Message indicating a GPS signal has been detected or lost
Parameters passed to GPSNOTIFYPROC:
lParam1
A non-zero value if a communication signal has been detected, otherwise a communications signal has been lost.
lParam2
A pointer to a NULL-terminated text status message: "Communications signal is on" or "Communications signal is off". On Windows CE platforms this will be a Unicode buffer; on all other platforms it is an ASCII buffer.
lParam3
Contains the user-defined parameter lUserParam passed to the
GpsSetNotificationCallback function.