Method for automatically adjusting measuring instrument and device using the same

• US 20040141417A1
• Filed: 06/03/2003
• Published: 07/22/2004
• Est. Priority Date: 09/10/2001
• Status: Active Grant

• Current Assignee: RION Company Limited
• Original Assignee: RION Company Limited
• Inventors: Takeda, Nobuhiko, Kobayashi, Kazuyoshi, Ohya, Masaharu, Wakabayashi, Tomoharu, Takinami, Hiroaki
• Granted Patent: US 6,931,341 B2
• Time in Patent Office: Days
• US Class Current: 367/98
• CPC Class Codes: G01D 3/032 affecting incoming signal, e.g. by averaging; gating undesired signals
• CPC Class Codes: H03M 1/1019 by storing a corrected or correction value in a digital look-up table
• CPC Class Codes: H03M 1/188 Multi-path, i.e. having a separate analogue/digital converter for each possible range

Abstract

The present invention provides an apparatus that automatically adjusts self-noise which apparatus can lower the lower limit value of a measurement range by reducing the effects of self-noise on measured values. This apparatus corrects self-noise when amplifying an output signal from a sensor 1 so as to conform to a sensor sensitivity G, further processing the amplified signal, and then outputting the processed signal as a measured value. This apparatus includes a sensor sensitivity adjusting circuit 3 that adjusts an amplification factor so as to conform to the sensor sensitivity G, a self-noise value calculating circuit 4 that calculates a self-noise component F·N from the amplification factor adjusted by the sensor sensitivity adjusting circuit 3 so as to conform to the sensor sensitivity G, and a measured value correcting circuit 6 that calculates a true measured value F·S from the self-noise component F·N calculated by the self-noise value calculating circuit 4 as well as a measured value L containing the self-noise component F·N.

Claims

1. A measuring equipment automatic adjusting method of correcting self-noise when amplifying an output signal from a sensor so as to conform to the sensitivity of the sensor, further processing the amplified signal, and then outputting the processed signal as a measured value, the method being characterized by comprising calculating a self-noise component from the sensor sensitivity, using this self-noise component as an element to calculate a correction value, and using this correction value to reduce the effects of the self-noise on the measured value.

2. A measuring equipment automatic adjusting apparatus which corrects self-noise when amplifying an output signal from a sensor so as to conform to the sensitivity of the sensor, further processing the amplified signal, and then outputting the processed signal as a measured value, the apparatus being characterized by comprising sensor sensitivity adjusting means for adjusting an amplification factor so as to conform to the sensor sensitivity, self-noise value calculating means for calculating a self-noise component from the amplification factor adjusted by the sensor sensitivity adjusting means so as to conform to the sensor sensitivity, and measured value correcting means for calculating a true measured value from the self-noise component calculated by the self-noise value calculating means as well as the measured value containing the self-noise component.

3. A measuring equipment automatic adjusting method of adjusting an amplification factor of a signal processing circuit in which analog signals are simultaneously inputted to an amplifying circuit and an attenuating circuit and in which the amplified signal and the attenuated signal are then subjected to A/D conversion and synthesized with each other, the method being characterized by comprising, after generating a digital signal as a reference signal and subjecting this digital signal to D/A conversion, using said amplifying circuit to amplify the converted signal, subjecting the amplified signal to A/D conversion, then executing an arithmetic process on the converted signal to calculate a value, using said attenuating circuit to attenuate the signal, subjecting the attenuated signal to A/D conversion, then executing an arithmetic process on the converted signal to calculate a value, calculating an amplitude ratio of these values, comparing this amplitude ratio with an amplification ratio of said amplifying circuit to said attenuating circuit, calculating an adjustment amplification factor for the signal synthesis of the analog signal inputted to said amplifying circuit or said attenuating circuit, storing this adjustment amplification factor, and for actual signal processing, multiplying the amplification factor of said amplifying circuit or the attenuation factor of said attenuating circuit by said adjustment amplification factor.

