boundaries of each string or subframe and the counter 340 may provide information to make the bit computing unit 332 identify bit indexes received by the bit computing unit 332 then in step 406 the decision unit 336 determines target strings or target subframes according to the plurality of reference values stored in the buffer 334 in step 408 it is determined if the target strings or the target subframes pass parity check if yes the flow enters step 410 if not the flow enters step 412 to finish the process in step 410 the target strings subframes are transmitted to a navigation database 360 to update the information stored therein then in step 412 the process is finished the present invention provides a decoding mechanism for gnss navigation data that can increase data decoding sensitivity following takes glonass system as an example to illustrate the decoding flow however please be noted the present invention is not limited thereto in the glonass system each satellite sends modulated strings 1 15 continuously and repeatedly during thirty minutes as shown in fig1 after the satellite sends modulated strings 1 15 the satellite will immediately send the same modulated strings 1 15 again in addition fig2 is a string structure of each string shown in fig1 referring to fig2 each string has eighty five bits having indexes 1 85 respectively because contents in fig1 and fig2 should be understood by a person skilled in this art further descriptions are omitted here when the received signal d in containing glonass navigation data the output of the demodulator 310 includes a plurality of strings.