Method of differential-phase/absolute-amplitude polar qam

Abstract

A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2 N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

1 . A method of amplitude scale tracking to substantially reduce scale variations in a received quadrature amplitude modulated signal, the method comprising the steps of: 
 (a) determining an amplitude ratio of two or more consecutive sampled amplitude values;    (b) determining whether the amplitude ratio represents a valid transition;    (c) identifying, for a determined valid transition, one or more ideal amplitude levels corresponding to one or more sampled amplitude values of the valid amplitude transition;    (d) determining a scale factor value based upon the ideal amplitude level and the corresponding sampled amplitude level; and    (e) using the scaling factor value to scale and compensate for any changes in strength of the received quadrature amplitude modulated signal.    
   
   
       2 . The method as set forth in  claim 1 , wherein each sampled amplitude value of the two consecutive sampled amplitude values is approximately equal to √((I value) 2 +(Q value) 2 ).  
   
   
       3 . The method as set forth in  claim 1 , wherein the valid transition is determined as being within a pre-established tolerance of a nominal amplitude ratio.  
   
   
       4 . The method as set forth in  claim 3 , wherein the nominal amplitude ratio is of one or more higher amplitude values to one or more lower amplitude values.  
   
   
       5 . The method as set forth in  claim 3 , wherein the nominal amplitude ratio is of one or more lower amplitude value to one or more higher amplitude values.  
   
   
       6 . The method as set forth in  claim 1 , wherein the valid transition is determined as being within a pre-established tolerance of either a first nominal amplitude ratio or a second nominal amplitude ratio of any of the multiple possible pairs of amplitude levels, wherein the first nominal amplitude ratio is of a higher amplitude value to a lower amplitude value and the second nominal amplitude ratio is of the lower amplitude value to the higher amplitude value.  
   
   
       7 . The method as set forth in  claim 1 , wherein the scale factor comprises an average of a plurality of scale factors.  
   
   
       8 . The method as set forth in  claim 7 , wherein the average is a windowed/weighted average weighted in favor of the identified amplitude values closer to each received amplitude to be scaled.  
   
   
       9 . The method as set forth in  claim 1 , wherein step (e) includes—
 (e 1 ) determining an I value and a Q value corresponding to each of the two consecutive sampled amplitude values; and    (e 2 ) multiplying the I value and the Q value by the scaling factor value.    
   
   
       10 . A method of amplitude scale tracking to substantially reduce scale variations in a received quadrature amplitude modulated signal, the method comprising the steps of: 
 (a) determining an amplitude ratio of two consecutive sampled amplitude values, wherein each of the two consecutive sampled amplitude values is approximately equal to √((I value) 2 +(Q value) 2 );    (b) determining whether the amplitude ratio represents a valid transition as being within a pre-established tolerance of a nominal amplitude ratio;    (c) identifying, for a determined valid transition, one or more ideal amplitude levels corresponding to one or more sampled amplitude values of the valid amplitude transition;    (d) determining a scale factor value based upon the ideal amplitude level and the corresponding sampled amplitude level; and    (e) determining an I value and a Q value corresponding to the identified consecutive sampled amplitude values; and    (f) multiplying the I value and the Q value by the scaling factor value to compensate for any changes in strength of the received quadrature amplitude modulated signal.    
   
   
       11 . The method as set forth in  claim 10 , wherein the nominal amplitude ratio is of one or more higher amplitude values to one or more lower amplitude values.  
   
   
       12 . The method as set forth in  claim 10 , wherein the nominal amplitude ratio is of one or more lower amplitude values to one or more higher amplitude values.  
   
   
       13 . The method as set forth in  claim 10 , wherein the nominal amplitude ratio is either a first unique nominal amplitude ratio or a second unique nominal amplitude ratio, wherein the first unique nominal amplitude ratio is of an upper amplitude value to a lower amplitude value and the second unique nominal amplitude ratio is of the lower amplitude value to the higher amplitude value.