Electromagnetic interference reduction calculation method, device, and program, and its electronic circuit

1. A method of calculating electromagnetic interference reduction through spectrum diffusion that is a means of reducing electromagnetic interference, the method comprising:

inputting clock frequency of a target electromagnetic interference signal, modulation frequency used for said spectrum diffusion, maximum frequency shift, and measurement bandwidth of a measurement device as data from an input unit;

calculating electromagnetic interference reduction for every frequency which appears by modulation;

calibrating said electromagnetic interference reduction in consideration of influence by said measurement bandwidth of said measurement device; and

calibrating said electromagnetic interference reduction in consideration of influence by a filter property of a band filter of said measurement device,

wherein said calibrating said electromagnetic interference reduction in consideration of influence by said measurement bandwidth of said measurement device comprises:

adding one to an integral part of a value obtained by dividing said bandwidth by said modulation frequency,

setting the obtained value as the number of frequency spectra for calculation of electromagnetic interference reduction, and

performing calibration of said electromagnetic interference reduction by using a value obtained by adding up amplitudes of all frequency spectra,

wherein said calibrating said electromagnetic interference reduction with influence by a filter property of a band filter of said measurement device comprises:

setting said filter property of said band filter in advance by using a typical value of said measurement device, and

performing calibration of said electromagnetic interference reduction by using reduction value by said filter property for every target frequency.

2. The calculation method of electromagnetic interference reduction according to claim 1 , wherein

using a value obtained by dividing a value obtained by multiplying said clock frequency by modulation degree (%) for said spectrum diffusion by 100 as said maximum frequency shift.

3. The calculation method of electromagnetic interference reduction according to one of claim 1 or claim 2 , wherein

the maximum total sum of said amplitudes is calculated by using the amplitudes of said different orders of the Bessel functions.

4. The calculation method of electromagnetic interference reduction according to one of claim 1 or claim 2 , wherein

when calculating a spectrum of harmonic wave using the Bessel function, which harmonic wave is obtained by performing the integral multiple of the frequency of a basic wave included in said electromagnetic interference signal generated from the frequency spectrum of said electromagnetic interference signal,

calculation of the Bessel function is performed on a plurality of different orders, from the order of the Bessel function corresponding to a value which is obtained by subtracting said integral multiple value of a value obtained by adding one to the integral part of the value obtained by dividing said measurement bandwidth by said modulation frequency from a value obtained by dividing by said modulation frequency, said integral multiple value of the maximum frequency shift that is the expansion of the frequencies set through said spectrum diffusion of said basic wave, to the order of the Bessel function corresponding to the value obtained by adding said integral multiple value to the value obtained by dividing said integral multiple of said maximum frequency shift by said modulation frequency, and

the amplitude of the spectrum having the maximum amplitude is calculated from said amplitude of the order of the Bessel function having the maximum amplitude, of the plurality of different orders of the Bessel functions.

5. The calculation method of electromagnetic interference reduction according to claim 1 or claim 2 , wherein

when generating a plurality of spectra from the frequency spectrum of said electromagnetic interference signal through said spectrum diffusion, clock frequency, modulation frequency, maximum frequency shift, and measurement bandwidth are used as input data to set said spectrum diffusion.

6. A device for calculating electromagnetic interference reduction through spectrum diffusion that is a means of reducing electromagnetic interference, comprising:

an input unit which enters a setting condition of the spectrum diffusion,

a calculating unit which calculates electromagnetic interference reduction through the spectrum diffusion, and

an output unit which supplies calculation result of said electromagnetic interference reduction, in which

said calculating unit inputs clock frequency of a target electromagnetic interference signal, modulation frequency used for said spectrum diffusion, maximum frequency shift, and measurement bandwidth of a measurement device as data from said input unit, calculates said electromagnetic interference reduction for every frequency which appears by modulation, calibrates said electromagnetic interference reduction in consideration of influence by said measurement bandwidth of said measurement device and calibrates said electromagnetic interference reduction in consideration of influence by a filter property of a band filter of said measurement device,

wherein, when calibrating said electromagnetic interference reduction in consideration of influence by said measurement bandwidth of said measurement device, said calculating unit adds one to an integral part of a value obtained by dividing said bandwidth by said modulation frequency, sets the obtained value as the number of frequency spectra for calculation of electromagnetic interference reduction, and performs calibration of said electromagnetic interference reduction by using a value obtained by adding up amplitudes of all frequency spectra, and

wherein, when calibrating said electromagnetic interference reduction in consideration of influence by a filter property of a band filter of said measurement device, said calculating unit sets said filter property of said band filter in advance by using a typical value of said measurement device, and performs calibration of said electromagnetic interference reduction value by said filter property for every target frequency.

7. The calculation device of electromagnetic interference reduction according to claim 6 , wherein

said calculating unit uses a value obtained by dividing a value obtained by multiplying said clock frequency by modulation degree (%) for said spectrum diffusion by 100 as said maximum frequency shift.

8. The calculation device of electromagnetic interference reduction according to one of claim 6 or claim 7 , wherein

said calculating unit calculates the maximum total sum of said amplitudes by using the amplitudes of said plurality of different orders of the Bessel functions.

9. The calculation device of electromagnetic interference reduction according to claim 6 or claim 7 , wherein

when calculating a spectrum of harmonic wave using the Bessel function, which harmonic wave is obtained by performing the integral multiple of the frequency of a basic wave included in said electromagnetic interference signal generated from the frequency spectrum of said electromagnetic interference signal,

said calculating unit calculates the Bessel function on a plurality of different orders, from the order of the Bessel function corresponding to a value which is obtained by subtracting said integral multiple value of a value obtained by adding one to the integral part of the value obtained by dividing said measurement bandwidth by said modulation frequency from a value obtained by dividing by said modulation frequency, said integral multiple value of the maximum frequency shift that is the expansion of the frequencies set through said spectrum diffusion of said basic wave, to the order of the Bessel function corresponding to the value obtained by adding said integral multiple value to the value obtained by dividing said integral multiple of said maximum frequency shift by said modulation frequency, and

calculates the amplitude of the spectrum having the maximum amplitude, from said amplitude of the order of the Bessel function having the maximum amplitude, of the plurality of different orders of the Bessel functions.

10. The calculation device of electromagnetic interference reduction according to claim 6 , wherein

said input unit enters basic frequency, modulation frequency, maximum frequency shift, and measurement bandwidth of an electromagnetic interference signal.