Method for frequency detection and detecting variation of frequency
Method for frequency detection and detecting variation of frequency is disclosed. The method comprises the following steps. First of all, a pointer is provided over an electromagnetic position detection apparatus, wherein the pointer emits an electromagnetic signal with a frequency f 1 . Next a base integration signal is generated according to the integration of the electromagnetic signal with the frequency f 1 for a current integration period x. Then a current integration signal is generated according to the integration of the electromagnetic signal with the frequency f 1 for the current integration period x and a predetermined electromagnetic signal with a predetermined frequency f 0 for the predetermined integration period y. Finally, a frequency variation value Δf between the frequency f 1 and a current frequency f c is calculated and obtained according to the current integration signal and the base integration signal.
1. A method for frequency detection and detecting variation of frequency comprising:
providing a pointer on an electromagnetic position detection apparatus, the pointer emitting a signal with a frequency f 1 to the electromagnetic position detection apparatus;
generating a base integration signal according to a current integration period x and the signal with the frequency f 1 by the electromagnetic position detection apparatus;
generating a current integration signal according to the current integration period x and a predetermined integration period y and a predetermined signal with a Predetermined frequency f 0 by the electromagnetic position detection apparatus; and
calculating a variation of frequency Δf between the predetermined frequency f 0 and a current frequency f c according to the base integration signal and the current integration signal by the electromagnetic position detection apparatus, wherein the current frequency f c is calculated via selecting a number of cycles of the signal with the frequency f 1 and a number of cycles of the predetermined signal with the frequency f 0 .
2. The method according to claim 1 , wherein the pointer comprises a batteryless pointer.
3. The method according to claim 1 , wherein the predetermined integration period y is larger than the current integration period x.
4. The method according to claim 1 , wherein the predetermined integration period y is a multiple of the period of the predetermined signal with the predetermined frequency f 0 , and the current integration period x is a multiple of the period of the signal with the frequency f 1 .
5. The method according to claim 1 , wherein the predetermined frequency f 0 is higher than the frequency f 1 .