James L. Farrell

Amazon's directive for authors to "tell readers who you are" is especially appropriate here. There are (at least) three different authors with the name James L. Farrell, plus another navigation book author J. Farrell. Furthermore, one of the others named James L. Farrell is known primarily for books about Christianity -- and one of my books is entitled "Nuts & Bolts of Christianity." Readers seeing the name Farrell can therefore easily mistake one for another. At least one clarification is easy: I'm not the James L. Farrell who wrote about stock portfolios. Rather than spending more effort saying who I'm not, then, I'll just describe three books and my motivation for writing them.

First, one more clarification -- a fourth "book" listed was a NASA CR that appeared in multiple places. First, as a NASA Contractor Report in 1966, it documented work I performed for Goddard Space Flight Center. Since satellite attitude determination had not yet been formulated as a Kalman filtering application, it was also accepted for a Ph.D. dissertation at the University of Maryland. It was then presented at the 1967 International Federation of Automatic Control Conference in Vienna Austria and, finally, published in Automatica (May 1970).

The three books noted earlier will now be described in chronological order. For the two involving navigation, considerable additional material is freely available on JamesLFarrell.com. In fact, over a hundred pages of the last one can be seen ("try before you buy"), through a link provided under http://jameslfarrell.com/published-books-gnss-aided-navigation-and-tracking/gnss-aided-navigation-and-tracking.

Integrated Aircraft Navigation (Academic Press 1976) was the first book to combine modern estimation and inertial navigation, together with fundamental background material (various formalisms for expressing attitude and rotational dynamics, navigation/tracking interrelationships, detailed error propagation modeling, just enough matrix theory to cover the essentials, role of myriad external sensors such as optics or radar in various modes). It was guided before publication by two premier authorities in aerospace, Prof. Arthur E. Bryson of Stanford University and Dr. Bernard Friedland who was then at Singer-Kearfott. After publication it received favorable reviews from Dr. Wm. Klepczynski (then at the Naval Observatory) for the Institute of Navigation and from Dr. Jos. d'Appolito (then with TASC) for IEEE.

Shortly after publication, the book was eclipsed by appearance of GPS. Still there were five hard cover printings and the book, now available in paperback (http://jameslfarrell.com/wp-content/uploads/2010/06/ian1a.pdf), continues to be useful to those entering the field with a need to start with basic theory and principles for insight into practical operation. There were numerous testimonials from coursed I taught in the 1980s but, of greater significance currently, Prof. H. Hablani wrote a recent one visible from ny Facebook business page at http://www.facebook.com/pages/Vigil-Inc/118017154946809?sk=app_190322544333196

Practicality likewise provided motivation to write Nuts & Bolts of Christianity (2005). Vast numbers of practical-minded people don't readily relate to most literature involving spirituality or to religion in any form. The tone often seems highly theoretical, lofty, stilted, imperial ("talking down" to readers), possibly not even valid, or otherwise unrelated to readers' observations and experiences. So many sincerely want information that just makes sense, applying what's right to the here-and-now, with some reassurance that we really aren't alone and cast adrift by a God too busy to care about us. With no claim to be authoritative all I tried to do was to show, from today's happenings, glimmers of encouragement despite a very dark environment. You are not here by mistake nor accidentally (quite the opposite; there is a purpose that you can eventually discover). You are not being ignored (quite the opposite; an infinitely wise Supreme Being with unlimited generosity will guide you if you never quit trying). Etc., etc., etc., with illustrative practical examples.

My last book, GNSS Aided Navigation & Tracking, gives "cookbook" formulations enabling readers to realize state-of-the-art performance by processing raw inertial and GPS/GNSS data. This public domain no-strings-attached material can serve as pseudocode algorithms, already flight-validated with test results included and interpreted as part of the presentation. Support from theory and practice accompany the formulations for processing of gyro and accelerometer outputs, plus GPS pseudorange and carrier phase with rigorously derived integrity testing criteria for data acceptance-vs-rejection. Commonality between tracking and inertial navigation behavior is developed to an extent not previously recognized. Both striking differences and similarities among very different modes of tracking are presented, with ramifications heavily influencing the various algorithmic representations. Considerable innovation introduced by this author offers major improvements in robustness plus unprecedented situation awareness available from the thorough integration steps shown in this book.

All of this discussion is only the beginning of the book's description; the website mentioned above contains several one-page summaries, blog pages,PDF manuscripts, and even (as already mentioned) over a hundred pages for online viewing.