JPH07151682A - Gas density measuring processor - Google Patents

Abstract

PURPOSE:To provide a gas density measuring processor which eliminates the calibration of phase synchronization and makes possible the using of an inexpensive and low speed DSP (a digital signal processor) or the like. CONSTITUTION:After demodulation with a fundamental wave orthogonal demodulation section 1 and a double wave orthogonal demodulation section 2, harmonic components are removed with harmonic component-removing sections 3 and 4 and respective amplitude values of a fundamental wave and a double wave with a measure computing section 5. Then, a ratio is determined to obtain a measure of the density of a gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gas concentration measurement used in a gas detector for highly accurately measuring the concentration of gas such as methane gas and carbon dioxide gas by utilizing the absorption spectrum peculiar to each gas. The present invention relates to a processing apparatus, and particularly to a gas concentration measurement processing apparatus using a frequency modulation method.

[0002]

2. Description of the Related Art Each gas has an absorption spectrum peculiar to gas molecules, and an attempt to measure the gas concentration by oscillating a laser at a frequency at which this absorption spectrum exists was made by CB Moore in 1965. It was done for the first time.

This principle will be briefly described below. The absorption spectrum of gas has a minimum value at various frequencies according to the vibrational energy of the gas molecule.
When one is taken out, it has a characteristic generally called Lorentz type as shown in FIG. The horizontal axis of FIG. 5 is frequency, and the vertical axis is transmittance. The frequency f of the minimum value of this absorption spectrum is shown.
The transmittance at c decreases with increasing gas concentration. Therefore, when the gas is irradiated with laser light having an oscillation frequency of fc, the transmitted signal is received by the photodetector and converted into an electrical signal, and the change amount of the transmittance is calculated, the change amount of the transmittance is calculated. Since it is a measure of the gas concentration proportional to the gas concentration, the gas concentration can be measured by multiplying this measure by a coefficient obtained by, for example, measuring a gas whose concentration is known in advance.

As one developed by paying attention to this principle, 2
There are a wavelength difference method and a frequency modulation method, and these two methods are currently the mainstream of gas concentration measurement using a laser. For detailed explanation and experimental results of the two-wavelength difference method, see: K. Uehara: Appl. Phys. B, Vol.38, No.1, pp.37--4
0, 1985. ・ Hideo Tai, Kazunari Yamamoto, Ken Abe, Takashi Ueki, Hiroaki Tanaka, Kiyoji Uehara: Transactions of the Society of Instrument and Control Engineers 24, pp.452--458, 19
88. ・ Hideo Tai, Hiroaki Tanaka, Kiyoji Uehara: Optics, Vol.19, No.
4, pp.238--244, 1990.

A detailed explanation of the frequency modulation method and experimental results are as follows: DTCassidy: Appl. Opt., Vol.27, No.3, pp.610--6
14, 1988. Hideo Tai, Masayuki Matsuura, Hiroaki Tanaka, Kiyoji Uehara: Optics, Vol.
19, No. 9, pp.616--619, 1990.

First, the two-wavelength difference method will be described.
After that, the frequency modulation method according to the present invention will be described. FIG. 10 shows a block diagram of a gas detector using the two-wavelength difference method. In FIG. 10, the frequency switch 40 is a laser
The oscillation frequency of 10 is for switching between the frequency fc at which the transmittance is minimal in the gas absorption spectrum of the gas cell 20 and the frequency fn at which the gas absorption spectrum does not exist. The signal converted by the photodetector 30 into an electrical signal is the laser
By changing the oscillation frequencies fc and fn of 10, the transmittance changes as shown in FIG. 5, the amplitude value changes, and the difference in the amplitude becomes the change amount of the transmittance, which is a measure of the gas concentration.

Here, for general applications, it is convenient to make the optical path length from the laser 10 to the photodetector 30 variable.
For example, the longer the optical path length of the laser light passing through the gas, the greater the change in transmittance, and the gas concentration can be measured with high accuracy, so a multiple reflection type gas cell can be selected,
This is because a small gas cell may be selected because it is easy to carry. When the optical path length becomes long, the laser light diverges and the laser light is attenuated by the influence of dust in the surroundings, so that the amplitude of the input signal to the gas concentration measurement processing device 80 becomes small. As a result, the difference in amplitude representing the change in transmittance is reduced, and the gas concentration value converted from the output value of the gas concentration measurement processing device 80 is reduced. In order to prevent the above-mentioned problems from occurring, a method of dividing the difference in amplitude by the amplitude at a frequency where there is no absorption spectrum of gas is taken. Further, since the difference in the amplitude is proportional to the optical path length of the laser light passing through the gas, the optical path length is divided when converting to the concentration. By multiplying the gas concentration measurement thus obtained by an appropriate proportional constant, the gas concentration can be obtained without depending on the optical path length.

