24 September 2004 Limit parameters of GPS disciplined quartz frequency sources
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Proceedings Volume 5582, Advanced Optoelectronics and Lasers; (2004) https://doi.org/10.1117/12.583378
Event: 2003 Chapter books, 2003, Bellingham, WA, United States
Fivefold decrease of RMS jitter of 1 pps pulse from GPS receiver after SA switch-off and relatively short period required to filter it out has enabled the construction of GPS synchronized frequency sources of parameters almost order of magnitude better than with SA. New design challenge has been to achieve 10-11 frequency accuracy over time period of 1000 seconds. Basic block diagram of GPS disciplined frequency source is presented in fig 1. The only non purely digital blocks of the source are quartz oscillator and digital to analog converter D/A and their specs decide about the parameters of the output frequency signal. Design requirements for internal quartz oscillator as well as digital to analog converter based on required minimal frequency control loop time of about 10000 seconds have been derived and presented. To summarize, quartz oscillator has to exhibit aging not worse than 3 • 10-11/24h and temperature coefficient 1•10-12/°C while digital to analog converter has to be an 18-bit device with 1 LSB differential nonlinearity and extremely low temperature coefficient. Alternately as devices with very low temperature drift are very expensive, the converter can take its reference voltage from the oscillator, where the reference source is temperature stabilized. This of course places higher demands on the oscillator voltage reference source.
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Krzysztof Weiss, Krzysztof Weiss, Aleksander Lisowiec, Aleksander Lisowiec, Wojciech Steplewski, Wojciech Steplewski, "Limit parameters of GPS disciplined quartz frequency sources", Proc. SPIE 5582, Advanced Optoelectronics and Lasers, (24 September 2004); doi: 10.1117/12.583378; https://doi.org/10.1117/12.583378

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