IS-GPS-800A - US Coast Guard Navigation Center

where, ISC L1CD is provided to the user as subframe 2 data.The values of ISC L1CP and ISC L1CD are measured values that represent the mean SV group delay differential betweenthe L1 P(Y)-code and the L1C P -code or L1C D -code respectively as follows,ISC L1CP = t L1P(Y) - t L1CPISC L1CD = t L1P(Y) - t L1CD ,where t L1x is the GPS time of the L1 frequency x signal (a specific epoch of the signal) transmitted from the SVantenna phase center.3.5.3.9.2 L1/L2 Ionospheric CorrectionThe two frequency (L1C P and L2C) user shall correct for the group delay and ionospheric effects by applying therelationship(PR L2C 12 PR L1CP ) c (ISC L2C PR 12 ISC L1CP ) c T1 GD .12The two frequency (L1C D and L2C) user shall correct for the group delay and ionospheric effects by applying therelationship(PR L2C 12 PR L1CD ) c (ISC L2C PR 12 ISC L1CD ) c T1 GD .12For the preceding equations, the following definitions apply:PR = pseudorange corrected for ionospheric effects,PR i = pseudorange measured on the channel indicated by the subscript,ISC i = inter-signal correction for the channel indicated by the subscript (see paragraph3.5.3.9.1, see paragraph 30.3.3.3.1.1 of IS-GPS-200 for ISC L2C ),T GD = see paragraph 20.3.3.3.3.2 of IS-GPS-200,c = speed of light,and, denoting the nominal center frequencies of L1 and L2 as f L1 and f L2 respectively, 12 = (f L1 /f L2 ) 2 = (1575.42/1227.6) 2 = (77/60) 2 .50 IS-GPS-800A8 June 2010