软件无线电卫星便携地面站中的直接数字频率合成器

理想的软件无线电需要高效且高速的数字下变频器.通常数字下变频采用查找表方法实现,即输入信号的采样乘上一个预先存储在ROM中的正弦余弦函数值.为了得到高精度,这种方法需要很大的查找表,这就意味着占用芯片面积大、功耗大、工作速度低和增加成本.文中描述了一个基于CORDIC算法的直接数字频率合成器.它能大幅度地减少查找表的大小,从而达到高精度的要求.

DDFS in a SDR Portable Satellite-Earth Station

An ideal software radio needs efficient high speed digital down converters. The common approach for digital down conversion (DDC) is the so-called ROM table approach where the samples of the input signal are multiplied with amplitude values of the sine-and cosine-function stored in ROM. To achieve high resolution, this technique requires a large look-up table which means large chip area, high power consumption, lower speed, and increased costs.In this paper, a CORDIC-based direct digital frequency synthesizer is described. It is able to reduce the size of the look-up table considerably.