| 摘要 |
PURPOSE:To increase the measuring accuracy of the reproducing level, by performing a DC conversion after detecting the difference between the maximum and minimum values of a frequency conversion signal. CONSTITUTION:A reference signal fs is produced 3 to measure the electromagnetic conversion characteristics of a test head 1, and both the frequency and the level of the signal fs are varied 4 in steps. An auxiliary reference signal fp whose phase to the signal fs shifts in a certain speed and in coupling to the frequency change of the signal fs is produced 7, and the signal fp is divided 9. Then both the signals fs and fp are recorded alternately to the head 1. Furthermore the signal fp among the reproduced signals of the head 1 is detected 11; while the signal fs is sampled and held 15. Then the peak value is detected 18 for the output of a circuit 15 to obtain the DC voltage. This voltage receives a digital conversion 24. |
