| 摘要 |
PROBLEM TO BE SOLVED: To produce an analog signal for transmission by converting a digital signal into analog format, providing an analog signal at a transmission fre quency using an analog signal image produced by a DA converter(DAC), and using the projected analog signal image. SOLUTION: A digital transmitter produces an analog signal at a desired frequency, using the analog signal image from the DAC. By setting or adjusting the conversion rate for the DAC or the digital signal frequency, the analog signal image produced from the DAC can be positioned in the desired frequency band. When the digital signal is converted into analog format, the DAC produces an analog signal image repeated at integral multiples of half the conversion rate, so that the analog signal image can be produced at an appropriate frequency band suitable for amplification and transmission.
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