Take a look at this screenshot. I've got comcast coming to investigate low signal. My cable-modem is suffering dropouts because it too, is only broadcasting upstream at 23dBmV, which is lower than they want to see. They said the downstream and upstream stregnth are linked in a ratio that was difficult to explain. Thoughts on this? This shot is from an Explorer 8000 digital box...
--Alex
The RF measurements from the digital set-top box have little relationship to the modem performance. The modem operates at different frequencies has a different path from the pole. Post the measurements from the modem and people here can offer an opinion.
By the way, the measurements made by the Explorer 8000 look fine for digital video.
-Gary
I have a ScientificAtlanta modem that doesnt have that cute little page on
192.168.100.1, or whatever it is. In my post, the upstream signal is low, says comcast. I was just wondering if any experts might know what they're going to try to do, to fix that issue. The low upstream on the cable box (the link) is preventing us from running the Video On Demand browser, since the device isn't screaming loud enough to be heard back at the termination system. The problem is causing issues with Cable TV, as well as modem performance.-Alex
There are many possible root causes for your problems, so it's pretty hard for anyone here to diagnose them for you with the extremely limited info you've provided. I could be anything, including stuff inside your home such as poor splitters, bad cable, rusty F-connectors, loose F-connectors, or other types of problems. Outside your home there could be the same problems as well as failure of the active equipment in the cable plant.
In any case, I expect the Comcast tech to first make a measurement at the entry point to your home, which will quickly determine if the problem is inside or outside. Since you have both a video and data problem, this it should be easy for the tech to find.
Good Luck,
-Gary
I left out info on the wiring in my house. I personally roughed-in RG6 cabling when I moved in, then had Comcast use the good compression (not crimp) connectors everywhere. Modem working fine up till ~3 weeks ago; nothing I know of changed at that time in my house. I'm using splitters sold to me by Mr. Nielsen, recently installed. Everything shiny, nothing rusty/loose. I did recently however notice that there's 38volts between the grounding braid of one line, and a good ground. I disconnected this paticular TV from the splitter. My modem seems to move between pages faster (latency & packet loss-related). Comcast queried my modem while on the phone and said it was only broadcasting at 23dBmV. Also, my SA-8000 cable box continues to receive at ~-12dBmV and its upstream channel is 19dBmV, still low. Mother-in-law has *exact* same SA-8000 box, and her numbers are -2dBmV downstream and 37dBmV upstream. (just to show these number are the optimal numbers to make a cablemodem work & cable box work properly.
PS..... Examine again the screenshot below, what do "0/Sec (avg)" and "709 uSec" mean?
--alex
Alex,
How do you know that the cable modem is only transmitting at 23dBmV? You can't "do the math" and determine that from the transmit level of a DCT. The CMTS in the headend tells the cable modem what level to transmit at. If there is no problem with the modem itself, for some reason the CMTS thinks the modem is talking loud enough.
You don't have an amplifier on the return path, do you? Assuming the answer is no, I'd lean towards a defective modem. It's good that Comcast is coming out...
CIAO!
Ed N.
Alex Bats> Take a look at this screenshot. I've got comcast coming to investigate low
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