Position detection device

A position detection device comprising:

• a computer system, including a central processing unit (CPU), the computer system being configured to provide a demodulation section for receiving a modulated wave signal which is obtained by an amplitude modulation of an alternating current excitation signal on the basis of position information of a target detection device to be detected, and demodulating the position information from the modulated wave signal by using a plurality of sampling values of the modulated wave signal during a period of the alternating current excitation signal, and
• the demodulation section comprising:
• an alternating current excitation signal sampling section configured to sample the alternating current excitation signal so that the number of the alternating current excitation signals sampled during a first period in which alternating current excitation signals has a positive value is equal to the number of the alternating current excitation signal during a second period in which the alternating current excitation signal has a negative value;
• a detection section configured to receive an output of the alternating current excitation signal sampling section, and execute an eliminating process of eliminating an influence caused by a sign of the alternating current excitation signal from the position information when the position information is demodulated from the received modulated wave signal;
• and
• an avoidance section configured to avoid using the alternating current excitation signal having not more than a regulated value in the demodulation of the position information,
• wherein the regulated value is more than a changed value of the alternating current excitation signal during a time difference between a sampling time of the alternating current excitation signal sampled by the alternating current excitation signal sampling section and the sampling time of the modulated wave signals.