| 摘要 |
PURPOSE:To enhance the advantage of the spectrum modulation system to the utmost with simple circuit constitution by selecting the polarity of an interpolation signal depending on the result of the comparison between an output of an interpolation signal arithmetic means and a prescribed threshold level and the past output result. CONSTITUTION:A comparison means 50 compares an output of an interpolation signal arithmetic means 10 and a prescribed threshold level 90 and the polarity of an interpolation signal is selected depending on the result of comparison and the past output result. Thus, it is possible to select the polarity of the interpolation signal only when the amplitude of the interpolation signal is a prescribed value or below. When the spread spectrum system is adopted, the polarity switching signal for the interpolation signal is a signal with less correlation with respect to a spread signal. Thus, a modulation wave with a constant envelope is obtained with simple circuit constitution and a specific peak is not given in the frequency distribution, the band is not spread, and an interpolation signal capable of being spread at inverse spread is generated even in the case of adopting the spread spectrum system. |
