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Discussion Starter · #1 ·
I just recently moved into a college dorm room. It comes with a coaxial cable drop that, up until today, had been used exclusively by the cable modem provided to me by the building management. The connection provided the modem had been quite stable up until I attached a splitter and divided the cable line between the modem and a newly purchased LCD HDTV.


I now suffer occasional network drop offs. They are rare, but their were none before the splitter was applied. The picture quality from the HDTV is also a bit subpar, with higher numbered channels being worse than lower numbered. Picture quality improves slightly when the TV is plugged directly into the drop, at the very least higher numbered channels improve to the level of lower numbered channels.


The coaxial cabling I am using was also provided by the building. They are clearly used, and I suspected getting my own cabling would improve the situation, but I am unsure. After some research, the possibility of adding a coaxial drop amplifier + splitter was also considered, but I don't know enough about such devices to know what specs I should be looking for.


In order to not waste anybody's time, I gathered as much information regarding signal strength from the modem and TV as I could. Since I cannot access the diagnostic information of my modem directly when the coaxial line is plugged in (the page is blocked when a cable connection is detected, likely a setting applied by the cable modem provider), I used a program called Cable Modem Diagnostic 1.0.4. Unfortunately, I am unable to post a URL since I don't have enough posts.


My PC sits behind a router, which sits behind the cable modem. The data gathered was taken with and without the splitter applied, as well as with the PC plugged into the router and plugged directly into the modem:


(Cable Modem)


With Splitter (PC -> Router -> Cable Modem):


Upstream Level (Output): 108.6 db/uv

Difference: 0


Downstream (Input): 55.8 db/uv

Difference: 0


Up Frequency: 31.984 Mhz

Down Frequency: 585 Mhz

S/N: 23.4 db


-


Without Splitter (PC -> Router -> Cable Modem):


Upstream Level (Output): 105.6 db/uv

Difference: 0


Downstream (Input): 59.5 db/uv

Difference: 0.1 db


Up Frequency: 31.984 Mhz

Down Frequency: 585 Mhz

S/N: 34.8 db


---


With Splitter (PC -> Cable Modem):


Upstream Level (Output): 108.6 db/uv

Difference: 0 db


Downstream (Input): 55.8 db/uv

Difference: 0.1 db


Up Frequency: 31.984 Mhz

Down Frequency: 585 Mhz

S/N: 28.9 db


-


Without Splitter (PC -> Cable Modem):


Upstream Level (Output): 105.6 db/uv

Difference: 0 db


Downstream (Input): 59.7 db/uv

Difference: 0.1 db


Up Frequency: 31.984 Mhz

Down Frequency: 585 Mhz

S/N: 35.5 db



I do not have the necessary expertise to properly interpret the data, so I can't tell whether it points to new cabling or a drop amplifier as the solution. The following information on the signal strength to the TV was taken using its built-in signal meter. Data was taken with and without the splitter applied:


(LCD TV)


With Splitter:


Signal Unlocked


MOD Mode: 8VSB

SNR (dB): -10.10

Signal Power: -50.00


Freq. Offset (kHz): Too Random to Measure

Corrected Errors: 0

Uncorrected Errors: 30798


Physical Digital Channels: 69

Virtual Digital Channels: N/A


-


Without Splitter:


Signal Unlocked


MOD Mode: 8VSB

SNR (dB): -10.10

Signal Power: -50.00


Freq. Offset (kHz): Too Random to Measure

Corrected Errors: 0

Uncorrected Errors: 47279


Physical Digital Channels: 39

Virtual Digital Channels: N/A


The Freq. Offset value fluctuated too widely for me guesstimate an average, and none was provided by the Signal Meter.


Should I order high quality and better shielded cabling? Attach a drop amplifier to the line? Or both?


If an amplifier is needed, would specs should I be looking for?
 

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Looking at your numbers taken from the cable modem, the up and downstream power levels are good, the s/n ratio numbers are acceptable.


The TV numbers are also good if they are all in dbm.


From this signal levels are good so you don't need to amplify them.


I would look at my connectors and splitter make sure all are tight and I would physically remove them and re connect if the problem still exist I would wiggle them near each connector end and have someone monitor the signal level and SNR numbers and look for changes.


Let me know what happens.


If interested here is a link to a power conversion calculator.
http://www.soontai.com.tw/cal_exunit...ubmit=Continue
 

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Yeah, the numbers look pretty good.


What is the splitter and what type of cables are you using to connect everything? The $1.99 you get at Home Depot or Wally World are not of sufficient quality to work very well with CATV, especially internet. Same thing with jumper cables. They can't be the push-on kind or the kind you get with VCRs or have twist-on connectors.
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by egnlsn /forum/post/15516068


Yeah, the numbers look pretty good.


What is the splitter and what type of cables are you using to connect everything? The $1.99 you get at Home Depot or Wally World are not of sufficient quality to work very well with CATV, especially internet. Same thing with jumper cables. They can't be the push-on kind or the kind you get with VCRs or have twist-on connectors.

