Title :
The accuracy evaluation of NIST-7
Author :
Lee, W.D. ; Shirley, J.H. ; Lowe, J.P. ; Drullinger, R.E.
Author_Institution :
Time & Freq. Div., Nat. Inst. of Stand. & Technol., Boulder, CO, USA
fDate :
4/1/1995 12:00:00 AM
Abstract :
We have performed evaluations of the major systematic errors in NIST-7 with an overall uncertainty of less than a part in 1014. The complete evaluation process has been separated into two parts. With a computer-controlled, digital servo system and some new measurement techniques, we now perform core evaluations (second-order Zeeman and Doppler shifts, cavity pulling and phase shift, line overlap and some electronic shifts) with an overall uncertainty of less than one part in 1014 in just a few days of measurements. The complete evaluation of all small and subtle effects in both the physics and electronics requires a few hundred days of data. But, these small effects are not variable at the 10-14 level and their infrequent evaluation does not detract from the operational accuracy of the standard
Keywords :
Doppler effect; Doppler shift; Zeeman effect; atomic beams; atomic clocks; computerised instrumentation; frequency control; frequency measurement; measurement errors; measurement standards; physical instrumentation control; Doppler shifts; NIST-7; atomic beams; cavity pulling; computer-controlled system; digital servo system; electronic shifts; line overlap; magnetic fields effects; measurement standards; phase shift; second-order Zeeman shifts; systematic errors; uncertainty; Atomic measurements; Doppler shift; Frequency measurement; Magnetic field measurement; Measurement techniques; Microwave measurements; Performance evaluation; Power measurement; Servomechanisms; Stability;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
