摘要 |
PURPOSE: A radio transmission device and method using a digital-analog converter are provided to minimize the use of an analog device while maximizing the signal to noise ratio or the spurious-free dynamic range of an output signal. CONSTITUTION: A digital signal generator(110) creates a base band digital signal having bandwidth less than half of digital-analog conversion sampling frequency about data which is transmitted. A digital-to-analog conversion part(130) changes the base band digital signal into an analog signal. A frequency band determining part(150) determines the frequency band of an image signal which is fitted to predetermined signal-noise ratio in a output spectrum of the analog signal. A band pass filter(170) changeably passes through the analog signal which belongs to the frequency band. An analog transmission part(190) transmits the analog signal which is passed through a transmission antenna. |