Ghost Cancellation of Analog TV Signals: With Applications to IDTV, EDTV, and HDTV

Techniques that can cancel ghosts in received Analog TV (for IDTV, EDTV, And HDTV) signals are presented. The fact (hat there an short periods of time without the analog signal (the horizontal flyback Interval between the lines) Is utilized to periodically cleanse a finite Impulse response (FIR) or an Infinite impulse reponse (IIR) equalizer. This Hoe-by-line processing (cleansing) overcomes the limitations of standard equalizers to allow for 40-50 dB of suppression of ghosts, even with mills In the spectrum, as long As the ghost delay is less thin the period of time without the analog signal. Furthermore, by using time Inversion In combination with line-by-line processing, The stability problem. Of the conventional IIR equalizer can be eliminated. It is shown that It may be possible to implement this IIR equalizer on a single digital Integrated circuit. Alternatively, An FIR equalizer can be used which, although It requires multiple chips (i.e., more taps), can acquire and adept to the ghosted channel more rapidly than an IIR equalizer. With line-by-line processing, FIR and IIR equalizers can eliminate any ghost with delays up to 11 mu s in IDTV or EDTV, and Any ghost with delays up to the length of the interval between each line without the analog signal in HDTV. For larger delays, we show how a standard IIR or FIR equalizer can be used as a preprocessor to eliminate small ghosts and an adaptive antenna can be used to eliminate large ghosts. Thus, using these techniques to combination with line-by-line processing, we con eliminate the ghosting problem In nearly all TV receivers.