| 摘要 |
PROBLEM TO BE SOLVED: To reduce adjacent channel interference effectively in an adjacent area, in which an IBOC/CM system is used by making the power level of the sub-set of the digital modulation signal of the sub-band of a digital band lower than the power level of the second sub-set of the digital modulation signal of the second sub-band of the digital band. SOLUTION: An IBOC/AM system uses a digital band, using the analog host AM carrier wave with frequencies (fc) in 30 kHz width as a center. At the using of the IBOC/AM system in two adjacent regions to which the frequencies (fc) are assigned so as to be separated by 20 kHz, they mutually overlap by 10 kHz amount, and sub-adjacent channel interference is generated. In this case, a profile 301 is mounted in the region with the low frequencies (fc) among the two adjacent region mounts, and a profile 311 is mounted in the region with the high frequencies (fc). Thus, the profiles 301 and 311 do not overlap each other, and sub-adjacent channel interference can be prevented. |
