Method and apparatus for reception and noncoherent serial correlation of a continuous phase modulated signal

A non-coherent serial CPM correlator for despreading a received continuous phase modulated spread spectrum signal comprising:

• a power divider connected to a received spread spectrum signal, and having as outputs a real signal and an imaginary signal;
• a real serial correlator connected to said real signal and having as an output a real correlation signal, said real serial correlator comprising:
• a real power divider connected to said real signal, and having as outputs a first signal and a second signal, said first signal and said second signal being duplicates of one another,
• a real I demodulator connected to said first signal and to a first non-coherent local reference signal, and having as an output a real I signal,
• a real Q demodulator connected to said second signal and to a second non-coherent local reference signal, and having as an output a real Q signal, said second non-coherent local reference signal phase offset from said first non-coherent local reference signal by 90 degrees,
• a real I multiplier connected to said real I signal and to an odd chip signal representing the odd chips of a chip sequence and having as an output a real I product signal,
• a real Q multiplier connected to said real Q signal and to an even chip signal representing the even chips of said chip sequence and having as an output a real Q product signal,
• a real I integrator connected to said real I product signal and having as an output a real I correlation signal,
• a real Q integrator connected to said real Q product signal and having as an output a real Q correlation signal, and
• a real summer connected to said real I correlation signal and to said real Q correlation signal, and having as an output said real correlation signal;
• an imaginary serial correlator connected to said imaginary signal and having as an output an imaginary correlation signal, said imaginary serial correlator comprising:
• an imaginary power divider connected to said imaginary signal, and having as outputs a third signal and a fourth signal, said third signal and said fourth signal being duplicates of one another,
• an imaginary I demodulator connected to said third signal and to said first non-coherent local reference signal, and having as an output an imaginary I signal,
• an imaginary Q demodulator connected to said fourth signal and to said second non-coherent local reference signal, and having as an output an imaginary Q signal,
• an imaginary I multiplier connected to said imaginary I signal and to said odd chip signal, and having as an output an imaginary I product signal,
• an imaginary Q multiplier connected to said imaginary Q signal and to an inverse of said even chip signal, and having as an output an imaginary Q product signal,
• an imaginary I integrator connected to said imaginary I product signal and having as an output an imaginary I correlation signal,
• an imaginary Q integrator connected to said imaginary Q product signal and having as an output an imaginary Q correlation signal, and
• an imaginary summer connected to said imaginary I correlation signal and to said imaginary Q correlation signal, and having as an output said imaginary correlation signal;
• and
• means for combining said real correlation signal and said imaginary correlation signal into a final correlation signal.

A method for despreading a received continuous phase modulated spread spectrum signal comprising the steps of:

• dividing a received spread spectrum signal into a real signal and an imaginary signal;
• correlating said real signal to generate a real correlation signal, said step of correlating said real signal further comprising the steps of
• dividing said real signal into a first signal and a second signal, said first signal and said second signal being duplicates of one another,
• demodulating said first signal with a first non-coherent local reference signal to generate a real I signal,
• demodulating said second signal with a second non-coherent local reference signal to generate a real Q signal, said second non-coherent local reference signal phase offset from said first non-coherent local reference signal by 90 degrees,
• multiplying said real I signal with an odd chip signal representing the odd chips of a chip sequence to generate a real I product signal,
• multiplying said real Q signal with an even chip signal representing the even chips of said chip sequence to generate a real Q product signal,
• integrating said real I product signal to generate a real I correlation signal,
• integrating said real Q product signal to generate a real Q correlation signal, and
• summing said real I correlation signal and said real Q correlation signal into said real correlation signal,
• correlating said imaginary signal to generate an imaginary correlation signal, said step of correlating said imaginary serial further comprising the steps of
• dividing said imaginary signal into a third signal and a fourth signal, said third signal and said fourth signal being duplicates of one another,
• demodulating said third signal with said first non-coherent local reference signal to generate an imaginary I signal,
• demodulating said fourth signal with said second non-coherent local reference signal to generate an imaginary Q signal,
• multiplying said imaginary I signal with said odd chip signal to generate an imaginary I product signal,
• multiplying said imaginary Q signal with an inverse of said even chip signal to generate an imaginary Q product signal,
• integrating said imaginary I product signal to generate an imaginary I correlation signal,
• integrating said imaginary Q product signal to generate an imaginary Q correlation signal, and
• summing said imaginary I correlation signal and said imaginary Q correlation signal into said imaginary correlation signal;
• and
• combining said real correlation signal and said imaginary correlation signal into a final correlation signal.

An apparatus for despreading a received continuous phase modulated spread spectrum signal comprising:

• a power divider connected to a received spread spectrum signal, having as outputs a real signal and an imaginary signal,
• a first serial correlator connected to said real signal and having as an output a real correlation signal,
• a second serial correlator connected to said imaginary signal and having as an output an imaginary signal, and
• a calculation circuit connected to said first serial correlator and said second serial correlator, said calculation circuit outputting a unified correlation signal corresponding to a combination of said real correlation signal and said imaginary correlation signal.