The positioning signals broadcast by GNSS constellations are affected by significant errors, notably due to the crossing of the ionospheric layer or of the tropospheric layer. Several unwieldy means have been deployed to provide professional users with corrections of said errors. These means, however, all require the knowledge of at least one precise reference point at a given distance. According to the invention, positioning receivers that are not very precise, such as smartphones, present in a geographical zone, of unknown precise position, can contribute to the production of precise atmospheric error corrections if said receivers are sufficiently numerous.