The short answer is maybe.
First off, is this a real D4 channel bank or equivalent? If it is, then it is a real T1 span sharing your binder, possibly [probably] both pairs of the span. The nominal frequency of the signal on a real T1 span is 772 kilohertz, which puts it right smack in the spectrum of a typical xDSL signal, which starts at a few hundred kilohertz and goes up to a little over 1 MHz. The T1 signal is of a relatively low amplitude and usually plays nice with other services, but not always. If there is a corroded joint anywhere on the span, some of the 772 kilohertz signal can be "demodulated" and the resulting products can spew across a wide spectrum, causing no end of trouble.
If the T1 span in question is actually being carried over HDSL2 or HDSL4, then it is still possible to cause problems. Most manufacturers of HDSL equipment advertise their systems as having "full spectral compatibility with T1" etc., and this is usually true. However the same corroded joint or other non-linear junction somewhere can still cause partial demods and ghastly harmonics all over the place, walking on your relatively low-powered xDSL signal.
The DSLAM providing the xDSL may have some pretty useful testing functions built right in. It also should retain a fair amount of information concerning power and noise levels, but I can't speak to the usefulness [or lack thereof] of this information. I know that the "DSL statistics" displayed by most xDSL modems [the CPE end] is fairly useless - my Siemens modem tells me the upstream and downstream power levels and noise in a chart with no units of measurement. I know, I know, RTFM... but they should still show the units in any chart of data. Numbers without units are just numbers. They also make no effort to address the multiple separate modulated carriers - is the Tx power level shown an aggregate of all the carriers? An average? Who knows. Hopefully your DSLAM can provide more useful information.
Anyhow, I'll shut up for now and hopefully some of our resident T1 and OSP experts can weigh in and help you out. This thread might get moved to the T1 section, or the OSP section. But if the days go by and you still don't get an answer, you could try asking it in the McCarty OSP forum.
Jim
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Speaking from a secure undisclosed location.
