# Moca-Safe Amplified Splitter



## fyodor (Sep 19, 2006)

Hi

I was wondering if anyone knew of an amplified bidirectional splitter that worked with MoCA devices (i.e. will send data back through the splitter) I understand that generally you want something with 1ghz or higher filtering, but I'd appreciate suggestions for splitters that people have actually gotten to work.

Thanks
F


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## orangeboy (Apr 19, 2004)

I have mine set up so the splitter is after MoCA:


```
Wall
     |
MoCA adapter
     |
 Splitter ([URL="http://www.pctinternational.com/_products/northamer/amplifiers/dropamps.html"]http://www.pctinternational.com/_products/northamer/amplifiers/dropamps.html[/URL])
  /  |  \
S3  STB  TV
```
I dunno if this has a detrimental effect on anything.


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## fyodor (Sep 19, 2006)

Thanks-my issue is that the signal coming out of the wall is already pretty weak, so I was hoping to have a lossless split coming out of the splitter.

The MoCA adapter is (internally) a regular splitter with normal loss. So, right now I get some signal loss when the signal is split by the Moca adapter and passed on to the TV.

I was hoping to have an amplified splitter that I could put at the outlet, but this would require that the MoCA signal be able to go BACK through the amplified splitter.



orangeboy said:


> I have mine set up so the splitter is after MoCA:
> 
> 
> ```
> ...


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## blacknoi (Jan 23, 2006)

I've bought "electroline" amps from ebay. They either have a zero-loss split, or an amplification on the split! Bi-directional compatible.


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## fyodor (Sep 19, 2006)

blacknoi said:


> I've bought "electroline" amps from ebay. They either have a zero-loss split, or an amplification on the split! Bi-directional compatible.


Have you used them with MoCA devices? I've tried other bidirectional amps that don't work.

F


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## blacknoi (Jan 23, 2006)

fyodor said:


> Have you used them with MoCA devices? I've tried other bidirectional amps that don't work.
> 
> F


cable modems, cable boxes rented from the cable co used to play VOD + the tivo tuning adapter.

Would those qualify? They both send back data through the line.


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## TexasGrillChef (Sep 15, 2006)

Most Amps dont' work with MoCA. At least 99% of the inexpensive ones don't. (I have yet to see one that is)

I did see one at frys that actually said on the box that it is MoCA capable (Bidirectional) yet it was also $149. My apologies as I don't remember the brand or model number of the device.

One thing I did notice. Is that TWC in my area *SPLITS* the cable coming into my house. One split goes *DIRECTLY* to my cable modem. The other has a filter trap *AND* amp on it that goes to other splitters that then go to my TV's, TiVo's & Computers (TV tuner cards). Once I tried (just for laughs) connecting my cable modem to one of the other cables in the house. The Cable modem was never able to make "Connection" on those cable runs.

I do understand what your trying to do. I just don't think it's possible for an affordable price.

Here is what I would do though in your case.

1. Go back to where your cable comes into the house. Split it. One going to your cable modem. The other to your TV's TiVo's etc... On *THAT* cable run. Add a good amp.
Then go check all your TV's, TiVo's etc... You may not need any more amplification and where you would put that amp would have no effect on your MoCA.

2. Check all your cable connectors. Thats the one place that has the greatest signal loss.

TGC

P.S. TWC in our area doesn't have SDV so doesnt' use Tuning Adapters. So I don't know what effect that would have on how they ran the cabling in my house.


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## blacknoi (Jan 23, 2006)

Here's what I have and it plays nicely with all my twoway devices:

http://www.dropamp.com/shop/product_info.php?cPath=3&products_id=29



> 4-Port Amplifier
> [EDA 2400]	$89.99
> 
> Click to enlarge
> ...


Got it for about 40 bux on ebay.


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## fyodor (Sep 19, 2006)

Thanks, Blacknoi-it looks like this has a 1ghz cutoff, which is too low for MoCA back-communication. 

I've ordered one of the Monster low loss passive splitters. Hopefully between that and checking the connections, I can eek out some better performance.


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## mattack (Apr 9, 2001)

Have you tried calling your cable company? Others have said that they've gotten free splitters from their cable company.. Not always, but sometimes.

(I'm going to go through this tomorrow.. I'm having the cable guy come because even when I remove my splitter & amplifier, I don't get all of the channels on my now-cablecard-equipped TivoHD.. So I'm going to unplug everything BUT the TivoHD initially, to show that channels are still missing.. Then eventually try to get either a splitter or some way I can have the other 3 devices I want connected at the same spot connected too, while still getting all of the channels.)


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## lrhorer (Aug 31, 2003)

TexasGrillChef said:


> Most Amps dont' work with MoCA. At least 99% of the inexpensive ones don't.


