CMR Message Lengths

The Compact Measurement Record (CMR) Format, is a standard communications protocol used in Real-Time Kinematic (RTK) systems to transfer GPS carrier phase and code observations from a base station to one or more rover stations. The message lengths of the four CMR messages are as follows: CMROBS = 6 (frame) + 6 (header) + (8*L1 channels) + (7*L2 channels) - variable length depending on receiver tracking channels - OEM4 family receiver (192 bytes max.) - OEMV family receiver (222 bytes max.) CMRREF = 6 (frame) + 6 (header) + 19 = (31 bytes) - fixed length CMRDESC = 6 (frame) + 6 (header) + (variable: 26 to 75) - variable length depending on base station description - on all receivers (38 bytes minimum; 88 bytes max.) CMRPLUS = 6 (frame) + 3 (header) + 7 = (16 bytes) - fixed length