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Coherent demodulation of ais-GMSK signals in co-channel

Patent image
NSA

The present invention pertains to demodulation of GMSK signals by estimating a carrier frequency of the signal having a carrier residual, basebanding the signal, tracking the signal's carrier frequency, removing the carrier residual, detecting a data burst, generating a bank of poly-bit matched filters, applying the bank of poly-bit matched filters to the signal, determining a magnitude and phase of the output of each poly-bit filter of the bank of poly-bit matched filters, determining a maximum magnitude, determining the location of a baud center, generating a plurality of correlation signals by applying the bank of poly-bit matched filters at the baud center, estimating a carrier phase, removing the estimated carrier phase, applying a Viterbi decoding algorithm to the signal, and estimating the transmitted data sequence.

Inventors: 
Nelson, Douglas J.
Patent Number: 
Technical domain: 
Communications
FIle Date: 
2010-10-13
Grant Date: 
2012-09-25
Grant time: 
713 days
Grant time percentile rank: 
13
Claim count percentile rank: 
1
Citations percentile rank: 
1
'Cited by' percentile rank: 
1
Assignee: 
US DIRECTOR NAT SECURITY AGENC