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High resolution time interval counterIn recent years, we have developed two types of high resolution, multi-channel time interval counters. In the NIST two-way time transfer MODEM application, the counter is designed for operating primarily in the interrupt-driven mode, with 3 start channels and 3 stop channels. The intended start and stop signals are 1 PPS, although other frequencies can also be applied to start and stop the count. The time interval counters used in the NIST Frequency Measurement and Analysis System are implemented with 7 start channels and 7 stop channels. Four of the 7 start channels are devoted to the frequencies of 1 MHz, 5 MHz or 10 MHz, while triggering signals to all other start and stop channels can range from 1 PPS to 100 kHz. Time interval interpolation plays a key role in achieving the high resolution time interval measurements for both counters. With a 10 MHz time base, both counters demonstrate a single-shot resolution of better than 40 ps, and a stability of better than 5 x 10(exp -12) (sigma(sub chi)(tau)) after self test of 1000 seconds). The maximum rate of time interval measurements (with no dead time) is 1.0 kHz for the counter used in the MODEM application and is 2.0 kHz for the counter used in the Frequency Measurement and Analysis System. The counters are implemented as plug-in units for an AT-compatible personal computer. This configuration provides an efficient way of using a computer not only to control and operate the counters, but also to store and process measured data.
Document ID
19950025910
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Zhang, Victor S.
(National Physical Lab. Teddington, United Kingdom)
Davis, Dick D.
(National Physical Lab. Teddington, United Kingdom)
Lombardi, Michael A.
(National Physical Lab. Teddington, United Kingdom)
Date Acquired
September 6, 2013
Publication Date
May 1, 1995
Publication Information
Publication: NASA. Goddard Space Flight Center, The 26th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting
Subject Category
Physics (General)
Accession Number
95N32331
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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