The orbital error is one of the errors in GPS which affect the accuracy of GPS positioning. In this research GPS
broadcast, ultra-rapid, rapid and precise satellite ephemerides are used for processing different baseline lengths among
some CORS stations by using the Trimble Business Center software (TBC) and different satellite ephemerides (NRCan
ultra-rapid, NRCan rapid and IGS final) are tested in CSRS-PPP online application at the same CORS stations.
In this research, when using TBC software for processing the different baseline lengths by using the different satellite ephemerides and compared the coordinates of CORS stations which obtained from the different satellite ephemerides with
each other. The results showed that the best satellite ephemerides closest to rapid and final satellite ephemerides are the
ultra-rapid (00 UTC) and ultra-rapid (06 UTC). When processing the same CORS stations which used at TBC on CSRSPPP online application by using the different satellite ephemerides it is found also that the NRCan ultra-rapid closest to
final satellite ephemerides