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View Full Version : 100M PWR and SNR levels are too high on my CM


Gethin Jones
04-04-2012, 22:02
Hello,

Dia Hard Cable Modem users like myself, would already know the main IP Address to access the cable modem is 192.168.100.1. Therefore, if you set your VM CMSH to Modem Only Mode it is the same IP Address. The reason why I have mentioned this is because a novice would automatically think there is something wrong with their CM if they couldn't access their CM via 192.168.0.1 as you would to access the router.

My old modem was coming up 6 years old so I decided to order a super "Doopa" Hub which wasn't straight forward because I spoke to a n00b who completely messed everything up and we had to start from scratch.

It arrived today, and I must say it looks really nice. Updated the firmware ASAP that was successful and running the correct firmware version and ASAP changed to modem mode.

Done a speed test and it was utter pants. OMG I may as well have a 20MB CM. I checked the PWR and SNR levels and it's a wonder the speed is pants because the PWR and SNR levels are pants they need lowering. I have a 6dB Attenuator from work which brought the levels down to 4.3dBmV which is perfect. but the Upstream is 45.0dBmV which is too high.

The SNR 37.8dB which is too high as well, I have an engineer coming out on Friday...? Good Friday and an engineer. I'll believe that when I see him at my front door. I hope he can get these levels down because they are too high. I have an amplifier up in the attic because I have three TiVo STB one 1TB and two 500GB TiVo STB's and the PWR levels and SNR are great on these but pants on the cable modem. until he can hopefully get these levels down I'm basically paying for a 100MB service and getting 20MB instead which is naff.

I'm wondering is there a more powerful amp, the one I have at the modem which was off VM is great but the power levels on the modem are just hideous.

sollp
04-04-2012, 22:29
U/S is very good, no need to do any more

thenry
04-04-2012, 22:34
upstream power levels fine

---------- Post added at 21:32 ---------- Previous post was at 21:30 ----------

what this 'amp' your on about?

---------- Post added at 21:34 ---------- Previous post was at 21:32 ----------

www.speedtester.bt.com/

Peter_
04-04-2012, 22:40
Your Upstream at 45.0dBmV is spot as is your SNR at 38dB, I have no idea where you have got the idea that it is to high.

Your Downstream is to high and warrants an engineer though.

Do check out the correct power levels in this post HERE (http://www.cableforum.co.uk/board/35251144-post1.html)

thenry
04-04-2012, 22:44
down levels are fine with the attenuator. see pic2

jb66
04-04-2012, 22:52
Snr is too high? Thats basically saying your signal quality is too good! The higher the better

With the 6db attenuator on your signals are PERFECT

Peter_
04-04-2012, 22:56
Somehow I rather doubt that any notice will be taken and he will be back on the phone as soon as the engineer leaves the house.

Gethin Jones
05-04-2012, 01:15
Okay if the PWR and SNR levels are within normal parameters then, either somebody in faults in feeding me BS and basically waisting an engineer call out when there isn't anything wrong. Or I am not on the correct network, because there is no way that I am on a 100MB service. I should be hitting at least 90Mb/s and I am getting 26.7Mb/s which is pants which is making me think if I am on the right network because this is utter trash for what I am paying. I used to be on Cardiff and now I am on Newport for some reason. When I was on Cardiff it was awesome great speeds but now it's basically a 30MB service. That is an appalling speeds and unacceptable. I have done some calculations and my estimation would be an 8dB forward path attenuator would bring these down to the following levels...?

1.9dBmV
2.0dBmV
1.8dBmV
1.6dBmV

I would be happy as a pig in Cough! with these power levels and it should increase the speeds.

https://www.cableforum.co.uk/images/local/2012/04/111.png (http://www.speedtest.net)

With regards to the amplifier, it's a 4 way broadband signal amplifier booster which you can get off a VM engineer FREE... The power adapter is plugged into the mains which is connected to coaxial which powers the booster in the attic to give the power levels a boost because the power levels into the property before the amplifier booster was added were borderline.

