Using easy bit decisions to improve the DPSK demodulation of SPS data

摘要

A method (1000) of data demodulation, said method comprising: providing (1010) a first input signal comprising a transmitted data word; processing (1014) said first input signal with a differential phase change key demodulator to obtain from said first input signal a first set of first easy decision information values corresponding to bit index positions in said word of transmitted data; providing (1018) a second input signal; processing (1022) said second input signal with a differential phase change key demodulator to obtain from said second input signal a second set of second easy decision information values corresponding to the bit index positions in said transmitted data word; performing (1026) a mathematical function in said first and second sets of corresponding first and second easy decision information values in order to obtain a third set of substitute easy decision information values corresponding to the respective bit index positions in said transmitted data word, wherein said embodiment (1026) of said mathematical function comprises at least one of: averaging the magnitude of said first easy decision information value and the magnitude of said second easy decision information value corresponding to a particular bit index position in said data word, adding the magnitude of said first easy decision information value and the magnitude of said second easy decision information value corresponding to a particular bit index position in said word of data, or multiply the magnitude of said first information value easy decision with the magnitude of said second easy decision information value corresponding to a particular bit index position in said data word; and switching a difficult decision bit value based on said substitute easy decision information values, wherein said switching of said bit value comprises: switching the binary value of a difficult decision bit associated with the magnitude of absolute value plus low of substitute easy decision information.