Patent ID: 7408594

Claim:
A method of automatically switching on/off a low noise amplifier (LNA) that serves to boost weak video signals in a TV tuner ( 2 ), the method comprising: (a) determining ( 23 , 24 , 25 ) whether a tuned-in signal meets predetermined minimum criteria for picture reproduction; (b) if the determination in step (a) is negative, switching off said LNA ( 33 ); (c) if the determination in step (a) is positive, determining ( 27 , 28 ) whether said tuned-in signal requires boosting; (d) if the determination in step (c) is negative, switching off said LNA ( 33 ); (e) if the determination in step (c) is positive, switching on said LNA ( 29 ); (f) measuring a change in signal-to-noise ratio of the LNA-amplified tuned-in signal after switching on said LNA in step (e), and (g) if said measured change in step (f) is an increase and exceeds a predetermined threshold ( 31 ), maintaining said LNA in a switched-on state, and otherwise switching off said LNA ( 33 ).