4. A measuring equipment automatic adjusting apparatus which adjusts an amplification factor of a signal processing circuit in which analog signals are simultaneously inputted to an amplifying circuit and an attenuating circuit and in which the amplified signal and the attenuated signal are then subjected to A/D conversion and synthesized with each other, the apparatus being characterized by comprising signal generating means for generating a digital signal as a reference signal, a D/A converter which subjects the digital signal generated by the signal generating means to D/A conversion, an amplifying circuit which amplifies an output signal from the D/A converter, an attenuating circuit which attenuates the output signal from the D/A converter, a first A/D converter which subjects an output signal from the amplifying circuit to A/D conversion, a second A/D converter which subjects an output signal from the attenuating circuit to A/D conversion, arithmetic means for executing an arithmetic process on the output signals from the first A/D converter and second A/D converter, comparison means for calculating an amplitude ratio of a value based on the output signal from the first A/D converter to a value based on the output signal from the second A/D converter, the values being calculated by the arithmetic means, to compare this amplitude ratio with an amplification ratio of the amplifying circuit to the attenuating circuit, amplification factor correcting means for calculating an adjustment amplification factor for the signal synthesis of the analog signal inputted to the amplifying circuit or attenuating circuit on the basis of a result of the comparison carried out by the comparison means, and memory means for storing the adjustment amplification factor calculated by the amplification factor correcting means, wherein for actual signal processing, the amplification factor of the amplifying circuit or the attenuation factor of the attenuating circuit is multiplied by the adjustment amplification factor.

5. A measuring equipment automatic adjusting method of adjusting an amplification factor of a signal processing circuit in which analog signals are simultaneously inputted to an amplifying circuit and an attenuating circuit and in which the amplified signal and the attenuated signal are then subjected to A/D conversion and synthesized with each other, the method being characterized by comprising generating a first digital signal as a first reference signal, subjecting this first digital signal to D/A conversion, using said amplifying circuit to amplify the converted signal, subjecting the amplified signal to A/D conversion, then executing an arithmetic process on the converted signal to calculate a value, generating a second digital signal as a second reference signal, subjecting this second digital signal to D/A conversion, using said attenuating circuit to attenuate the converted signal, subjecting the attenuated signal to A/D conversion, then executing an arithmetic process on the converted signal to calculate a value, comparing an amplitude ratio of these values obtained with an amplification ratio of said amplifying circuit to said attenuating circuit, calculating an adjustment amplification factor for the signal synthesis of the analog signal inputted to said amplifying circuit or said attenuating circuit, storing this adjustment amplification factor, and for actual signal processing, multiplying the amplification factor of said amplifying circuit or the attenuation factor of said attenuating circuit by said adjustment amplification factor.

6. A measuring equipment automatic adjusting apparatus which adjusts an amplification factor of a signal processing circuit in which analog signals are simultaneously inputted to an amplifying circuit and an attenuating circuit and in which the amplified signal and the attenuated signal are then subjected to A/D conversion and synthesized with each other, the apparatus being characterized by comprising signal generating means for generating a first and second digital signals as two types of reference signals, a D/A converter which subjects the first and second digital signals generated by the signal generating means to D/A conversion, an amplifying circuit which amplifies the first digital signal outputted by the D/A converter, an attenuating circuit which attenuates the second digital signal outputted by the D/A converter, a first A/D converter which subjects an output signal from the amplifying circuit to A/D conversion, a second A/D converter which subjects an output signal from the attenuating circuit to A/D conversion, arithmetic means for executing an arithmetic process on the output signals from the first A/D converter and second A/D converter, comparison means for calculating an amplitude ratio of a value based on the first digital signal to a value based on the second digital signal, the values being calculated by the arithmetic means, to compare this amplitude ratio with an amplification ratio of the amplifying circuit to the attenuating circuit, amplification factor correcting means for calculating an adjustment amplification factor for the signal synthesis of the analog signal inputted to the amplifying circuit or attenuating circuit on the basis of a result of the comparison carried out by the comparison means, and memory means for storing the adjustment amplification factor calculated by the amplification factor correcting means, wherein for actual signal processing, the amplification factor of the amplifying circuit or the attenuation factor of the attenuating circuit is multiplied by the adjustment amplification factor.

7. A measuring equipment automatic adjusting method of automatically adjusting an internal calibration signal which method adjusts a calibration signal contained in measuring equipment, the method being characterized by comprising generating a digital signal as an internal calibration signal, subjecting this digital signal to D/A conversion, amplifying the converted signal, subjecting the amplified signal to A/D conversion, then executing an arithmetic process on the converted signal to calculate an effective value, comparing the effective value with a predetermined calibration value to calculate an adjustment factor for the internal calibration signal, storing this adjustment factor, and for self-diagnosis for determining whether or not calibration has been actually completed, using a signal obtained by multiplying said digital signal by said adjustment factor.

