| 摘要 |
PURPOSE:To attain demodulation of high quality by interpolating a omitted pulse existing in a PDM wave at the time of demodulating a PDM wave by a pulse counting type FM receiver. CONSTITUTION:A capacitor 7 is turned on by an electronic switch 4 based on a PDM wave pulse to obtain a saw-like pulse (saw wave) 13. A differential amplifer 9 finds out a difference between the saw wave and an output from a delay circuit 8, a box car circuit 10 stores a peak value up to a succeeding pulse and an (amplifier + slicer) 11 extends the positive component of a difference between the output of the circuit 10 and the saw wave and slices the magnified value to a fixed value to obtain an output pulse 12. The pulse 12 is applied to a fine delay circuit 14, a difference between the output of the circuit 14 and the output pulse is found out by a differential amplifier 15 and the positive polarity component of the differential output is outputted from a rectifier element 16 and delayed by a delay circuit 17 to obtain a pulse string including a pulse (interpolating pulse) on a position close to a pulse omitted position. Only the interpolating pulse in the pulse string is extracted and added to a PDM wave 3 by an adding circuit 20 through a delay circuit 18 to obtain an interpolated PDM signal 3'. |
