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cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

cHarley

Member

[Connectivity] Advice on high US dBvM

I have just installed Blast 50/10 using a BYOD Zoom 5341J and TP-Link R600VPN router, finally dumping ATT DSL as Uverse rolled into the neighborhood. I have had CC cable TV here for 10+ years.

My underground drop to the premise is less than 6 months old and feeds a 1 YO CC supplied (6 port) distribution amp. All 6 amplifier ports are in-use, feeding TV drops in 6 separate rooms, which means I need to add a splitter on one of the lines for the modem. I am using an Actronix 5-1000 2-way splitter.

If I remove a TV and connect the modem without a splitter, I have an US level of 49-50 dBvM. With the splitter, I'm looking at an US of 53 dBvM. At 53 dBvM I am not currently having any problems or errors in the modem log, but I know this level is on the high side.

My initial thought was to install an 8 port distribution amp and drop a new run to the modem, but getting from point A to B isn't realistically possible.

I would appreciate any advice or recommendations on the best way to proceed, without facing CC truck roll charges.

graysonf
MVM
join:1999-07-16
Fort Lauderdale, FL

graysonf

MVM

Can you run a second line to the room with the modem? That way you connect the modem directly to the distribution amp and split one of the other lines that run to a TV for the other TV.

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM to cHarley

Premium Member

to cHarley
Is the CC provided 6-port AMP an Active or Passive return??
Does it have a make and model number on it?

Saying something like +15dB Forward, -10dB Return?? Maybe Return Gain 0dB?

What does your modem report as the downstream level and SNR?

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

cHarley

Member

Thanks,

As stated, an additional drop isn't realistically possible from the amp to the modem location.

The amp is active return I think??, supplied by CC, make is unknown at the moment, it's in the attic.

Modem stats with the splitter are:



tshirt
Premium Member
join:2004-07-11
Snohomish, WA

tshirt to cHarley

Premium Member

to cHarley
said by cHarley:

My initial thought was to install an 8 port distribution amp and drop a new run to the modem, but getting from point A to B isn't realistically possible.

good case to put the modem at the amp location and use moca or Ethernet over powerline adapters to forward to the current modem/computer location(s)
said by cHarley:

I would appreciate any advice or recommendations on the best way to proceed, without facing CC truck roll charges.

if it's a Comcast amp they may be willing to service it (particularly for a 10 year, 6 tv/device customer) can you attach the modem to the drop and get an idea of the signals there?
Mr Matt
join:2008-01-29
Eustis, FL

Mr Matt to cHarley

Member

to cHarley
said by cHarley:

I would appreciate any advice or recommendations on the best way to proceed, without facing CC truck roll charges.

CC installed one of these RF Amps along with an 8 port splitter, in my structured wiring cabinet to replace the distribution Amp they were not satisfied with, which was included with the cabinet. The amplifier has a low loss modem port. Or you can connect a low loss splitter at the input of the 6 port distribution amp. Connect the other port of the splitter directly to the modem.

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM to cHarley

Premium Member

to cHarley
I would replace the splitter with an 8-port Active Return amp, many have a dedicated 9th passive port for Voice modems, in case of power loss).

Not a typical amp, but a +/-0dB amp(zero gain, zero loss).

It works like a lossless splitter, so that the input signal levels will be the same as what you have on every output.

»www.ppc-online.com/Produ ··· turn.cfm

Probably similar to your current amp, except you have additional ports, and don't need any additional splitters.

Would be really interesting to find out, if you can eventually get to the attic, and jot down the numbers on the existing amp.

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

1 edit

cHarley

Member

Again, thanks for the suggestions so far.

First, restated from the OP;
quote:
My initial thought was to install an 8 port distribution amp and drop a new run to the modem, but getting from point A to B isn't realistically possible.
Short of chopping up walls and ceilings, I have no pathway for running an additional cable drop from the distribution amp in the attic (2 story house) to the ground floor room that houses the modem, network switches and media/file server. I really need to make use of the ONE existing cable drop to the equipment room. This single drop needs to be split in the server room to feed both the modem and a HDHR Prime tuner.

