Method and apparatus for checking a gas detection device

Abstract

The invention relates to a verification method and a verification device capable of verifying a gas detection device (100). A radiation source (1) emits radiation into a measuring chamber (2), the intensity of the emitted radiation being controlled by an input signal [x Ref (t), x Üb (t)] is described. A detector (4) generates an output signal [y] depending on the intensity of incident radiation. Ref (t), y Üb (t)]. It is assumed that the gas detection device (100) is intact during a reference period (Ref_ZR). The aim is to verify whether it is also intact during a verification period (Üb_ZR). In both periods (Ref_ZR, Üb_ZR), a measure of the system behavior of a hypothetical system is calculated. This hypothetical system is connected to the input signal [x Ref (t), x Üb (t)] is excited and, in response to the excitation, delivers the measured output signal [y]. Ref (t), y Üb(t)]. The two measures for the two system behaviors are compared. Depending on the result of this comparison, information (state) about the state of the gas detection device (100) during the verification period (v_v_v) is derived.

Description

[0001] The invention relates to a method and a device for automatically checking a gas detection device. Such a gas detection device is capable of checking a spatial area for the presence of at least one target gas to be detected and / or determining the concentration of such a target gas.

[0002] Gas detection devices comprising a radiation source and a measuring chamber have become known. A gas sample to be examined enters the measuring chamber. Radiation emitted by the radiation source penetrates the measuring chamber. The target gas absorbs a portion of the radiation passing through the measuring chamber. A detector on the measuring chamber measures the intensity of the incident radiation. This intensity is a measure of the target gas concentration. A gas detection device that can be verified according to the invention also uses this principle.

[0003] Such a target gas can pose a health risk to humans. Therefore, it is essential that the gas detection device reliably detects a harmful target gas. On the other hand, it is desirable that the gas detection device generates relatively few false alarms. For both reasons, it is necessary to check the gas detection device from time to time.

[0004] The invention is based on the objective of providing a verification method and a verification device which makes it possible to verify a gas detection device with a radiation source, a measuring chamber and a detector with less effort than known methods and devices.

[0005] The problem is solved by a verification method having the features of claim 1 and by a verification device having the features of claim 10. Advantageous embodiments of the verification method according to the invention are, where appropriate, also advantageous embodiments of the verification device according to the invention, and vice versa.

[0006] The gas detection device to be tested comprises a measuring chamber. This measuring chamber is capable of holding a gas sample for analysis. The gas sample originates from a spatial area to be monitored. Furthermore, the gas detection device to be tested comprises a radiation source and a detector. The radiation source is capable of emitting radiation into the measuring chamber. This radiation is, in particular, electromagnetic or acoustic radiation. The radiation penetrates the measuring chamber at least once, and optionally several times. The detector is capable of generating a signal depending on the intensity of the incident radiation. This intensity is altered by the target gas to be detected.

[0007] The verification method according to the invention automatically verifies such a gas detection device. It is assumed that the gas detection device is intact during a reference period. At a minimum, the radiation source, the measuring chamber, and the detector must be intact; preferably, an optional evaluation unit and an optional power supply unit must also be intact. The verification process checks whether the gas detection device remains intact during a verification period. Typically, the verification period is after the reference period. However, it is also possible for the reference period to be after the verification period, in which case the gas detection device is to be verified subsequently.

[0008] The following steps are carried out in both the reference period and the review period: - The radiation source emits radiation into the measuring chamber. - A measure of the intensity of the emitted radiation is specified or measured. This measure refers to the intensity before the radiation enters the measuring chamber and is used as an input signal. The emitted radiation passes through the measuring chamber at least once, and optionally several times to lengthen the optical path. After passing through, the emitted radiation strikes the detector. The intensity of the incident radiation depends on the input signal. - The detector generates an output signal. This output signal depends on the intensity of the incident radiation and therefore on the input signal. A measure of the system behavior of a hypothetical system is calculated, either in the time domain or the frequency domain. This hypothetical system is excited by the input signal and generates the output signal in response to this excitation.

[0009] The reference system behavior is calculated as the behavior of the hypothetical system that, during the reference period, is excited by the specified or measured input signal and generates the measured output signal in response to this excitation. Similarly, the verification system behavior is calculated as the behavior of the hypothetical system that, during the verification period, is excited by the specified or measured input signal and generates the measured output signal in response to this excitation.

