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breynolds

join:2012-02-15
Melbourne, FL

Question about the "tap" that's installed before cable

BHNtechXpert, I have a question about the Internet "tap" that is installed before my cable modem.

I assume that it drops off only the frequency used by the modem, but not those used for TV. I have a bi-directional amp that was installed by BHN in the box outside. The "tap" is installed before the amp. My modem reports a signal strength of -8dBmV and SNR of around 34dB. Transmit power reports as 42.5dBmV.

I've purchased a new SiliconDust HDHomeRun Prime (HDHRP) CableCARD tuner, and I may be putting it in the wiring closet along with my cable modem, router, and switch. The HDHRP has an internal three-way splitter, plus I'll need to connect the Tuning Adapter before the tuner, which will attenuate the signal a little too. So, I'm going to need to move that coax cable so that it connects AFTER the amplifier, instead of before.

Is the internet "tap" necessary? If I install the "tap" before the Tuning Adapter and CableCARD tuner (with the "internet" output going to the modem, and the "TV" output going to the TA and tuner), will it block the out-of-band frequencies that are required for the TA and CableCARD to work?

Will the bi-directional amp attenuate my cable modem's transmit power too much, and cause problems?

What would happen if I just use a regular splitter instead of the "tap"?
--
Brian Reynolds, Melbourne, Florida


BHNtechXpert
BHN Staff
Premium,VIP
join:2006-02-16
Saint Petersburg, FL
kudos:153

Re: Question about the "tap" that's installed before c

That is not a tap. That sounds like a MOCA filter but you don't have WHDVR service right? The tap is outside your home inside that little ped looking thing (unless you are above ground) in which case its on the pole.

As with all things like this I am going to refrain from comments or suggestions because we have perfectly good techs that can properly do this and make sure all is balanced and working properly. If you go and do this yourself you end up costing yourself time, us money and time and it impacts your experience until we get out there and resolve the issue.
--
~All truth goes through three phases. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident. - Arthur Schopenhauer ~


tim tim tim

join:2010-08-14
Lutz, FL
kudos:2
I second that comment ^

breynolds

join:2012-02-15
Melbourne, FL
reply to BHNtechXpert
Yes, it is in the gray plastic box on the side of the house. My cable comes from above ground, up on the pole. This thing is in the box on the side of my house.

The "tap" was installed before MOCA even existed. It says "tap" right on it. One output says something like "data" or "internet" and the other output says something like "TV" or "video". I'll have to brave the wasps and take a look tomorrow.

And no, I don't have whole-home DVR service from BHN... nor do I have any MoCa adapters in my house.
--
Brian Reynolds, Melbourne, Florida


CableMan1

join:2002-01-22

1 edit
reply to breynolds
The tap sounds like a DC coupler that techs use when installing modems. It's basically a splitter that loses usually 6,9, 12 or even 16 dB. The tap leg loses 6,9,12,16 to the modem and the through/out leg only loses 1 or 2dB to have more signal for tv's, boxes, etc...

It most likely does not filter any frequencies. I have never seen one that does.

If you move the tap leg you will affect the downstream/upstream signal of the modem depending on the amp forward/reverse loss. If it's a 4 port 8dB amp you will probably be pushing the modem up into the mid 50's because the amp ports will add to the reverse power and so will a splitter you use for the modem and tuner. Depends on the specs of the amp.

Best to have another line ran from that closet back to the amp. You'll still need to watch for the reverse power level going into the tuning adaptor. If that goes too high you may run the risk of losing SDV channels.

tim tim tim

join:2010-08-14
Lutz, FL
kudos:2
actualy the best is to have a tech go out and see it in person instead of us all guessing what he is calling a "tap" because a tap is exactly what bhntech explained it as.


CableMan1

join:2002-01-22
If it says tap on it, it is some sort of directional coupler. It has an input, output and a tap leg designed to lose a certain amount of signal.




opp

@bhn.net
reply to breynolds
Mine has 2 way splitter one tap going to modem the other goes to a 4 way splitter for TV's. I've always assumed was done this way to get max signal to and from modem.

breynolds

join:2012-02-15
Melbourne, FL
reply to CableMan1
said by CableMan1:

If it says tap on it, it is some sort of directional coupler. It has an input, output and a tap leg designed to lose a certain amount of signal.

[att=1]

That's exactly what it looks like.
--
Brian Reynolds, Melbourne, Florida


opp

@bhn.net
reply to CableMan1
said by CableMan1:

The tap sounds like a DC coupler that techs use when installing modems. It's basically a splitter that loses usually 6,9, 12 or even 16 dB. The tap leg loses 6,9,12,16 to the modem and the through/out leg only loses 1 or 2dB to have more signal for tv's, boxes, etc...