My TiVo service was 54.0dBmV and the TiVo kept power cycling because the PWR was too high. With the amplifier booster these have dropped to 43.0 on all the TiVo STB's and it's perfect.

OMG I just checked my appointments and I do have an engineer booked for Friday... I'm impressed. :)

boroboi
05-04-2012, 04:18
Well if your power levels are already fine, lowering them further won't increase your speeds, the fault must lie somewhere else.

General Maximus
05-04-2012, 10:03
test time dude, I think you have got the same problem I had. For some reason the shub is pants (for some people) at doing speed tests and although my vmng300 always gave me reliable speed test results, the shub would never budge over 36mbit. Buuuuuuuut, when I downloaded multiple files from somewhere like gamershell, torrents or newsgroups I would still get my 12mb/sec proving that I was getting full speed. I don't know what it is in terms of how the shub is designed that it can screw speed tests up so much but I do advise you to give it a blast on newsgroups if you use them to see what sort of speed you get or go to www.gamershell.com, start downloading 8-10 different very large files (1gb) from gigabit servers and see what speed you get cumulatively. You need large files because if you get your full speed they need to be large enough that you wont have downloaded them by the time you have started the other files going and you can see them all ticking away happily. When I did it each one was getting 1-2mb/sec.

Although I was getting my full speed I was concerned how the shub was handling the downloads because it meant that if i only ever downloaded 1 or 2 files at a time (which most people do) I would only get 1-2mb/sec and not be taking advantage of up to 12mb/sec. That is why I went back to my vmng300 :romance:

sollp
05-04-2012, 21:40
Okay if the PWR and SNR levels are within normal parameters then, either somebody in faults in feeding me BS and basically waisting an engineer call out when there isn't anything wrong. Or I am not on the correct network, because there is no way that I am on a 100MB service. I should be hitting at least 90Mb/s and I am getting 26.7Mb/s which is pants which is making me think if I am on the right network because this is utter trash for what I am paying. I used to be on Cardiff and now I am on Newport for some reason. When I was on Cardiff it was awesome great speeds but now it's basically a 30MB service. That is an appalling speeds and unacceptable. I have done some calculations and my estimation would be an 8dB forward path attenuator would bring these down to the following levels...?

1.9dBmV
2.0dBmV
1.8dBmV
1.6dBmV

I would be happy as a pig in Cough! with these power levels and it should increase the speeds.

https://www.cableforum.co.uk/images/local/2012/04/111.png (http://www.speedtest.net)

With regards to the amplifier, it's a 4 way broadband signal amplifier booster which you can get off a VM engineer FREE... The power adapter is plugged into the mains which is connected to coaxial which powers the booster in the attic to give the power levels a boost because the power levels into the property before the amplifier booster was added were borderline.

My TiVo service was 54.0dBmV and the TiVo kept power cycling because the PWR was too high. With the amplifier booster these have dropped to 43.0 on all the TiVo STB's and it's perfect.

OMG I just checked my appointments and I do have an engineer booked for Friday... I'm impressed. :)

Hi, The splitter you are talking about is a HDU,(if it's provided by VM as you say) it's not used to amplify the signal, it's job is a no loss splitter but it does in effect amplify the signal,(if we are splitting hairs).

Gethin Jones
06-04-2012, 03:22
With the Easter Bank Holiday weekend coming up I managed to book off a long weekend and don’t go back until Wednesday which is a bonus. Well today I decided to run some extensive tests on my Rig and it looks as though there is a pattern with the connection. Throughout the day the connection is utter pants there is no doubt about that. I am lucky to reach 30Mb/s on a 100MB connection. I have just run another test on the connection, and I couldn’t believe my eyes. 86.43Mb.All day the connection has sucked really bad averaging about 27.86Mb on a 100Mb connection. What the heck is causing the connection to be a slow during the day and then awesome in the early hours of the morning I don’t know, because I’m not a broadband engineer.

