Time-Quantized Frequency Modulation, Time-Domain Dither, Dispersive Codes, and Parametrically Controlled Noise Shaping in SDM*
نویسنده
چکیده
Time-domain quantization (TDQ) and noise shaping applied to linear frequency modulation (LFM) offers an alternative although unconventional means of generating uniformly sampled 1-bit code with characteristics similar to that generated by feedback sigma–delta modulation (SDM). Fundamental insight into the SDM process emerges by exploiting the relationship between uniform quantization and phase modulation. Linearity and output noise spectra are benchmarked against linear pulse-code modulation (LPCM) and error spectra derived by comparing 1-bit SDM against an identical feedback loop but without quantization. Sony FF class SDM is discussed and an example is shown to achieve almost noiseless performance from 0 Hz to 30 kHz by incorporating parametrically determined noise shaping stabilized by step-back in time closed-loop control.
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