Note: CC Voice/VOIP is not a concern.

I did get up in the attic and got a better look at what's installed up there.

The incoming cable feeds a PCT-MA2-M mediadrop amp (passive return).
»www.amazon.com/PCT-BI-DI ··· 00F28DP2

The amp then feeds a 6 port Extreme BDS106VF splitter.
»www.amazon.com/EXTREME-B ··· 0GF7RMWQ

I guess I didn't realize (or forgot) that when CC replaced my (single piece) distribution amp last year, that they did so with a separate amp and splitter.

I did find a comparable amp to what I have but with active return listed on Amazon. What I'm not sure of, is how much help this will be with the 6 port (-9 dB/port) splitter between the amp and modem?
»www.amazon.com/PCT-1-Por ··· CMNA613B

Now, to possibly further complicate this a bit more, I really can't afford any additional TV signal (dB) loss. The distribution amp replacement by CC last year was one of several truck rolls in an attempt to correct low signal levels at higher frequencies (above 700Mhz). The cable drop in the equipment/server room with the Actronix -3.5 dB 2-way splitter on a good day gives me -6.5 dBvM at 729 Mhz (a frequently watched channel) and the HDHR Prime will start having problems at -10 dBvM. In this config, I have the 53 dBvM US on the modem.

So, do I just give the Active return amp (above) a shot with my existing splitters? Better ideas?

Thanks

ComTech 4
Premium Member
join:2002-11-28
USA

ComTech 4 to cHarley

Premium Member

to cHarley
said by K3SGM:

I would replace the splitter with an 8-port Active Return amp, many have a dedicated 9th passive port for Voice modems, in case of power loss).

Not a typical amp, but a +/-0dB amp(zero gain, zero loss).

It works like a lossless splitter, so that the input signal levels will be the same as what you have on every output.

»www.ppc-online.com/Produ ··· turn.cfm

To be honest this is your best answer short of calling Comcast out to fix it.
Then just use the antronix 2way between your modem and the tv. Your return should drop down 9db. your upstream should look look like 44.

new on ebay »www.ebay.com/itm/9-PORT- ··· 90913615

cHarley
join:2013-07-10
Boynton Beach, FL

cHarley

Member

Thank you both for the advice, I just placed an order for the EVOI-9-U/U amp.
cHarley

cHarley to ComTech 4

Member

to ComTech 4
said by ComTech 4:

To be honest this is your best answer short of calling Comcast out to fix it.
Then just use the antronix 2way between your modem and the tv. Your return should drop down 9db. your upstream should look look like 44.

new on ebay »www.ebay.com/itm/9-PORT- ··· 90913615

Just to clarify, are you recommending that I use this to replace my existing 6-port splitter AND amp, or just to replace the existing splitter?

Thanks

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

Replace the Amp AND splitter.
DO NOT connect an Amp to an Amp, and don't reuse the original amplifier

The Amp has an 8-port splitter built into it. You just need to connect the incoming cable to the input port, and the other cables to the output ports..

Just remember to put 75-ohm terminating resistors on all unused ports.

cHarley
join:2013-07-10
Boynton Beach, FL

cHarley

Member

OK, that's what I thought.

Thank you for the assistance.

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

Check back here when you get the new amp, just to let us know if the problem is now fixed.

Any further questions, feel free to ask....

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

cHarley

Member

Just a follow-up to let you know that the 9-PORT-PPC-EVOL seems to be a good choice. The US is now down to 44.5 dBmV and the Zoom modem seems happy. The only (potential) downside that I see is that I've lost 3-4 dBvM of signal strength & quality on my (TV) outputs, which leaves stations located above 700Mhz close to marginal at -9.2dBmV. My HDHR Prime is happiest between -9 and +9 dBvM.

I think in my case, the same unit with active return and +3dBvM outputs vs zero loss would have been ideal.

Thanks again for the help.

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

Do you have other splitters in the house, or does the cable drop from outside go directly into the new amplifier in the attic?

