| 摘要 |
PURPOSE:To shorten a synchronization completion time by storing the interval time ta between a reception start time and an epoch signal input time and resetting a PN code in next reception the time ta after the reception start time. CONSTITUTION:When a signal S1 from a satellite is supplied to a balanced modulator 16, its time tc is stored in ECU 44. The same PN code with the transmission side is supplied from a PN code generator 40 to the modulator 16 and the signal is spread reversely to supply a correlation value to a comparator 38 through a band-pass filter 34 and a detector 36. When the correlation value exceeds a threshold value, a switch 32 is switched to a synchronous tracking side 32B to perform synchronization by a DLL (delay lock loop) 25. When a epoch signal (e.g. code when a PN register enters an all '1' state) is inputted at the time of synchronous tracking, the ECU 44 calculates and stores the tc and interval time ta. In next reception, the PN code generator 40 is reset the ta after the signal reception. Then, the phase relation with the last reception is obtained and the synchronism speeded up.
|
