Signal Quality differences in CT1/PRI?

Jawaid Bazyar (bazyar@hypermall.com)
Wed, 27 Aug 1997 23:17:58 -0600 (MDT)

Hi,

I've seen mentioned here before reference to the differences in signal
quality between CT1 and PRI, regarding the fact that PRI is 8-bit
data values whereas CT1 is 7-bit.

My first question is: doesn't a lot of the voice network use CT1-type
(i.e. 7-bit) transmission?

My second question is: what differences does that one bit make in modem
connection quality? I'd like to hear about real-world examples.

I ask because I've been getting pretty lousy connection rates to my
PortMaster (CT1, 26400 right now but as low as 21K or 19.2K), and in
testing from the same end-user modem to a PortMaster on PRI, get
consistent 28.8 connects.

I understand that there can be a difference, but that big?

I seem to have had the worst problems after a long series of rainstorms we
had recently, so I'm keeping open the possibility that the analog lines
here were wet and nasty.. I just got the test account on the PRI so I
haven't got a lot of test data.

But, I thought I'd ask here if anyone has done hands-on comparisons of
CT1 and PRI and could enlighten me.

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