There are two reaons for this. One is that the MoCA carriers are usually between 860 MHz and 1.5GHz. An amp that passes 1.5GHz is not a trivial thing. The more important reason is that MoCA devices use at least approximately the same frequency going both directions. This means the MoCA signal *can't* pass through an amplifier section, since any ordinary RF amplifier can only pass signal in one direction. A MoCA compatible amplifier must employ a pair of bidirectional diplexers on both the input and output of the amplifier section. This is not a trivial thing to implement, as anything which can bypass a signal from the output of an amplifier to its input can potentially produce disastrous results. It can take some very careful phase alignment to get it to work.



TexasGrillChef said:


> I did see one at frys that actually said on the box that it is MoCA capable (Bidirectional) yet it was also $149.


That's not surprising. If it worked well, I'm a little surprised it was even that low.



TexasGrillChef said:


> One thing I did notice. Is that TWC in my area *SPLITS* the cable coming into my house. One split goes *DIRECTLY* to my cable modem. The other has a filter trap *AND* amp on it that goes to other splitters that then go to my TV's, TiVo's & Computers (TV tuner cards).


This is a completely different matter. DOCSIS modems employ carriers that work in two different bands, compatible with the CATV plant topology. My SBG900, for example, is currently receiving on 591.00 MHz and transmitting on 23.0008 MHz. My 3 Tuning Adapters are receivng a 75 MHz downstream carrier and transmitting somewhere around 40 MHz, as I recall. Frequency-wise, the DOCSIS modems are designed to function in the same way the STBs and DVRs do. The STBs and DVRs usually require a higher level downstream signal, though.



TexasGrillChef said:


> Once I tried (just for laughs) connecting my cable modem to one of the other cables in the house. The Cable modem was never able to make "Connection" on those cable runs.


The downstream signal may have been too hot, or your amp may not be 2-way. I really don't know, since I wasn't there.



TexasGrillChef said:


> P.S. TWC in our area doesn't have SDV so doesnt' use Tuning Adapters. So I don't know what effect that would have on how they ran the cabling in my house.


The STBs and DVRs are 2-way, though, and highly similar to a DOCSIS modem. Do you have a CATV company owned DVR or STB? IF not, and the DOCSIS modem didn't work, then there' a chance the DVRs and STBs wouldn't either, at least not for VOD, SDV channels, IPV, etc.


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## lrhorer (Aug 31, 2003)

fyodor said:


> Thanks, Blacknoi-it looks like this has a 1ghz cutoff, which is too low for MoCA back-communication.


Actually, not. MoCA devices can operate between 860 and 1000MHz. That's not the problem. See my previous message.



fyodor said:


> I've ordered one of the Monster low loss passive splitters. Hopefully between that and checking the connections, I can eek out some better performance.


I'm sorry to tell you it's a waste of money, like virtually all Monster products. A hypothetically perfect 2-way splitter has a flat loss of 3.01 dB. A typical high quality 2-way splitter will have a loss of about 3.5 dB up to about 500 MHz and about 4 - 4.5 dB up to its rated bandwidth of perhaps 1 - 1.5 GHz. Unless you have several splitters in cascade, saving 0.5 dB per splitter isn't going to make any difference.

A diplexer might help. Its through loss should be less than 3.5 dB on both legs, because it splits the signals chromatically, rather than achromatically across the entire spectrum. Assuming it is a high quality diplexer, that is. Why do you believe your signals to be low, though?


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## lrhorer (Aug 31, 2003)

blacknoi said:


> Noise figure: 3 dB


That's not a terribly good noise figure. It's probably OK for a house amp, I guess, but I would definitely make sure it is placed as close to the cable entry point as possible. I ask you the same question, though: what leads you to believe you need an amplifier?


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## lrhorer (Aug 31, 2003)

orangeboy said:


> I have mine set up so the splitter is after MoCA:
> 
> 
> ```
> ...


Well, everything is a compromise, and adding extra devices rarely produces fully positive side-effects, but that is about the most straightforward approach, and is likely to be effective in most situations, but I ask yet a third time of a third person: what makes you believe you need an amplifier?


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## orangeboy (Apr 19, 2004)

lrhorer said:


> Well, everything is a compromise, and adding extra devices rarely produces fully positive side-effects, but that is about the most straightforward approach, and is likely to be effective in most situations, but I ask yet a third time of a third person: what makes you believe you need an amplifier?


Sorry about that - I lost track of this thread!
I'm an apartment dweller and the last location I lived I had poor performance with my services. I was told that the cabling started on the first floor and daisy-chained through all the other apartments before reaching mine on the second floor. A subcontractor for BHN installed the amplifier, which seemed to help. I moved to a new (third floor) location across town and brought the amp with me. I just continue to use it out of habit?

