can comcast put an amp near the pole instead of at the house? - Page 2 - AVS Forum
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post #31 of 43 Old 02-24-2013, 04:54 PM
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Quote:
forward levels would wind being flat out of the tap in a normal system
Every system I ever set up or swept had a tilt (around 5dB on a 450 MHz system on up to 10dB, 12dB or more on an 860MHz sytem) on the feeder. This was needed back in the 'all analog' day to ensure that adjacent channels ended up within a dB or 2 of each other. As I recall there was also an FCC spec that said peak to valley at the groundblock needed to be less than 5 or 6dB. In fact I've worked with designs that required equalizers near the end of line to attenuate the low channels to keep a positive slope at the taps, so I'd say flat out of the tap is not 'normal'.
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post #32 of 43 Old 02-24-2013, 05:28 PM
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I'm running 25dB over at my house.

I think all typical scenarios are out the window when the drop in question is a couple hundred feet.

CIAO!

Ed N.
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post #33 of 43 Old 02-25-2013, 01:44 AM - Thread Starter
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Just wanted to get a few other people's opinion...
If they can't get the drop signal any stronger, is -3db (at around 550mhz) too weak to amp without getting too much noise?
Or would an amp be worse?
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post #34 of 43 Old 02-25-2013, 03:18 AM
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Quote:
Originally Posted by egnlsn View Post

I'm running 25dB over at my house. Current SCTE spec's for Docsis 3.0 have 18-20 tap over tap value in order to have upstream channel bonding work correctly.

I think all typical scenarios are out the window when the drop in question is a couple hundred feet.
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Originally Posted by olyteddy View Post

Every system I ever set up or swept had a tilt (around 5dB on a 450 MHz system on up to 10dB, 12dB or more on an 860MHz sytem) on the feeder. This was needed back in the 'all analog' day to ensure that adjacent channels ended up within a dB or 2 of each other. As I recall there was also an FCC spec that said peak to valley at the groundblock needed to be less than 5 or 6dB. In fact I've worked with designs that required equalizers near the end of line to attenuate the low channels to keep a positive slope at the taps, so I'd say flat out of the tap is not 'normal'.

You are correct, but consider that if you start off with 23-value tap off your amp by the time you get to a 14 value it will be flat or it might even have an inline Eq in the system depending how old it is, tap spacing,etc.

All Comments made are my own and not of my employer.
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post #35 of 43 Old 02-25-2013, 07:36 AM
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Good to know about that DOCSIS spec. And, I believe, the OP is in a DOCSIS 3.0 system.

Thanks! wink.gif

CIAO!

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post #36 of 43 Old 02-25-2013, 08:23 AM
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To the OP
Are all of your splitters rated to 1ghz?
You mentioned a 3 way split is it balanced?
If not is the modem connected to the 3.5db leg?
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post #37 of 43 Old 02-25-2013, 04:43 PM - Thread Starter
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It's balanced
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post #38 of 43 Old 02-26-2013, 04:34 AM
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Is it rated to 1GHZ?
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post #39 of 43 Old 02-26-2013, 04:51 AM - Thread Starter
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5-900mhz, but I tried a 1ghz 2 way splitter and my signal was still -14 at my modem and near that on a random cable box channel...
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post #40 of 43 Old 02-26-2013, 04:55 AM
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From your original post I assume that you are having issues with all of your devices?
Or just some of them if so give more detail.
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post #41 of 43 Old 02-26-2013, 05:30 AM - Thread Starter
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All, my cable boxes range from -13 to -20, my modem usually around -18.

I made a diagram for myself and calculated for loss over distance and everything.

So I've concluded: replacing inside wiring should help 25% and enough for issues to cease. The other 75% is just a weak signal at the house (-2db). So if that's just from a really long drop, and I replace inside wiring, I guess I'll have to put on an amp, I just don't know if amping would be okay with a -2db signal coming into the amp...
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post #42 of 43 Old 02-26-2013, 08:14 AM
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Keep in mind that when he posts signal levels, it is the level of the QAM carrier as he reads it off either his cable modem or his STB.

CIAO!

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post #43 of 43 Old 02-26-2013, 11:12 AM
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With a -2dbmv at your entry point you can try an amp but make sure you get something that doesn't have much loss on the return path and a decent noise figure.
No promises!!
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