GPS uses PN codes for the timing difference measurement, as well as allowing multiple satellites on a single channel. I believe the dithering (selective availa

GPS uses PN codes for the timing difference measurement, as well as allowing multiple satellites on a single channel. I believe the dithering (selective availability) was turned off years ago, thus the L2 channel ads only ionospheric correction (which can also be accomplished with local sources). The FCC symbol rate limitation needs to go. It’s a hindrance on HAM radio. Just regulate it by bandwidth, or better yet EIRP PSD, but that would be tough to control.