| 摘要 |
<p>SIGNAL SYNTHESIZER SPECTRUM CONTOUR SCALER A digital signal representative of a first analog signal, such as a voice signal, having varying parameters, such as frequency or amplitude, is converted by a synthesizer into an analog output signal which varies in substantially the same manner as the first signal. The synthesizer receives a transmitted digital signal representing the first analog signal and synthesizes the varying parameters thereof to provide the analog output signal. First, the digital input signal is applied to a serial-to-parallel converter and subsequently input to a modulated frequency generator controlled by the operation of a modulation controller. Digital data processed through the modulated frequency generator is time and frequency scaled, and it is this time and frequency scaling that provides improved accuracy in recreating the proper amplitude relationship of the first analog signal. Following time and frequency scaling, the processed digital data is input to an amplitude accumulator and subsequently converted into the analog output signal in a digital-to-analog converter. Time scaling is implemented by apparatus that utilizes the transmitted digital data information to interpolate between spectrum segments to present a smooth spectrum to the output analog signal. For frequency scaling, the frequency scaler interpolates between harmonic frequencies of the first analog signal in consecutive frames and the processed digital data of the time scaling. Both the time domain scaling and the frequency domain scaling are based on the value of a cosine squared function extending between adjacent data points on adjacent frames.</p> |
