Abstract: The present invention is a filtering apparatus in an 8 Phase Shift Keying (8PSK) system. The filtering apparatus comprises a ?/16 phase shift module, a weight distribution module, and a combination module. The ?/16 phase shift module is used for shifting a second vector from a 3?/8 phase shift module with ?/16 radians to generate a corresponding third vector. The weight distribution module is used for distributing a plurality of selected weights to a predetermined distribution waveform and storing a plurality of corresponding weighted distribution waveforms. The combination module, according to the third vector, is used for determining which weight distribution waveforms to be selected from the weight distribution module and combining the selected weighted distribution waveforms to generate a modulation signal. The filtering apparatus and method of the present invention may save a lot of memory in the filtering process.

Abstract: The present invention is a filtering apparatus in an 8 Phase Shift Keying (8PSK) system. The filtering apparatus comprises a &pgr;/16 phase shift module, a weight distribution module, and a combination module. The &pgr;/16 phase shift module is used for shifting a second vector from a 3&pgr;/8 phase shift module with &pgr;/16 radians to generate a corresponding third vector. The weight distribution module is used for distributing a plurality of selected weights to a predetermined distribution waveform and storing a plurality of corresponding weighted distribution waveforms. The combination module, according to the third vector, is used for determining which weight distribution waveforms to be selected from the weight distribution module and combining the selected weighted distribution waveforms to generate a modulation signal. The filtering apparatus and method of the present invention may save a lot of memory in the filtering process.

Abstract: The present invention discloses an envelope detection circuit by using a peel cone approximation concept. The envelope detection circuit comprises an absolute value comparision mechanism, a read only memory and a multiplier/adder mechanism. Particularly, the present invention uses a divider to generate an address of the read only memory to obtain less error and less hardware cost.

Abstract: The present invention discloses an apparatus and method for implementing an inverse arctangent function using piecewise linear theorem to simplify and used to transform a right-angled coordinate point X and Y to a phase angle &thgr; of an inverse arctangent function. The present invention uses T-line combination to approach an inverse arctangent function between 0 degree to 45 degree, and determines which piecewise linear region the right-angled coordinate point is located at. A coefficient table stored in a memory is used to compute {circumflex over (&thgr;)} which is the approximate value of the phase angle &thgr;. The phase angle {circumflex over (&thgr;)} between 45 degree to 360 degree can be mapped to the approximate phase angle {circumflex over (&thgr;)} between 0 degree to 45 degree using linear combination.