Good to see the Upstream levels are normal, but the -9.2dB DS levels don't make sense, especially with that amplifier in place.

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

cHarley

Member

No, there are no other splitters other than the one 2-way in the room with the HDHR Prime and modem, which is after the 9-way zero loss amp. The 9-PORT-PPC-EVOL is attached to the incoming cable feed.

Channels on lower freqs (165 Mhz) are great with +8.5dBvM, but as the freq climbs the levels drop, and become marginal around 729 Mhz where they are down to -9.2.

I really wouldn't care much except CC puts USA up at 729 Mhz and it's a frequently watched/recorded station. But rest assured, HSN, QVC, and most of the other never watch junk, gets lower freq priority and comes in great.



K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

I would care if the signal levels varied that much.

At the low end, the signal is borderline too high, and at the upper end, borderline unusable.

An almost -18dBmV slope from 165MHz to 729MHZ isn't right at all, it's like there is a coax simulator, tiering filter, or an extra 300ft of excess coax balled up somewhere.

What DS frequencies are the modem on, what's the SNR, and what are the signal levels with the new amp? Are all of the unused amp ports capped with 75 ohm terminators?

You're absolutely sure there is nothing else screwed into the drop line, and the drop comes directly from outside and right into the amplifier.

Is the service overhead or underground, and do you have any idea when it was first installed. Can you approximate the length of the drop, and what type of coax it is?(RG6,RG11,RG59)

Is there a ground block, and are the connections there tight?

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

3 edits

cHarley

Member

said by K3SGM:

I would care if the signal levels varied that much.

At the low end, the signal is borderline too high, and at the upper end, borderline unusable.

An almost -18dBmV slope from 165MHz to 729MHZ isn't right at all, it's like there is a coax simulator, tiering filter, or an extra 300ft of excess coax balled up somewhere.

What DS frequencies are the modem on, what's the SNR, and what are the signal levels with the new amp? Are all of the unused amp ports capped with 75 ohm terminators?

Prior to installing HSI last month, I've had CC out at least 6 times over the past 2 years, twice they were supervisors, in an attempt to improve my TV signal levels. They have run a new (underground) drop from the ped to the premise, replaced the ground block and ground, replaced the distribution amp twice and have "re-made" all connections at each outlet. There is no excess cable coiled anywhere. All utilities here are underground. All unused ports are terminated.

Modem Stats:


said by K3SGM:

You're absolutely sure there is nothing else screwed into the drop line, and the drop comes directly from outside and right into the amplifier.

YES
said by K3SGM:

Is the service overhead or underground, and do you have any idea when it was first installed. Can you approximate the length of the drop, and what type of coax it is?(RG6,RG11,RG59)

Underground, new ~40' RG6 drop from ped to premise 6 months ago. 2nd time in 2 years.
The existing (in wall) distribution cable in the premise from the amp to outlets is RG59.
said by K3SGM:

Is there a ground block, and are the connections there tight?

Yes, new 6 months ago (see above)

Do you know what the CC specs for an acceptable vs unacceptable signal level? At what levels can they say "it's as good as it's going to get" vs having to do something about it?

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

6 visits by Comcast in 2 years?

Maybe you really need a 7th visit now, because if your seeing your higher end signals down -9.2dBmV, and lower end signals up at +8.5dBmV, something isn't balanced properly, and it doesn't seem like it's anything inside of the house.

owlyn
MVM
join:2004-06-05
Newtown, PA

owlyn to cHarley

MVM

to cHarley
Take the terminators off one by one and see what happens.

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

Removing the terminators, what do you expect that to do??

This sounds like an outside problem now, almost like it's a 650/700MHz plant that they are stretching to 750MHz without upgrading the electronics. Hence the sharp roll-off of the gain on the upper frequencies.

The modem in this case is well within the specs for proper signal levels.

owlyn
MVM
join:2004-06-05
Newtown, PA

owlyn

MVM

I am expecting US levels to drop.

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

cHarley to K3SGM

Member

to K3SGM
Thanks again.

