Digital Modulation

jpkishere

Member
I have Time Warner Digital cable and broadband and I just bought a CE1001F (Cable Electronics) and it works fine if I unplug my incoming cable. Tested using channel 101..

If I plug in my digital cable feed, it works (although w/ alot of static) on channels 122 and 123 only.. I tried the other channels (65-125)

Anybody know of a way to fix this so it works better? Don't want to give up my digital cable for this..

(This is not using a digital set top box, just plain old cable plugged into TV directly)

Here is the URL of the modulator:
http://www.cable-electronics.com/Product12.aspx
 
Hi, jpkishere. It looks like that particular modulator creates an analog channel, and I don't think it can co-exist with digital cable channels.
(This is not using a digital set top box, just plain old cable plugged into TV directly)
I'm not sure how to interpret this (I don't have digital cable). Do the digital channels go directly into the TV? (meaning the TV has a digital tuner?) Or are the channels analog by the time they get into the house? (which means that your modulator should work).
 
rocco said:
Hi, jpkishere. It looks like that particular modulator creates an analog channel, and I don't think it can co-exist with digital cable channels
Are there modulators that create digital channels? Do you have to watch them through a digital cable box even though you generate them internally? How do you mix your own digital channels in with the ones coming from Time Warner? Is there a digital splitter/combiner?
 
I have an analog modulator and digital cable. They can co-exisit. I have never seen a modulator that creates digital channels. This is not to say there aren't any out there, but I would think most people would not want one. If it created digital channels you would need a cable box (in most cases) to see the modulated channels. Why, most TVs have a NTSC tuner and not a QAM tuner. QAM is the modulation used by most digital cable systems.

With a modulator you're going to need to find a block of channels that doesn't already have channels on it. This is often not easy. Not only does the channel you want to broadcast on need to be empty, often so do surrounding channels. The modulator I have is a 2 channel modulator. It requires the channel immediately preceding and following it also be empty. For instance I am modulating 2 video sources. One on channel 73 and another on channel 75. So I need to have channels 72 though 76 empty. Comcast has not cooperated though, they have all sorts of channels in this range. So I used a notch filer to clear out the 70-79 range. Here's an example.
http://www.channelplus.com/product_detail.php?productId=76

Are you required to use cable boxes (or use a CableCard) on all your TVs? If not you are not in an all digital market. Meaning some of your channels many be broadcast using analog signals. That is why the satellite companies state they are 100% digital and the cable companies are not. If the cable company is using a hybrid digital analog system, most likely the channels below 100 are analog. If this is the case I'd think you'd be best served modulating onto a channel under 100. Doing this the modulated channels would be available through the cable box, and to televisions without cable boxes.

I can expand on this but I have to run out right now. If you want to post more about your setup I'll try and incorporate that into my follow up. For example how many TVs, do they all have cable boxes, what type of cable boxes are they.

Fletch
 
rocco said:
I'm not sure how to interpret this (I don't have digital cable). Do the digital channels go directly into the TV? (meaning the TV has a digital tuner?) Or are the channels analog by the time they get into the house? (which means that your modulator should work).
Well, I am not sure how it works either.. Upstairs on my main tv I have a set top box which allows me to get stations higher than 77..

so I am guessing on my normal tv, it is just getting regular analog signals.. (only gets stations up to (and including) 77)

if i disconnect the outside feed from cable it works fine w/ no fuzzy ness..
 
Fletch said:
I can expand on this but I have to run out right now. If you want to post more about your setup I'll try and incorporate that into my follow up. For example how many TVs, do they all have cable boxes, what type of cable boxes are they.
Thanks for the info.. Here is my setup..

I do not have to use a cable box or cable card, only if I want the "higher" channels, so yes I would assume I get analog and digital stations..

My modulator offers me the following options.. UHF 14-69, Cable 65-94 and 100-125

I guess for UHF I would need an antenna? but have tried from 65-125 and only 122/123 come in somewhat.. although very fuzzy..

i have 3 TVs currently, but my main cable feed comes into an amplifier and supplies cable to 5 total outlets.. My cable box is a DVR which is made by Scientific Atlanta and is an Explorer 8300HD it is only hooked up to my main TV. the other tv's i just plug directly into cable (no set top box)

And of course, I have stations on 70-77.. 78 and 79 are empty..

thanks!!
 
Your regular TVs are just getting analog cable. You can use the analog modulator to inject a signal to those TVs. You will probably not be able to get it to work with the TV connected to the cable box (i.e., through the cable box).

You will probably need to split your cable into analog and digital "sections."

1) Cable (A) comes into house from outside.

2) Use splitter (1) splits cable (A) into 2 sections: cables ( B ) and ( C ). You will use cable ( B ) for all digital connections and cable ( C ) for all analog connections.

3) Cable ( B ) runs to your digital cable box (the DVR) and/or cable modems (etc.).

4) Cable ( C ) will be used for analog cable. You should run cable ( C ) to into filter (2) to prevent your modulated channel from entering the common cable grid (going out to your neighbors) and/or interfering with your digital signal going to the DVR.

5) From filter (2), you will run cable (D) to some combination of combiners, splitters, and amplifiers. It is here that you will inject your modulated signal (on a cable channel (100-125)).

6) You can run cable (D) into one half of a two-signal combiner (3) (looks like the reverse of splitter (1) - some are interchangeable, some aren't).

7) Cable (E) runs from your modulator into combiner (3).

8) The output from combiner (3) is cable (F). You can feed this cable into your amplifier/splitter (4). Note that some splitters and amplifiers also have the combiner functionality built in. Sometimes, with a splitter you can also get away with using one of the outputs for an input (but you can't do this with the amplifier unless it's bidirectional).

With this configuration, you will not be able to view the modulated signal on the set connected to the digital box unless you run an additional cable from the amplifier to the TV.

You can try feeding the modulated signal into the pre-digital connection, but you will probably have problems.

And, you really don't have much choice about using filter (2). You are not supposed to feed stuff back out to other people (and you probably don't want to anyway).
 
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