| 摘要 |
<p>PROBLEM TO BE SOLVED: To shorten the operation time of a radio frequency signal and to save the electric power by making the frequency resolution of a 1st analog demodulated signal wider than a channel interval and the frequency resolution of a 2nd analog demodulated signal finer than the frequency resolution of the 1st analog demodulated signal, and adjusting their frequencies according to their frequency resolution and tuning a receiver. SOLUTION: A purely modulated signal for transmission of the GSM transmission band is supplied from a base band part to a mixer 610. Then it is mixed with a 116 MHz signal supplied to a multiplier 611 coupled with a VHF signal generator 605. The intermediate-frequency signal which is generated as a result passes through a mode switch 612 at 116 MHz. The mode switch 612 is switched to a GSM terminal RF stage in GSM mode and the intermediate-frequency signal is sent to a 2nd mixer 613. Then it is mixed with a local oscillator signal having a frequency within the range of 1006 to 1031 MHz and converted to a transmission channel frequency of the GSM transmission band.</p> |
