An early comment sent to this site raised a question as to how long I’ve been doing this kind of work. Yes I’m an old-timer. Some of my earlier Kalman filter studies are cited in books dating back to the 1970s — e.g., Jazwinski, Stochastic Processes and Filtering Theory, 1970 (page 267); Bryson & Ho, Applied Optimal Control, 1975 (page 374); Spilker, Digital Communication by Satellite, 1977 (page 636). My first book, published by Academic Press, initially appeared in 1976.
Early familiarizarion with Kalman filtering and inertial navigation paid huge dividends during subsequent efforts in other areas. Those included, at first, doppler nav with a time-shared radar beam (publication #20), synthetic aperture radar (publications #21, 22, 38, 41), synchronization (publication #19), tracking (publications #23, 24, 28, 30, 32, 36, 39, 40, 48, 52, 54, 60, 61, 66, 67, 69), transfer alignment (publications #29, 41, 44), software validation (publications #34, 42), image fusion (publications #43, 49), optimal control (publication #33), plus a few others. All these efforts made it quite clear to me — there’s much more to all this than sets of equations.
Involvement in all those fields had a side effect of delaying my entry into GPS work; I was a latecomer when the GPS pioneers were already established. GPS/GNSS is heavily involved, however, in much of my later work (latter half of my publications) — and my work in other areas produced a major benefit: The experience provided insights which, in the words of one reviewer quoted in the book description (click here) are either hard to find or unavailable anywhere else. Recognizing opportunities for synergism — many still absent from today’s operational systems — enabled me to cross the line into advocacy (publications #26, 47, 55, 63, 66, 68, 73, 74, 77, 83, 84, 85, 86). Innovations present in GNSS Aided Navigation and Tracking were either traceable to or enhanced by my earlier familiarization with techniques used in other areas.