| 摘要 |
PROBLEM TO BE SOLVED: To provide a portable terminal that reduces current consumption by reducing the time required for channel scanning and interrupting intermittent ly the power supply when the portable terminal is resident at the outside of a service area zone. SOLUTION: The portable terminal that has a reception circuit A, a PLL circuit B and applies frequency conversion to a signal received by the reception circuit A with a local oscillating frequency generated by the PLL circuit B is provided with power switches 8, 10 that apply power to the PLL circuit B and the reception circuit A and with a control section 1 that controls each section of the portable terminal. The control section 1 sets each circuit constant of the PLL circuit B so as to reduce a lock time of the PLL circuit B to conduct channel scanning, discriminates a reception level on the basis of an RSSI signal from the reception circuit A, turns off the power switches 8, 10 when absence of the corresponding channel is discriminated so as to interrupt power for the PLL circuit B and the reception circuit A, and turns on the power switches 8, 10 after a prescribed time to supply power thereby repeating channel scanning. |
