Paul, at 22:45 on Mar 19 1996, you wrote to Bill Grimsley...

PE> Those figures, used as they stand, do NOT measure line quality accurately.

Sorry Paul, but on the one hand I have you, a known anti-USR Zealot, and
none too bright in the modem-engineering area, telling me that the USR's
line probe figures are buggy, inaccurate, amd completely worthless (yet by
the same token, you still can't explain to me why this might be so), and on
the other, I have Joe from USR, all round nice guy and highly intelligent
individual, who tells me that the figures ARE accurate after all.

You'll therefore forgive me if I tell you to go fuck yourself ?

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--> Note: Copied from USR_MODEMS by WIMM/2 1.20

-> 1.  What EXACTLY does ATY11 measure ?

It measures the RX levels of a set of specific frequency tones which are
sent during the V.34 handshake sequence.  These RX levels are used to
determine the frequency response characteristics of the channel, which
in turn affects V.34's selection of carrier frequency and symbol rate.

-> 2.  Why is there such a VAST difference between USR & Rockwell ?

That depends on what kind of difference you mean.   If the rolloff is
the same general "shape", but the overall levels are different, that
would indicate that the remote modems are using different transmit
levels.

If the rolloff "shape" is different, that would indicate that individual
calls are being routed through different circuits, or the remote modem
is having a v.34 parameter negotiation problem.

Joe
-!- FidoPCB v1.5 beta-'j'
 ! Origin: U.S.Robotics Support-USA 847-982-5092 (1:115/500)


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--> Note: Copied from USR_MODEMS by WIMM/2 1.20

-> One could be forgiven for thinking so, but considering that ALL of
-> the Rockwell V.34s tested returned almost identical line levels, I'm
-> no longer convinced. After all, 13dB is a bloody large difference to
-> have to explain away.  I guess the question now is, how much faith
-> can we place in the USR's line stats?

They're pretty reliable.    What is the DSP date on the USR, and what
are the version numbers from the rockwell chipsets?

Joe
-!- FidoPCB v1.5 beta-'j'
 ! Origin: U.S.Robotics Support-USA 847-982-5092 (1:115/500)
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Regards, Bill

--- Msgedsq/2 3.20