[0010] In a properly functioning gas detection device, these two system behaviors correspond to each other except for an unavoidable tolerance. According to the invention, the two measures are compared with each other, i.e., the test system behavior with the reference system behavior. Depending on the result of the comparison, information about the state of the gas detection device during the test period is derived.

[0011] The invention can be applied again each time the gas detection device needs to be checked. In many cases, the invention eliminates the need to take the gas detection device out of service after a predetermined period, regardless of its condition.

[0012] The invention makes it possible in many cases to detect both faults in the radiation source and faults in the detector. In particular, a fault in the radiation source can be detected when a predefined input signal is used and the radiation source is supposed to follow this input signal. With a faulty radiation source, the actual intensity of the radiation usually deviates considerably from the input signal. A fault in the measuring chamber can also be detected, preferably also a fault in an optional evaluation unit and a fault in an optional, separate power supply unit of the gas detection device. Both faults that occur suddenly, for example due to an external influence, and faults that occur gradually due to aging or parameter drift can be detected thanks to the invention.This advantage is achieved because, in many cases, a faulty radiation source, a faulty detector, or a faulty measuring chamber leads to a significantly altered system behavior and thus also to a significantly altered measure of system behavior. The comparison therefore results in a deviation between the two measures of system behavior that is greater than a predefined tolerance.

[0013] According to the invention, the behavior of the test system is compared with the behavior of the reference system. The test system behavior describes the response of the hypothetical system to excitation by the radiation source during the test period, while the reference system behavior describes the response of the same hypothetical system to the same excitation during the reference period. The term "the same hypothetical system" naturally only applies if the gas detection device is also intact during the test period. In other words, the test system behavior describes the state of the gas detection device during the test period, and the reference system behavior describes the state of the gas detection device during the reference period. Specifically, the same device, and thus the same radiation source, the same measuring chamber, and the same detector, are used in both periods.If the radiation source, measuring chamber, and detector remain intact throughout the verification period, the verification system behavior ideally matches the reference system behavior. Preferably, a tolerance is specified, and the radiation source, measuring chamber, and detector are considered intact if the two system behaviors differ from each other by no more than this tolerance. This tolerance accounts for an unavoidable measurement error as well as potential measurement and process noise.

[0014] The reference system behavior is recorded under a condition in which the gas detection device—or at least the measuring chamber and the detector—is intact. In many cases, it is sufficient that the following two conditions are met: - During the reference period and the verification period, two gas samples are used that absorb the penetrating radiation with sufficient consistency. This is generally the case, in particular, if the two gas samples are chemically similar to a sufficiently high degree. - The input signal, i.e. the emitted radiation, is sufficiently broadband so that even a fault that only occurs in a sub-range of the frequency band can be detected.

[0015] Thanks to the invention, it is often unnecessary to ensure that further prerequisites are met, in particular that the gas sample used in the reference period has a specific chemical composition. Furthermore, it is frequently unnecessary to control the radiation source with the same temporal profile in both the verification and reference periods. Specifically, it is not necessary for the respective electrical voltage applied to the voltage source to be identical in both periods. This advantage is achieved because, according to the invention, two system behaviors of two hypothetical systems are calculated and compared, and these two system behaviors correspond with sufficient accuracy, even when different control methods and therefore different input signals are used in the two periods, provided the components of the gas detection device are intact.

[0016] According to the invention, a measure of the system behavior of the imagined system is calculated in each of the two time periods. In a preferred embodiment, the step of calculating the measure of the system behavior comprises the following step in each of the two time periods: A measure of the cross-correlation between the input signal and the output signal is calculated.

[0017] The input and output signals are time-resolved signals, i.e., signals in the time domain. Therefore, the cross-correlation is usually calculated in the time domain as well. In a further development of this approach, the respective cross-correlation for both time periods is transformed from the time domain to the frequency domain, in particular by a Laplace transform or a Fourier transform. This preferably allows the calculation of the respective transfer function in the complex domain of the hypothetical system. A reference transfer function describes the system behavior in the reference time period, and a verification transfer function describes the system behavior in the verification time period. The transfer function in the complex domain can sometimes also be calculated without using a cross-correlation.

