| 摘要 |
FOR PURPOSES OF SIMPLE CONSTRUCTION AND UNIVERSAL APPLICATION, A CIRCUIT ARRANGEMENT FOR FREQUENCY CONVERSION OF A COLOR SIGNAL TO A SECOND CARRIER FREQUENCY, WHICH COLOR SIGNAL IS PRESENT IN PICTURE LINES AND COMPRISES A COLOR BURST AND A CHROMINANCE INFORMATION SIGNAL MODULATED ON A CHROMINANCE SUB-CARRIER OF THE FIRST CARRIER FREQUENCY, THE CIRCUIT ARRANGEMENT BEING SWITCHABLE IN A MODE FOR CONJUGATE-COMPLEX FORMATION IN WHICH IT GENERATES AN OUTPUT SIGNAL IN WHICH, ADDITIONALLY TO THE FREQUENCY CONVERSION, THE COLOR SIGNAL HAS A PHASE POSITION IN ACCORDANCE WITH THE PAL STANDARD, WHICH ALTERNATES FROM PICTURE LINE TO PICTURE LINE, AND WHICH COLOR SIGNAL IS PRESENT IN A CONJUGATE-COMPLEX FORM IN EVERY SECOND PICTURE LINE, IS CHARACTERIZED IN THAT -THE COLOR SIGNAL MODULATED ON THE FIRST CARRIER FREQUENCY IS CONVERTED TO A THIRD CARRIER FREQUENCY BY MEANS OF A FIRST MIXER (1), WHICH THIRD CARRIER FREQUENCY IS HIGHER THAN THE FIRST, AND LOWER THAN THE SECOND CARRIER FREQUENCY, -A SECOND MIXER (20) IS PROVIDED BY MEANS OF WHICH THE COLOR SIGNAL HAVING THE THIRD CARRIER FREQUENCY IS CONVERTED TO THE SECOND CARRIER FREQUENCY, THE SECOND MIXER RECEIVES A SECOND MIXING SIGNAL DURING THE PERIODS WHEN THE CONJUGATE-COMPLEX FORMATION MODE IS ACTIVATED, AND RECEIVES A FIRST MIXING SIGNAL DURING THE REMAINING PERIODS, THE FREQUENCY OF THE FIRST MIXING SIGNAL IS CHOSEN TO BE SUCH THAT ITS SUM HAVING THE THIRD A CARRIER FREQUENCY CORRESPONDS TO A FREQUENCY IN CONFORMITY WITH THE SECOND CARRIER FREQUENCY THE FREQUENCY OF THE SECOND MIXING SIGNAL IS CHOSEN TO BE SUCH THAT THE DIFFERENCE BETWEEN THIS FREQUENCY AND THE THIRD CARRIER FREQUENCY CORRESPONDS TO A FREQUENCY IN CONFORMITY WITH THE SECOND CARRIER FREQUENCY, THE PHASE RELATIONS BETWEEN THE COLOR SIGNAL APPLIED TO THE SECOND MIXER (20) AND MODULATEC ON THE THIRD CARRIER FREQUENCY, THE FIRST MIXING SIGNAL AND THE SECOND MIXING SIGNAL ARE CHOSEN TO BE SUCH THAT THE CHROMINANCE INFORMATION SIGNAL IN THE OUTPUT SIGNAL OF THE SECOND MIXER (20) IS MODULATED ON THE CHROMINANCE SUBCARRIER WITH THE DESIRED PHASE POSITION, AND -THE OUTPUT OF THE SECOND MIXER (20) IS CONNECTED TO A BANDPASS FILTER (35) WHICH SUPPLIES, FROM ITS OUTPUT, THE COLOR SIGNAL MODULATED ON A CHROMINANCE SUB CARRIER HAVING THE SECOND CARRIER FREQUENCY. (FIG.1)
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