Abstract: 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 f1. Next a base integration signal is generated according to the integration of the electromagnetic signal with the frequency f1 for a current integration period x. Then a current integration signal is generated according to the integration of the electromagnetic signal with the frequency f1 for the current integration period x and a predetermined electromagnetic signal with a predetermined frequency f0 for the predetermined integration period y. Finally, a frequency variation value ?f between the frequency f1 and a current frequency fc is calculated and obtained according to the current integration signal and the base integration signal.

Abstract: An angle correcting method for a position pointer induced by a handwritten input device is disclosed. The steps of the method includes: firstly, an inclined angle table is provided. Then, a first induced voltage amplitude of a first position where the position pointer touches and a second induced voltage amplitude of a second position where is near to the first position are induced. The ratio of the first induced voltage amplitude to the second induced voltage amplitude is calculated to generate an amplitude ratio. Finally, the inclined angle table is looked up to find an inclined angle according to the amplitude ratio.

Abstract: 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 f1. Next a base integration signal is generated according to the integration of the electromagnetic signal with the frequency f1 for a current integration period x. Then a current integration signal is generated according to the integration of the electromagnetic signal with the frequency f1 for the current integration period x and a predetermined electromagnetic signal with a predetermined frequency f0 for the predetermined integration period y. Finally, a frequency variation value ?f between the frequency f1 and a current frequency fc is calculated and obtained according to the current integration signal and the base integration signal.

Abstract: An angle correcting method for a position pointer induced by a handwritten input device is disclosed. The steps of the method includes: firstly, an inclined angle table is provided. Then, a first induced voltage amplitude of a first position where the position pointer touches and a second induced voltage amplitude of a second position where is near to the first position are induced. The ratio of the first induced voltage amplitude to the second induced voltage amplitude is calculated to generate an amplitude ratio. Finally, the inclined angle table is looked up to find an inclined angle according to the amplitude ratio.