[c-nsp] Connectivity recommendations

[Bill Wichers]

> On Tuesday, 27-September-2005 13:24, Voll, Scott wrote:
>> How long of a run is the copper?
>
>
> 250 feet

Tut Systems makes a VDSL bridge (the XL-5050) for Ethernet that can do
some 50 Mb/s symmetric out to about 1000' or so. A pair is around $1300. I
just finished two projects over the past month that used the XL-4000 (more
expensive version that can do 10 Mb/s symmetric out to 4000'). I found the
units to work very well, but to have a very low tolerance for any ground
on either wire in the pair. We had a pair running on a span of about 2200'
in one project that had a bad underground splice -- not bad enough to show
up very well even on a TDR -- and the unit suffered from frequent retrains
and generally poor performance until we found the problem and switched it
to a different pair.

My expierience with the Tut units is that they work pretty well and are
generally reliable, but they have a very low tolerance for any impairments
on the copper pair, and they seem to be very sensitive to nearby lightning
strikes (one of the projects was to upgrade and replace some older units
that died). Using one of the T1-style surge protectors on the pair would
probably be a good idea if you use these units since the gas tubes used on
the normal phone entrance blocks don't seem to be enough protection.

     -Bill


*****************************
Waveform Technology
Systems Engineer