To obtain excellent reception sensitivity regardless of the posture of a telephone set by easily and reliably adjusting detection sensitivity while limiting a radiowave detection area to a narrow area such as the vicinity of an ATM.
Signal waves separately received by antennas T1, T2, T3 are input through a high-frequency switch 1 and a variable attenuator 2 to a pre-stage band-pass filter 3, are amplified to an appropriate level by a low noise amplifier 4 after selecting respective bands, and then are mixed with a local oscillation wave of a local oscillator 6 by a mixer 5 and converted to a fixed intermediate frequency. Only an intermediate frequency is selected by a pre-stage band-pass filter 3, then inputted to a logarithmic amplifier 7 for logarithmic amplification and demodulated by a detector 8, thereby outputting an RSSI voltage.
KATO NOZOMI
NATSUI TAKESHI
| JPH10232987A | 1998-09-02 | |||
| JPH1198564A | 1999-04-09 | |||
| JPH02127805A | 1990-05-16 | |||
| JP2002252878A | 2002-09-06 | |||
| JP2003198437A | 2003-07-11 |
Maki Reiko
Kimio Kikutani
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