Signal receiving apparatus, signal receiving method, signal receiving program and signal receiving system

1. A signal receiving apparatus comprising:

resonance means for receiving an input signal at a variable resonance frequency;

signal supplying means for supplying an electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means;

mixture means for mixing a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency; and

control means for changing a resonance characteristic of said resonance means and measuring the phase of a mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

2. The signal receiving apparatus according to claim 1 wherein:

said resonance means is configured to include an inductor and a capacitor group having a plurality of capacitors; and

said control means changes capacitances of said capacitors in order to change said resonance frequency.

3. The signal receiving apparatus according to claim 2 wherein:

when said phase of said mixed signal output after said resonance characteristic has been changed in a direction of increasing from said phase of said mixed signal output before said resonance characteristic is changed, said control means changes said capacitances of said capacitors in a direction to decrease the total capacitance of said capacitor group; and

when said phase of said mixed signal output after said resonance characteristic has been changed in a direction of decreasing from said phase of said mixed signal output before said resonance characteristic is changed, said control means changes said capacitances of said capacitors in a direction to increase said total capacitance of said capacitor group.

4. The signal receiving apparatus according to claim 1 , further comprising

a resistor provided to form a parallel circuit in conjunction with said resonance means including said capacitors and said inductor,

wherein said control means changes said resonance characteristic of said resonance means by controlling an operation to connect said resistor to said resonance means and disconnect said resistor from said resonance means.

5. The signal receiving apparatus according to claim 4 wherein said resistor has a variable resistance and said control means controls said resistance in accordance with said reception frequency.

6. The signal receiving apparatus according to claim 1 , further comprising

analog to digital conversion means for carrying out an analog to digital conversion process on a mixed signal output by said mixture means in order to convert the level of said mixed signal into a digital value, wherein

said control means measures said phase of said mixed signal output by said mixture means on the basis of said digital value representing said level of said mixed signal output by said mixture means as a signal on an orthogonal I side and said digital value representing said level of said mixed signal output by said mixture means as a signal on an orthogonal Q side.

7. The signal receiving apparatus according to claim 1 wherein, prior to an operation to measure said phase of said mixed signal output by said mixture means after said resonance characteristic of said resonance means has been changed, said signal supplying means raises the level of said electrical signal output by said signal supplying means before supplying said electrical signal to said resonance means.

8. The signal receiving apparatus according to claim 1 , further comprising

signal generation means for generating an internal signal having a frequency set at a value equal to said reception frequency,

wherein said signal supplying means produces an electrical signal having a frequency set at a value equal to said reception frequency on the basis of said internal signal generated by said signal generation means and supplies said electrical signal to said resonance means.

9. The signal receiving apparatus according to claim 1 wherein said mixing means also mixes a resonance signal output by said resonance means at said resonance frequency already adjusted to said reception frequency with a switching signal generated by a local oscillation circuit at a frequency set at a value equal to said reception frequency in order to output a mixed signal.

10. A signal receiving method to be adopted in a signal receiving apparatus having

resonance means for receiving an input signal at a variable resonance frequency,

signal supplying means for supplying an electrical signal to said resonance means,

mixture means for mixing two signals, and

control means for controlling said resonance frequency of said resonance means, said signal receiving method including the steps of driving:

said signal supplying means to supply said electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means;

said mixture means to mix a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency; and

said control means to change a resonance characteristic of said resonance means and measure the phase of a mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

11. A signal receiving program to be executed by a computer of a signal receiving apparatus having

resonance means for receiving an input signal at a variable resonance frequency,

signal supplying means for supplying an electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means, and

mixture means for mixing a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency,

said signal receiving program executed by said computer in order to carry out processing to change a resonance characteristic of said resonance means and measure the phase of a mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

12. A signal receiving system comprising:

signal receiving means for receiving an input signal; and

transmission-line decoding processing means for carrying out transmission-line decoding processing on said input signal received by said signal receiving means,

wherein said signal receiving means employs

resonance means having a variable resonance frequency,

signal supplying means for supplying an electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means,

mixture means for mixing a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency, and

control means for changing a resonance characteristic of said resonance means and measuring the phase of a mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

