Digital cable, like analog cable and antenna signals, are fully compatible with quality splitters. With any digital cable installation, correct usage of splitters is important. Without proper splitter installation, signal loss results, creating snowy and distorted images that may prove unwatchable on some channels. Understanding how amplified and non-amplified splitters work, along with following practical coaxial installation steps gives you the best image quality possible.
How Splitters Work
Splitters are boxes incorporating a coaxial cable threaded input, with multiple threaded output legs. The cable entering the structure screws to the splitter's input. Each coaxial cable leading to digital cable boxes or television tuners screws to the outputs. Most splitters use a simple internal network of aluminum or copper wire, although a few use a circuit board to maintain the proper 75 ohm impedance necessary for coaxial signals. Splitters cause a drop of 3 decibels per output on the splitter, normally compensated for by the television tuner.
The primary splitter in the basement or lower level will be, ideally, the only one in the home. Splitter inputs and outputs incur 3 decibels of loss compared to the original feed. Stacking another splitter therefore adds 6 more decibels of loss. A digital signal has a maximum of 12 decibels of loss, prior to it failing to register at the cable box or television tuner. Combining these losses with the natural loss caused by the coaxial cable run itself may mean some channels are unwatchable or missing entirely.
One method in countering excessive losses when using splitters with digital cable feeds is to use an amplified splitter, or distribution amplifier. These AC-powered devices compensate for the losses incurred at each output on the splitter. Additionally, the amplifier boosts the signal on each coaxial output, so long coaxial runs across the house do have the same negative effect as an un-amplified feed. These amplifier/splitter combos are normally larger, with multiple coaxial outputs.
Coaxial Routing Tips
Coaxial cables, like all electrical wires, have resistance. This resistance impedes low-level signals such as those found with digital cable. Over longer distances, this can become a problem. Keeping each coaxial run below 100 feet helps this considerably. Eliminating sharp 90 degree bends in the coaxial cable maintains the proper impedance required on a coaxial signal. It's prudent for you to use amplified distribution splitters in the lower level, basement, or access room, regardless of the distances used per run.