Sunday, June 15, 2008
Beefing Up Your Cable Signal
Last week I told you I was watching an older TV equipped with rabbit ears while we were away. It was an acceptable way to catch the news in the wilds of Maine, but that’s about it. It really pointed out how spoiled I’ve become by cable.
I hate poor reception, it really drives me to distraction. I’m forever tweaking the cable plant in my house, and I usually can’t stop myself from messing with my friends and relatives connections if the picture on their TV looks a little fuzzy or their home network is sluggish.
Hey, I grew up working the rabbit ears on top of our TV like a Navy Signalman, and sometimes adding things like tinfoil to them, all in a vain attempt to pull in that one extra station. I don’t think I ever really got a good look at Uncle Gus out of NH, but I certainly tried.
When cable first arrived on the scene, I thought I’d died and gone to heaven. As I began to explore and expand the capabilities of my cable drop, I quickly found out that it can look just as bad as those old rabbit ears did if you’re too cavalier with it.
The key to good cable reception is keeping down the signal loss. It’s a lot like antenna reception in that way. The stronger the signal that reaches the TV, the better the picture quality. Every foot of cable, every splitter, every DVD and VHS connection, causes signal loss. Even the type of cable you use enters into the equation. You always want to use RG6 cable. It costs a little more but has less signal loss then RG59.
There’s a certain tipping point that’s dependent on both the strength of your signal at its point of entry, and the number of wacky things you do with it from there. You can calculate it all out here, but you’ll know when you hit it ‘cause you’ll start getting a washed out, grainy and/or wavy picture, or pixilation on the SD and HD digital channels. It’s a huge disappointment if you’re feeding a cool new flat panel.
I currently have 3 separate runs split off of the main. The 2 runs for the upper floors are relatively long, but we get a good strong signal from the street and the cable and connectors are in good shape, so picture quality has always been good on these TV’s.
The third leg goes into the basement, and this is the one I abuse…
I split this leg 3 times. Two short runs (15’) and a long run that goes about 50’ into yet another splitter that feeds both an HD cable box and a DVD-Recorder and VCR that are tied together in series.
The HD from the cable box looked good, but the feed from the recorders just didn’t look crisp by the time it wound its way back to its respective TV input. Having both the DVD and VCR on improved the picture to the PIP, as both devices were pre-amping the signal, but as soon as I had one or the other on by itself, the reception was poor on a lot of the channels.
As I said before, I hate a crappy picture, so I tore into things. I pretty much knew from the start that I was going to need to amplify the signal, but if your going to do something, you might as well do it right.
First I tried reconfiguring. While I was doing it, I replaced a couple of the cables and checked all of the connections. A bad cable or a loose connection is often the cause of poor reception. While you’ve got the cables unplugged, shine a light into their connectors and be sure you can still see the white dielectric, it has a tendency to shrink back into the jacket with age. If it has, either replace the cable or trim it back and crimp on a new connector.
Anyways, all that work and no change. I still had a crappy picture.
Next I went out and got an amplifier for the line. For my application I needed a Bidirectional amp. There are a couple of different types, and you need to get the right one for your particular setup.
Here’s what you need to know:
In-line signal amp: 10 db, single direction amp. Gain not adjustable. Ok for basic cable, but not for digital with a set top box or cable modems.
Bidirectional amp or Forward Gain: If you have digital cable boxes in the house or get voice and data through your cable provider, you need a bidirectional amp. It has a portion of the bandwidth (5-42MHz) reserved as a return band to the provider, which allows two way communications for the voice and data connections and also the interactive features on the cable box. This single port bidirectional amp boosts your signal by up to 10 db and the gain is adjustable via a small knob. This device boosts only the incoming signal. It does not boost the return signal to the provider.
There are also Reverse Gain and Two Way Active amps, the former beefs up only the return band, the latter, both. You’d want one of these if your box is timing out during interactive functions or you have a troublesome link between your cable modem and your provider.
So I got the amp that was right for the job, and it really did the trick. I put the amp in line right where the feed comes into the house, then came off of it with a 6 foot cable that ties into the input of the first splitter. This way it’s distributed evenly throughout the whole system, and it’s amplifying the best signal possible. This is important, as once you start splitting the cable, you water down the signal, and you don’t want to amplify crap.
Not only did it clear up the feeds to the recorders, it also made the sets that we already thought looked good, look even better!
The amp I’m using is a single input, single output. They come in all kinds of configurations (1 in, 4 out, etc.), and once again, you want to get the one that’s right for your specific application. Keep in mind though, that too strong a signal can be every bit as problematic as a weak signal. I barely needed to tweak the gain at all for my setup. I have it set at 3 of 10. Any higher and the signal is too strong on the shorter runs.
Okay, here's the stuff to remember:
Most reception problems are caused by cables or connectors, check them first, and use the right components for the job:
Use RG6 cable and connectors
Use 1GHz splitters
Research and come up with the best wiring scheme in regards to signal loss. Pay attention to the amount of signal loss on the outputs.
And if all that fails:
Be sure to get the right amplifier for your situation.
Don’t put it too close to the end device; keep it at or near the cable’s entry point. Amplifying crap just gives you amplified crap.
And as always, when in doubt, look it up. Broadband Reports FAQs section is a wealth of information on all things broadband and dsl related.