For advanced cable networks, this range can be extended to 862 MHz. Each channel occupies 6 MHz, so to handle more channels, the system must have broader bandwidth. Phase Noise Phase noise is the amount of noise added by small frequency movements of the local oscillators, a component of the tuner. Some applications, like analog TV, are impervious to phase noise, while others, like cable modems, can be severely compromised by excessive phase noise. Noise Figure Noise figure is a measure of how much noise is added to the signal by passing it through the tuner.
All tuners add noise.
For some applications like analog TV, there is no clearly defined boundary on how much noise can be added. Other applications, especially in digital ones like cable modems and set-top boxes, there are very clearly defined boundaries of how much noise can be added by the tuner. Distortion Distortion is a measure of how much the tuner distorts or changes the incoming signal. All tuners distort the signal to some degree. Image Rejection All tuners have the undesired effect of tuning to the desired channel as well as to an image channel.