Click OK.
8. Double-click the Connection icon.
9. Click the Connect button. Type user names and passwords as needed.
Under normal circumstances, after the login information has been transmitted,
you will see a message that says, "... starting PPP session." If you see a large
amount of "garbage" characters underneath this line, then most likely there is
some sort of interference on the phone line.
Actually, those "garbage" characters are probably legitimate binary
data which make up the PPP packets. In fact you should see these same
characters with EC (error correction) enabled.
As I understand it, after an initial text based login sequence, the
dial-up session switches to binary PPP mode. This means that any
strange characters received during the username and password phase are
genuine garbage, while those received after the session switches to
PPP mode may or may not be so.
In any case, a better test for line quality is to enable EC and then
query the modem's last call diagnostic report. The modem will tell you
how many "I-frames" were transmitted and received, and how many of
these resulted in errors. On a good connection I get about 1 error in
1000 packets, while on a bad connection I can get as many as 1 in 20.
You can minimise the error rate, and therefore maximise your
throughput, by limiting the modem's max connect speed.
See
http://www.modemsite.com/56k/x2-linklimit.asp
BTW, if you choose to disable EC, you can get an idea just how noisy
your last connection was by viewing the total CRC errors in your
ppplog. Note that in the case of external serial modems some of these
CRC errors may be caused by serial buffer overruns.
See
http://www.modemsite.com/56k/ppp.asp
snip
Query the modem's last call diagnostic report, as described elsewhere
in this thread.
Okay.
Per your other post that talked about obtaining the last call diagnostic report:
I am using the directions at http://www.modemsite.com/56k/x2-hyperterm.asp and
http://www.modemsite.com/56k/usehyper.asp
to try to obtain this but so far no luck. I'm having problems at about step 5 of
the first site. But I'm unfamiliar with a lot of what exactly this is doing, so
I'll keep studying it, experimenting and trying.
Have you enabled command echo with ATE1? Until you do this, you may be
typing blind.
BTW, if you wish to retrieve the modem's last call diagnostic report,
avoid using the AT&F command just prior to doing so. On some modems
this will reset the diagnostic data. On others, like my own
Rockwelloid, AT&F resets the "reason for disconnect", but leaves the
data intact.
snip
With a PSU now twice the size of the original one, I am not getting the freeze
ups I used to get before. Before, I had to tread carefully before bringing up a
few applications simultaneously and quickly, due to seeing lock-ups before. Or I
avoided doing this at all. Now it seems I can start up as many applications as I
would ever want, as quickly as I want, and I do not get lock-ups.
I have to wonder about how PSUs are rated. Your initial post stated
that your PSU was a 90W device which, at face value, seems seriously
low. But then I doubt that many, if any, PC PSUs actually deliver
anything near their claimed output. In fact I've only ever heard of
one PC PSU that even regulates properly. By that I mean that the vast
majority of PSUs "regulate" by taking a weighted average of the +5V
and +12V rails, and then assume that the other supply rails will fall
within spec solely on the basis of their turns ratio. A poor design,
IMHO ...
- Franc Zabkar
--
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