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Cable connection bad power levels

  • 16 October 2021
  • 5 kommenttia
  • 196 katselukerrat

Hello everyone!

I recently started using Elisa’s broadband cable internet subscription in my apartment. I have a Fritz!Box 6660 cable modem connected to TV/Data splitter/filter which is connected to a TV cable wall outlet. For a couple weeks now, the connection has been sub-optimal, so I started looking into what may be going wrong. After quite a bit of research, I came to the conclusion that my power level numbers are not at all where they should be for both Downstream and Upstream.

I’ve contacted Elisa customer support and they said that my numbers are in fact  bad but my neighbors’ numbers are perfectly fine, so it must be an issue on my end. I told them I was using a different TV/Data splitter/filter than Elisa provides, so they suggested getting one directly from Elisa. Once I did that, I expected my power levels to go back to normal, but alas, they are exactly the same as with the other TV/Data splitter/filter.

I’ve also tried connecting the cable modem directly to the TV cable wall outlet without using any splitters/filters and, to my surprise, the power levels got better. I was noticing minimum power levels of -15.5 dBmV as opposed to -18.0 dBmV when using the splitter/filter, although the Upstream power levels stayed the same at 51 dBmV.

At this point I’ve tried 2 different TV/Data splitters/filters, 3 different coax cables and a direct outlet-to-modem connection.
I’ve attached screenshots of the power levels seen using Elisa’s own provided cable and TV/Data splitter/filter (correctable error counts are from ~45 mins of uptime). Any help is greatly appreciated!


 

 

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Vastauksen tähän kysymykseen jakoi mökörölli 17 October 2021, 06:13

Katso alkuperäinen viesti

5 kommenttia

Screenshot of upstream power levels as well:
 

 

Käyttäjätaso 4
Kunniamerkki

Yes, you have low signal levels, and even worse, you have very low SNR/MSE. I don’t believe problem is at your end (ie. splitter/cable or modem). If Elisa has verified your neighbours have decent signal, then problem is somewhere on your apartment buildings cabling. If your building has chained antenna system, then it’s probable that some antenna outlet in the chain before you is broken, or someone has changed their outlet for something that is not suited for the location (for example too much attenuation for the output).

Each splitter causes attenuation of about 3-4dB. TV/Data splitter does attenuate downstream by that much, but it does filter out upstream frequencies from the TV output, so upstream is just pass-through to the “data”-port without notable attenuation, it will be somewhere in the range of 0.2-0.5dB depending of the quality of the splitter.

Anyway it’s then something that your apartment building maintenance/administration has to take care of. Give them a call and let them investigate the problem.

Käyttäjätaso 4
Kunniamerkki

Need to clarify myself a little bit about splitters and their attenuation. Each split, ie. every 1 to 2 split does cause attenuation of about 3-4dB. Multi-way splitters do cause the signal drop depending of the number of ports/legs (splits) it has. They do not usually drop as much per leg. For example 6-way splitter will output 11dB less to each output leg compared to the input level. That’s overall about 2dB drop per amount of outputs.

Thanks mökörölli! Your answer is very detailed and helpful.
I’ve decided to contact the maintenance company in an effort to find out what the root cause is.
In the meantime, I noticed a lot of people online are encouraging to terminate open coax ports to reduce interference. My apartment has 5 wall outlets with this TV/Radio connection (attached picture). I was thinking, should all of these unused TV outlets be terminated with IEC female → F Female + F terminator plugs? Would this improve my power levels to the one specific TV cable outlet I have connected to my cable modem?

Thanks again for your time!
 

 

Käyttäjätaso 4
Kunniamerkki

Thanks mökörölli! Your answer is very detailed and helpful.
I’ve decided to contact the maintenance company in an effort to find out what the root cause is.
In the meantime, I noticed a lot of people online are encouraging to terminate open coax ports to reduce interference. My apartment has 5 wall outlets with this TV/Radio connection (attached picture). I was thinking, should all of these unused TV outlets be terminated with IEC female → F Female + F terminator plugs? Would this improve my power levels to the one specific TV cable outlet I have connected to my cable modem?

Thanks again for your time!
 

 

There is no need for end consumers to terminate these IEC type of sockets. They are already terminated somewhere. Chained networks are terminated on the last socket, and in star topology each socket is a “last” socket, and therefore terminated. If you have a star topology and are using a socket that is not terminating socket, then it needs to be terminated, or even better, to use terminating socket as should be. Each splitter or tap you might have with unused “legs” needs to be terminated with a F-terminator plug.

Anyways, lack of termination would not cause the issue you are having, which is low signal power level. It could cause interference, which could lower your SNR and/or cause error counters to count up fast. I think in your case SNR/MSE is directly related to low signal power. Any splitters/taps should not lower SNR/MSE, only signal power/strength.

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