> On Thu, 3 Oct 1996, Douglas C. Semonche wrote:
>
> > Apparently the digital to analog conversion
> > impacts data speed negitively and most
> > users get 21 to 24 K connections.
>
> We had this problem before with Channel Banks (Our phone company uses D4
> > If I buy the new Microcom ISPort modems and
> > plug them into my portmaster would the additional
> > analog to digital conversion on the modem adapter
> > make the connect speeds worse? Anyone have any
> > experience with this?
>
> No matter what you do, you won't get fast connects with a channel bank.
> Because of the conversions (A to D at the CO and then D to A at the
> demark) you loose enough bits to cause problems with "analog" modems.
This is due to the use of a Universal SLC at the CO. Have the telephone
company install an integrated SLC, which keeps the connection digital
right into the switch.
They'll cite switch loading problems. Baloney. ISPs peak at much
different times than their normal traffic, hence the switch has a very
low probability of being under overload conditions.
> The difference between channelized T-1 and Channel Banks is less D-A/A-D
> conversions. This is really important to the modem world. <G>
Oh, they can still run it through a process like this:
switch -> d/a -> POTS across the co -> a/d -> channelized-T1 to premises
Where d/a is also a demux, and the a/d is a mux
Get detailed engineering specs on the project, make *sure* they don't go
analog in the office, and you'll be okay.
- Matt
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