| 摘要 |
<p>PURPOSE: To enable the detection of vestigial sideband (VSB) amplitude modulated signal by providing a synchronous detector at a digital controlled oscillator to be used for a phase tracker and detecting the real number portion of final intermediate frequency(IF) signal according to the digital description of carrier wave. CONSTITUTION: With the VSB amplitude modulated signal as a base band, a sample from a digital circuit 2 for synchrodyne is applied to a quantizer 84, and a quantize level is generated. A signal, from which the quantize level is removed by a digital adder/subtracter 85, is defined as the input signal of quantizer 84, and correction required for correcting a detection error is performed to a difference signal from the subtracter 85 at the quantizer 84. The sample from the digital signal 2 is applied to an average square error inclination detecting filter 90 as an input signal, and this output is clocked by a rectangular wave response generated by a symmetric clipper or limiter 81. A product signal from a digital multiplier 86 is converted to an analog control signal by a digital/analog converter 88 and this is utilized by an oscillator 80.</p> |
