自适应加重网络增量调制理论分析及电路实现

Theoretical analysis and circuit implementation of adaptive weighted delta modulation

分析音乐信号数字传输处理———自适应加重网络增量调制的原理和适用性, 从理论上推导和完善了自适应加重网络的传递函数表达式, 描绘了音乐信号的自适应加重曲线. 采用瞬时频率法检测信号的频率, 接收端根据音乐信号频率大小自动改变去加重网络的上限频率, 从而实现降低噪声和提高信噪比,发送端则要采用预加重网络以补偿接收端去加重网络产生的失真. 在工作频率为3kHz时可提高信噪比约7dB, 给出了整个自适应加重网络的具体框图和部分电路.

Adaptive weighted delta modulation was developed to improve digital transmission and processing of music signals. Its mechanism and applicability were analyzed in detail. The transfer function for the adaptive weighting was derived theoretically and the characteristic curve of adaptive weighting for the music signal was generated as well. The method of detecting instantaneous frequency was used to find signal frequency. The upper bound frequency was adaptively adjusted based on the signal frequency of the music, thus decreasing noise and increasing the signal to noise ratio (SNR) at the receiver. At the transmitter, a pre-weighted network was used to compensate distortion (generated) by the de-weighted network at the receiver. An improvement of 7 dB is achieved at an operating (frequency) of 3 kHz. The block diagram for this adaptive weighted system and related circuits are given.