How Do Cable Splitters Work

Cable Setup. Drawing by Tom Walton.

Signal Division and Frequency

A cable splitter reduces electrical signal over the distance an electric current travels. The job of the cable splitter is to break up a signal into separate electrical paths. A cable splitter divides an electric signal to an array of ports on the splitter. This division of electrical current is run from the cable outlet to multiple televisions within a home. Your digital cable company typically supplies about 1 gigahertz (GHz, or 1000 megahertz) of electrical signal, or frequency bandwidth, to your cable outlet. You do not need a cable splitter higher than 1 GHz.

A larger splitter will distribute less signal strength to each port. This decrease in signal strength occurs because each additional port divides the electrical signal from the source, as well as the distance the signal has to travel. Try to even out the cable signal distribution to all of the televisions in your home. Read the numbers located on the out legs of the splitters. Each number indicates how much of the cable signal is lost after running through that out leg. The numbers represent decibels (dB), which measure amplification of a signal. A typical double splitter has 3.5 dB amplification lost on each out leg.

The amount of signal lost indicated on the splitter occurs between 50 and 100 megahertz; higher frequency means more loss over distance. The number engraved on the backside of a cable splitter is the shielding specification for the splitter (the amount of leakage resistance). Subtract the shielding numeric value from the out leg to determine how much signal is lost.

Passive/ Active Cable Splitters

Active cable splitters utilize a power source to slightly amplify the digital signal to make up for lost signal through a passive splitter. Passive splitters do not run on a source of power. There is one input side to the splitter, with two or more out legs.

Cable Splitter Setup

Cable splitters work in conjunction with other components in a cable setup. The first thing necessary is the incoming cable line, which runs through the cable splitter. The cable splitter will typically have one out leg running to a modem, which is connected to a computer. Another out leg on the cable splitter runs to a cable amplifier. This cable amplifier can have up to eight ports. Hook up your additional modems and televisions to one of the ports on the cable amplifier. The amplifier can also be placed before the splitter in the cable system to improve picture quality and the overall function of your cable modem.

On occasion, the cable splitter set up may produce too much signal, which can lead to poor color or distorted images on your cable television screen. To rectify the more complex cable setup signal, a two way splitter is placed on the cable modem. Additional splitters help run the signal out of the system and into the air.