What do these numbers on a cable splitter really mean?

Hello all,
I have been having problems with my cable modem. I split the line where it comes in the house. One leg to my modem, the other to the TV.
My internet kept dropping signal. I was sure to get a splitter that provided a direct pass-thru to 7dB on both outputs.
There is a three way splitter on the line coming in from you pole. It has output 7dB, 7dB, and 3.5dB.
Anyway, the cable guy came out and switched the hookup on the three-way splitter. He took the line that goes to my cable modem and TV off of a 7dB terminal and out it on the 3.5dB terminal. All is well now.
how is this possible?
Thank fred.
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Hello all,
I have been having problems with my cable modem. I split the line where it comes in the house. One leg to my modem, the other to the TV.
My internet kept dropping signal. I was sure to get a splitter that provided a direct pass-thru to 7dB on both outputs.
There is a three way splitter on the line coming in from you pole. It has output 7dB, 7dB, and 3.5dB.
Anyway, the cable guy came out and switched the hookup on the three-way splitter. He took the line that goes to my cable modem and TV off of a 7dB terminal and out it on the 3.5dB terminal. All is well now.
how is this possible?
Thank fred.
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The 'db's are attenuation. The signal from the 3.5 db output is TWICE as big as from a 7 db output. He merely doubled the signal to your cable modem, which is reasonable. If you still have good pictures on your tvs, all is cool and good.
Lee h

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The numbers on the splitter tell how much signal loss there is in the splitter. To split a signal 2 ways requires atleast a 3 db loss. From that you can split it more and each time you will get more loss. Internally your splitter seems to split the signal to two parts and one goes to the 3db port. The other goes to another internal splittter and that split gives you the 7 db loss for each output. It is a log scale so that means a 3 db will loose half the power, 6 db will loose 75% of the power, 7 db will loose about 80 % of the power, 10 db will loose 90% . The db loss numbers add so that 3 +3 = 6. There will usually be some fractions left over in the losses so that is why you get 3.5 and 7 for the losses. Cable modems usually need more signal to work than the tv sets. My cable comes to a 2 way splitter. One goes directly to the cable modem and the other goes to another splitter that goes to the other tv sets in the house. The modem works fine and the TV sets (one with digital box, two with the basics) have good vidio on them.
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replying to Ralph Mowery, shawn wrote: hi so what is the differens from -17db to +15db? witch one is the bast? as i can understand-17db is be better than + 15db. thx
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caedfaa9ed1216d60ef78a6f660f5f85 snipped-for-privacy@example.com says...

I don't fully understand what you are asking.
A splitter can not have a + db number. If there is an amplifier , then you can get + db.
Think of the signal starting out as 0 db. Any positive number will be gain, the larger the number,the more gain. Any negative number will be loss. The larger the number after the - sign will be greater loss. That is a -3 db would be less loss than -6 db.
Each 3 db is twice the signal or twice the loss. Every 10 db is 10 times. It is a log scale. Where 3 db is 2 times, 6 db is 4 time and 10 db is 10 times. 13 db would be 20 times the gain or loss.16 db would be 40 times the gain or loss.
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Twice signal power is different from twice signal. You would need twice the voltage to double signal, or 4 times the power or 6dB. I like voltage.
Greg
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replying to Ralph Mowery, Sean Peak wrote: I keep losing Internet service, I have 4 rooms for cable TV which is provided by my Internet service provider. Main line comes in to a 4 way splitter , main line to the Input, rest to tv''s and my Internet an I have good tv quality but costantly losing my Internet service. Why?
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On 4/16/2017 9:44 PM, Sean Peak wrote:

Hard to say. It may not even be your house. When I had problems with drop outs they found a connection problem two streets away. Could be your router, could be a connection. Have you called your provider? They have instruments to check signal.
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[snip]

I had such cable problems (frequent loss of internet connection, a lot of bup-bup-bup (erratic short audio/video dropouts) on TV, etc.). I had to have one of their (cable company's) technicians out. He was good and found a 30-foot section of cable causing an erratic 14dB loss. After replacing that, everything was OK.
--
Mark Lloyd
http://notstupid.us/
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caedfaa9ed1216d60ef78a6f660f5f85 snipped-for-privacy@example.com says...

It could be many things. At my house when I had cable TV and internet The man installed a 2 to 1 splitter where one side went to the cable modem. The other side went to another splitter that went to 3 TV sets.
At another house I lived in with no internet, but the same thing can apply. I lost or had very weak signals on several TV chanels, All other chanels were fine. Turned out to be a bad connector on the power pole where the cable came into the house. All the cable man did was cut off the connector and put another one on.
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You have to be sure it is a 1ghz splitter and not a 900 mhz for the internet portion of it. Digital TV does better through the gigahertz splitter also. They're kind of hard to find except through the cable co. But not impossible. Try radio shack.
--
Steve Barker


"Fred Wilson" < snipped-for-privacy@comcast.net> wrote in message
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Steve Barker LT wrote:

Hmm, 900MHz vs. 1000NHz(1 GHz, so that ~10% difference makes visible difference. You must be a fan of those super expensive Monster cables.
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Actually not. Won't even look at them. But my RR modem will not work through a 900 Mhz splitter and works flawlessly with the 1Ghz splitter that is on it now. And yes, it makes a visible difference. Otherwise there wouldn't be such an animal.
Screw monster cables. They're for yuppies kids.
--
Steve Barker



"Tony Hwang" < snipped-for-privacy@shaw.ca> wrote in message
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Lowes has a good selection too. That's where I got my last digital spliter when I was upgrading my dad's cable system.

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On Sun, 09 Jul 2006 22:56:58 GMT, "Steve Barker LT"

Higher frequency splitters are easier to find now that they are used for satellite.
--
Mark Lloyd
http://notstupid.laughingsquid.com
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On Sun, 09 Jul 2006 22:56:58 GMT, "Steve Barker LT"

My cable modem is a Motorola SB5120, which can provide information about the connection. According to its status page, the downstream (receive) channel is on 117MHz (channel 99) and the upstream channel is on 35MHz (T-12?, below channel 2).
--
Mark Lloyd
http://notstupid.laughingsquid.com
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Fred Wilson wrote:

For one thing, the signal coming from the 3.5dB port is 3.5dB stronger than that from the 7dB port, the numbers in question being the level of attenuation relative to the input port. That increase in signal level might have been just what was needed to improve the situation. Of course it might have been just a bad connection and any disconnect-reconnect might have fixed it just as well.
--
John McGaw
[Knoxville, TN, USA]
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Fred Wilson wrote:

Hi, That splitter must have some attenuator(simple resistor netowork or such) built-in. Any splitter, connector introduces certain amount of signal loss. When source signal is marginal this can become an issue.
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Follow-up if I may...
So is it possible to drive the signal too much?
Where might I find the best splitter to up in there? I have the modem off one leg and a digital tv off the other. Can I get a splitter that directly passes through the signal on both output legs with no signal loss?
Thanks.
Fred
Fred Wilson wrote:

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