[H] Cable Modems & Splitters
For four people, we have a ton of TVs and modems. If you want to know why, you don't need to wonder, I'm married and my wife is handicapped (walks with a crutch). In this house are 3 modems (2 for internet and one for phone), 3 digital cable boxes and 4 analog TVs. Of course this is all done with splitters. Recently we just replaced all the internal cabling with RG6, which if I read it correctly, helps a little but not much. Oh, yeah, the problem--We get internet access dropouts. When hot and humid, we get a lot of dropouts, otherwise we can go for weeks without a dropout. We were told that our 'transmit' was in the red, so I had one of their service technicians here to look at the line and after some stuff that he seemed to know and some that sounded like incomplete regurgitation, he announced that we had too many splitters. Anyways, He did reterminate the outside cables and checked that the input level was correct. Although I'm an EE, RF is not my field, so I did a little reading up. It seems that when it comes to transmit signal levels, there is a hand-shaking between the modem and the receiver where the modem is told how high to crank its output so that the receiver gets the proper level. At a certain point, the modem tops out, usually due to too many splitters. At this point, there is apparently little headroom for signal level increase due to temperature and too high a signal level causes dropouts. Why the hand-shaking does not compensate for that, I have no idea. So, anyways, apparently with too many splitters, you end up with too much return loss, causing the modem to boost signal to the max. Add elevated temperature to that and you get dropouts. The technician mentioned zero or low return loss amplifiers, but confessed that Cox does not have them. I've seen them for one in and two out, but I'd probably really need a one in and three out. Of course, the first step would be to use the phone modem for one of the internet modems as it does have an internet tap, however, I don't know if the dual purpose would cause some problem if the phone and internet were used at the same time. Okay, does any of this make sense? What have I got wrong? Also, would a low return loss amp be the best bet? Any suggestions greatly appreciated! ThanksSteve __ Information from ESET Smart Security, version of virus signature database 4319 (20090809) __ The message was checked by ESET Smart Security. http://www.eset.com
Re: [H] Cable Modems & Splitters
I don't understand why you would need more than one modem. The normal practice is to have one modem, which feeds a router, which is connected to the individual PCs either via Ethernet cable or a Wi-Fi wireless connection. Gary VanderMolen, MS-MVP (Mail) -- From: "Steve Tomporowski" For four people, we have a ton of TVs and modems.
Re: [H] Cable Modems & Splitters
If all of your runs come back to one place, I'd chuck all of the splitters and get a single amp. Not just any amp--the stuff you can usually find locally typically inserts so much noise that you're better off w/o an amp at all. http://www.cabletvamps.com/drop%20amps.htm Electroline amps are considered to be among the best available. They do have one model with 0 return loss. Greg > -Original Message- > From: hardware-boun...@hardwaregroup.com [mailto:hardware- > boun...@hardwaregroup.com] On Behalf Of Steve Tomporowski > Sent: Sunday, August 09, 2009 9:29 AM > To: hardware@hardwaregroup.com > Subject: [H] Cable Modems & Splitters > *snip* > > Okay, does any of this make sense? What have I got wrong? Also, would > a low return loss amp be the best bet? > > Any suggestions greatly appreciated! > > ThanksSteve >
Re: [H] Cable Modems & Splitters
LOL, Gary, remember I already address this, I'm married;-) Gary VanderMolen wrote: I don't understand why you would need more than one modem. The normal practice is to have one modem, which feeds a router, which is connected to the individual PCs either via Ethernet cable or a Wi-Fi wireless connection. Gary VanderMolen, MS-MVP (Mail) -- From: "Steve Tomporowski" For four people, we have a ton of TVs and modems. __ Information from ESET Smart Security, version of virus signature database 4319 (20090809) __ The message was checked by ESET Smart Security. http://www.eset.com __ Information from ESET Smart Security, version of virus signature database 4319 (20090809) __ The message was checked by ESET Smart Security. http://www.eset.com
Re: [H] Cable Modems & Splitters
Greg, Thanks, this is excellent. Steve Greg Sevart wrote: If all of your runs come back to one place, I'd chuck all of the splitters and get a single amp. Not just any amp--the stuff you can usually find locally typically inserts so much noise that you're better off w/o an amp at all. http://www.cabletvamps.com/drop%20amps.htm Electroline amps are considered to be among the best available. They do have one model with 0 return loss. Greg -Original Message- From: hardware-boun...@hardwaregroup.com [mailto:hardware- boun...@hardwaregroup.com] On Behalf Of Steve Tomporowski Sent: Sunday, August 09, 2009 9:29 AM To: hardware@hardwaregroup.com Subject: [H] Cable Modems & Splitters *snip* Okay, does any of this make sense? What have I got wrong? Also, would a low return loss amp be the best bet? Any suggestions greatly appreciated! ThanksSteve __ Information from ESET Smart Security, version of virus signature database 4319 (20090809) __ The message was checked by ESET Smart Security. http://www.eset.com __ Information from ESET Smart Security, version of virus signature database 4319 (20090809) __ The message was checked by ESET Smart Security. http://www.eset.com
Re: [H] Cable Modems & Splitters
Cable modem should be on 1st *tap*, no later. Taps should be used instead of splitters, working from highest to lowest attenuation as you run down a cable segment. If splitting, do it sooner rather than later. Distribution amps have 0 insertion loss, unlike splitters. Taps are unbalanced splitters that attenuate one leg but not the other. Advantage? Nearer devices get just what they need leaving more db left over going to devices further down the segment. Greg Sevart wrote: If all of your runs come back to one place, I'd chuck all of the splitters and get a single amp. Not just any amp--the stuff you can usually find locally typically inserts so much noise that you're better off w/o an amp at all. http://www.cabletvamps.com/drop%20amps.htm Electroline amps are considered to be among the best available. They do have one model with 0 return loss. Greg -Original Message- From: hardware-boun...@hardwaregroup.com [mailto:hardware- boun...@hardwaregroup.com] On Behalf Of Steve Tomporowski Sent: Sunday, August 09, 2009 9:29 AM To: hardware@hardwaregroup.com Subject: [H] Cable Modems & Splitters *snip* Okay, does any of this make sense? What have I got wrong? Also, would a low return loss amp be the best bet? Any suggestions greatly appreciated! ThanksSteve
