| 摘要 |
PROBLEM TO BE SOLVED: To correct deviation in reference oscillation frequency caused by aging of a VC-TCXO (voltage controlled, temperature compensated crystal oscillator) in a radio terminal. SOLUTION: A reference counter 261a is set to the same frequency as a frequency (40 kHz or 60 kHz) of a long-wave standard radio signal received by a long-wave standard radio receiving unit 120 in a PLL 260a, and a local oscillation frequency output from a VCO (voltage controlled oscillator) 280 is divided into a frequency (reference frequency) of the reference counter 261a also for a fractional N divider 264. A phase difference between the long-wave standard radio signal and the reference frequency is detected, a frequency control voltage for correcting the phase difference is controlled, and deviation in reference oscillation frequency of a VC-TCXO 250 is corrected. Furthermore, while a radio terminal 100 receives no long-wave standard radio signal, deviation in reference oscillation frequency of the VC-TCXO 250 is corrected by the frequency control voltage stored in a memory 113. COPYRIGHT: (C)2011,JPO&INPIT
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