In the two-wavelength difference method, the signal converted into an electric signal by the photodetector 30 and input to the gas concentration measurement processing device 80 is a direct current signal, and therefore a direct current offset caused by a drift of an operational amplifier or the like. Since the components cannot be removed, the gas concentration cannot be detected with high accuracy. Further, there is a drawback that the concentration of the gas cannot be detected with high accuracy due to the interference of external light. The frequency modulation method described below was devised to improve this drawback.
In this method, the gas concentration can be measured only by the AC component signal so that the gas concentration measurement is not adversely affected by the presence of a DC offset component or extraneous light.

FIG. 6 shows the principle of the frequency modulation method. The laser is frequency-modulated at the modulation frequency fm with the center frequency fc, and the measured gas is irradiated. Since the absorption spectrum of gas shows a characteristic called Lorentz type and becomes a quadratic function with respect to the detuning frequency, the signal converted into an electric signal by the photodetector has a frequency twice that of the modulation frequency. (Hereinafter, this signal is referred to as a second harmonic signal). The amplitude value of this signal increases as the gas concentration increases, because the transmittance decreases, and it becomes a measure of the gas concentration and can be converted to the gas concentration by multiplying it by an appropriate proportional constant.

A method of canceling the influence of the optical path length by the frequency modulation method will be described below as in the case of the two-wavelength difference method. Current control must be performed to frequency modulate the laser. When this current control is performed and frequency modulation is applied at the frequency fm, amplitude modulation is also automatically applied at the frequency fm. Therefore, the signal converted into an electric signal by the photodetector also includes a signal having a frequency of fm generated by amplitude modulation (hereinafter, this signal is referred to as a fundamental wave signal). Using this fundamental wave,
By dividing the amplitude value of the second harmonic by the amplitude value of the fundamental wave, it is possible to cancel the influence of the divergence of laser light or the surrounding dust caused by the lengthening of the optical path. Will be a measure of. As a method of estimating the amplitude of the fundamental wave and the second harmonic of the frequency modulation method for measuring the gas concentration, a phase-sensitive phase sensitive detection is used.

FIG. 11 shows a conventional gas detector using a frequency modulation method. In this method, the reference signal from the frequency modulator 50 of the laser 10 is connected to the fundamental wave phase sensitive detector 91 and the second harmonic phase sensitive detector 92 of the gas concentration measuring device 90, and the fundamental wave amplitude values A and 2 are connected. By manually shifting the phase little by little so that the amplitude value B of the harmonic wave becomes maximum, phase synchronization is performed, and the amplitude value A obtained by this calibration is divided by the amplitude value B to obtain a measure of the gas concentration. It can be converted to the gas concentration by multiplying it by an appropriate proportional constant.

[0012]

In the phase sensitive detection conventionally used in the frequency modulation method, the reference signal from the frequency modulator 50 of the laser 10 is used as a gas concentration measurement processing device.
90 fundamental wave phase sensitive detector 91 and 2nd harmonic phase sensitive detector 92
There is a problem that you have to connect to. As an example, when measuring the concentration of methane gas generated in a paddy field, it is necessary to separate the laser 10 and the gas concentration measurement processing device 90 by several tens of meters, and it is very difficult to prepare such a long-distance cable.

In addition, in the phase sensitive detection method, the phase is manually shifted little by little so that the amplitude values of the fundamental wave and the second harmonic wave are maximized before estimating the gas concentration in order to perform phase synchronization. There is also a problem that it takes several minutes to find.

