question on DSL signal

David W. Hess dwhess at
Tue Feb 5 14:52:38 UTC 2008

On Mon, 4 Feb 2008 15:01:52 -0500, David Banning
<david+dated+1202587312.e4b61b at> wrote:

>I notice very inconsistent results. Sometimes it's up for a week
>without a single drop, while other times it's up for 30 seconds,
>down for a minute, up for 2 minutes, down for 1.  That can go on
>for 10 hours, and then maybe it's stable again for a day or so.
>It's always appears to be the DSL signal itself, as I can see the
>modem sync light starts flashing when the signal goes down.
> . . .

I had similar symptoms last year during the hottest part of summer after a big storm.  The
thought was that the heat and humidity had compromised the wiring between my location and
the central office.  As it ends up, the problem had existed for years but the previous
owner had figured 384 down 128 up was the maximum the line length would permit and the
phone company was hardly going to admit there was a problem unless pressed.

>So here's my question:
>1. is there anyone who has a lot of experience monitoring DSL lines
>   that can tell me how common this is?

It depends on the condition of the infrastructure which varies widely in the US from area
to area.

>2. Is there any way to avoid it?

Is this DSL installed on a line that also has a dial tone?  If so when the service becomes
erratic, try leaving the phone off hook in order to continuously draw a current through
the line.  If the line is suffering from a dry open, then the DSL connection will be
restored while the phone is off the hook.

On telephone lines used for dial service, a line with a dry open condition will manifest
as a scratchy/noisy telephone line.  When used in DSL service, performance will be very
limited because of the high impedance state when no current is flowing through it.

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