James L. Farrell

On the last day of ION-GNSS 2010, a serendipitous thing happened. While walking toward the upstairs exit I met Brad Parkinson, alone for just 5 minutes, waiting for his wife. Conversation immediately turned, not surprisingly, toward interoperability. He was very interested in how the Ohio...more >>

Just a short time ago I read August's Expert Advice by the Masked Engineer. I wish to lend full unflinching support to everything stated in that tract. One advantage I have over that author: I'm self-employed — no one tells me to be quiet. At the same time I have bent over backwards to offer...more >>

Recent attention given to aging GPS satellites and availability gaps from lagging constellation replenishment have provoked deep concern, particularly within the aviation community. Available remedies include exploitation of well known but unused methods plus new techniques; those discussed here...more >>

The May 2008 Innovation column describes carrier-phase sequential changes with the immediate benefit of integer cancellation; no need for ambiguity resolution. In a nutshell, the column correctly notes usefulness of carrier phase sequential changes — but it describes 11 different "caveats" (a...more >>

Terry McGurn's closing observations in his November 2007 column on accuracy evoke a grateful reaction from me. Glib summaries of performance are incomplete. Pinpointing moving objects within ever-smaller fractions of size is not always most important; frequently, it's knowing where they'll be a...more >>