There's no name brand on the splitter, but it does read:


2-Way Splitter

5-900 MHz


Its small and fairly mundane looking. It probably is some cheapie they got at Home Depot. The cabling is similarly unbranded, but it does read:


RG-59/U Coaxial Cabling


All of them have the screw-on connectors. Though, I thought all coaxial cabling used screw on connectors?
 

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Quote:
Originally Posted by Crimson Moon /forum/post/15521215


There's no name brand on the splitter, but it does read:


2-Way Splitter

5-900 MHz


Its small and fairly mundane looking. It probably is some cheapie they got at Home Depot. The cabling is similarly unbranded, but it does read:


RG-59/U Coaxial Cabling


All of them have the screw-on connectors. Though, I thought all coaxial cabling used screw on connectors?

The connectors I refer to screw onto the cable itself. My bet is that the cables are copper-braid cables. CATV, especially services that utilize the return path (cable modems and telephone, and settop boxes (for OnDemand)) need 100 percent shielding (or as close as possible) all the way from the headend to and throughout the home. Most copper-braid cables have ~65-~85% shielding. That's 15-35% holes, where interference leaks in and disrupts the signals.


Splitters need to be soldered together, not just glued. Gluing creates a loss of shielding, where interference leaks in and disrupts the signals.


I would bet that if you replaced that splitter and the cables with ones suitable for cable TV, all would be well. The splitter should be 5-1000MHz and NEEDS to be solder-backed, and the cables NEED to be dual shield (or better) and preferably have compression connectors.
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by egnlsn /forum/post/15522381


The connectors I refer to screw onto the cable itself. My bet is that the cables are copper-braid cables. CATV, especially services that utilize the return path (cable modems and telephone, and settop boxes (for OnDemand)) need 100 percent shielding (or as close as possible) all the way from the headend to and throughout the home. Most copper-braid cables have ~65-~85% shielding. That's 15-35% holes, where interference leaks in and disrupts the signals.


Splitters need to be soldered together, not just glued. Gluing creates a loss of shielding, where interference leaks in and disrupts the signals.


I would bet that if you replaced that splitter and the cables with ones suitable for cable TV, all would be well. The splitter should be 5-1000MHz and NEEDS to be solder-backed, and the cables NEED to be dual shield (or better) and preferably have compression connectors.

Well, that certainly answers my question. Thanks very much for the assistance!
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by egnlsn /forum/post/15522381


I would bet that if you replaced that splitter and the cables with ones suitable for cable TV, all would be well. The splitter should be 5-1000MHz and NEEDS to be solder-backed, and the cables NEED to be dual shield (or better) and preferably have compression connectors.
http://www.monoprice.com/products/pr...seq=1&format=2


I'm guessing this type of cable would work? Its quad shielded, but it doesn't mention if it uses compression connectors or not.

http://www.monoprice.com/products/pr...=2#description


Likewise, would this splitter be okay? Its 5-2400 MHz but it doesn't mention if its solder backed or not.
 

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Quote:
Originally Posted by Crimson Moon /forum/post/15522724

http://www.monoprice.com/products/pr...seq=1&format=2


I'm guessing this type of cable would work? Its quad shielded, but it doesn't mention if it uses compression connectors or not.

http://www.monoprice.com/products/pr...=2#description


Likewise, would this splitter be okay? Its 5-2400 MHz but it doesn't mention if its solder backed or not.

Stay away from gold. Too many potential problems caused by the gold plating.


Here is a good source for Splitters used by many cable companies and Jumper Cables made with the same cable and connectors used by cable companies.
 

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Quote:
Originally Posted by flavaflay /forum/post/15644748


What makes gold something to avoid? Does that rule also apply to an f-type adapter I am planning on getting, the Leviton gold-plated f-type adapter ( http://www.leviton.com/OA_HTML/ibeCC...2:US&item=5407 )?

It has to do with the dissimilar metals. Common Path Distortion (also known as Common Mode Disorder) is the culprit.


I guess it is more of a problem outside where moisture can cause corrosion at the connections, but humidity indoors could eventually result in the same scenario. I just think that it is best to stay away from gold. If that's all there is, though, that's all there is...
 

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I switched all my cables and splitter. I put in a 2300MHZ splitter, and used Veritas RG6 quad shield cable good to 3000MHZ.

I also used Compression F fittings.

The cable was cut to length and compressiin fittings installed at the local Radio Shack store,not saying thay all have this cable.

you cannot believe the significant change, the huge increase in channels and the clarity.

cableing/connectors are the signal carriers.RG6 is a low loss cable and a must for digital & HD reception.dont let anyone tell you any diffrence.

hope this helps.
 

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Quote:
Originally Posted by BOBBY DIGITAL /forum/post/15660507


did you try a drop amp that had dual or triple output and is the power led on the one you have lit up?

Huh? Why would he do that? New wire and splitter fixed his problem.
 
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