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sam9194

join:2005-08-16
Lake Zurich, IL

[Connectivity] Chicago area uplink interruptions?

Hello all. This is my first post to the Comcast HSI forum. I've had Comcast HSI for 8 years, about half at one address and one at another and over that entire stretch I have had a fast, consistent connection basically 100% of the time. In the last few months, however, I started having this problem with my ViaTalk VoIP line where during a call the party on the other end is unable to hear me for 5-30sec stretches of time. I can hear them during that time and, if they don't hang up, the call isn't dropped and eventually they'll start hearing me again. Well at first I thought this was a ViaTalk issue and posted on that forum about it. But a few nights ago I finally noticed some occasional losses of connectivity while surfing the web. So I made a call from the VT line to my cell phone and left the phones sitting there with the call going. I continued surfing until the problem happened again, and when it did, I checked the call and noted that same problem happening. So it's clearly an uplink problem which explains why web pages don't load... the uplink requests for the pages don't get there, and also explains the VoIP call behavior as well.

My signal stats are:

Downstream:
Frequency 711000000 Hz
Signal to Noise Ratio 35 dB
QAM QAM256
Network Access Control Object ON
Power Level -1 dBmV

Upstream:
Channel ID 2
Frequency 24000000 Hz
Ranging Service ID 7444
Symbol Rate 2.560 Msym/s
Power Level 47 dBmV

And I see no noteworthy errors in the log.

I'm posting to see if anyone else has experienced this uplink problem recently. Also, to eliminate my Netgear 802.11b router from the equation, I'd like to run some kind of continuous ping test, or something, while directly connected to the modem. Can anyone suggest a good way to set up a continuous test like that, or some free software to do it?

Thanks in advance.

sam9194

join:2005-08-16
Lake Zurich, IL

Well, I think I solved the problem. I replaced my Motorola SB5120 with an SB5101 and my HSI connection is working much better. Virtually no dropped pings (less than 1%) and absolutely no consecutive dropped pings, which occurred before during my uplink outages. I also did a 45 minute test (listening to my clock radio on a call from my VT line to my cell phone) and have made a few more calls all with absolutely no drop outs. I wasn't able to get the Comcast tech support person to tell me what my uplink SNR was with the old or new modem... they didn't know what I was talking about and said everything "looked fine". But I *did* see my downlink SNR go from ~35 to ~41, not that I was really having any downlink issues, but the 6dB increase certainly doesn't hurt. I suspect my uplink SNR may have improved too, but I guess I'll never know. In any case, it really seems there was something wrong with that SB5120.



Chris 313
Come get some
Premium
join:2004-07-18
Houma, LA
Reviews:
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While I'm not an expert on signals, your story brings to mind the problem with the SB5120s. They were more vulnerable to line noise then the 5100, 5101 and 5102. It has to do with the differences between chipsets used in the modems.

»Comcast High Speed Internet FAQ »What are the differences between the Motorola SB5100, SB5101 & SB5120?

The 5101 you have now is more capable of taking less then optimal signals vs the 5120.

Good luck with your setup.


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