| US 7,542,748 B2 | ||
| Signal processing circuit comprising an attenuating unit, a detecting unit, and an attenuation rate setting unit | ||
| Yasuji Saito, Gunma (Japan); Yutaka Hirakoso, Koga (Japan); and Masaaki Taira, Akashi (Japan) | ||
| Assigned to Sanyo Electric Co., Ltd., Osaka (Japan) | ||
| Appl. No. 10/599,240 PCT Filed Feb. 23, 2005, PCT No. PCT/JP2005/002894 § 371(c)(1), (2), (4) Date Sep. 22, 2006, PCT Pub. No. WO2005/091512, PCT Pub. Date Sep. 29, 2005. |
||
| Claims priority of application No. 2004-085123 (JP), filed on Mar. 23, 2004. | ||
| Prior Publication US 2008/0233915 A1, Sep. 25, 2008 | ||
| Int. Cl. H04B 1/10 (2006.01); H04B 1/16 (2006.01) | ||
| U.S. Cl. 455—205 [455/249.1; 455/296] | 6 Claims |
| 1. A signal processing circuit, comprising
an attenuating unit that attenuates a demodulated signal acquired by detecting a received signal;
a detecting unit that detects a first signal indicating intensity of the demodulated signal;
an attenuation rate setting unit that sets an attenuation rate of the attenuating unit,
depending on the first signal and a second signal indicating a change in an envelope curve acquired based on an intermediate
frequency signal of the received signal, or
depending on the first signal, the second signal, and a third signal indicating electric field intensity acquired based on
the intermediate frequency signal; and
a difference determining unit that determines whether a predetermined threshold is exceeded by a difference between the demodulated
signal and a signal obtained by smoothing the demodulated signal, to detect noise, wherein the attenuation rate setting unit
sets a first attenuation rate for the attenuating unit based on the detection of noise by the difference determining unit,
and
after a predetermined period has elapsed from the setting, sets a second attenuation rate smaller than the first attenuation
rate for the attenuating unit.
|