Ionospheric measurements from Navstar satellites

For several months three Navstar satellites had been extensively tracked by monitor stations located in California, Alaska, Hawaii, and Guam. Data was acquired on the ionospheric delay encountered by the navigation signal from the satellites. This paper describes the measurement techniques used at the monitor stations, the data obtained from these measurements, and the methods used to calculate ionospheric delay. Typical plots of this delay for various combinations of monitor stations and satellites are presented.