Is it important how I split cable for multiple tvs?

[rhendrix9]

I would like to split my cable into three lines. Is it important what I use?
I've seen mention of amplified splitters and there seems to be a question of whether or not they do anything.
Would just a regular old little non powered spltter fro RS work?
Thanks

[jameshgross]

A three way passive split could result in low signal level to all devices.
Radio Shack makes agood cable amp with four outputs. A much perferred solution.

[gadgetguy]

Can we assume this is Analog cable? It depends on the signal strength you're starting from. A good strong signal split 3 ways passively for relatively short runs will not show any loss, but amplifying that signal could make the signal to the TVs overdriven and look awful.
A good but weaker signal can be maintained using an amplified splitter.
A poor weak signal will end up being a poor strong signal when an amp is utilyzed and while it may have looked OK going to one TV, after splitting and amplifying can actually look worse.
I would try a passive device first and if the results aren't acceptable return it for an amplified splitter.

Edit: It also depends on how long the cable runs are after the split, the quality of the cables, connectors, couplers (if used), etc. Every connection point is a potential loss point. It's possilbe that amplification may be required for only one of the runs and not for the other two, or some variation thereof. It's best to get an amp that can be adjusted if you can (the cheaper ones are usually a static boost).

[painkiller]

I would add another caveat. Or two.

All your cables should be the same type at the very least as well. Meaning, for current cable and satellite hookups - RG-6 cable is used. Older stuff used RG-58, which will not work well with hdtv.

And the cable lengths should be proper lengths. Do not trim to fit. Video is particular to the type & length of cable. If you buy and install the cables already with connectors on both ends, you're fine.

[SingSing]

Try a simple spiltter first and figure out whether you need any amplifier or not.

I have a four way spiltter that feed the comcast cable signal to four outlets in three floors. The cable signal is good enough to feed all the TVs well. I do put a terminators on my unused TV outlets.

[BJ_M]

rg-58 is 50ohm cable , you mean RG-59

High quality RG59 can be just as good and sometimes better than a lot of rg6 (the rg59 i use is 3500mhz bandwidth - higher than most rg6) ... non the less, dual shield CATV type (foil plus 60-90% braid shield) RG6 is one of the best all around cables to use ...

each split of a splitter drops 3.5dB , except at higher freq. , where the loss is closer to 7.5dB ...

hence why i use and suggest to use only 2.4ghz splitters .... if you have good cable signal - a 4 way split may be ok without an amp ..

i suggest using a high quality amp - not radio shack

[painkiller]

I stand corrected.

RG-59 it is.

(I didn't catch my typo.)

[Drewlo]

each split of a splitter drops 3.5dB , except at higher freq. , where the loss is closer to 7.5dB

Actually, all the splitters I know of are flat loss.. Equal loss at high frequencys as well as low. If you run through a 2-way splitter the loss is -3.5dB per leg, a balanced 3-way is -5.5dB on each leg, an unbalanced 3-way is 1 leg at -3.5dB and the other 2 at -7dB, and a four way is -7dB on all legs.

So, if you run through a 4-way split, you are losing 7dB on the high end AND the low end on each leg. And by the way, you DO cut cable legnth to fit. All the runs off of a splitter absolutely DO NOT need to be the same length. The more cable you have means higher signal loss, so you wouldnt have 4 100 foot runs off a splitter just because ONE of the runs is 100 feet away. Always cut to fit..

No cable system in the US runs higher then 860MHz, so a 2.4GHz splitter wont do you any good at all. A 1000MHz splitter will do just fine. Satellite runs higher at 1.3GHz-1.7GHz, so you would need a higher range splitter.

And if you do choose an amp, make sure it also amps the return signal.. So if you have a modem or STB, it will still work after you install it.

All in all its better to let your cable company come and check your signal and add your outlets. They have the tools to measure the signal and tell you what you need to do. Analog is easy enough, but if you want digital cable, thats a whole other ballgame.

In the end, there are multiple ways to set up a house.. If you need advice, PM me.

Regards,

Drew

[BJ_M]

sweep tests on splitters show higher loss at higher freq. , do the tests yourself if you don't believe (i have as well as other electrical engineers as it is pretty basic stuff) ...

Jumboband digital freq. are moving to as high as 997.25 for video (1001.75 for Audio Carrier) in some locations.

Those cheap (even 1ghz) splitters are crap, there are some good ones - cables companies use (for the most part) decent ones, but if you are using HD in your house or want to have the best quality signal, just use 2.3/2.4 ghz splitters or at least decent 1ghz (not radio shack) splitters ...

