NTSC/HDTV community receiving system

A NTSC/HDTV community receiving system comprising:

• system control means for generating a control signal corresponding to one of an HDTV system and a NTSC system;
• first tuning means for tuning an HDTV signal to a desired channel;
• second tuning means for tuning a NTSC signal to a desired channel;
• first intermediate frequency detecting means for detecting an HDTV intermediate frequency signal from the tuned HDTV signal from the first tuning means;
• second intermediate frequency detecting means for detecting a NTSC intermediate frequency signal from the tuned NTSC signal from the second tuning means;
• analog to digital converting means responsive to the control signal from the system control means for converting the HDTV intermediate frequency signal from said first intermediate frequency detecting means and the NTSC intermediate frequency signal from said second intermediate frequency detecting means to digital signals at different sampling rates;
• demodulating means for demodulating a NTSC frame color signal into an original state and demodulating the resultant digital HDTV signal from said analog to digital converting means into a base band level state;
• first comb filtering means for removing a NTSC interference signal from the demodulated HDTV signal from said demodulating means and extracting a NTSC line color signal from the resultant digital NTSC signal from the analog to digital converting means;
• second comb filtering means for extracting a first motion coefficient, the NTSC frame color signal and a NTSC frame luminance signal from the resultant digital NTSC signal from the analog to digital converting means and the NTSC line color signal from the first comb filtering means and outputting the extracted NTSC frame color signal to the demodulating means;
• decoding means for decoding the resultant HDTV signal from said first comb filtering means to extract original HDTV color and luminance signals;
• scan rate transforming means for line and pixel-interpolating resultant NTSCI and NTSCQ color signals from said demodulating means and the NTSC frame luminance signal from said second comb filtering means to match a scan rate of the NTSC signal to a scan rate of the HDTV signal;
• and
• display state control means for controlling display states of the resultant original HDTV color and luminance signals from said decoding means and the resultant original NTSC color and luminance signals from the scan rate transforming means.