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A synoptic study of Sudden Phase Anomalies (SPA's) effecting VLF navigation and timingSudden phase anomalies (SPA's) observed on VLF recordings are related to sudden ionospheric disturbances due to solar flares. Results are presented for SPA statistics on 500 events observed in New York during the ten year period 1961 to 1970. Signals were at 10.2kHz and 13.6kHz emitted from the OMEGA transmitters in Hawaii and Trinidad. A relationship between SPA frequency and sun spot number was observed. For sun spot number near 85, about one SPA per day will be observed somewhere in the world. SPA activity nearly vanishes during periods of low sun spot number. During years of high solar activity, phase perturbations observed near noon are dominated by SPA effects beyond the 95th percentile. The SPA's can be represented by a rapid phase run-off which is approximately linear in time, peaking in about 6 minutes, and followed by a linear recovery. Typical duration is 49 minutes.
Document ID
19750003227
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Swanson, E. R. (Naval Electronics Lab. Center San Diego, CA, United States)
Kugel, C. P. (Naval Electronics Lab. Center San Diego, CA, United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1973
Publication Information
Publication: NASA. Goddard Space Flight Center Proc. of the 5th Ann. NASA and DOD Precise Time and Time Interval Planning Meeting
Subject Category
Aircraft Communications And Navigation
Accession Number
75N11299
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19750003203Collected WorksProceedings of the fifth annual NASA and Department of Defense Precise Time and Time Interval Planning Meeting19750003203Collected WorksProceedings of the fifth annual NASA and Department of Defense Precise Time and Time Interval Planning Meeting
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