Accession Number : ADD004429

Title :   Self Learning Monitor for VLF Wave Propagation.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Swanson, Eric R

Report Date : 26 Jul 1977

Pagination or Media Count : 7

Abstract : This document describes a monitor for notifying a vehicle using VLF navigation of an abnormal condition of VLF wave propagation. Sensing means, including an antenna, oscillator, IF mixer, and phase tracker is provided to periodically sense changes in the phase angle of a VLF wave received by the monitor, and to couple a succession of values of an updating quantity into a data processing means, each value corresponding to a sensed amount of phase change. The data processing means learns what comprises a normal condition of VLF wave propagation by averaging successive values of the updating quantity, and provides notice of an abnormal condition whenever a received value of the updating quantity varies from the previously computed average by an amount in excess of a preselected criterion.

Descriptors :   *PATENTS, *GLOBAL POSITIONING SYSTEM, *RADIO NAVIGATION, *MONITORS, RADIO TRANSMISSION, VERY LOW FREQUENCY, ELECTROMAGNETIC WAVE PROPAGATION, ANOMALIES, SELF ORGANIZING SYSTEMS

Subject Categories : Navigation and Guidance

Distribution Statement : APPROVED FOR PUBLIC RELEASE