| 摘要 |
PURPOSE:To convert an FM signal into a digital signal with low distortion factor and high S/N by applying prediction coding AD conversion to an FM input signal while applying FM negative feedback. CONSTITUTION:The circuit acts like an FM negative feedback loop and an output of a VCO 5 is tracked to an input FM signal, then a signal (f1-f2) is an error signal of tracking, the FM detector 3 applies FM detection to the error signal and a quantizer 4 quantizes the error signal. A DPC output is obtained from the output of the quantizer 4, a predicting device 7 integrates the output of the quantizer 4 digitally and the output of the prediction device 7 becomes an output of prediction signal and used as a PCM output. The output of the prediction device 7 is converted into an analog signal by a DA converter 6 and the signal controls a VCO 5. The output of the VCO 5 is inputted to a mixer 1, where it is multiplied with the input FM signal. |
