О смысле всего сущего

По ссылке что-то пишут. Дескать, на орбите атомные часы тикают быстрее, чем на земле, благодаря сумме эффектов: релятивистский и гравитационный (с разными знаками). Это компенсируют подстройкой частоты часов на спутнике перед запуском. Ну и http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html
приёмник должен учитывать небольшую релятивистскую поправку с параметрами, полученными от спутника.

The engineers who designed the GPS system included these relativistic effects when they designed and deployed the system. For example, to counteract the General Relativistic effect once on orbit, the onboard clocks were designed to "tick" at a slower frequency than ground reference clocks, so that once they were in their proper orbit stations their clocks would appear to tick at about the correct rate as compared to the reference atomic clocks at the GPS ground stations. Further, each GPS receiver has built into it a microcomputer that, in addition to performing the calculation of position using 3D trilateration, will also compute any additional special relativistic timing calculations required [3], using data provided by the satellites. [3] - While the primary general relativistic correction is taken care of on-board by the design clock frequency before launch and does not need to be computed by an individual receiver, the special relativistic corrections that require knowledge of the orbital parameters of the specific GPS satellites whose signals are being measured are not. As described in the GPS Interface Control Document ICD-GPS-200C (10 Oct 1993), applying these corrections is the responsibility of the user's equipment (Section 20.3.3.3.3.1, "User Algorithm for SV Clock Correction"). The calculations are relatively straightforward and require very little beyond basic arithmetic, and make use of information transmitted in the data packets that come down from each spacecraft.