RF modulator on digital cable? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 9 Old 03-11-2009, 07:19 PM - Thread Starter
Newbie
 
embedded_tom's Avatar
 
Join Date: Dec 2004
Location: Long Island
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I've searched the forums for similar ideas, but I think what I want to do are slightly different. Let me know if I'm wrong!

I'd like to RF modulate the output of a security DVR onto my OptimumOnline digital cable network. Ideally, the channel would be viewable via both the cable box (SA 8300HD in the family room) and my cable-ready TV (bedroom), but I'm fairly certain that the cable box won't see an analog channel. To overcome this, I thought I would use the old VCR still connected to an aux input to the family room TV.

My problem is that I can't find any definitive information about the digital cables frequency usage. Can I insert a channel using my HMM-10H RF mod (CH14-CH83 or CH65-CH139) with an RF dist amp (HVM-1308) and the appropriate notch filter, onto the digital cable without interfering with digital channels or the cable modem? And if this works, will it still work after the digital changeover in June?

Thanks.

tom
embedded_tom is offline  
Sponsored Links
Advertisement
 
post #2 of 9 Old 03-12-2009, 05:44 PM
AVS Special Member
 
11001011's Avatar
 
Join Date: Aug 2004
Location: N.W. Washington
Posts: 1,361
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Without knowing exactly where the QAM channels are I would say you are asking for trouble.

Oh and digital cable has nothing to do with the digital TV conversion that was pushed back to June.

A 'phile and his money are soon parted...
11001011 is offline  
post #3 of 9 Old 03-13-2009, 04:47 AM
AVS Special Member
 
RCbridge's Avatar
 
Join Date: Jul 2002
Location: Limerick Pa
Posts: 1,902
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 14
Do you have access to a spectrum analyzer?
RCbridge is offline  
post #4 of 9 Old 03-13-2009, 08:47 AM - Thread Starter
Newbie
 
embedded_tom's Avatar
 
Join Date: Dec 2004
Location: Long Island
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by 11001011 View Post

Oh and digital cable has nothing to do with the digital TV conversion that was pushed back to June.

True, but I read (somewhere on these forums) that after the changeover that some cable co's are planning to reshuffle the cable frequencies assigned to the analog channels and I thought that might impact what I'm trying to do.

RCbridge: Yes. I have an 8591E at work that I use for RF design. Tell me more...

tom
embedded_tom is offline  
post #5 of 9 Old 03-13-2009, 04:06 PM
AVS Special Member
 
egnlsn's Avatar
 
Join Date: May 2007
Location: Taylorsville, UT
Posts: 2,230
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 31
Your HMM-10H goes up to 860MHz, and more likely than not, your cable system goes up to 750MHz. You could get an LPF-750 and tune your HMM-10H to something above ~780MHz (~channel 122) or so and connect the modulator via a DC-12. The cable would go into the LPF, which connects to the DC-12's OUT leg. The HMM-10H connects to the TAP leg of the DC-12, and the IN leg goes to your distribution system.

CIAO!

Ed N.
egnlsn is offline  
post #6 of 9 Old 03-13-2009, 05:52 PM
AVS Special Member
 
11001011's Avatar
 
Join Date: Aug 2004
Location: N.W. Washington
Posts: 1,361
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by embedded_tom View Post

True, but I read (somewhere on these forums) that after the changeover that some cable co's are planning to reshuffle the cable frequencies assigned to the analog channels and I thought that might impact what I'm trying to do.

Yes, no, maybe... That's sort of the problem. Cable systems are considered a private network and do not have to follow all same exact rules and regulations as broadcast TV.

Cable can go all digital anytime they want or never. But I do think the FCC has requested they keep the "lifeline basic service" (Ch2-Ch13) analog for a while longer.

A 'phile and his money are soon parted...
11001011 is offline  
post #7 of 9 Old 03-13-2009, 08:28 PM
AVS Special Member
 
egnlsn's Avatar
 
Join Date: May 2007
Location: Taylorsville, UT
Posts: 2,230
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 31
Quote:
Originally Posted by 11001011 View Post


Cable can go all digital anytime they want or never. But I do think the FCC has requested they keep the "lifeline basic service" (Ch2-Ch13) analog for a while longer.

Unless a system is already all digital, they must transmit the locals in analog for until 2012.

CIAO!

Ed N.
egnlsn is offline  
post #8 of 9 Old 03-14-2009, 05:50 PM - Thread Starter
Newbie
 
embedded_tom's Avatar
 
Join Date: Dec 2004
Location: Long Island
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by egnlsn View Post

Your HMM-10H goes up to 860MHz, and more likely than not, your cable system goes up to 750MHz. You could get an LPF-750 and tune your HMM-10H to something above ~780MHz (~channel 122) or so and connect the modulator via a DC-12. The cable would go into the LPF, which connects to the DC-12's OUT leg. The HMM-10H connects to the TAP leg of the DC-12, and the IN leg goes to your distribution system.

Whoa! I was thinking that the RF mod would be inserting a channel before the cable frequencies, not after. Cool.

But do I really need a DC-12? My distribution box (it's amplified) has two auxiliary inputs just for this purpose (RF modulators).

Quote:
Originally Posted by 11001011 View Post

Yes, no, maybe... That's sort of the problem. Cable systems are considered a private network and do not have to follow all same exact rules and regulations as broadcast TV.

Cable can go all digital anytime they want or never. But I do think the FCC has requested they keep the "lifeline basic service" (Ch2-Ch13) analog for a while longer.

Hmmm. It sounds like I might be able to make something work for now, but not for the long term.

Thanks for the info everyone. I think I'll look to other means of accomplishing this idea.

tom
embedded_tom is offline  
post #9 of 9 Old 03-14-2009, 10:53 PM
AVS Special Member
 
egnlsn's Avatar
 
Join Date: May 2007
Location: Taylorsville, UT
Posts: 2,230
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 31
If your distribution amp has a couple of inputs for modulators, no, you would not need a DC-12. You may, however, need to pad down the output of the modulator. It puts out 25dBmV, and even with the internal combining network of the amp, that may still be too much.

CIAO!

Ed N.
egnlsn is offline  
Reply Cable, Digital Cable - Non-HDTV

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off