Further, the phase sensitive detection is performed by a DSP (Digital Si
The computation cannot be performed at the processing speed of the gnal Processor) or CPU (Central Processing Unit), so digitization cannot be performed and miniaturization and cost reduction cannot be achieved. An object of the present invention is to maintain the accuracy of a gas concentration measurement processing device using a conventional phase-sensitive detection, and it is not necessary to connect a reference synchronized signal from a laser frequency modulator to the gas concentration measurement processing device. In addition, there is no need to manually shift the phase little by little for calibration to find the maximum point of the amplitude level, and a gas concentration measurement processor that can realize circuit miniaturization and cost reduction by using DSP and CPU. Is to provide.

[0015]

In order to solve the above-mentioned problems, an asynchronous envelope detection is adopted.
In the invention described above, a high frequency component removing unit is further provided. In addition, in the second invention, a multiple sum processing unit is provided. The reason for providing the high frequency component removing unit and the reason for providing the multiple sum processing unit will be described in detail in the section of operation.

[0016]

[Function] Since the asynchronous envelope detection is adopted, it is not necessary to connect the signal synchronized with the reference to the gas concentration measurement processing device, and the phase is manually shifted little by little for calibration, and the maximum amplitude level point is obtained. There is no need to find the operation, and it is possible to process using DSP and CPU. Further, the high frequency component removing unit or the multiple sum processing unit removes the high frequency component. As described above, the parameters necessary for measuring the gas concentration by the frequency modulation method are generated by the fundamental wave signal of the signal converted into the electric signal by the photodetector and the absorption spectrum of the gas to be measured. It is the amplitude value of the harmonic signal. Dividing the amplitude value of the second harmonic signal by the amplitude value of the fundamental wave signal gives a measure of the gas concentration, which can be converted to the gas concentration by multiplying it by an appropriate constant.

However, when the amplitude ratio between the fundamental wave signal and the second harmonic wave signal is calculated by using the envelope detection of the asynchronous method, the gas concentration does not change each time the power is turned on again. A phenomenon such as a change in the amplitude ratio occurs. When the power is turned on, this amplitude ratio is constant, and when the power is turned off and then on again, this amplitude ratio becomes constant at a value different from the previous value. There is no stopping it from happening.

The above phenomenon will be described in detail. In order to process the signal converted into an electric signal by the photodetector with DSP
When harmonic components are removed by LPF (Low Pass Filter), the signal sampled by the AD converter is

[0019]

[Equation 1]

It can be expressed as However, the first term is the fundamental wave component, the second term is the second harmonic wave component, the third term is the white noise component, fm is the frequency of the fundamental wave, fs is the sampling rate, and θ and φ are initial phases. Here, in order to express the number 1 simply

[0021]

[Equation 2]

If you put

[0023]

[Equation 3]

It can be rewritten as What is necessary for measuring the gas concentration is the amplitude A of the fundamental wave and the amplitude B of the second harmonic wave of the equation (3). First, in order to obtain the amplitude A of the fundamental wave, the frequency transition is performed with the local frequency as the frequency of the fundamental wave, and harmonic components are removed by the LPF.

[0025]

[Equation 4]

Therefore, when the norm of Equation 4 is obtained,

[0027]

[Equation 5]

And the amplitude A of the fundamental wave is obtained. It seems that the amplitude B of the second harmonic wave may be obtained by using the same operation as described above, but when measuring a low concentration gas, the second harmonic wave has a problem. The reason for this is that when measuring low-concentration gas, the amplitude value A of the fundamental wave component is much larger than the amplitude value B of the second harmonic wave component, so the frequency transition at the second harmonic wave frequency 2fm. LP after going
This is because at F, the fundamental wave component that has become a harmonic component due to the frequency transition cannot be sufficiently attenuated. Even if the fundamental component is attenuated by using HPF (High Pass Filter) as a pre-processing for frequency transition, the fundamental component is lower than the second harmonic component for lower concentration gas. Also has a large value and cannot be sufficiently attenuated by the LPF, which eventually affects the second harmonic component. The frequency is changed to extract the second harmonic component with the local frequency as the second harmonic frequency, and when the LPF is passed, the output is

[0029]

[Equation 6]

Therefore, the signal of only the direct current component for estimating the amplitude of the second harmonic is not generated, and the harmonic components of the second and third terms are generated due to the frequency shift of the fundamental wave component. I will end up. FIG. 7 shows Equation 6 as a vector. Also,
Amplitude values X0 and Y0 of two second harmonic signals having different initial phases
Is expressed as a vector as shown in FIG. That is, if the initial phase changes depending on the timing of turning on the power, the amplitude value of the second harmonic wave also changes.

