Signal amplifier's have two important specifications. The amount of signal amplification provided by the unit and the signal to noise ratio. Both of these are measured in dB. Noise is any signal interference that is not related to the TV signal. If the level of the noise over shadows the TV signal from the broadcaster the digital signal will drop out no matter how strong the TV signal is. Some noise cannot be avoided but that doesn't mean you have to add more noise than necessary with the amplifier. You can get better/improved digital TV reception using amplifiers with lower noise level ratings. Any noise figure rated 3 dB or lower is excellent.