Direct conversion - How to make it work in TV tuners

The problems of direct conversion tuners are briefly discussed and solutions presented to automatically correct the inherent gain and phase errors using digital signal processing. We have built a hardware prototype for reception of analog and digital signals to carry out experiments. The direct conversion affects also the design of the preselection in the RF and IF filters, the local oscillator and to some extent the AGC system (Automatic Gain Control). Novel ideas are discussed that perform an important advance towards an alignment-free tuner.