8. A measuring equipment automatic adjusting apparatus for an internal calibration signal which apparatus adjusts a calibration signal contained in measuring equipment, the apparatus being characterized by comprising digital signal generating means for generating a digital signal as an internal calibration signal, a D/A converter which subjects the digital signal generated by the digital signal generating means to D/A conversion, effective-value calculating means for amplifying an output signal from the D/A converter, subjecting the amplified signal to A/D conversion, and then executing an arithmetic process on the converted signal, signal comparing means for comparing an effective value calculated by the effective-value calculating means, with a predetermined calibration value, factor calculating means for calculating an adjustment factor for the internal calibration signal on the basis of a result of the comparison carried out by the signal comparing means, and memory means for storing the adjustment factor calculated by the factor calculating means, wherein a signal obtained by multiplying said digital signal by said adjustment factor is used for self-diagnosis for determining whether or not calibration has been actually completed.

9. A measuring equipment automatic adjusting method including output voltage value adjusting method of executing signal processing on an input signal, subjecting the processed signal to D/A conversion, amplifying the converted signal, and outputting from an output terminal a voltage that is in a desired proportional relationship with said input signal, the output voltage value adjusting method being characterized by comprising calculating a correction factor using a reference voltage, an output terminal voltage for the reference voltage, and a desired output terminal voltage for the reference voltage, storing the correction factor, and for actual measurement, multiplying said input signal by said correction factor to calculate a correction value, subjecting this correction value to D/A conversion, amplifying the converted signal, and outputting the amplified signal to an output terminal.

11. A measuring equipment automatic adjusting method for measuring equipment characterized in that the automatic adjusting method for measuring equipment according to claim 9 is applied to an acoustic measuring instrument such as a sound level meter, a vibrometer, or a frequency analyzer.

10. A measuring equipment automatic adjusting apparatus including output voltage value adjusting apparatus which executes signal processing on an input signal, processing the resulting signal through a D/A converter and an amplifier to obtain a voltage that is in a desired proportional relationship with said input signal, and then outputting this voltage from an output terminal, the output voltage value adjusting apparatus being characterized by comprising reference voltage generating means for generating a reference voltage, an A/D converter which subjects to A/D conversion an output terminal voltage obtained from the reference voltage generated by the reference voltage generating means, adjustment value calculating means for calculating a correction factor using an output signal from the A/D converter, a desired output terminal voltage for the reference voltage, and the reference voltage, memory means for storing the correction factor calculated by the adjustment value calculating means, and signal processing means for reading the correction factor from the memory means and calculating a correction value from said input signal and said correction factor, wherein said correction value is outputted to the output terminal through said D/A converter and said amplifier.

12. A measuring equipment automatic adjusting apparatus for measuring equipment characterized in that the automatic adjusting apparatus for measuring equipment according to claim 10 is applied to an acoustic measuring instrument such as a sound level meter, a vibrometer, or a frequency analyzer.

13. A measuring equipment automatic adjusting method of automatically correcting an error in amplification factor for each range of a range switch for a measuring instrument, the method being characterized by comprising using a reference signal to calculate a correction amount from the error in amplification factor for each range of the range switch, storing the correction amount in a memory, reading from the memory a correction amount corresponding to a range of the range switch selected for actual measurement, and adding the correction amount to a measured value to obtain a final measured value.

15. The measuring equipment automatic adjusting method for measuring equipment according to claim 13, characterized in that said range switch is a level range switch and/or frequency characteristic switch provided in an acoustic measuring instrument such as a sound level meter, a vibrometer, or a frequency analyzer.

14. A measuring equipment automatic adjusting apparatus which automatically corrects an error in amplification factor for each range of a range switch for a measuring instrument, the apparatus being characterized by comprising reference signal oscillating means for generating a reference signal, correction amount calculating means for using the reference signal generated by the reference signal oscillating means to calculate a correction amount from the error in amplification factor for each range of the range switch, memory means for storing the correction amounts calculated by the correction amount calculating means so that the correction amounts correspond to the respective ranges, and correction processing means for reading from the memory means a correction amount corresponding to a range of the range switch selected for actual measurement and adding the correction amount to a measured value.

16. The measuring equipment automatic adjusting apparatus for measuring equipment according to claim 14, characterized in that said range switch is a level range switch and/or frequency characteristic switch provided in an acoustic measuring instrument such as a sound level meter, a vibrometer, or a frequency analyzer.