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Gemstone
Premium
join:2000-12-20
Long Island
reply to Tursiops_G

Re: [OOL] Cable Modem rebooting every day

I just noticed that the cable going to my cable modem first goes to the "cable IN" of the UPS under my desktop PC. Then there is another short cable from the "cable OUT" of the UPS to the cable modem. I wonder if this is really necessary and what additional lose is thru the UPS connection?
--
Go Mark Martin!



Tursiops_G
Technoid
Premium,MVM
join:2002-02-06
Norwalk, CT
kudos:1

That really depends on the quality of the UPS.
Try disconnecting the UPS cable surge suppressor and go straight into the Modem.
On a properly installed cable with a ground block, an extra surge suppressor isn't necessary, IMHO.

-Tursiops_G.
--
If You're Unsure, "RTFM"... If You're SURE, "RTFM" Anyway.



ModemDoc

@rcn.com
reply to Gemstone

If a loop thru a UPS was needed, it would be standard on every install but the fact is that it's not needed. It's amazing some of the stuff customers put into the cable line that probably not only degrade their own signal but also possibly cause return path noise that affects others. Get rid of it!



Gemstone
Premium
join:2000-12-20
Long Island

said by ModemDoc :

If a loop thru a UPS was needed, it would be standard on every install but the fact is that it's not needed. It's amazing some of the stuff customers put into the cable line that probably not only degrade their own signal but also possibly cause return path noise that affects others. Get rid of it!

This was all done by the cable installer years ago! He put the 4-way splitter first before the 2-way and also said that since I had the UPS with the cable pass thru it should be used. Never had issues that I was aware of until possibly now. But I understand what you are saying and will clean up everything now that I'm aware.
--
Go Mark Martin!


ModemDoc

@rcn.com

Unfortunately CV uses contractors form vast majority of installs and they dont have training and qualifications of in house techs. Swap the modem like others have suggested but be aware that if you have marginal signal, a D3 modem may have trouble getting online because it has channel bonding on down and upstream. Good luck.



Gemstone
Premium
join:2000-12-20
Long Island

I removed the UPS pass thru connection and connected direct to the cable modem. These are now my power levels this morning:
--
Go Mark Martin!


Tursiops_G
Technoid
Premium,MVM
join:2002-02-06
Norwalk, CT
kudos:1

That alone shaved about 3dB of loss off of your signals...

Getting new splitters and re-arranging your hookup should give you about 3dB More improvement... If it does, you're well within DOCSIS 3 Modem requirements.
--
If You're Unsure, "RTFM"... If You're SURE, "RTFM" Anyway.



Gemstone
Premium
join:2000-12-20
Long Island

said by Tursiops_G:

That alone shaved about 3dB of loss off of your signals...

Getting new splitters and re-arranging your hookup should give you about 3dB More improvement... If it does, you're well within DOCSIS 3 Modem requirements.

I ordered what are supposed to be high quality, loss splitters from an ebay seller... I ordered a 2-way and a 4-way splitter. They are made by Monster Cable. I know the Monster Cable stuff is generally over priced and over hyped but these splitters looked better than the "generic" ones being sold. Here's the 4-way I bought and the 2-way is similar:

»www.ebay.com/itm/Monster-Cable-L···84207a4f
--
Go Mark Martin!


Tursiops_G
Technoid
Premium,MVM
join:2002-02-06
Norwalk, CT
kudos:1

I would have just gone down to the CV walk-in center and gotten them there, but it's your call...

Did you need 3 TV runs, plus Modem, or 4?
--
If You're Unsure, "RTFM"... If You're SURE, "RTFM" Anyway.



Gemstone
Premium
join:2000-12-20
Long Island

Click for full size
This is my "from" and "to" hook up plan... I realize I probably over paid for the splitters and could have gone for the freebies from CV but I need 4 outputs for 4 TV's as shown.
--
Go Mark Martin!


Tursiops_G
Technoid
Premium,MVM
join:2002-02-06
Norwalk, CT
kudos:1

Yep.
You'll shave approx. another 3dB of loss from your DS/US signals...
+7dBm/+48dBm has Loads of margin for a DOCSIS 3 modem.

With the 4-way after the 2-way, TV3/TV4 will have the same signal level range as TV1/TV2... (Taking a SWAG, -1 to -3dBm, depending on cable length ?)... should be adequate for the STBs.

-Tursiops_G.
--
If You're Unsure, "RTFM"... If You're SURE, "RTFM" Anyway.



ModemDoc

@rcn.com
reply to Gemstone

Glad u got better levels after reconfiguration but why not just reuse old splitters before spending money to buy new? U have margin on forward path for d3 but 48db on upstream is 2db away from knocking u offline. D3 hitting 50db transmit will cause u to go offline. See what happens after swapping for D3 modem. Different modems tend to give different levels in diagnostics.



