A digital signal amplifier is a device that increases the strength of an incoming digital television signal to provide improved reception. The amplifier is only able to improve signals that it is already at least partially receiving and is unable to extend the range of any existing antennas to which it might be attached. It is intended to allow a signal to travel an additional short distance from an antenna, through any necessary wires, to a television or convertor box.
The need for a digital signal amplifier in some areas or buildings is a result of the nature of a digital signal. An analog signal is much more resilient than a digital signal and is able to pass through many barriers and atmospheric conditions without completely being absorbed. A digital signal has a shorter range and can be affected by a much wider variety of conditions over a distance.
There are different types of digital signal amplifiers. Some of them are built into antennas that are meant to be used indoors. Others are separate units that can be attached to interior or outdoor antennas. The amplifier needs to be attached to an antenna. This is because the amount of resistance the digital signal encounters by traveling through the cables that attach the television to the antenna is actually enough to degrade the signal so it cannot be converted into an image.
A digital signal amplifier also can be used as part of a larger component system. Just as with an antenna and the corresponding cable, having the signal pass through multiple components can weaken it enough so it never reaches the television or converter box. Some components, such as line splitters, can have amplifiers built into their design so the signal is strengthened as it moves in and out of installed electronics.
Using a digital signal amplifier is only one step in ensuring that a signal is received and converted properly. Another issue can be the direction of the source of the signal. The poor ability of a digital signal to pass through obstacles means that even something as simple as having an amplified antenna facing the wrong direction could make a large difference.
A similar device is called a digital cable signal amplifier. It works in much the same way as a digital signal amplifier, except it is designed to work inside a house. This is because a digital signal coming in through a cable line can only travel a maximum of 15 feet (about 5 meters) before it degrades.