The results are what I’d expect from a 100Mb connection. 27.86Mb during the day is utter pants, I’ve checked my entire system for answers to the low speeds and came up empty. I have a Netbook and a laptop and they are all running Windows 7 x64 Ultimate and these are fast machines as well. The connection is the same on all of them so I know it’s not isolated to my main rig. There is an answer somewhere, why am I being throttled during the day…? I’m in work for Censored… and there isn’t anybody on the internet. I have set the router logs to be emailed to me 00:00 every night and I checked them on the way to work and the connection is sound… there aren’t any disconnections; the connection is solid throughout the day. So it begs the question. If the PWR and SNR levels are fine, then why is my connection really slow during the day…?

I have tested the connection with all the TiVo STB’s turned off during the day and tested the speed and again it is hovering around about 27.0Mb. 01:00 in the morning and its running like it should be. I am the only 100Mb service in my close. There are only 17 houses in the close, and it’s like living in a small village if you catch my drift. There are two Super Hub modems in the close and I am the fastest. There are a few Sky connections and a few BT Hub connections apart from that; there shouldn’t be an issue with a wired connection. I’m scratching my head because there isn’t anything on my system causing this. There has to be an answer somewhere?

If you look at the attached image you can clearly see downloads speeds are awesome and what I would expect to see on a 100Mb connection. However, it’s a different kettle of fish during the day. The download speeds are just inane 27.0Mb is terrible.

General Maximus
06-04-2012, 09:19
are you basing all this solely on speed tests or hae you done some actual downloading because I have already explained what the problem is?

borrissey
06-04-2012, 11:01
Gethin do you live in Newport?

Tazz
06-04-2012, 11:42
Just use speedtest london namesco...

Sephiroth
07-04-2012, 10:46
......
What the heck is causing the connection to be a slow during the day and then awesome in the early hours of the morning I don’t know, because I’m not a broadband engineer.

.......
If the PWR and SNR levels are fine, then why is my connection really slow during the day…?

I have tested the connection with all the TiVo STB’s turned off during the day and tested the speed and again it is hovering around about 27.0Mb. 01:00 in the morning and its running like it should be. I am the only 100Mb service in my close. There are only 17 houses in the close, and it’s like living in a small village if you catch my drift. There are two Super Hub modems in the close and I am the fastest. ..... I’m scratching my head because there isn’t anything on my system causing this. There has to be an answer somewhere?

........

Because I'm at a distance from you, I can only speculate as to what's going on in your area. Let mesay at the start, disconnecting the TIVO has no bearing on matters when power levels are OK. They are on a different frequency from your broadband and do not subtract capacity from your circuit.

My postulation is high utilisation most likely at the optical node but also possibly at the line card.

It works like this (but can vary in different parts of the country according to who was the original cable supplier):

1/
A small street cabinet connects either 16 or 32 customers. A larger street cabinet connects 48 or 96. It is passive equipment.

2/
The cable from a cabinet passes along to another cabinet configured as above.

3/
5 or 6 cabinets go to an optical node (with 240V labelled) and it's fibre from there. This cabinet is active.

4/
In high density population areas, you might get 20 coax cabinets feeding the optical node.

5/
The optical node originally would have supported only 2 upstream channels and these might have been split between two nodes at the VM end line card. So that's a heck of a lot of users who think they're getting, say 5 meg upstream sharing just 40 meg upstream capacity.

6/
A downstream bonding group currently has 4 downstream channels with c. 200 meg capacity to share across one or two optical nodes. VM intend that this should rise to 8 downstream channels. VM are also introducing bonded upstream channels.

7/
The optical node connects via fibre to a line card on a UBR/CMTS at the local hub. Many optical nodes terminate on a single line card. An individual's downstream and upstream (both shared with other users) terminate on the same line card and (AFAIK) in the same Service Group.


Hope that sheds some light on what could be happening.