Agilent 1959-11 free download

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HEWLETT-PACKARD JOURNAL T E C H N I C A L I N F O R M A T I O N F R O M T H E - d p - L A B O R A T O R I E S Vol. 1 1 No. 3-4 'UBLISHED BY THE HEWLETT-PACKARD COMPANY, 1501 PAGE MILL ROAD, PALO ALTO, CALIFORNIA NOV.-DEC, 1959 A New Clock for Improving the Accuracy of Local Frequency and Time Standards In line with the continually advancing ma to reduce comparison error, it should be noted turity of the electronics field as a whole, the that the accuracy of WWV carrier and time portion of the field concerned with frequency signals is currently 2 parts in 10'°. control has made significant forward strides in COMPARISON CONSIDERATIONS recent years. As a result, high-precision fre When calibrating a local standard against quency standards employing quartz resonators the transmissions from a standard radio sta presently achieve stabilities of a part in 109 tion such as WWV or WWVH, the necessary per day or better, while atomic standards ex comparison can be made by either of two basic hibit accuracies of one or two parts in 1010. methods. The more widely used but less pre In order to operate a frequency standard at cise method is the direct frequency comparison or near presently attainable accuracies, it is in which the local standard frequency (or its necessary to minimize the error that may occur harmonic) is directly compared with the car in comparing the standard with the primary rier frequency of the received standard trans signal against which the standard will be cali mission (or its harmonic). In this method the brated. In precision work such comparison maximum accuracy achievable is determined error should be minimized, not only so that by the uncertainty that variations in the trans the uncertainty in the standard will be re mission medium introduce into the transmis duced, but also so that the drift characteristic sion. For th