TELEVISION CIRCUIT AND FREQUENCY CONVERSION CIRCUIT

摘要

PURPOSE: To simplify a circuit by providing a real part filter for demodulating a horizontally reinforced signal in an ADTV main picture part signal with a specific cut-off characteristic and calculating a picture signal by the use of an output from the real part filter. CONSTITUTION: An f-ν separation circuit 2 separates a horizontally reinforced signal component HH' and a chrominance signal C from an input signal Vs consisting of YL+YM+C+HH' signals in an ADTV main picture signal. The component HH' is demodulated by a complex filter 7 and a complex modulation circuit 10 and a horizontally reinforced signal HH with 4.2 to 6MHz is extracted and outputted from a horizontal high pass filter(HPF) 14. Since an output Re from a real part filter 8 has the same phase as that of the component HH', the filter 8 is provided with a cut-off characteristic of about 2MHz and the output Re is subtracted from the input signal Vs by a subtractor 5 to obtain YL+YM+C signals. Consequently the arrangement of a BPF of 2 to 4.2MHz on an output line of the component HH' from the circuit 2 can be omitted.