fine tuning cable TV reception
As well as transferring my VHS tapes to DVD one of my goals is to capture live TV on my JVC DR-M10S. I want to fine tune my analog cable TV reception (without going to digital cable). As per your email response I purchased RG6 cable (quad shielded no less) and associated tools/connectors, an FM trap, attenuator, 1-to-4 bi-directional amp/splitter (Radio Shack $50), and DC block.
I have started to replace the RG59 cable with the quad-shield RG6. Before I try to add all of the other equipment I need clarification on certain points. My current configuration is a single Time Warner cable input which is then split into 2, one for the Road Runner cable modem, the other for the TVs and PC. I used to run the input signal directly into a Magnavox 1-to-4 amp/splitter but had occasional problems with my modem communication. Time Warner came out, measured the signal strength with some kind of fancy meter, and said that the signal to the modem was too strong. They supplied and installed a 1-to-2 bi-directional splitter (subsequently referred to as splitter #1) to bypass the amp/splitter. This fixed my cable modem problems. The other output from splitter #1 is then split again with a 1-to-2 splitter (subsequently referred to as splitter #2). The reason for this is that I have 5 active TV hookups, but at the time the biggest amp/splitter I could find was 1-to-4. I now see that there are 1-to-6 and even bigger amp/splitters, so I may investigate this possibility. One output from splitter #2 goes to a TV, while the other output goes into a soon to be replaced Magnavox 1-to-4 amp/splitter. The 4 outputs from the amp then go to 3 TVs and my JVC HRS-9911U VCR. The VCR is connected to the DR-M10S using both coax and s-video/audio, and the DR-M10S is connected to my WinTV PVR 350 the same way. This allows me to watch TV on my PC while having the VCR and DVDR turned off (or having them record other programs). Now for my questions. Since Time Warner determined that the strength from the amplified signal was too strong for the cable modem, perhaps I do not need to worry about installing an amp and should only use a splitter. Or I only need to amplify certain drops. How can I measure the signal strength at the end of each cable, and what values are optimal? They used what looked like an expensive specialty meter, and my attempts to measure the voltage with my cheap voltmeter have not been successful. Do you know of a reasonably-priced meter? I have also read that amplifying the signal will also amplify the noise, which is not good. Comments? When and how should I use the FM trap, attenuator, and DC block? Do I use all of them? In what order? It looks like the attenuator is designed to reduce distortion caused by strong signals. Any recommendations regarding a 1-to-4 or 1-to-6 amp/splitter? I just bought a Radio Shack #15-2506. I did notice that if I power on either the VCR or DVDR and have it broadcast the TV signal through the coax to my WinTV PVR 350, the picture is much improved compared to watching it directly from the cable TV input. Perhaps these devices have some way to clean up the signal before passing it on. If they are powered off and used only as a pass-through then the quality deteriorates significantly. |
The way I look at it, my eyes are the most important signal meter. I've had cable guys come to my house before when I complained about the cable modem not working, or certain channels not coming in clearly. I'd often get stupid comments from them like "well the strength is good" which got my response of "big deal, it's not looking good and/or not working right ... so go outside and fix it" (which they did).
If your cable signal is "too strong" then you're the only person in the world that I've ever met in this situation. Most oftem, it's the other way, caused from inept cable workers, cheap equipment, and old wiring. I'd bet my money the Time Warner guy had something backwards or was reading upside down. I guess go ahead and pay attention to what those guys say, but don't take it as gospel of any kind. Be very wary of them. I guess the easiest way to understand how to wire up all this equipment, is to understand what it does (in practice, not according to the specs). So we'll attack from that stance. And we'll go ahead and assume that you've got a decent signal strength to start with (meaning your gadgets will be enough, no need to call out the cable guys).
I have many combinations. This is one I used for a long time: ... I'll add this image tomorrow. Words cannot explain ... |
1 Attachment(s)
Now then, I realize this looks like one of Stephen Hawking's universal diagrams, but it is actually a rig I had running for more than a year.
To follow the diagram, start with the SOURCE at top left. You will ALWAYS move OUT of the item. Nothing here is bi-directional. It all goes ONE WAY only. It only gets confusing because some device have multiple outs, or multiple ins (generally just the VCR/DVD recorder units). Attachment 106 I've since condensed to far fewer items, although I can still re-rig this when needed (not often anymore). The PRIMARY PVR system got the most attention. It has the best care taken to give it a clean signal. And it has always gotten a pretty clean signal. The SECONDARY PVR system has issues, way to far down the line. Same for the DVD recorder in this image, too far down. Both had buzzing problems in the audio, unavoidable. Hopefully, you can see what I was doing. I'm not exactly sure how many times you want to split the signal, and into how many pieces of equipment. |
If you need me to draw you a diagram, let me know. I'll see what I can do. Or inversely, if you've got all this figured out, let me know.
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Thanks for the diagram - it clarifies what you explained earlier.
I noticed that you have more than one amp. When should I use more than one? Do you have any recommendations regarding splitter, amp, and amp/splitter brands? I just bought a $50 1-to-4 Radio Shack bi-directional amp/splitter that has a dial to adjust the gain. Haven't had time to try it out yet. |
I ran amps every time the signal got significantly weaker at a long run or at a split. Everythig I did was in reponse to me not liking what I saw on screen or hearing from the speakers.
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