RADIO WAVE RECEIVER

• US 20100304698A1
• Filed: 05/05/2010
• Published: 12/02/2010
• Est. Priority Date: 05/28/2009
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: SOMEYA, Kaoru
• Granted Patent: US 8,428,531 B2
• Time in Patent Office: Days
• US Class Current: 455/193.1
• CPC Class Codes: H03J 2200/06 Tuning of antenna
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H03J 3/20 of single resonant circuit by varying inductance only or capacitance only
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant

Abstract

A radio wave receiver including an antenna for receiving a radio wave; a tuning unit that can discretely changing a frequency characteristic of the antenna; an oscillation generator that can oscillate the antenna and a circuit portion of the tuning unit; a reception processing section for extracting a signal of a desired wave out of a reception signal received from the antenna; a controller for generating an oscillation signal at the circuit portion by the oscillation generator, and switching a setting of the tuning unit to search a setting state of the tuning unit under which the oscillation signal is extracted by the reception processing section; and a compensator for applying a variation to a frequency characteristic of the oscillation signal or a frequency characteristic associated with signal extraction of the reception processing section when the controller searches the setting state.

Claims

1. A radio wave receiver comprising:

an antenna for receiving a radio wave;

a tuning unit that can discretely changing a frequency characteristic of the antenna;

an oscillation generator that can oscillate the antenna and a circuit portion of the tuning unit;

a reception processing section for extracting a signal of a desired wave out of a reception signal received from the antenna;

a controller for generating an oscillation signal at the circuit portion by the oscillation generator, and switching a setting of the tuning unit to search a setting state of the tuning unit under which the oscillation signal is extracted by the reception processing section; and

a compensator for applying a variation to a frequency characteristic of the oscillation signal or a frequency characteristic associated with signal extraction of the reception processing section when the controller searches the setting state.

2. The radio wave receiver according to claim 1, wherein the compensator applies to the frequency characteristic the variation whose magnitude is set so as to enable the oscillation signal to be extracted in the reception processing section when a resonance frequency of the antenna approaches a frequency of the desired wave in a case where the frequency of the desired wave exists in a gap between discrete variations of the resonance frequency of the antenna due to a switching of the setting of the tuning unit.

3. The radio wave receiver according to claim 1, wherein the compensator has a variable reactance that is connected to the antenna and can continuously change the frequency characteristic of the antenna, and a characteristic changing unit for continuously changing a reactance value of the variable reactance.

4. The radio wave receiver according to claim 3, wherein the variable reactance is a varicap diode, and the characteristic changing unit is a signal generator for repetitively outputting a continuously-varying control voltage to the varicap diode.

5. The radio wave receiver according to claim 1, wherein the reception processing section comprises a frequency converter for converting a frequency of the reception signal received from the antenna, and a band-pass filter for extracting a signal having a frequency converted by the frequency converter from a frequency of the desired wave, wherein the compensator applies a variation to a frequency conversion amount of the frequency converter.

6. The radio wave receiver according to claim 5, wherein the frequency converter is a mixer for mixing the reception signal and a local oscillation signal to vary the frequency of the reception signal, and the compensator comprises a frequency-variable local oscillator for supplying the local oscillation signal to the mixer, and a signal generator for repetitively outputting a control signal for continuously varying a frequency of the local oscillation signal.

7. The radio wave receiver according to claim 1, wherein the reception processing section has a band-pass filter for extracting the signal of the desired wave, and the compensator is a band width changing unit for spreading a pass band of the band-pass filter.

8. The radio wave receiver according to claim 7, wherein the band width changing unit comprises an alternate filter having a broader pass band than the band-pass filter, and a switching unit that can switch the band-pass filter and the alternate filter to each other or connect the band-pass filter and the alternate filter in parallel.