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View Full Version : Modulated Cameras Through HD Cable boxes


Toronto122
03-08-2005, 07:17 PM
Ok, here's the problem...

We have clients with cameras and HD Cable boxes. We USED to not have a problem choosing a channel, say 122 and 124 for the modulator to send the camera signal to. Now that HD is using up so much band width, when you connect a modulator, the HD channels get messed up. Without going to a composite video switcher, is there another solution anyone's using?
sirroundsound
03-08-2005, 09:23 PM
Knock out a couple of the french channels. I don't remember exactly where they were but I think it was around ch. 50 - 60, the guys at Tin lee might know, and they are close by.
AHEM
03-08-2005, 09:42 PM
How would you "knock out" the channels? With a bandpass filter of some sort?
Fastfred
03-09-2005, 07:53 AM
Channel Vision makes inexpensive notch filters that take out channels in the mid sixties or the mid seventies, depending on which one you purchase. Model 3205-61/68 or 3205-71/78. Basically, a combination low pass and high pass filter.

You may need to split the signal in the room before it hits the cable box (a practice I recommend); send the raw signal to the tv tuner, and set it to only stop on the modulated channels. The second leg goes to the box, and the box goes via audio video connections into the germaine connections on the TV.

Customer continues to get best picture on cable available, and by switching the the tuner, they easily find camera.
sirroundsound
03-09-2005, 08:05 AM
Tin Lee, which is here in Toronto, can make a filter to remove just about any channel you wish. Channel vision and that other company (channel plus?) also make filters for more common applications. If Toronto122 hasn't yet called Positive Marketing, that woulod be another place to try. You shoudl be able to get the frequencies from the cable company, find a shopping channel or french channel that you want to remove, then get a filter to remove it.
Modulate your signal, and your on your way.
Fastfred
03-09-2005, 08:11 AM
Gee, my cable system doesn't have a French channel. Do they speciallize in french maids? I'm going to call my cable operator right now....
sirroundsound
03-09-2005, 08:30 AM
Thats what they sell on the french shopping channel...
sirroundsound
03-09-2005, 08:30 AM
The joys of being in Canada.
Toronto122
03-09-2005, 09:38 AM
If I use a notch filter, doesn't it mess with the two way communication of the cable box? That seems to be the problem we've been having...
MikeTech
03-09-2005, 09:45 AM
I just had to swap out notch filters on a job with digital hd boxes. The channel plus i had installed blocked the on demand channels from working. I installed a Leviton model that works great now.
Toronto122
03-09-2005, 10:07 AM
What channel range does it block or is it variable? I'll have to try it!!!

Thanks!!!
MikeTech
03-09-2005, 10:10 AM
Channel Plus - NF-469 blocks 64 - 70

Leviton - 47690-NFA blocks 75-80