Orthogonal frequency coding for SAW device applications

This paper presents the concept of orthogonal frequency coding (OFC) for applications to SAW device technology. OFC is the use of orthogonal frequencies to encode a signal. which spreads the signal bandwidth in a manner similar to a fixed M-ary frequency shift signal. Also, a pseudo noise (PN) sequence can be added for additional coding. The OFC technique provides a wide bandwidth spread spectrum signal with all the inherent advantages obtained from the time-bandwidth product increase over the data bandwidth. The theory of OFC is presented and discussed, defining the fundamental equations and showing the time and frequency domain relationships. The application of OFC to SAW devices for tagging is introduced.