M. Sylvander et al., ABSOLUTE IONOSPHERIC VERTICAL ELECTRON-CO NTENT INFERRED FROM TRANSMISSIONS OF THE GLOBAL POSITIONING SYSTEM, Comptes rendus de l'Academie des sciences. Serie II. Mecanique, physique, chimie, astronomie, 320(9), 1995, pp. 793-799
The signals transmitted at 1,575.42 and 1,227.6 MHz by the GPS satelli
tes are dispersively retarded by propagation through the ionosphere. U
sing the phase delay and group delay (pseudorange) recorded at both fr
equencies by GPS receivers, we construct an observable to measure the
total electron content in the ionosphere. After correction for a recei
ver-generated offset between the two group delays, this observable yie
lds the diurnal variation of the vertical electron content above the r
eceiver. Comparisons with a standard model and with data obtained from
the European Incoherent Scatter (EISCAT) VHF radar indicate that the
technique is accurate in mid-latitude regions.