Gemstone
Premium
join:2000-12-20
Long Island

said by ModemDoc :

Glad u got better levels after reconfiguration but why not just reuse old splitters before spending money to buy new? U have margin on forward path for d3 but 48db on upstream is 2db away from knocking u offline. D3 hitting 50db transmit will cause u to go offline. See what happens after swapping for D3 modem. Different modems tend to give different levels in diagnostics.

You are right but I bought the new splitters already. No big deal I can use the freebie CV splitters for some other things.
--
Go Mark Martin!


Tursiops_G
Technoid
Premium,MVM
join:2002-02-06
Norwalk, CT
kudos:1

1 edit
reply to ModemDoc

Click for full size
Isn't the Max D3 upstream spec currently +54dBmV?
in that case, +48dBmV would be 6dB below the cutoff...

(Edit):
I've been running at +47/+48dBmV for much longer than the screenshot (modem rebooted due to power failure) with absolute rock-solid stability.

-Tursiops_G.

--
If You're Unsure, "RTFM"... If You're SURE, "RTFM" Anyway.


ModemDoc

@rcn.com

54db cutoff for modems transmitting at lower symbol and lower bandwith rate such as QPSK or 16qam. CV is using 64QAM which is twice the channel width which means lower maximum transmit of about 50db.

For shiggles add a splitter before your modem to create a 3.5db loss and see what it does to your modem.



kickass69

join:2002-06-03
Lake Hopatcong, NJ
reply to ModemDoc

That's not accurate. Once you hit 54 dBmV or higher is when you tend to have issues though anything in the 50s isn't desirable.

At my mother's place, she's at 51 and 52 on her upstream channels without any issues.



MuDvAyNe
Premium
join:2002-03-02
Brooklyn, NY

Exactly. If you hit 55 transmit on a d3 modem than you will lose your 2 bonded upstream channels. The Internet will still work but your speeds will suffer.
--
Mets, Cowboys, Devils



Gemstone
Premium
join:2000-12-20
Long Island
reply to Tursiops_G

I finally installed the new splitters I bought and reconfigured them per my diagram as shown a few posts ago... I also bought a new length of good quality RG6 to go from the 2-way splitter direct to my cable modem... Looks like my downstream power levels have improved!... In fact before this screen shot it reported 7bDmV downstream... Now says 6 dBmV... Still more than 3 or 4 dBmV...

--
Go Mark Martin!


Gemstone
Premium
join:2000-12-20
Long Island
reply to ModemDoc

Click for full size
Yesterday I installed the new ARRIS modem... Had a problem with one of my phone lines.. Tech can to my house and fixed that and called in for a truck to clean up the hookups on the pole outside my house... Apparently he saw extra old splitters up there... Cable truck arrived this morning and cleaned up those hookups... Here are the DN and UP numbers now with the ARRIS modem... (My apologies, I have 2 threads going on this topic. But looks like I am done!)
--
Go Mark Martin!

cablewizzard

join:2009-06-14
Hicksville, NY
kudos:1
reply to ModemDoc

said by ModemDoc :

Glad u got better levels after reconfiguration but why not just reuse old splitters before spending money to buy new? U have margin on forward path for d3 but 48db on upstream is 2db away from knocking u offline. D3 hitting 50db transmit will cause u to go offline. See what happens after swapping for D3 modem. Different modems tend to give different levels in diagnostics.

You don't know what you're talking about.

cablewizzard

join:2009-06-14
Hicksville, NY
kudos:1
reply to ModemDoc

said by ModemDoc :

54db cutoff for modems transmitting at lower symbol and lower bandwith rate such as QPSK or 16qam. CV is using 64QAM which is twice the channel width which means lower maximum transmit of about 50db.

For shiggles add a splitter before your modem to create a 3.5db loss and see what it does to your modem.

This level of misinformation is bordering on trolling - and I have to ask you to stop posting purported technical facts that just aren't true.

Not only are you blatantly wrong on your numbers, but the surrounding facts as well:
Transmit modulation change does NOT happen on a per-modem basis and is NOT dependent on how much return signal strength is present: doing so would permit "weak" modems to hog the US channel for a much longer periods of time: That is a concept only happening on dialup modems and WIFI, not DOCSIS. We fail individual modems that are impaired (and if FEC fails enough, they'll fail station-maintenance and dereg and reboot!), not make accommodations for them by letting them talk at lower speeds.

Modulation changes are driven by the CMTS for the entire upstream PORT (and all modems) at once - independent on whether some services (like VOIP) enjoy more robust lower QAM level transmission on a per-grant basis (that's a function of Packet Cable: VOIP traffic can be transmitted at another (selectable) mod level to make it more resilient/stable).
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