Analog TV broadcast signal receiving apparatus and analog TV broadcast signal demodulating apparatus

An analog television broadcast signal demodulating apparatus comprising:

• analog-to-digital conversion means for converting into a digital signal an analog television broadcast signal following conversion into a predetermined intermediate frequency band signal;
• complex frequency conversion means for converting said intermediate frequency band digital signal into a baseband frequency band digital signal by multiplying said intermediate frequency band digital signal coming from said analog-to-digital conversion means by a frequency signal coming from a complex variable frequency oscillator;
• a variable band limitation filter configured to band-limit the digital signal output by said complex frequency conversion means;
• picture/sound separation means for having
• picture/sound separation filter means,
• said picture/sound separation means being further configured to separate the digital signal coming from said variable band limitation filter into a picture signal band digital signal and a sound signal band digital signal;
• a vestigial sideband filter configured to demodulate said picture signal band digital signal coming from picture/sound separation means into a picture signal component;
• digital-to-analog conversion means for converting a digital signal from said vestigial sideband filter into an analog picture signal before feeding said analog picture signal to a picture processing circuit;
• digital-to-analog conversion means for converting said sound signal band digital signal coming from said picture/sound separation filter means into an analog sound signal before supplying said analog sound signal to a sound demodulation processing circuit;
• a storage section configured to store a plurality of sets of a control signal for controlling said complex variable frequency oscillator in oscillation frequency, a filter coefficient for said variable band limitation filter, a filter coefficient for said picture/sound separation filter means, and a filter coefficient for said vestigial sideband filter with regard to each of a plurality of television broadcasts;
• and
• a control section configured such that when settings are input to receive selectively a television broadcast, said control section retrieves from said storage section the set of said control signal and of said filter coefficients corresponding to the selected television broadcast and feeds the retrieved set to the sections involved,
• wherein said picture/sound separation means includes
• second complex frequency conversion means for frequency-converting the digital signal coming from said variable band limitation filter in such a manner that either said picture signal band component or said sound signal band component of said digital signal is turned into a predetermined frequency band, and
• said picture/sound separation filter means includes:
• an extraction filter configured to extract either said picture signal band component or said sound signal band component coming from said second complex frequency conversion means following the frequency conversion;
• and
• subtraction means for subtracting either said picture signal band component or said sound signal band component extracted by said extraction filter from the digital signal supplied by said second complex frequency conversion means.

An analog television broadcast signal receiving apparatus comprising:

• tuner means for converting an analog television broadcast signal into a predetermined intermediate frequency band signal;
• demodulation circuit means for obtaining a picture output signal and a sound intermediate frequency signal from said predetermined intermediate frequency band signal coming from said tuner means;
• picture processing circuit means for converting said picture output signal into a display-ready picture signal;
• sound demodulation processing circuit means for demodulating said sound intermediate frequency signal;
• and
• control means;
• wherein said demodulation circuit means includes
• analog-to-digital conversion means for converting said predetermined intermediate frequency band signal coming from said tuner means into an intermediate frequency band digital signal,
• complex frequency conversion means for converting said intermediate frequency band digital signal into a baseband frequency band digital signal by multiplying said intermediate frequency band digital signal coming from said analog-to-digital conversion means by a frequency signal coming from a complex variable frequency oscillator,
• a variable band limitation filter configured to band-limit the digital signal output by said complex frequency conversion means,
• picture/sound separation means for having
• picture/sound separation filter means,
• said picture/sound separation means being further configured to separate the digital signal coming from said variable band limitation filter into a picture signal band digital signal and a sound signal band digital signal,
• a vestigial sideband filter configured to demodulate said picture signal band digital signal coming from picture/sound separation means into a picture signal component,
• first digital-to-analog conversion means for converting a digital signal from said vestigial sideband filter into an analog picture signal before feeding said analog picture signal to said picture processing circuit means, and
• second digital-to-analog conversion means for converting said sound signal band digital signal coming from said picture/sound separation filter means into an analog sound signal before supplying said analog sound signal to said sound demodulation processing circuit means;
• said control means includes
• a storage section configured to store a plurality of sets of a control signal for controlling said complex variable frequency oscillator in oscillation frequency, a filter coefficient for said variable band limitation filter, a filter coefficient for said picture/sound separation filter means, and a filter coefficient for said vestigial sideband filter with regard to each of a plurality of television broadcasts;
• and
• when settings are input to receive selectively a television broadcast, said control means retrieves from said storage section the set of said control signal and of said filter coefficients corresponding to the selected television broadcast and feeds the retrieved set to the sections involved,
• wherein said picture/sound separation means includes
• second complex frequency conversion means for frequency-converting the digital signal coming from said variable band limitation filter in such a manner that either said picture signal band component or a sound signal band component of said digital signal is turned into a predetermined frequency band, and
• said picture/sound separation filter section includes:
• an extraction filter configured to extract either said picture signal band component or said sound signal band component coming from said second complex frequency conversion means following the frequency conversion;
• and
• subtraction means for subtracting either said picture signal band component or said sound signal band component extracted by said extraction filter from the digital signal supplied by said second complex frequency conversion means.