Energy Efficient Highway Addressable Remote Transducer Coherent 8-ary Phase Shift Keying Modem

A method for demodulating an analog signal comprising a highway addressable remote transducer message, said method comprising:

• providing a highway addressable remote transducer modem comprising a coherent phase shift keying demodulator and at least one microcontroller configured to execute computer program instructions for operating said highway addressable remote transducer modem, said coherent phase shift keying demodulator comprising analog-to-digital converters, a high pass filter, an energy detector, mixers, root raised cosine filters, a decision estimator, an adaptive equalizer, and a data slicer;
• receiving and converting said analog signal comprising said highway addressable remote transducer message into digitized samples using one of said analog-to-digital converters, by sampling and digitizing said received analog signal at a sampling rate;
• processing said digitized samples by said high pass filter for removing low frequency interfering signals from said digitized samples;
• comparing signal amplitudes of said processed digitized samples with predetermined threshold values and applying a fast energy detection algorithm on said processed digitized samples by said at least one microcontroller using said energy detector for determining further signal processing of said processed digitized samples;
• generating an in-phase component and a quadrature phase component of each of said processed digitized samples by said mixers by mixing said each of said processed digitized samples with an in-phase carrier signal and a quadrature phase carrier signal respectively;
• generating an in-phase signal and a quadrature phase signal corresponding to said each of said processed digitized samples by said root raised cosine filters by pulse shaping said generated in-phase component and said generated quadrature phase component of said each of said processed digitized samples respectively;
• performing a coarse estimation of a phase error of said each of said processed digitized samples by said decision estimator by determining a final phase error correction using said generated in-phase signal and said generated quadrature phase signal corresponding to said each of said processed digitized samples;
• performing a fine estimation of said phase error of said each of said processed digitized samples by said decision estimator using said determined final phase error correction by determining a resultant final phase error correction;
• estimating a timing offset in each of subsequent said processed digitized samples by said decision estimator on applying said determined resultant final phase error correction to an in-phase signal and a quadrature phase signal generated by said root raised cosine filters corresponding to said each of said subsequent said processed digitized samples and on determining coefficients of said adaptive equalizer by said decision estimator for obtaining demodulated digitized samples;
• and
• assembling a character for character generation of said demodulated digitized samples by said data slicer.