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[bkenobi]

I have my CM15A in the office.  I do not get enough coverage with it's antenna, so I converted it to coax and installed a Radio Shack antenna in the attic.  I have a single run of coax from the structured media box to the office and a couple to the attic, so I used that pair to link the antenna to the CM15A.  I was getting a lower than desired boost in signal strength, so I added an amplifier to the run and everything works wonderfully!

Up until now, I've been a DirecTV user.  I don't have a TV in the office that's hooked up since I didn't want to pay for a receiver that's never used.  So, using the coax run hasn't been an issue.  I wanted cable TV when we bought the house, but it wasn't run out our way.  Yesterday I found out that a new cable TV company has just extended service to our area and perhaps even across the street, so I'm almost certainly going to switch.

SO...  According to the sales rep I spoke to, the service they provide includes: Digital cable, analog cable, cable internet, phone.  My question is about using the same line for running my X10 RF antenna on the same line as the digital/analog cable/internet.  As far as I know, X10 is in the 310MHz range.  According to Wikipedia, there might be interference on channels 38 or 39 if the frequency range is still used.

http://en.wikipedia.org/wiki/North_American_cable_television_frequencies

It wouldn't be exceptionally difficult to install a new cable run from the office to the structured media box.  It also might be possible to move the CM15A to the same area as the structured media box and use a USB->ethernet adapter (already have one and 1 unused connector in the office but never tested how the unit works).  Anyone know if I will have interference on either TV or CM15A if I just use a signal combiner?  What about potential damage using a signal amplifier?

[Dan Lawrence]

Who is the cable provider?   That may make the difference.  I've had X10 before the cable company wired Baltimore City, no interference to x10 at any time.   Now the cable provider is Comcast, no problems arose.   

[bkenobi]

The company is called Wave Broadband.  I don't know anything about them since they are new to the area.  We've had Comcast in the past, but that was at our last house when we only had 1 light hooked up to X10 and used a firecracker/TM751 as the extent of our setup.

http://www.wavebroadband.com/

[dhouston]

If I understand correctly your current setup has an antenna in the attic that feeds a coax to the media box where another coax feeds it to your office. You want the cable from the media box to office to carry both TV and X10 RF.

Other than signal losses from using two combiner/splitter devices, you should be OK. Any interference should be limited to 1-2 channels and that only when sending X10 RF.

[bkenobi]

Yes, that is exactly what I'm suggesting. Interference when x10 rf is received is perfectly acceptable for this setup, so i think its worth giving it a try. Thanks for the input!

[Noam]

Who is the cable provider?   That may make the difference.  I've had X10 before the cable company wired Baltimore City, no interference to x10 at any time.   Now the cable provider is Comcast, no problems arose.   

Dan -
I don't think the OP is concerned with interference between the cable TV signal and the PLC signals. It sounds like the OP is trying to use a single Coax cable to carry BOTH the cable signal AND the extended CM15A antenna signal. That sounds like a totally different scenario than the one your described.

[Noam]

... It also might be possible to move the CM15A to the same area as the structured media box and use a USB->ethernet adapter (already have one and 1 unused connector in the office but never tested how the unit works). 

I had a LOT of trouble a few years ago when I tried a USB-over-CAT5 adapter (essentially a USB extension, using CAT5 in between the two halves). The CAT5 cable was picking up a lot of electrical noise from random stuff in my house, and that interrupted the USB signal, causing the CM15A to re-initialize the connection. After too many re-inits in a short window, the CM15A went into an "error" mode, and needed to be restarted. I worked with two engineers from the AHP team at X10, and together we concluded that the usb-over-CAT5 extenders weren't providing the uninterrupted USB connection that I needed. I tried a number of them, and had similarly bad results.
I also tried a USB-to-network host, which plugs into my network, and provides a USB port that can be mapped to any PC on the network (using a driver and TSR on the PC). The problem with the one I tried was that there was no way to auto-start the virtual port. You needed to log into the PC, open the utility, and then "connect" the port. That was a deal-breaker for me, as the system wouldn't work after a reboot until I did that.

In the end, I just used a long (around 75-foot) extension cord to move the CM15A closer to the PC, but still plug it into the front of my XTB-IIR booster in the other room.

[dave w]

Yes, that is exactly what I'm suggesting. Interference when x10 rf is received is perfectly acceptable for this setup, so i think its worth giving it a try. Thanks for the input!

$0.02
I think the sound subcarrier for channel 38 will be your biggest problem, but I think Dave Houston's concern about combiner / splitter losses will be the major road block.

[Brian H]

If your cable company is using the Hypeband channel 38. There will be a very strong signal always on the X10 310 MHz and you may receive nothing from your X10 extended antenna. If it is strong enough, it may overload the CM15As receiver.
Also if you have any Digital Decoders. Make sure the coupler splitter is rated to pass the reverse channel data back to their head end.
When I added my own cable runs in my home. I used splitter couplers rated for Cable TV use with a back channel passage.
Even my amplified cable amp has a back channel rating.

[bkenobi]

Sounds like the usb to ethernet adapter is out then.  I didn't think about the possibility of the cable breaking the x10 signal, but that's definitely  a possibility now that i think about it.  The new run is only 15 feet through a crawl space, so I should probably just go that route. The only reason i was trying to avoid it is dealing with the insulated wall and having to go into that crawl space.  Meh, it's sounding more like a choice between that or not having cable in that room.  I guess neither is a huge deal.

[dhouston]

If you already have the combiner/splitter devices, it may be worth a try. I assume the amplifier will be between the antenna and first combiner/splitter. You may have enough signal strength to counter the cable signal - it will need to be stronger than the cable signal for the CM15A RF receiver to dig it out of the combined signal.

Would it be possible to use the existing cable as a pull-wire to install two new cables? That keeps you out of the crawl space.

[bkenobi]

Hadn't considered using the cable as a pull.  That's an option depending on if they stapled it down.  We have a mostly full basement, but there are 2 rooms that were left as crawl spaces.  It's not a huge ordeal to go in them, but obviously they are still crawl spaces and never fun.  My last house had one that was between 2 and 5 feet deep, so it was pretty manageable to get around.  I haven't been in this crawl space yet, but the other one was quite tight (closer to 18" at it's highest).  I'll probably take a look in there to see how bad it would be to work in.

[dhouston]

About 50 years ago, I spent about two years installing commercial sound systems (office buildings, banks, bars, restaurants, supermarkets, malls, etc.) in the San Francisco area. I saw a lot of crawl spaces, including one above a dropped ceiling in the North Beach area that I thought might become my last residence - but I finally wriggled out of it. Rats like to gnaw on electrical wire and they had chewed through several speaker wires.

[bkenobi]

I've been in a handful of attics and crawl spaces, but never as a job.  I can say that I've learned enough in that short time to know that they are not where I want to make a living!  They really show what kind of shape a person is in.

[frank]

In the end, I just used a long (around 75-foot) extension cord to move the CM15A closer to the PC, but still plug it into the front of my XTB-IIR booster in the other room.

Sounds like reliable way to 'place' the cm15a near the distribution point.  I had been planning to buy a pair of usb-over-Ethernet extenders until I read your post.

I'm thinking of running about 80' or so of 14-2 from an outlet near the pc to a breaker in the breaker box to achieve what you did with the extension cord.  I will just pick up one side of the 220.
 
Do you still consider this the most reliable way to 'centralize' the cm15a when the PC is remote from that location?

Thanks,
Frank