Statistical process control for frequency control

Some possibilities of using statistical process control (SPC) tools to improve the accuracy, precision and quality of frequency control are discussed. The tools presented are process flow charts, Pareto charts, cause and effect charts, histograms, scatter diagrams/regression, control charts and experiments in the control of frequency standard processes. Some of the major variables considered are crystals, thermistors, selastic, and workmanship. Their relationships to frequency stability are studied. No experimental work has been done. A few approaches to studying frequency control using the preventative method of SPC are discussed. The major emphasis is on reducing the variation of the frequency stability by studying variation and being able to sort out the signal (assignable causes) from the noise (random causes). Some specific items included are when and how to look at the distributions of the data along with when and how to look at the data over time