扩频系统最佳失真度量化及载噪比评估方法

Optimal Distortion Quantization and Carrier-to-noise Ratio Evaluation Method for Spread Spectrum Systems

扩频系统接收机模拟中频信号的量化会带来信噪比损失,在一定程度上影响扩频系统的抗干扰性。为提升接收机输入端量化信噪比,针对服从高斯分布的噪声且低信噪比的接收机模拟中频信号,提出一种自适应功率的模拟中频信号的"最佳失真度量化方法"。首先分析数模转换器的特性划定量化门限,然后依照输入信号的统计特性,设计出最佳功率的计算方法,并提出新的评价指标"载噪比",可以在捕获前预先衡量量化损失。通过仿真计算了"最佳失真度量化方法"的载噪比,并与"传统法"进行对比。实现结果表明,所提方法的载噪比相对于"传统法"的均值提升0. 27 dBHz。

The quantization of the analog intermediate frequency( IF) signal in the spread spectrum system receiver will bring the signal-to-noise ratio( SNR) loss,which will affect the anti-interference of the spread spectrum system to some extent. In order to improve the quantized SNR at the input of the receiver,an ‘optimal distortion quantization method’for the analog IF signal of adaptive power is proposed,and the receiver IF signal with low SNR obeys the Gaussian distribution noise. Firstly,according to the characteristics of the analog-to-digital converter( ADC),the threshold is quantified. Secondly,according to the statistical characteristics of the input signal,the calculation method of the optimal power is designed. Finally,a new evaluation index ‘carrier-to-noise ratio’is proposed,which can measure the quantization loss before the capture. The carrier-to-noise ratio of the ‘optimal distortion quantization method’is calculated by simulation and compared with the ‘traditional method’. The results show that the carrier-to-noise ratio of the method is increased by an average of 0. 27 dBHz.