By Len Jacobson
The first time I ever heard of the Magnavox Research Laboratory in Torrance, California, was in 1966, as a young engineer working at Hughes Aircraft. We were building large (46-foot diameter) ground stations for the Defense Satellite Communications System (DSCS). Magnavox was supplying the secret anti-jam modems used in the terminals.
Because of this, I also learned a little about spread-spectrum pseudo-noise (PN), something quite esoteric at the time and not taught in engineering school. I noticed a widespread respect for Magnavox from my colleagues who referred to the company and its equipment as “Magicbox.”
Within a year I had transferred to the Hughes division responsible for developing satellites. We were working on a study known as 621B, for using satellites for positioning. Our teammate for the study was Magnavox. That team was responsible for the payload signal design, for which the team chose PN as the modulation to provide for multiple access, ranging, data transmission, and anti-jam.
Before long, my boss decided to leave Hughes and go work for Magnavox. He took two of his systems engineers with him. I was one of them.
In1968, the U.S. Air Force could not yet sell the 621B concept as an Advanced Development Program, so instead opted to experiment and prove that PN modulation could be used to accurately measure a half-mile of cable. Hughes bowed out since there wasn’t any satellite procurement in the offing. Magnavox and the other 621B contractor, TRW, each took on the challenge of measuring the cable.
Where Hughes had been 10-deep in Ph.D.s in every discipline, Magnavox was 10-deep in PN experts, which I believe at that time was the world’s majority. Thus it was natural for the Air Force to ask them to continue, and develop a receiver to be used in the next phase of 621B. An inverted range was set up with four PN transmitters, and an aircraft with the receiver and a bottom antenna flew over them. The aircraft’s position was determined using the PN range measurements and the known locations of the transmitters. The data from that receiver, called the MX450, was used to help justify the Department of Defense (DoD) decision to proceed into the Advanced Development Phase of GPS. Some of the people who contributed to this were named in Dr. Brad Parkinson’s recent articles on the origins of GPS. During that time I was working on the next generation of spread-spectrum modems for the DSCS.
Magnavox went on to develop these PN satcom modems for all three services, and thus was a natural choice to develop the first military GPS receivers (known as X and Y sets and the first Manpack), as well as the first C/A receiver, the Z set, and the very first spaceborne receiver called GPSPAC.
As soon as we completed the first Manpack, I approached Col. Paul Weber, the Joint Program Office Army Deputy Program Manger, and asked if he would pose with the Manpack on his back for a brochure we wanted to produce to show to potential Army and Marine Corps users. He agreed, dressed in his combat uniform, and went with our photographer into the wild woods of San Pedro (near the Port of Los Angeles) for the picture shown in the brochure.
Magnavox also developed the military GPS Engineering Models in competition with Rockwell Collins. Magnavox lost the production contract to Rockwell Collins a year after I left to join IEC, now known as L-3 Communications.
Magnavox also pioneered commercial GPS sets for use in the marine and survey markets. Today, you will still find many of the original GPS user equipment developers still at it as consultants and engineers at Raytheon, Navcom, Trimble, IEC, and others. Perhaps our most famous alumni is Dr. Min Kao, the “min” of Garmin.
LEN JACOBSON is a consultant to the GPS industry and has served as an expert witness in many legal proceedings involving GPS. He is the author of the book GNSS Markets and Applications, published in 2007, and is a longstanding member of this magazine’s Editorial Advisory Board.