We had four modulated channels within our system.

channel 90 - esceint CD system
channel 105 - camera multiplexer
channel 110 - satellite receiver
channel 120 - satellite receiver

All of these are now covered with data, making channel 83 the only one I can get a decent signal on.

I first bought a channel vision 3205/61-68 filter hoping I could open up some channels and no kill anything that was important.

didn't work.

I then called TWC to kill everything but local channels and cable Internet. They came today, installed two filters in line at the d-marc point.

didn't work.

Has anyone run into a soulution yet?

I am at my wits end. I am seriously thinking demodulating the channels outside the system, then re modulating them back into the system where I want. Then running an unaltered feed right into the modem. I know this would work, but would prove to be expensive.

Is there any good answer?

I know this is my first post, and I am including a huge thanks in advance,
D

Are you combining your modulated channels with the cable feed?
You can kill signals with channel deletion filters, (channel vision 3205/61-68 filter) is that what this product is?

Do you have a spectrum analyzer?

Yes we are combining the modulated channels with the cable feed after the D mark in, a USTEC panel

Yes that is a channel vision custom block filter.

I do not have a specturm analyser.

Thanks,
D

I looked up that filter you mentioned it is a band stop type.
It is supposed to block channels 61-68 and pass everything else.
You say that you are adding channels 90,105,110 and 120!

Do you know the frequency of the downstream of your cable modem?
Are the channels that you are injecting truly 90, 105,110 and 120 (what are the frequencies)?

If all is how you described them you need to block the same channels that you are using and combine them after your filter.

I all likelihood, the cable company's filter is designed to only block out the analog basic. They have no need to block out the digital signals since they are encrypted. Furthermore, the cable company needs some flexibility in assigning its internet download channels and would be needlessly hamstrung if it built filters that just passed narrow bands in the cable bands.

As I understand it, when your modem logs on, it is assigned to one of the download channels and stays there until it is logged off. I think that most, if not all, modems will display the download frequency as well as its strength and quality by calling up a test screen.

Your best bet is to find the highest lowpass filter you can buy off the shelf and modulate above it. 700 Mhz (ch 107 or 108) lowpass filters are common, and I think Channel Plus makes one that passes up to channel 118.

RC bridge, that is where the modded channels were. I have since moved them to where ever I try.

Currently I have both of the cable supplied filters and the channel plus 61-68 in place at the d marc, and still no difference.

AntAltMike, I will look into that other filter right now.

Anyone have any idea of what is the best analog tuner, that is cheap (in case I end up buying 15 of those to use as demodulators, and then get modulators to inject back into the panel.

TIA!

I do believe I am going to go the route of breaking the local channels out of the feed, and into whatever modulated channels I choose. Then bypassing the "break out" and taking a feed directly into the cable modem.

It will be expensive, but I know it will work. Money is not an issue, we just want this right.

I will be drawing up a diagram and getting prices together. If anyone has any opinions, or know of a great place to get tuners and/or modulators, please post them here.

Wish me luck,
D

I assume that you modulated those channels somewhere between 62 and 67!
And it still didn't work.

Is it possible to split the incoming cable to provide a seperate feed for the modem only?

Make your diagram and then I may be able to help you a little more.
I know you said that you don't have one but a spectrum analyzer would make it so much easier to troubleshoot.

RC bridge, yes I put those modded channels in between the block filter:)

Yes, I would split the incoming single to feed the modem before I break out the channels we want with separate tuners.

Thanks

I tried one more filter before giving up and it worked.

Channel Plus LPF-470 Low Pass Filter kicks ass. I still have to break out the connection for the modem before the filter, but all in all, this works 100%. No noise, things are back to normal and we are happy.

No clue why the notch filter did not work, but I will save it for future issues..

Thanks for all your ideas and help people.
D