Modem Downstream power too high

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satougg4

Jul 9, 2018
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The last time I posted, I was detailed and long-winded. I'll try to be more concise here in hopes of a response.

I've already tried replacing the modem and all wires, except for the coax which runs inside the house's walls.

Inside, my modem Upstream power is 57dB. Downstream is about -1.7dB and SNR is 43.5dB.

Outside, at the box connecting to the street, my Upstream is 44dB, Downstream is about 17dB and SNR 44.7dB.

Question: Does downstream power decrease when adding coax length to the run? Upstream definitely increases.

Question 2: Is the downstream power so high at the box, to give me a chance to have a good level by the time it reaches the modem?

Question 3: Is it (high downstream power) a problem that would not be fixed by simply adding more cable between it and the modem?

~Satou
 
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Ralston18

Ralston18

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Oct 11, 2014
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Who is your ISP? What make and model is the modem? What specific problem(s) are occurring?

Where and how are you making the measurements?

Would not be concerned about the measurements per se unless they are clearly showing some adverse value and you know that both the measurement and spec'd values are accurate.

For example - Comcast information:

http://www.dslreports.com/faq/16085

See what you can find for your hardware and ISP.
 
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bill001g

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Aug 9, 2012
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You likely have some issue with the cable in the wall. The downstream power is decreasing a lot..about 18.7db total. The upstream is 13db but that may be more that the cable company equipment can't tell the modem to go any higher.

I would look for splitters in the cable first. Try to remove them and connect the wires with a simple barrel connector. If you have to have the splitters make sure they are the newer ones rated for data.

That is more loss than just cable length. The cable alone will lose less than 2db for 100ft. Maybe the ends of the cable are damaged.
 
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satougg4

Jul 9, 2018
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ISP: SuddenLink.

Modem: Motorola MB7220. Before this, it was a Motorola SB5101U. That one seemed to peak at 54dB upstream and had intermittent connectivity issues. This one (MB7220) has had a single disconnect, but my concern is any further degradation of the line, and it will have problems too. Considering a fix for the line, and returning the 7220 because it didn't really fix the line quality.

The upstream is way out of spec, should be under +50dB.

I made measurements using the modem's signal page 192.168.100.1, with a new short coax cable, at the end of the line inside (without splitters) and at the box outside, by disconnecting the run and connecting the modem to the box directly with the short coax.



Yeah, I think so too. The cable inside is about 50-60 feet IIRC. Will try the barrel connector. Currently the splitter doesn't change the signal much, maybe 0.5dB.

If the ends of the cable are damaged, is it possible to fix (in that case) by snipping the ends a few inches and connecting a new RG6 end? "F connector"

ty for the responses so far
 
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bill001g

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Aug 9, 2012
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Changing the ends is pretty simple to try. Without expensive testing equipment is it hard to tell where a wire is bad. Sometimes there is a splitter or splice you do not know about. I saw one where mice or something had chewed the wire under a house and it let water into the cable and it was all corroded
 
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satougg4

Jul 9, 2018
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Hmm. I'll have a look along the entire wire and see if there is an extra splice. After that, I'll try replacing the ends. I found a super cheap compression tool, are they all the same or are some better than others?
 
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