With the amp, 2 channels came in at 94, most others came in at 95, and some peaked at 100. Just split with a Radio Shack splitter, a few channels came in as low as 77, the remainder split about evenly between either 81 or 86, with a couple peaking at 90. I think I like the mid/high 90s better than 80s (unless we're talking about outside temperatures) 

I've been meaning to say thanks for contributing! It's nice to have someone technically knowledgeable of cable systems and specifications. :up:


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## lrhorer (Aug 31, 2003)

orangeboy said:


> Sorry about that - I lost track of this thread!
> I'm an apartment dweller and the last location I lived I had poor performance with my services. I was told that the cabling started on the first floor and daisy-chained through all the other apartments before reaching mine on the second floor.


It's entirely possible. There are a lot of poorly designed plants out there, especially in multi-dwelling units and apartment complexes. Proper plant design is not terribly difficult, but it does require someone who knows what they are doing. Add to that the fact many people cut corners when it comes to the cost of implementing proper engineering, and one often encounters bad signal levels due to improper implementation or maintenance.



orangeboy said:


> A subcontractor for BHN installed the amplifier, which seemed to help. I moved to a new (third floor) location across town and brought the amp with me. I just continue to use it out of habit?


An amplifier is only required if the signal levels are outside the specified sensitivity of the tuner in question. Suppose the TiVo has a minimum sensitivity of -15 dBmV, and an overload spec of +5 dBmV. If the input signal is -5 dBmV, then it does not need an amp. A level of 0 dBmV is not "better" than a level of -10 dBmV. What's more, depending on your input signal levels, it is quite possible an amplifier may increase signal levels beyond the upper boundary for good reception. Indeed, it may increase what may be an already hot level, making a bad situation worse. In general, one would like to avoid being at the ragged edge on either end, as signal levels will vary some with time and temperature, but as long as one is 3 or 4 dB away from the lower or upper boundary, one should be fine.



orangeboy said:


> With the amp, 2 channels came in at 94, most others came in at 95, and some peaked at 100. Just split with a Radio Shack splitter, a few channels came in as low as 77, the remainder split about evenly between either 81 or 86, with a couple peaking at 90. I think I like the mid/high 90s better than 80s (unless we're talking about outside temperatures)


Actually, it is just like the outside temperatures. You want them neither too hot nor too cold. An amplifier is then analogous to a heater. If the temperature is in the 30s, then a heater is probably in order. OTOH, if the temperature is in the 70s or 80s, then it's just fine, and the last thing you really need is a heater. While 100 is bearable, it's getting very close to not being bearable, and you certainly don't want to haul out a heater in 80 degree temperatures so you can get it closer to 100.

Every amplifier adds noise and distortion to a signal, and if it is unnecessary, then all it does is unnecessarily degrade the signal, not improve it. If it is necessary, which may sometimes be the case, then one compromises some aspects of the signal quality in order to obtain generally acceptable results. It is the responsibility of the CATV company to provide the consumer with acceptable signal levels under ordinary circumstances. In practical terms, this means with fewer than 4 outlets and interior drops no more than 30m in length, the CATV company should themselves be responsible for providing proper signal levels without subscriber intervention unless the dwelling is an unusually long way from the subscriber tap.

This means the majority of subscribers should not need an amplifier. My house is an example of an exception. I have 9 outlets, and some of the drops are over 30m in length. Generally speaking, if an amp is required, it needs to be inserted at the entry point into the dwelling, before the signal levels drop to an unusable level. The noise produced by the amplifier has a fixed value. Thus, the contribution to the Signal / Noise ratio by the amplifier is directly related to how low the signal is at the point where it enters the amplifier. The lower the signal, the greater the amplifier's contribution to the overall S/N ratio.



orangeboy said:


> I've been meaning to say thanks for contributing! It's nice to have someone technically knowledgeable of cable systems and specifications. :up:


Thank you. It's extremely gratifying for my efforts to be appreciated.


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## orangeboy (Apr 19, 2004)

lrhorer said:


> Actually, it is just like the outside temperatures. You want them neither too hot nor too cold. An amplifier is then analogous to a heater. If the temperature is in the 30s, then a heater is probably in order. OTOH, if the temperature is in the 70s or 80s, then it's just fine, and the last thing you really need is a heater. While 100 is bearable, it's getting very close to not being bearable, and you certainly don't want to haul out a heater in 80 degree temperatures so you can get it closer to 100.


Very interesting! In light of this, I'm going to remove the amp and let the signal come in at the more tepid range 

Thanks again!


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## fyodor (Sep 19, 2006)

Hi All

I just thought that I'd add a post-script to this. With the new TV season coming up I decided to give this another crack.

Per Lhorer's suggestion, I replaced the splitter going into the Tivo/MoCA Bridge with a diplexer and my issues with weak signal seem to have gone away. On the problem channels I went from getting signal strength in the low 80s to to signal strength in the low 90s.


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