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Pacomartin

join:2013-03-18
Bethlehem, PA
Reviews:
·RCN CABLE
reply to cdr1000

Re: [Connectivity] Picture keeps freezing - New York

The level of 49 dBmV is within specification, but it is very high. Check it when you are having a problem and see if it is even higher.

Look for obvious radio interference, or see if you have equipment like dehumidifier plugged into the same circuit. If possible use RG6 coaxial cable on the stretch from street.

Ideally, you should have a single split from point of entry where half goes to cable modem, and the other half goes to the televisions.

If you have TiVo then put a MoCa filter on both the point of entry and on the cable modem.



Waylonj

@rcn.com

Lack of moca filter can cause issues with TiVo talking to a neighbors TiVo but should have no impact of the OP's complaint of freezing picture and audio.

said by Pacomartin:

The level of 49 dBmV is within specification, but it is very high. Check it when you are having a problem and see if it is even higher.

Look for obvious radio interference, or see if you have equipment like dehumidifier plugged into the same circuit. If possible use RG6 coaxial cable on the stretch from street.

Ideally, you should have a single split from point of entry where half goes to cable modem, and the other half goes to the televisions.

If you have TiVo then put a MoCa filter on both the point of entry and on the cable modem.



Johkal
Cool Cat
Premium,MVM
join:2002-11-13
Happy Valley
kudos:10

1 recommendation

reply to Pacomartin

said by Pacomartin:

The level of 49 dBmV is within specification, but it is very high. Check it when you are having a problem and see if it is even higher.

Look for obvious radio interference, or see if you have equipment like dehumidifier plugged into the same circuit. If possible use RG6 coaxial cable on the stretch from street.

Ideally, you should have a single split from point of entry where half goes to cable modem, and the other half goes to the televisions.

If you have TiVo then put a MoCa filter on both the point of entry and on the cable modem.

49 dBmV is not very high. It is the recommended high limit to address a +3 dBmV swing. How do we know what the signal levels are at the point where the TV is? The modem signal levels are only an indication of that connection point in the dwelling.

The OP would need to monitor the levels to see if there are major swings +/-.
--
In God we trust; all others bring data!



Pacomartin

join:2013-03-18
Bethlehem, PA
Reviews:
·RCN CABLE

said by Johkal:

49 dBmV is not very high.

The OP would need to monitor the levels to see if there are major swings +/-.

I said that 49 dBmV was within specification. But the upstream power level tends to fluctuate depending on various influences such as temperature. Since mine is usually around 31 dBmV I don't expect transients to push it into the 50's . But with 49 dBmV you might have some intermittent problems.

I do agree that you should take a reading every time you turn on the computer and look for fluctuations. If some of them go into the high 50's, then you have an issue. An extremely low reading may indicate some kind of instability.

The difference between 31 dBmV and 49 dBmV is a change in "intensity" by a factor of 63, and a change in power level by a factor of 8. So it is a relatively big difference.


Johkal
Cool Cat
Premium,MVM
join:2002-11-13
Happy Valley
kudos:10

3 edits

Just note that the recommended range is 35 dBmV to 49 dBmV. Too weak of a signal can be a issue.

From your previous post:

"The highest item of interest is the power levels. They should resemble
Downstream 0 dBmV
Upstream 30 dBmV
Signal to Noise Ratio: 38 dB"

I wouldn't recommend a target for the upstream at 30 dBmV. Target is as I said. Preferably you want to see 40 dBmV to 45dBmV by opinion. Also, there is no limit to how high you want the SNR to be. The higher the better. It's when the SNR is too low is when issues occur.

Any way, the OP needs to see what the levels are at the connection where the TV is & keep an eye on big swings with their Upstream level.

As example: I recently had an issue with my TV reception in my living room either pixelating on certain channels or getting an error on others. I wasn't sure if it was my DVR or some point in my cabling to this connection. My setup is a 2-way splitter with one leg to the modem & the other leg goes to a 6-way which feeds the rest of the house. My modem signal levels were"perfect"(by recommendation) which only told me that my feed coming in, the leg of the 2-way splitter & my cable/cable ends were all good to the modem. I did all my troubleshooting with checking each leg of the 6-way splitter & the other leg of the 2-way & all cable & cable ends. At this point it looked like either my DVR might be the issue or the cable to the livingroom which is about a 60' run. Not wanting to bring the modem up to use it to check signal levels, I had my ISP come out and check with a meter. Immediately it showed my Downstream had dropped at that outlet to -21 dBmV. Long story short as the tech checked everything all the way back to the Ped for any/all connection issues, it came down to me having to replace the cable to that outlet.
--
In God we trust; all others bring data!



