A high definition (HD) amplifier is a device that boosts the signal reception capacity of a high definition television antenna. The HD amplifier is most often an inline modulator device that is affixed to the signal reception cable between the antenna and the television. Most HD signal amplifiers can also be used with cable and satellite television to boost the resolution and signal strength provided by either medium. The technical specifications of an HD amplifier vary by model and application, though typically all HD amplifiers operate between 40 and 900 Mhz with a gain of 36 dB millivolts per meter, which gives increased strength and clarity to the HD signal that the amplifier processes.
Over-the-air broadcasts can benefit the most from the use of an HD amplifier. These broadcasts are suspcetible to signal degradation and to electromagnetic interference from other signals. To install an HD amplifier with an HD antenna for over-the-air HD broadcasts, two lengths of coaxial cable, are needed. One connects the HDTV to the "out" port on the amplifier while the other cable connects the HD antenna to the "in" port on the amplifier.
The HD amplifier is powered by the signal that passes through the input cable. It then processes the signal to eliminate noise, static, and degradation. High end amplifiers do need to be plugged into an electrical outlet and often function at a higher level to boost and process signals to eliminate image and audio defects.
To use an HD amplifier with cable TV service, check for compatibility with the cable provider's set top box. Not all set top boxes will allow the processed signal from an amplifier to display properly. Also, many models of set top box also provide an internal HD signal booster that would make the installation of an external HD amplifier unnecessary.
For satellite TV service, HD satellite dishes usually have a signal amplifier that provides clean and crisp HD signals to the television. An HD amplifier may be useful for satellite and cable applications if the television itself is located in an area susceptible to interference or noise that can disrupt the signal. The installation of an amplifier near the television can diminish or entirely eliminate the interference.
When using an inline HD amplifier, it is not sufficient to merely connect both cables to the device and let it hang in between. The HD amplifier must be secured to a stable structure, such as a wall, a baseboard, an entertainment center or other fixture. Most HD amplifiers have screwhole fittings molded into the device that can be used to affix the device to something nearby.