On the other hand, in the phase synchronization type phase sensitive detection, such a problem does not occur because the phase is manually adjusted before measuring the gas concentration so that the amplitude value becomes maximum. According to the present invention, a phase-asynchronous envelope detection is provided with a harmonic component removing unit or a multiple sum processing unit, and the harmonic component is removed in the measurement of the amplitude of the second harmonic. I made sure that there was no fluctuation. Second of the above equation 6
The harmonic components of the term and the third term are line spectra of frequency fm and frequency 3fm, respectively. The signals of this harmonic component are

[0032]

[Equation 7]

Adding N times given by
(Where M is an arbitrary integer and GCM (fs, fm) is f
The greatest common divisor of s and fm)

[0034]

[Equation 8]

[0035]

[0036]

[Equation 9]

Then, the harmonic components can be removed.
Therefore, the impulse response

[0038]

[Equation 10]

The harmonic component can be completely removed by passing the signal given by the equation (6) through the comb filter having. This will be explained below on the frequency axis. The frequency response of the filter given by equation 10 is

[0040]

[Equation 11]

It becomes As an example, M = 1, fs = 8f
If m, then N = 8, and the response given by equation 11 is
As shown in FIG. 9, frequency fm and frequency 3fm
The components in the region of are completely removed. Therefore, by passing the signal given by Eq. 6 through the filter given by Eq. 10, the in-phase / quadrature component B of the second harmonic wave with the harmonic component removed
X (e to the power of −jφ) is obtained, and the amplitude value B of the second harmonic wave can be obtained by performing the norm calculation similar to the equation 5. Since the amplitude value B of the second harmonic wave does not include a harmonic component, the amplitude value does not change every time the power is turned on, and the gas concentration can be measured with high accuracy.

When measuring low-concentration gas, since the amplitude value A of the fundamental wave is much larger than the amplitude value B of the second harmonic wave, as described above, the number of waves on the second harmonic wave side is increased. Although the filter given by 10 was inserted, when measuring a high concentration gas, it is necessary to put the filter given by several 10 on the reverse fundamental wave side. By dividing the amplitude value B of the second harmonic wave thus obtained by the amplitude value A of the fundamental wave, a measure of the gas concentration can be obtained with the same degree of accuracy as the phase sensitive detection, and the appropriate proportional constant should be multiplied. Can be converted to gas concentration.

[0043]

EXAMPLE An example in which the gas to be measured is methane gas will be described below. The laser sets the center frequency at the wavelength of 1.6538 μm where the transmittance becomes the minimum in the absorption spectrum of methane gas, sets the modulation frequency fm of the frequency modulation to 32.5 kHz, and the maximum frequency deviation is frequency modulated at full width at half maximum. And set the sampling rate fs to the modulation frequency f
It was set to 260 kHz, which is 8 times m. Also, in Equation 7, M
= 1, the filter of the equation 10 was realized with N = 8. Texas Instruments TMS320C25 was used as the DSP for the arithmetic processing.

The respective embodiments of the first and second inventions will be described below. FIG. 2 shows a gas concentration measurement processing apparatus of Example 1 (first invention). In the fundamental wave quadrature demodulation unit 1 shown in FIG. 2, an input signal s (n) is received, and the input signal is supplied to a multiplier 11 which outputs a local signal 13 [2cos (2πfmn / f
s)] and is filtered by a low pass filter (LPF) 12 and the result is output. Further, the input signal s (n) is multiplied by the local signal 16 [2sin (2πfmn / fs)] orthogonal to the local signal 13 in the multiplier 14,
It is filtered by LPF15 and the result is output.

The harmonic component removing section 3 receives the output of the LPF 12 and removes the harmonic component by the comb filter 31 having an impulse response of h (n) of several 10 to remove the in-phase component of the input signal s (n). Is output. Further, receiving the output of the LPF 15, harmonic components are removed by the comb filter 32 having an impulse response of h (n), and the quadrature component of the input signal s (n) is output.

