In a transcription system including a plurality of signal receivers positioned adjacent a writing surface, a method for calibrating the transcription system by determining separation distances between the signal receivers comprising: using times of flight of position signals from at least two calibration marks to the signal receivers to determine separation distances between the at least two calibration marks and the signal receivers; and using the determined separation distances between the calibration marks and the signal receivers and the known separation distances between the calibration marks to determine separation distances between the signal receivers.