| 摘要 |
PURPOSE:To shorten the PN pull-in time by estimating so that the phase of the PN signal is put close to the phase of a reception signal in a recovery mode. CONSTITUTION:A traveling object containing a receiver enters the shade of a cover and a reception signal Sin is cut off. Thus the signal level of a correlation output S1 has a sudden fall, and a detection output S3 is supplied to a switch control circuit 7. A switching circuit 4 gives a switching action to a switch input terminal 2 and a phase control output S5 can be supplied to a clock generating circuit 5. While the S3 is supplied to a phase control circuit 8 as a trigger signal and therefore a phase error output S2 is held. Then the PN signal SPN changes in response to the phase of the signal Sin at a time point when the cut-off of signals is produced in the clock generating circuit 5. When the traveling object gets out of the cover and the reception state is recovered, the signals Sin is supplied to a correlation circuit 1. Then a PN synchronizing state is immediately reset. |