Re: [H] Cable Modems & Splitters
Just got back from Colorado Springs. It just seems wrong that it takes a whole day each way to travel there! Are you talking about the taps off a dist amp? Or is this a device I haven't heard of? Because it sounds good. The problem I'm having most is that there is too much return loss. Well, I've rewired a bit to help the problem, but from what I understand, the modem has internal gain that is remotely selected to overcome return loss, but it has only so much and when it hits the top end, then there can be dropout problems. I've read where they say that gain tends to go up with temperature, but they never say the temperature of what. The modem is in an air-conditioned enviroment and all the cabling in the neighborhood is underground which I believe will limit the effects of temperature. Steve maccrawj wrote: Cable modem should be on 1st *tap*, no later. Taps should be used instead of splitters, working from highest to lowest attenuation as you run down a cable segment. If splitting, do it sooner rather than later. Distribution amps have 0 insertion loss, unlike splitters. Taps are unbalanced splitters that attenuate one leg but not the other. Advantage? Nearer devices get just what they need leaving more db left over going to devices further down the segment. Greg Sevart wrote: If all of your runs come back to one place, I'd chuck all of the splitters and get a single amp. Not just any amp--the stuff you can usually find locally typically inserts so much noise that you're better off w/o an amp at all. http://www.cabletvamps.com/drop%20amps.htm Electroline amps are considered to be among the best available. They do have one model with 0 return loss. Greg -Original Message- From: hardware-boun...@hardwaregroup.com [mailto:hardware- boun...@hardwaregroup.com] On Behalf Of Steve Tomporowski Sent: Sunday, August 09, 2009 9:29 AM To: hardware@hardwaregroup.com Subject: [H] Cable Modems & Splitters *snip* Okay, does any of this make sense? What have I got wrong? Also, would a low return loss amp be the best bet? Any suggestions greatly appreciated! ThanksSteve __ Information from ESET Smart Security, version of virus signature database 4337 (20090815) __ The message was checked by ESET Smart Security. http://www.eset.com __ Information from ESET Smart Security, version of virus signature database 4337 (20090815) __ The message was checked by ESET Smart Security. http://www.eset.com
Re: [H] Cable Modems & Splitters
You can use taps with DA same as splitter, key point is taps split passing 0db insertion loss to the next split down the segment (which has it's own loss) where splitters evenly apply loss to each of N legs. Return loss I have not looked into as we have our modem on 1st tap and no digital cable. Since the point of the exercise is achieve near 0db at each TV without having to distort the signal by over-amplifying taps have advantages if all you're connection points are along a single segment & spaced apart. Taps are how modems are installed generally since they're 1st in line & thus can be highly attenuated. Bottom line is there's a reason why cable co's 1. locate modem on it's own feed, or 2. locate modem on a tap right after the demarc. The further into your system you move the modem, the more trouble you will have. If you buy a DA (and buy you will as old 900mhz stuff won't work) make sure it's designed to allow return signals for digital devices like modems & catv boxes. Steve Tomporowski wrote: Just got back from Colorado Springs. It just seems wrong that it takes a whole day each way to travel there! Are you talking about the taps off a dist amp? Or is this a device I haven't heard of? Because it sounds good. The problem I'm having most is that there is too much return loss. Well, I've rewired a bit to help the problem, but from what I understand, the modem has internal gain that is remotely selected to overcome return loss, but it has only so much and when it hits the top end, then there can be dropout problems. I've read where they say that gain tends to go up with temperature, but they never say the temperature of what. The modem is in an air-conditioned enviroment and all the cabling in the neighborhood is underground which I believe will limit the effects of temperature. Steve maccrawj wrote: Cable modem should be on 1st *tap*, no later. Taps should be used instead of splitters, working from highest to lowest attenuation as you run down a cable segment. If splitting, do it sooner rather than later. Distribution amps have 0 insertion loss, unlike splitters. Taps are unbalanced splitters that attenuate one leg but not the other. Advantage? Nearer devices get just what they need leaving more db left over going to devices further down the segment. Greg Sevart wrote: If all of your runs come back to one place, I'd chuck all of the splitters and get a single amp. Not just any amp--the stuff you can usually find locally typically inserts so much noise that you're better off w/o an amp at all. http://www.cabletvamps.com/drop%20amps.htm Electroline amps are considered to be among the best available. They do have one model with 0 return loss. Greg -Original Message- From: hardware-boun...@hardwaregroup.com [mailto:hardware- boun...@hardwaregroup.com] On Behalf Of Steve Tomporowski Sent: Sunday, August 09, 2009 9:29 AM To: hardware@hardwaregroup.com Subject: [H] Cable Modems & Splitters *snip* Okay, does any of this make sense? What have I got wrong? Also, would a low return loss amp be the best bet? Any suggestions greatly appreciated! ThanksSteve __ Information from ESET Smart Security, version of virus signature database 4337 (20090815) __ The message was checked by ESET Smart Security. http://www.eset.com __ Information from ESET Smart Security, version of virus signature database 4337 (20090815) __ The message was checked by ESET Smart Security. http://www.eset.com
