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Discussion Starter · #1 ·
I'm wondering if it makes a difference *where* a cable is split? My Comcast cable is split at the point where it enters the back of my house, then both cables run from the back to the front (probably 30-40 feet) before one side goes on to the cable modem, and the other side goes to my home run splitter for feeding cable outlets in the house. I'm having signal problems now that I have to use DTAs.


If I were to remove the splitter at the back of the house, and then only do the first split 40 feet later, would the resulting signal strength be better?


Also, in my searches here I've seen using a Tap recommended for the split between the Cable modem and the Video side (cable outlets). Does that do anything to increase the signal to the Video side?
 

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Discussion Starter · #4 ·
With my current setup (split at the point of entry, as described above) here is the report from my Cable modem:

Code:
Code:
Downstream
        Freq/Power:     597.000 MHz     1 dBmV   
        Signal to Noise Ratio:  38 dB    
        Modulation:     QAM256   
Upstream
        Freq/Power:     33.000 MHz      54 dBmV  
        Channel Type:   DOCSIS 1.x (TDMA)        
        Symbol Rate:    2560 kSym/sec    
        Modulation:     QAM16
Does that suggest a Tap is appropriate? And does the Tap do anything for the amount of signal passed to the output side (vs a regular splitter) or does it just attenuate how much signal goes to the Tap port?


Oh, and I currently have a Motorola BDA amp feeding the video side. Because I have a lot of drops and tuners to feed, I have 2 8-way splitters. The output of the Amp goes into splitter one, and then one of the outputs from splitter one goes to splitter 2. I admit that the places with signal problems are coming out of the second splitter. Is there some better way to arrange this, without buying a differnt amp/splitter (if that would even help)?
 

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I have a comcast just an internet/phone but I split the cable going to my modem and 3TVs and I'm experiencing some drops of signal on internet. I mentioned it to comcast tech and he said it affects the signal to the modem using splitter.He then gave me a splitter with a tap line where I could use it going to my moto signal booster and split the output going to 3TVs. Its been a month and I don't experience internet drop but lets see.
 

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There is a problem with those numbers. While the downstream is fine, the upstream is way too high. That's something that Comcast will need to resolve. I wouldn't be surprised if you occasionally lose connectivity. Call them and tell them that your internet goes out every now and then. After they resolve their issue, give us those numbers again and we'll go from there. For now, I'd leave the 2-way splitter in.
 

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Yeah, upstream numbers are too high. I'd expect higher numbers going through splits (my upstream is relatively high because I through many splits), but it seems that you have a direct connection to the modem after the first split. Cable company needs to resolve that issue if that's the case.
 

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Quote:
Originally Posted by NGage /forum/post/17023966


Thanks for the reply guys. What should the upstream number be? Is it the 54 dBmV that's high?

Preferable would be ~45-50.


The threshold is 55, and with you sitting right there at 54, it wouldn't take much for your sync to go away. You do want a strong output, but not much more than ~48-50dBmV
 

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Discussion Starter · #11 ·
Before I contacted Comcast, I remembered that my cable line comes through a whole-house surge protector. I was going to remove the surge protector temporarily, and found that the connections to it were not even finger tight. So, I've tightened those up.


I've gathered that there may be some delay before the cable modem is told to lower it's signal, so I'll report back tomorrow what my numbers are then.
 

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a tap, or directional coupler, is used when you would want more signal to go to one leg rather than equal splits you would pick up anywhere from 1-4db difference.


upstream is the return and should never be more than 52, itll work past that but not very well. ideal is a return in the 40's. only an active amplifier can lower that number, however if you have a high return it might be a problem at the tap which would need comcast.


i work for time warner up here and honestly if your having problems its best to have a tech come out, unless you have a DSAM meter with your areas channel line and a good understanding of cable loss and noise, idk if comcast charges but we dont.
 
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