Patent Number: 6,297,691

Title: Method and apparatus for demodulating coherent and non-coherent modulated signals

Abstract: A receiver receives modulated message signals in non-coherent FSK and coherent 8PSK protocols. A selectively configurable processor demodulates the message signals, and includes a demodulator that derives in-phase and quadrature signals based on the message signals. A phase detector is responsive to the in-phase and quadrature signals and delayed in-phase and quadrature signals to derive a phase signal. A selector is responsive to the in-phase and quadrature signals to selectively connect a loop filter between the phase detector and the demodulator. When the selector connects the filter between the phase detector and demodulator, the demodulator is responsive to filtered phase signals to lock onto a frequency of the message signals so that the processor operates as a phase locked loop to demodulate coherent modulated signals. When the selector disconnects the filter from between the phase detector and the demodulator, the demodulator demodulates non-coherent modulated signals and the phase detector supplies a phase signal representing the slope of the phase of the demodulated signal.

Inventors: Anderson; Stephen D. (Edina, MN), Hulse; Daniel V. (Prior Lake, MN), Moore; Kevin B. (Chaska, MN), Kammann; Paul D. (Golden Valley, MN), Maalouf; Gabriel A. (Minneapolis, MN)

Assignee: Rosemount Inc.

International Classification: H04L 27/233 (20060101); H04L 27/227 (20060101); H04L 27/00 (20060101); H03D 003/00 (); H04L 027/14 (); H04L 027/227 (); H04L 027/32 ()

Expiration Date: 10/02/2018