Pacomartin

join:2013-03-18
Bethlehem, PA
Reviews:
·RCN CABLE

said by Johkal:

Just note that the recommended range is 35 dBmV to 49 dBmV. Too weak of a signal can be a issue.

Well the chart on the RCN speedtest says 25 to 50 dBmV

I should note that I am at the end of a cable distribution line.

Near the end of a line, you have low tap values at the pole. low tap values are installed so you will still get a good forward high frequency level. In that case, lower upstream signal is normal. So the OP may not be in the same sitution.

Anyway, we are not fundamentally in disagreement. I said that 49 dBmV is within spec,the OP should take a number of observations over a period of time at different times of the day and at different outside temperatures and keep a table.


Johkal
Cool Cat
Premium,MVM
join:2002-11-13
Happy Valley
kudos:10

Just remember that a modem's operating range is different than the tighter recommended range. 25 is in the basement. LOL!



Pacomartin

join:2013-03-18
Bethlehem, PA
Reviews:
·RCN CABLE

Well, there is some inconsistency on the FAQ on this website. Quote
"Upstream Power: The lower this number is, the better. If it is above 55, you may want to see if you can reconfigure your splitters."
»Cable Modems and Wiring Issues »What kind of signal levels do I want on my cable modem?

While I may not agree that "the lower the number is, the better", I think that the network requests that power it needs to receive the signal. I can't do anything about the +30 dBmV number. Whereas a high number, I can examine the quality of my cable and the quality of my splitters.

NOTE: There were a number of comments that disagree with "the lower the number is, the better". In particular, they say that a low number is a problem with DOCSIS 3 (I only have DOCSIS 2).



Johkal
Cool Cat
Premium,MVM
join:2002-11-13
Happy Valley
kudos:10

1 recommendation

That FAQ is outdated & has been for a number of years.

Please review the RCN FAQ: »RCN Forum FAQ »What should my cable modem signal levels be?



Pacomartin

join:2013-03-18
Bethlehem, PA
Reviews:
·RCN CABLE

said by Johkal:

That FAQ is outdated & has been for a number of years.

Well, if the number is too low, is there anything you can do after the POE?


Johkal
Cool Cat
Premium,MVM
join:2002-11-13
Happy Valley
kudos:10

If your Downstream is in spec & the SNR is good, there would be little on your end you could do to increase the Upstream without causing your Downstream to drop below recommended. Normally it is a "Balancing" issue that your ISP has to look into.

Given your specs, if you increased your Upstream by +10 to 40 dBmV, your Downstream should proportionally drop to -10 dBmV.
Not a good trade off.
If you have no issues, don't worry about it. If you start seeing issues, you would need your ISP to correct it.
--
In God we trust; all others bring data!



Middlem

@rr.com

said by Johkal:

If your Downstream is in spec & the SNR is good, there would be little on your end you could do to increase the Upstream without causing your Downstream to drop below recommended. Normally it is a "Balancing" issue that your ISP has to look into.

Given your specs, if you increased your Upstream by +10 to 40 dBmV, your Downstream should proportionally drop to -10 dBmV.
Not a good trade off.
If you have no issues, don't worry about it. If you start seeing issues, you would need your ISP to correct it.

The OP has TV issues not modem. If he dropped his upstream by to from 49 to 39, the downstream goes up by 10. So his average downstream of 4 would up to 14. Less cable and splitter loss increases downstream level an reduces transmit level.


cdr1000

join:2004-02-18
10100

After a huge fiber cut all services were restored.
Everything works.
Will be building Mythbuntu HTPC with output to TV.
Mythbuntu supports Ceton InfiniTV 4 PCIe and different remotes.



Johkal
Cool Cat
Premium,MVM
join:2002-11-13
Happy Valley
kudos:10
reply to Middlem

You do realize I wasn't replying to the OP. I was replying to Pacomartin See Profile

He was asking about his signal levels not the OPs which happen to be :

Downstream 0 dBmV
Upstream 30 dBmV
Signal to Noise Ratio: 38 dB