GPS·C (GPS Correction) was a Differential GPS data source for most of Canada maintained by the Canadian Active Control System, part of Natural Resources Canada.
Real-time data was collected at fourteen permanent ground stations spread across Canada, and forwarded to the central station, "NRC1", in Ottawa for processing.
CDGPS required a separate MSAT receiver, which output correction information in the RTCM format for input into any suitably equipped GPS receiver.
On April 9, 2010, it was announced that the service would be discontinued by March 31, 2011.
The service was decommissioned on March 31, 2011 and finally terminated on April 1, 2011, at 9:00 EDT.