Cable Modem works fine without splitter, but can't find signal with splitter.

[chuckywang]

If I hook up my Cable Modem (Motorola Surfboard) directly to the wall coax, the cable modem detects the signal fine and works. However, when I try to connect the cable modem to a splitter (which is then connected to the wall), my cable modem can't go past the "Upstream Ranging" phase of initiation.

The splitter I'm using has 1 input and 2 outputs. The bandwidth range is 5-1000 Mhz and it also says -140 dB EMI.

Any ideas why this is happening? I only have one wall port, but I want internet and cable TV.

Help!

 

[bluestrobe]

I'm not up to date on power levels and db of cable coax but my guess is that the outlet only has enough signal for one device. The signal degrades the more spliters, connections, and splices it runs through. Locally here someone can only run one splitter before the signal degrades to the point of not working.

I would check to see where the wall outlet goes. If it hits a splitter or something else before the pole then you might have a problem. Another solution is to buy a cable coax amplifier if your ISP/modem allow it. Someone else might chime in that could help more than me.

 

[skyking]

I think you are on target there, bluestrobe. I would guess that somewhere that particular jack has been split down already, and by some possibly junky splitter. I have always been able to get a cable modem working within the first split or so of the demarc or line connection into a dwelling.

 

[chuckywang]

Yes, the jack has been split down before with a 4-way splitter (that goes to four jacks in the basement). However, the jack works fine if I just connect the cable modem up to it directly. The bandwidth is lighting fast, so I don't know how one 2-way splitter gets a signal to go from "lightning fast" to "can't even detect DHCP'.


Can people post their SNR and upstream and downstream power levels for their own cable modem? I want to compare these levels with mine.

 

[xSauronx]

Originally posted by: chuckywang
Yes, the jack has been split down before with a 4-way splitter (that goes to four jacks in the basement). However, the jack works fine if I just connect the cable modem up to it directly. The bandwidth is lighting fast, so I don't know how one 2-way splitter gets a signal to go from "lightning fast" to "can't even detect DHCP'.


Can people post their SNR and upstream and downstream power levels for their own cable modem? I want to compare these levels with mine.

maybe *your* splitter is crappy? id try another one if you have one handy

 

[RebateMonger]

Originally posted by: chuckywang
The bandwidth is lighting fast, so I don't know how one 2-way splitter gets a signal to go from "lightning fast" to "can't even detect DHCP'.

Remember, this is a digital signal. Like satellite TV or digital cell phones, it goes from "perfect" to "horrible" or "non-existant" very quickly when the lower S/N limit is reached. You either get perfect reception, or no reception at all. There's little in-between.

Cable Modem makers advise users to only split the incoming Cable signal ONCE in front of the Cable modem. Use a 1 IN==>2 OUT splitter. If you need additional splits, do those on a second splitter, DOWNSTREAM from that initial 1 IN==>2 OUT splitter.