13. A signal receiving system comprising:

signal receiving means for receiving an input signal;

transmission-line decoding processing means for carrying out transmission-line decoding processing on said input signal received by said signal receiving means; and

original-information decoding processing means for carrying out original-information decoding processing on a decoded signal obtained as a result of said transmission-line decoding processing carried out by said transmission-line decoding processing means,

wherein said signal receiving means employs

resonance means having a variable resonance frequency,

signal supplying means for supplying an electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means,

mixture means for mixing a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency, and

control means for changing a resonance characteristic of said resonance means and measuring the phase of a mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

14. A signal receiving system comprising:

signal receiving means for receiving an input signal;

transmission-line decoding processing means for carrying out transmission-line decoding processing on said input signal received by said signal receiving means;

original-information decoding processing means for carrying out original-information decoding processing on a transmission-line-decoded signal obtained as a result of said transmission-line decoding processing carried out by said transmission-line decoding processing means; and

output means for outputting an image or a sound on the basis of an original-information-decoded signal obtained as a result of said original-information decoding processing carried out by said original-information decoding processing means,

wherein said signal receiving means employs

resonance means having a variable resonance frequency,

signal supplying means for supplying an electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means,

mixture means for mixing a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency, and

control means for changing a resonance characteristic of said resonance means and measuring the phase of a mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

15. A signal receiving system comprising:

signal receiving means for receiving an input signal;

transmission-line decoding processing means for carrying out transmission-line decoding processing on said input signal received by said signal receiving means;

original-information decoding processing means for carrying out original-information decoding processing on a transmission-line-decoded signal obtained as a result of said transmission-line decoding processing carried out by said transmission-line decoding processing means; and

recording control means for controlling an operation to record original-information-decoded signal obtained as a result of said original-information decoding processing carried out by said original-information decoding processing means,

wherein said signal receiving means employs

resonance means having a variable resonance frequency,

signal supplying means for supplying an electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means,

mixture means for mixing a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency, and

control means for changing a resonance characteristic of said resonance means and measuring the phase of a mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

16. A signal receiving apparatus comprising:

resonance means for receiving an input signal at a variable resonance frequency;

signal supplying means for supplying an electrical signal having a frequency set at a value equal to a desired reception frequency to said resonance means;

mixture means for mixing a resonance signal, which is output by said resonance means when said resonance means receives said electrical signal from said signal supplying means, with a switching signal having a frequency set at a value equal to said desired reception frequency; and

control means for changing a resonance characteristic of said resonance means in an operation to control said resonance frequency of said resonance means in accordance with a mixed signal output by said mixture means before said resonance characteristic is changed and said mixed signal output by said mixture means after said resonance characteristic has been changed.

17. The signal receiving apparatus according to claim 16 wherein said control means measures the phase of said mixed signal output by said mixture means before said resonance characteristic is changed as well as said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed in an operation to control said resonance frequency of said resonance means in order to change said resonance frequency in a direction to reduce a difference between said phase of said mixed signal output by said mixture means before said resonance characteristic is changed and said phase of said mixed signal output by said mixture means after said resonance characteristic has been changed.

18. The signal receiving apparatus according to claim 16 , further comprising a resistor provided to form a parallel circuit in conjunction with said resonance means,

wherein said control means changes said resonance characteristic of said resonance means by controlling an operation to connect said resistor to said resonance means and disconnect said resistor from said resonance means.

19. The signal receiving apparatus according to claim 16 , further comprising

analog to digital conversion means for carrying out an analog to digital conversion process on a mixed signal output by said mixture means in order to convert the level of said mixed signal into a digital value,

wherein said control means measures said phase of said mixed signal on the basis of said digital value representing said level of said mixed signal output by said mixture means as a signal on an orthogonal I side and said digital value representing said level of said mixed signal output by said mixture means as a signal on an orthogonal Q side.

20. The signal receiving apparatus according to claim 16 , further comprising

signal generation means for generating an internal signal having a frequency set at a value equal to said desired reception frequency,

wherein said signal supplying means produces an electrical signal having a frequency set at a value equal to said desired reception frequency on the basis of said internal signal generated by said signal generation means and supplies said electrical signal to said resonance means.