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Forum Discussion
Mid/High-Split modems affecting TV Cable Pixels Reception?
This past year, I was using the Xfinity XB8 modem which utilized the newer enhanced Xfinity Mid/High-Split spectrum (32x8) allocation in DOCSIS. As advertised saw my upload speed go to over 120 Mbps...
Is your cable TV set top box connected a host router that's connected to the CM modem or is the set top box connected to the ISP signal using another coax cable line?
I split the Comcast/Xfinity Cable initially into two…
Split #1 – Cable Modem, Router, Various Ethernet Connected and Wifi Devices
Split #2 – Split to 4 Devices; 3 TV’s with Xfinity Device and a 3rd Party
Device with Xfinity Cable Card.
If the Cable Modem is a Netgear CM2000, I get 950mb download, and 25mb upload, and no TV pixelation. Works great.
If the Cable Modem is an Xfinity XB8 in Bridge Mode not utilizing the built in router, I get 950mb download and 128mb upload. Since increased upload speed is due to recent Xfinity upgrades to take advantage of 32x8 modems. But it causes sporadic TV pixelation on all devices when using TV Cable. My understanding is that since the Xfinity XB8 has 32x8 mid/high-split spectrum, I would get the same results with the Netgear CM3000, which has this newer capability.
From information I am getting, concluding that this is occurring since these newer modems are transmitting on Set-Top Boxes (STB) downstream band, which is causing the pixelation on TV Cable. Noted that it was mentioned a tool called iHat attempts to detect this known problem from Xfinity, but it does not support all STB’s?
So is the incoming ISP cable coax line into the home, have a coax cable line splitter and your making the split with this, one line going to the CM modem and the other line going to the TV STB?
Yes I am making these splits outside of the house. One split line going to the CM Modem, and the other split line going to another splitter which goes to 4 different STB's.
K, Something the ISP will need to send a on site tech to have a look into then. Possible this coax splitter maybe causing problems as well. They are known to induce some interferences or cut the power level down maybe too much, depending on how good the splitter was built. Have a tech check things up to this splitter then into the home.
Something to try as well for a quick test, remove the splitter. Then connect up the STBs directly to the main ISP cable coax line. Test the TV STB out. See if there is any differences. Internet will be down during this quick test so find time when nobody needs the internet if you do this. Put the splitter back after testing.
Make sure power levels for the CM modem are with in these guide lines:
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router