It most likely does not filter any frequencies. I have never seen one that does.

Interesting was opposite of what I thought. Why weaken signal to modem, do they overload easily?


BHNtechXpert
BHN Staff
Premium,VIP
join:2006-02-16
Saint Petersburg, FL
kudos:153
said by opp :

said by CableMan1:

The tap sounds like a DC coupler that techs use when installing modems. It's basically a splitter that loses usually 6,9, 12 or even 16 dB. The tap leg loses 6,9,12,16 to the modem and the through/out leg only loses 1 or 2dB to have more signal for tv's, boxes, etc...

It most likely does not filter any frequencies. I have never seen one that does.

Interesting was opposite of what I thought. Why weaken signal to modem, do they overload easily?

Regardless of device too much is just as bad as too little.
--
~All truth goes through three phases. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident. - Arthur Schopenhauer ~


breynolds

join:2012-02-15
Melbourne, FL
said by BHNtechXpert:

said by opp :

said by CableMan1:

The tap sounds like a DC coupler that techs use when installing modems. It's basically a splitter that loses usually 6,9, 12 or even 16 dB. The tap leg loses 6,9,12,16 to the modem and the through/out leg only loses 1 or 2dB to have more signal for tv's, boxes, etc...

It most likely does not filter any frequencies. I have never seen one that does.

Interesting was opposite of what I thought. Why weaken signal to modem, do they overload easily?

Regardless of device too much is just as bad as too little.

True, but when my signal at the modem is -8dB, it makes you wonder why they put an attenuator before the modem. It works fine as-is, but I may be moving some wiring next weekend. It would be really cool to get the TA and Tuner out of the living room.

I've been on a mission lately to reduce the number of "boxes" in the living room. Right now, I'm down to a PC, a "smart" AVR (lots of streaming options and built-in amplification for the porch/pool area), a Tuning Adapter, and a turntable. I'm going to call BHN in a few minutes (God help me) to get the CableCARD swapped to the new tuner. So, I'll then have an external tuner (vs. the internal one I have now) added to the mix. If it works well for the next week, I'll move it (and the TA) to the wiring closet next weekend.
--
Brian Reynolds, Melbourne, Florida

tim tim tim

join:2010-08-14
Lutz, FL
kudos:2
Reviews:
·Bright House
reply to opp
Its not about overloading the modem or not, they want the modem off of the first split to just have less connections to go bad. Also, you dont want to amplify a modem and its very common for that dc to feed an amp and then whatever split configuration to feed tv's.


news

@videotron.ca
reply to opp
said by opp
Interesting was opposite of what I thought. Why weaken signal to modem, do they overload easily?
[/BQUOTE :

You want good signal for all your CPE (Customer Promise Equipment), with minimum signal loss...

If you connect a cable modem to the tap side of a coupler 6 and a 4-way splitter on the through side. You will lose 6 dB on the cable modem and about 9 dB on the tv's or STB. If you connect the cable modem on the through side instead, you will lose only 2 dB on the cable modem but 13 dB on the tv's or STB, it's a lot!!!!

It doesn't matter if the downstream and upstream power to your cable modem is +- 4 dB, the important thing is to be in the specifications. You have to balance the signal so all the CPE are in the good range. You need a signal meter to do that...



BHNtechXpert
BHN Staff
Premium,VIP
join:2006-02-16
Saint Petersburg, FL
kudos:153
reply to breynolds
Barn I really wish you would just let us do this...create a direct forums thread with exactly what needs to be done and I will assist with it. You could cause way more harm than good to be honest with you. We have the correct equipment and will make sure its done right the first time.

breynolds

join:2012-02-15
Melbourne, FL
Using the modem's diagnostic page, and the tuner's diagnostic page, I can make sure I'm not over-driving them. I have quality splitters and cables on hand already. It's really no big deal. I've just always wondered what that "tap" was. CableMan answered my question. I know exactly how to proceed now.
--
Brian Reynolds, Melbourne, Florida


BHNtechXpert
BHN Staff
Premium,VIP
join:2006-02-16
Saint Petersburg, FL
kudos:153
reply to breynolds
So how did that work out for you?

breynolds

join:2012-02-15
Melbourne, FL
Everything is working fine. The modem, tuner, and Tuning Adapter all report good signals. I can't remember the exact numbers, but they were all within -5 to +5dB and SNR was better than 35.
--
Brian Reynolds, Melbourne, Florida