OK...got it Mark!
Though I'm not sure what you mean by "looked like raw sweep", I can't imagine a bad terminator that would cause a problems at previous amps. Though I have seen return problems that were so severe it did cause response problems at the previous amp...very rare.
A couple things, remember that when sweeping return, you are not sweeping the bandwidth where US DOCSIS carriers are located. Depending on your system, that could be a very large bandwidth form say 3.2 MHz to possibly 25.6 MHz. That means your return sweep could look perfect, but have severe problems at the DOCSIS carriers that can't be seen with sweep.
I have seen this numerous times where the sweep was good, but modem TX levels spiked until maxed out. Obviously, the causes of these problems were varied and tracked by patiently monitoring sweep and TX levels (usually with two techs stationed at different amps) until we narrowed down the problem to a specific span.
As far as "looking like raw sweep", there is no reason why raw sweep (and I am assuming Stealth) has to look terrible, even with the difficulties encountered in todays systems. The sweep on both forward and return should be very flat and stable. It seems over the years, sweep setup has not been done properly and everyone just figures to let it go and reference out any issues.
I hope this helps...
Re: Return Path
Member #: 100
Registered: 1996-2001
Posted:
46
Name:
Gary Muth
Name:
Gary Muth
Company:
Global Telecom Services, Inc.
Occupation:
Director of Engineering
Location:
Tariffville, CT
Experience:
~43 years
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