I just went back and did some random testing trying to find channels in different parts of the freq spectrum, and it seems to be a progressive loss from the low to high end.

Here are some samples:
Freq (Mhz) - Signal Strength(dBvM)

165 / 6.8 dBvM
255 / 3.3
315 / 1.6
387 / 0.6
507 / -1.8
573 / -6.1
663 / -8.6
729 / -9.6
741 / -9.9
cHarley

cHarley to owlyn

Member

to owlyn
The US levels are fine now with the new amp.
The problem now is TV channel signal strength across the spectrum.

K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

I think we fixed the initial cable modem problem, the amp is working properly, and this is more and more about an additional underlying TV signal problem now.

The last thing I would suggest is running a new temporary cable from the ground block, and verify the problem is 100% outside.

If you have the same results, CC needs to fix their problem, since you will have proven it's not something wrong in your house.

A service call won't cost you anything at that point, you probably don't even need to be at home, because it's an outside plant problem.

Maybe it's time to open this up as a new topic in the TV forum, and go forward from there??

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

cHarley

Member

I agree, we've eliminated the HSI US issue and it's migrated to TV signal issues and time to move on. At this point it's probably easiest to just carry the HDHR Prime outside to the ground block and connect it there and retest the levels. If the spread is the same I'll turn it over to CC.

I would still like to know what CC considers an acceptable signal strength spread (min/max) across the low-high spectrum.

Thanks again for the assist.


K3SGM
- -... ...- -
Premium Member
join:2006-01-17
Columbia, PA

K3SGM

Premium Member

said by cHarley:

I would still like to know what CC considers an acceptable signal strength spread (min/max) across the low-high spectrum.

I believe the FCC used to state the requirement of +10dBmV at the ground block(mine is about +8dBmV), but that was back around 30 years ago, when the entire plant bandwidth was only 250-350 MHz, and there wasn't such a thing as a cable modem..
The different technology, in addition to cable plant variations, have probably changed that over time.

I don't think it was commonplace for a tech to even carry a signal meter with them until the past 5-8 years, that had been left up to the plant engineers to take those measurements.

It's a good question to ask in the CC TV forum, (they seem to have more CC employees and contractors over there).

I don't have their TV service, so I don't have the equipment to take signal measurements with.

flwpwr
@comcast.net

flwpwr to cHarley

Anon

to cHarley
Since there is no such thing as a 6 way splitter, its an 8 way with 2 ports blocked off, which means your loss is a bout 10.5.

So if you're at +2 to +6, can we split the line before the amp?
This would acquire total signal change of -15 from the amp, and +10.5 from the splitter giving us
-2.5 to +1.5 which is fine, so the answer to your question is

incoming drop line to 2way splitter, feeding modem line on one leg and amplifier on other leg, amp feeds 6 way splitter, then splitter.

Verify your levels are near what I said on the downstream and under 51 on the upstream since I cannot see your cmts receive it may not be a simple 10 db reduction, you may be at max transmit but realistically need more to be where you are supposed to be at the other end, so this is a maybe not a definite.

I'd put the 2 way in and feed the modem then test the levels, if they are good then hook up the amp and 6 way leaving one outlet open, put a terminator on that port it if you have one, though its not a big issue on drop cable with its attenuation levels.

That said without more info I cannot comment on your levels except the 4 db change between carriers on the downstream would make me climb the pole/find the ped and verify my levels are that wonky coming out of my tap. It would be preferred they are a little more flat on levels, though it may not be possible or plausible depending on your setup outside.

cHarley
join:2013-07-10
Boynton Beach, FL
Motorola MB8600
(Software) pfSense

cHarley

Member

Thanks, but as noted above, the modem is located in a room where it is not realistically possible to run an additional drop and MUST share (split) the existing outlet with a HDHR Prime.

The modem US level issues have all been resolved by using a 9 port zero gain/zero loss amp with active return.

The only problem now is the incoming TV signal level (dBvM) that drops in a linear fashion from a high at 165Mhz of +6.8dBvM to a low of -9.9dBvm at 741Mhz.