In the measure calculator 5, the in-phase component output from the comb filter 31 is squared by the multiplier 51, and the quadrature component output from the comb filter 32 is squared by the multiplier 52. The squared values are added by an adder 53, a square root operation is performed by a square root unit 54, an amplitude value A of the fundamental wave is calculated, and this value is put into a divider 59 as a denominator. The second harmonic quadrature demodulation unit 2 receives the input signal s (n), and the input signal is applied to the multiplier 21 by the local signal 23 [2cos (4πfm n /
fs)] and filtered by LPF22, and the result is output. Also, the input signal s (n) is calculated by the multiplier 24
And the local signal 26 [2si orthogonal to the local signal 23
n (2πfm n / fs)] and filtered by LPF25, and the result is output.

The harmonic component removing unit 4 receives the output of the LPF 22 and removes the harmonic component by the comb filter 41 having an impulse response of h (n) of several 10 to remove the in-phase component of the input signal s (n). Is output. Further, receiving the output of the LPF 25, the comb filter 42 having an impulse response of h (n) removes the harmonic components, and outputs the quadrature component of the input signal s (n). In the measure calculator 5, the in-phase component output from the comb filter 41 is squared by the multiplier 55, and the quadrature component output from the comb filter 42 is squared by the multiplier 56.
These squared values are added by the adder 57 to obtain the square root device.
The square root operation is performed in 58, the amplitude value B of the second harmonic is calculated, this value is put into the divider 59 as the numerator, and the amplitude value B of this second harmonic is divided by the amplitude value A of the fundamental wave. Is output as a measure of the gas concentration.

By multiplying the output value by a predetermined coefficient, the gas concentration can be obtained. In the first embodiment, the harmonic component removing portions are provided on the fundamental wave side and the second harmonic wave side, respectively. However, as described in the section of action, it may be provided on only one side depending on the concentration of the gas to be measured. Example 2 (second invention)
Is a general-purpose CP as well as a DSP that reduces the calculation amount of the first embodiment.
Even in U, the gas concentration measurement process can be performed. In order to reduce the amount of calculation, the sampling rate for sampling the input signal to the gas concentration measurement processing device is fixed to 8 times the frequency of the fundamental wave (fs = 8fm). When the sampling rate is determined in this way, the value of the local signal of the fundamental wave is as shown in Table 1.

[0049]

[Table 1]

When n is 8 or more, the values of the local signals shown in Table 1 are repeated. The values of the local signal cos (2πfm n / fs) in Table 1 are ± 1 and ± 1 / √
The registers for calculation at the time of (2) are a and b, respectively, and the value of the local signal sin (2πfm n / fs) is ± 1 and ± 1 /.
√ (2) is the calculation register for c and d,
Let e be a register for calculation when the value of cos (4πfm n / fs) is ± 1, and f be a register for calculation when sin (4πfm n / fs) is ± 1. When the input signal to the gas concentration measurement processing device is s (n), the fundamental wave quadrature demodulation unit 1 of the first embodiment is used.
And the in-phase and quadrature components of the second-harmonic quadrature demodulation unit 2 are calculated by using the registers defined above, and n =
Repeat until K (where K is a multiple of 8),

[0051]

[Table 2]

After that

[0053]

[Equation 12]

Each can be obtained by calculating However, n mod 8 in Table 2 means the remainder when n is divided by 8, and AI and AQ in Equation 12 are the in-phase component and the quadrature component of the fundamental wave, respectively, and BI and BQ are the in-phase component of the second harmonic wave, respectively. It is an orthogonal component. . Since the above calculation is a summation calculation, the fundamental wave orthogonal demodulation units 1 and 2 of the first embodiment are used.
This means that the quadrature demodulation of the harmonic quadrature demodulation unit 2 and the LPF filter processing have been performed, and the number of repetitions of this sum is a multiple of the cycle of the fundamental wave.
It means that the filter processing of Further, since the divider 59 of the first embodiment divides the amplitude value B of the second harmonic by the amplitude value A of the fundamental wave, it is not necessary to perform division by the number K of repetitions of the equation 12.

