The June meeting was held at the 1998 NAWCC National Convention in Portland, OR. Bill Givens opened the meeting and introduced Gordon Uber, who spoke on "The GPS System for Timing Applications." This was an overview of the GPS system, its satellites, and their internal rubidium and cesium clocks. The performance of various receiver modules was discussed, along with the TAC-2 interface and TAC-32 software. A commercial version of this system is now available from CNS Systems for about $800. Systems with Garmin GPS-20 or GPS-25 receivers achieve about 1 microsecond accuracy, and Motorola Oncore receivers approach 50 nanosecond accuracy. Various efforts are under way to discipline rubidium and quartz oscillators to the GPS 1 pulse/second signal, providing frequency accuracy approaching that of a cesium standard.

Bryan Mumford described his GPS interface for his MicroSet Timer. This permits the timing of high precision pendulum clocks to be referenced to UTC.

Tom Van Baak brought a cesium clock to show.

Gordon Uber brought copies of Blair Martin's 1962 master's thesis "An Analytical Investigation of the Ultimate Limitations on the Accuracy of the Pendulum Clock" and also of George Airy's 1827 paper "On the Distrubances of Pendulums and Balances, and on the Theory of Escapements." Contact him for copies.

Images of Meeting

CLOCKS and TIME / NAWCC Home Page / NAWCC Chapter Home Pages / HSC Home page