Method of compactly communicating ionospheric and tropospheric corrections in a network of global navigation system satellite receivers

A method of communicating corrections for information related to satellite signals from a first global navigation satellite system (GNSS) apparatus at a first location to a second GNSS apparatus at a second location comprising:

• determining at the first GNSS apparatus for a first satellite in a constellation of satellites a first ionosphere correction for ionosphere signal path delay;
• determining at the first GNSS apparatus a second ionosphere correction for a second satellite which is assumed to be directly over the first location;
• comparing the first ionosphere correction to the second ionosphere correction for ionosphere signal path delay;
• calculating a difference between the first ionosphere correction and the second ionosphere correction;
• and
• transmitting from the first GNSS apparatus to the second GNSS apparatus a message including only the difference between the first ionosphere correction and the second ionosphere correction.