FIG. 3 shows an embodiment using the multiple sum processing described above. The details of the multiple sum processing unit 6 are shown in FIG. In the figure, a to f are the registers a to f. The multiple sum processing unit 6 receives the input signal s (n) and performs the above-mentioned arithmetic processing to perform the in-phase component AI of the fundamental wave, the quadrature component AQ of the fundamental wave, the in-phase component BI of the second harmonic wave, and the second harmonic wave. The quadrature component BQ is output. In the measure calculation section 7, the four signals output from the multiple sum processing section 6 are received, the in-phase component AI of the fundamental wave is squared by the multiplier 71, and the quadrature component AQ of the fundamental wave is squared by the multiplier 72. Then, the squared values are added by the adder 73, and the sum is input to the divider 77 as a denominator. The in-phase component BI of the double wave is squared by the multiplier 74, the quadrature component BQ of the double wave is squared by the multiplier 75, and the squared values are added by the adder 76, and the divider 77 It is put in as a molecule. The divider 77 performs the division and outputs the value, and the square root 78 performs the square root operation and outputs the gas concentration measure.
The concentration of gas can be obtained by multiplying the output value by a predetermined coefficient.

According to the first or second aspect of the present invention, the circuit can be downsized and the cost can be reduced by performing the gas concentration measurement process using the DSP or the general-purpose CPU as in the first and second embodiments. Further, since the signal to be handled has a low frequency as compared with the phase sensitive detection used in the conventional apparatus, there is little dependence on the ambient temperature and the characteristics of parts over time, and stable measurement is possible.

[0057]

The gas concentration measuring and processing apparatus of the present invention employs an asynchronous envelope detection method, and is provided with means for removing harmonic components of a signal obtained by passing through the gas to be measured. Therefore, it is not necessary to connect the signal synchronized with the reference from the laser frequency modulator to the gas concentration measurement processing device, and manually shift the phase little by little to find the maximum amplitude level. No operation required. Moreover, the gas concentration can be measured with the same accuracy as the phase-sensitive detection used in the conventional gas concentration measurement processing device. Moreover, since the gas concentration measurement process can be performed using the DSP and the general-purpose CPU, the circuit can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a gas concentration measurement processing device of a first invention.

FIG. 2 is a block diagram of a gas concentration measurement processing device according to the first embodiment.

FIG. 3 is a block diagram of a gas concentration measurement processing device according to a second embodiment.

FIG. 4 is a block diagram showing details of a multiple sum processing unit of the gas concentration measurement processing apparatus according to the second embodiment.

FIG. 5 is a diagram showing an absorption spectrum of gas.

FIG. 6 is a principle diagram of a frequency modulation method.

FIG. 7 is a vector diagram after the second harmonic orthogonal demodulation.

FIG. 8 is a vector diagram after two-wave orthogonal demodulation of two signals having different initial phases.

FIG. 9 is a diagram showing a frequency response of a comb filter.

FIG. 10 is a block diagram of a gas detector using a two-wavelength difference method.

FIG. 11 is a block diagram of a gas detector using a conventional frequency modulation method.

[Explanation of symbols]

 1 fundamental wave quadrature demodulation unit 2 2nd harmonic quadrature demodulation unit 3,4 harmonic component removal unit 5,7 measure calculation unit 6 multiple sum processing unit

Claims (1)

[Claims] 1. A fundamental wave signal (frequency) of an optical signal having absorption characteristics of the gas to be measured, obtained by injecting light amplitude-modulated and frequency-modulated at a predetermined frequency (fm) into the gas to be measured. fm) and a second harmonic signal (frequency 2 fm) for measuring the gas concentration in a gas concentration measurement processing device, which receives an input signal in which the optical signal is converted into an electric signal, and extracts an in-phase component and a quadrature component of the fundamental wave signal. A fundamental wave quadrature demodulation unit (1) for obtaining and outputting the same, a second harmonic quadrature demodulation unit (2) for receiving the input signal and obtaining and outputting an in-phase component and a quadrature component of the second harmonic signal, and the fundamental wave demodulation Output from the second harmonic wave demodulation unit and a fundamental wave harmonic component removal unit (3) that receives signals of the in-phase component and the quadrature component output from the unit, and removes the harmonic components contained in those components. Receive in-phase and quadrature component signals Double wave harmonic component removing unit for removing a harmonic component contained in the component (4)
And a signal for the in-phase component and the quadrature component output from the fundamental harmonic component removing unit and the second harmonic component removing unit, and calculates and outputs a gas concentration measure proportional to the gas concentration. A gas concentration measurement processing device, comprising: a signal processing section including a section (5).