The present invention provides a digital signal processing method and system thereof for producing precision platform orientation measurements and local Earth's magnetic measurements by measuring threes axes gravity acceleration digital signals by an acceleration producer, detecting Earth's magnetic field vector measurement by an Earth's magnetic field detector to achieve digital three-axes Earth's magnetic field vector signals, and producing pitch, roll, and heading angles using said three-axes gravity acceleration digital signals and said digital three-axes Earth magnetic field vector signals by a Digital Signal Processor (DSP) chipset.