| 摘要 |
<p>PURPOSE:To reduce interference given to an existing television receiver by dividing a high frequency component included in a luminance signal into two frequency bands, converting them into low frequencies, then adding one to a high frequency included in a signal Q and the other to that included in a signal I whose frequency band is limited. CONSTITUTION:A luminance signal YL with a wide frequency band the same as a luminance signal included in a signal NTSC and high frequency components YH1 and YH2 is separated from the high frequency band luminance signal Y by high-pass filters 22 and 24 and subtractors 21 and 23. The component YH1 is multiplied by a subcarrier (frequency fSC) by a multiplier 31, and passed through a band-pass filter 32, whereby it is shifted to a low frequency band by the fSC. The component YH2 is shifted to a low frequency band by 1.25 fSC in the same manner. The frequency- shifted signals YH2' and YH1' are added to the signal I with a limited frequency band by adders 5 and 6. After a modulator 9 applies perpendicular double phase modulation to the outputs of the adders 5 and 6 with the aid of a subcarrier, an adder 11 adds them to the signal YL. Accordingly the components YH1' and YH2' never overlap with a low frequency included in the luminance signal, thereby reducing the interference given to an existing receiver.</p> |
