| 摘要 |
PROBLEM TO BE SOLVED: To conduct synchronization processing in a short time and excellently. SOLUTION: A signal from each satellite is supplied to receiving processing circuits 5-1-5-4 of channels 1-4, and processing of inverse spread spectrum and PSK demodulation is conducted to obtain navigation messages DT1-DT4. In a CPU 11, position measurement is conducted by utilizing the time of each navigation message and orbit data. In the CPU 11, the synchronous state of each channel is judged in the level of inversely spread spectrum output (relative output) of a signal from the satellite, and synchronous process is conducted in off synchronous state. In the synchronous process, although time base data more than bit number is required after reaching synchronous (bit demodulation) state, when other channel (i) synchronous-processed exists in synchronous process of a channel (j), time base data more than bit number of channel (I) is used. The bit number of the channel (i) is varied positively and negatively to detect error per word, and from this result, bit number of the channel (j) is correctly decided. |
