Noise/Noise figure/Noise factor

[kq6qv]

For TVs there are two main sources of noise:
1. Atmosphere noise. There are many types of sources for this noise. A light switch creates a radio wave every time it opens or closes. Motors in some appliances produce nasty RF noise.
2. Receiver noise. Most of this noise comes from the first transistor the antenna is attached to. Some receivers are quieter than others.

Receiver noise dominates on the VHF and UHF bands, and atmospheric noise is usually insignificant.

The noise figure and noise factor are the same thing, but the noise figure is expressed in dB. Every amplifier has a noise figure. The noise figure must be subtracted from the antenna gain. Thus the noise figure tells how much of the antenna gain you are throwing away by not buying a quieter amplifier. The amplifier in question is the OTA receiver or the mast-mounted amplifier, whichever the antenna connects directly to.

Noise management is discussed at http://www.hdtvprimer.com/ANTENNAS/basics.html . If you do not manage the noise properly, you might be throwing away a large portion of the antenna signal.