[Drewlo]

What cable company uses "jumboband digital freqs" in the US? The frequencies you mention are analog frequencies anyway, not digital. 997.25MHz is the video carrier and 1001.75 is the audio carrier for ANALOG channel 158. There is no audio/video carriers in digital, the aud/vid is modulated into either: BPSK, QPSK, 8VSB, 16QAM, 64QAM, 256QAM and soon 512QAM and 1024QAM. This allows multiple PSs to be put together and transmitted on 1 frequency. I would like to see a cable company that uses jumboband to transmit "digital frequencies". You link me and I will believe it. The reason cable companies use QAM modulation (digital) is so they dont have to go above 860MHz. Digital modulation can put up to 16 channels in one 6MHz bandedge, where as your analog example can only transfer one channel per 6MHz.

Digital for most companies starts at 555MHz. So from 555-861MHz (Center Frequencies), you can have up to 16 channels every 6MHz.

861MHz-555MHz=306/6MHz=51*16 channels=816.

That is 816 virtual channels.. Of course this isnt exactly accurate because with HD you can only put 3 on a 6MHz bandedge, VOD and switched digital video also add some different numbers, but this gives you an idea why no cable company would NEED to go above that. And with everyone going digital in 2009, cable gets to have 54-555MHz for digital because they will no longer be trasmitting any analog.

I have a QAM analyzer/SLM at work, so at some point tomorrow, I will test the splitters and post back.

[edDV]

What cable company uses "jumboband digital freqs" in the US? The frequencies you mention are analog frequencies anyway, not digital. 997.25MHz is the video carrier and 1001.75 is the audio carrier for ANALOG channel 158. There is no audio/video carriers in digital, the aud/vid is modulated into either: BPSK, QPSK, 8VSB, 16QAM, 64QAM, 256QAM and soon 512QAM and 1024QAM. This allows multiple PSs to be put together and transmitted on 1 frequency. I would like to see a cable company that uses jumboband to transmit "digital frequencies". You link me and I will believe it. The reason cable companies use QAM modulation (digital) is so they dont have to go above 860MHz. Digital modulation can put up to 16 channels in one 6MHz bandedge, where as your analog example can only transfer one channel per 6MHz.

Digital for most companies starts at 555MHz. So from 555-861MHz (Center Frequencies), you can have up to 16 channels every 6MHz.

861MHz-555MHz=306/6MHz=51*16 channels=816.

That is 816 virtual channels.. Of course this isnt exactly accurate because with HD you can only put 3 on a 6MHz bandedge, VOD and switched digital video also add some different numbers, but this gives you an idea why no cable company would NEED to go above that. And with everyone going digital in 2009, cable gets to have 54-555MHz for digital because they will no longer be trasmitting any analog.

I have a QAM analyzer/SLM at work, so at some point tomorrow, I will test the splitters and post back.

You lost me here. There are no digital or analog frequencies. Digital over cable is an analog process. "16QAM, 64QAM, 256QAM and soon 512QAM and 1028VSB4QAM" are all about modulating digital data over analog RF. How does this relate to spliters that operate at analog baseband?

8VSB is a modulation scheme to modulate digital to over the air analog RF.

Magnetic digital recording is still an essentially analog process as well.

This is the kind of crap that Comcast places in your house.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120027775602

I can't find a frequency response plot yet.

PS: this is the kind of splitter they use up on the pole. It allows power distribution as well for downstream amplifiers. The spec sheet shows fairly flat response. Nothing that a typical TV or VCR coulden't handle.

http://www.arrisistore.com/product.php?pid=251401

Prices seem to be in the $6-10 range in small quantity.

[BJ_M]

In the U.S., digital cable systems with 750 MHz or greater activated channel capacity are required to comply with a set of SCTE and CEA standards. The current upper limit is actually 864mhz (52 6-MHz channels).

here is a chart showing loss at higher freq. http://www.blondertongue.com/distribution/outdoorPassives.pdf

see also "Digital and Analog Communication Systems" - Leon Couch

As i stated - using a high quality 1ghz splitter is OK , but most are not that great and for a few $ more - you can get high quality 2.*ghz splitters .. I get these types below for about 5$ each in quantity (sold by Monster Cable, ultralink and others) (not in stupid gold plating though) ...





http://www.idealindustries.com/IDEAL-EZ/prodcat.nsf/Tables/Splitters?OpenDocument

[edDV]

Digital over analog modulation intro references.

http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation
http://en.wikipedia.org/wiki/8VSB
http://en.wikipedia.org/wiki/COFDM
http://en.wikipedia.org/wiki/ATSC
http://en.wikipedia.org/wiki/DVB