THE STATE OF THE ART IN AMATEUR TIMEKEEPING

摘要

One might assume precise time metrology is the exclusive domain of national scientific laboratories, military infrastructure, or professional calibration centers. But there are a number of amateurs who in recent years have built home timing labs purely as a hobby, the performance of which now rivals that of some national labs. An even larger number of individuals, perhaps hundreds, own atomic standards and use them to satisfy or fuel their curiosity about the world of ultra-precise timekeeping. The following paper describes an extreme case of one home timing lab. First, its motivation and history: from a pair of wrist watches 30 years ago, accurate to seconds per week, to a pair of active hydrogen masers today, stable to parts in ten to the 15th. Second, its accomplishments: in the form of Web-published experiments, including stability analysis of TCXO and OCXO, stability comparison of 12 GPS-disciplined oscillators, probing the cesium hyperfine clock transition, hydrogen maser auto-tuning results, GPS performance with and without selective availability, homemade software tools, and PC-based instrumentation systems. Finally, the paper describes the technical challenges that a home timing lab faces, many of which are the same challenges as a national timing laboratory, though on a smaller scale. Solutions to such problems as budget, power, temperature, space, redundancy, time transfer, security, computer logging and networking, and automated operation are discussed.