| 摘要 |
PURPOSE:To perform the adjustment of frequency characteristics automatically, quickly and with good accuracy, by detecting one optimum value of the intermediate frequency output of FM receiver and providing the control means processing this and two threshold values with comparison. CONSTITUTION:The positive and negative peak values of the response output by sweep signal from the intermediate frequency circuit are detected with the peak hold circuit 22 and 23 and held. The positive and negative peaks of the curcuits 22 and 23 are separately selected at the hold output selection circuit 24, and binary signal in A/D conversion 25 is fetched to the computer CM21, which cintrols the pulse motor 37 to establish a single peak. Further, CM21 calculates the threshold values of -3dB and -10dB from the output of the circuit 25 to produce the threshold values 2 and 3. The output 1 and the threshold values 2, 3 are compared 28, 29, the time width corresponding to the output waveform between the two threshold values is counted at the counters 33 and 34, and the output is inputted to CM21. The CM21 controls the adjusting driver 39 so that the difference can be equal to adjust the symmetry and the adjustment of S-shaped charcteristics can automatically be made by controlling the driver 40. |
