Once the optimum time constant has been established, the last item to note is how long the disciplining must occur in order to bring the clock to within the desired frequency error with respect to the reference clock. This is again limited by the composite instability of the two sources. As a rule of thumb, one can achieve relative accuracy comparable to the ADEV at a given averaging time after disciplining for three to four averaging periods. In the case of CSAC disciplined to GPS, as seen in Figure 2
, the CSAC-GPS error can be reduced to 8x10-13
after three to four 104
second averaging periods (about ten hours) and 1x10-13
seconds after three to four 105
seconds (several days).
About the author:
is the Director of Business Development for the Quantum Chip Scale Atomic Clock product line at Symmetricom. Previous to this role, Steve was the Sales Manager for Symmetricom’s Space, Defense, and Avionics product line.
Prior to joining Symmetricom, Steve worked for Hewlett-Packard and its spinoff Agilent Technologies, for 27 years. While at HP/Agilent, he served in management roles in Marketing, R&D, and General Management. During his management career he was part of an HP management team that was the subject of a Harvard Business School case study, which is still taught at HBS today. He also lived in the Netherlands for two years during one of his marketing assignments.
Steve’s technical background is in RF and microwave measurements, and semiconductor test. He brings a great deal of experience to the real-world applications of Symmetricom’s oscillators and atomic clocks.
About the contributor:
is the Applications Engineer for the Quantum Chip Scale Atomic Clock (CSAC) product line at Symmetricom. Elisabeth works with customers to help them maximize the benefits they can achieve using CSACs in a wide variety of applications. Prior to working at Symmetricom, Elisabeth was an electrical engineer at BAE Systems US for 6 years. She received her BSEE degree from the University of Massachusetts at Amherst.
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