[0018] In one embodiment, the verification method according to the invention is implemented using a signal processing unit. This signal processing unit calculates the respective measure of the system behavior both during the reference period and during the verification period, compares these measures, and provides the status information about the gas detection device.

[0019] In one implementation, this signal processing unit is an integral part of the gas detection device being tested. The gas detection device can therefore test it itself. In another embodiment, the signal processing unit is part of a computing unit. This computing unit is located separately from the gas detection device. A data connection is established between the gas detection device and the computing unit, at least temporarily. This configuration makes it easier to incorporate a high-performance signal processing unit. This is particularly advantageous when the gas detection device is portable, especially a portable device carried by a user.

[0020] According to the invention, the gas detection device comprises a measuring chamber and a detector. In one embodiment, the gas detection device additionally comprises a reference chamber and a reference detector. While the measuring chamber is filled with a gas sample, which may contain the target gas or at least one of the gases to be detected, at least during the verification period, the reference chamber is filled with a reference gas that is ideally free of the target gas or gases. The two chambers are arranged parallel with respect to the emitted radiation. Therefore, the radiation emitted by the radiation source penetrates both the measuring chamber and the reference chamber at least once each. This applies to both the reference period and the verification period.

[0021] According to the invention, the detector generates a time-resolved signal, namely the output signal, depending on the intensity of the incident emitted radiation. This radiation has penetrated the measuring chamber at least once. According to the embodiment just described, the reference detector also generates a time-resolved signal depending on the incident emitted radiation. This radiation has penetrated the reference chamber at least once.

[0022] The design, incorporating the output signal from the detector and the signal from the reference detector, allows these two signals to be compared, thereby enabling the detection of a target gas or the exclusion of its presence. The target gas(es) only affects the measuring chamber, not the reference chamber. Ambient conditions, particularly ambient temperature and humidity, however, affect both chambers.

[0023] According to the invention, a measure of the system behavior of a hypothetical system is calculated in both the reference period and the verification period. This hypothetical system is excited by the respective input signal and provides the output signal. In the embodiment just described, the input signal is, by way of exception, the signal generated by the reference detector after radiation has penetrated the reference chamber at least once. This applies both to the step of calculating the reference system behavior and to the step of calculating the verification system behavior.

[0024] This design often compensates to a certain extent for the influence of environmental conditions on the respective system behavior. It is often not necessary to create exactly the same environmental conditions during the reference period and the verification period.

[0025] The gas detection device is verified by the verification method and the verification device according to the invention. In one embodiment, the invention is used to adjust and / or calibrate the gas detection device. According to this embodiment, the output signal depends on the intensity of incident radiation after this radiation has penetrated the measuring chamber and additionally on the value of a parameter used. The system, which is excited by the input signal and provides the output signal in response to the excitation, also depends on the parameter value used. For example, the output signal includes a measure of the concentration of a gas to be detected, whereby this concentration can vary over time. The parameter describes a functional relationship between a raw output signal of the detector and the target gas concentration and is, for example, a proportionality factor.

[0026] According to the invention, the reference system behavior is calculated during the reference period. In the embodiment with the parameter, several possible values ​​are specified for the parameter. Each possible parameter value corresponds to a hypothetical system. For each possible parameter value, the verification system behavior of this hypothetical system is calculated during the verification period and compared with the previously calculated reference system behavior. A comparison result is thus calculated for each possible parameter value. The value actually used for the parameter is determined based on this comparison result. For example, the value used for the parameter is the one that results in the smallest deviation between the reference system behavior and the verification system behavior.

[0027] In many cases, this design simplifies the calibration of the gas detection device. Often, it is not necessary to use a calibration gas sample with a specific, sufficiently precise chemical composition, with the gas detection device analyzing this calibration gas sample. However, this design can also be used in conjunction with a calibration gas sample.

[0028] The invention is described below using an exemplary embodiment. Here, it is shown that... Fig. 1 the transmittance of methane as a function of wavelength; Fig. 2. the transmittance of propane as a function of wavelength; Fig. 3 schematically the gas detection device during the reference period; Fig. 4 schematically the signal processing unit of Fig. 3 in detail; Fig. 5 schematically the gas detection device during the inspection period; Fig. 6 schematically the signal processing unit of Fig. 5 in detail; Fig. 7 a different design of the gas detection device with a measuring chamber and additionally a reference chamber in the reference period; Fig. 8 the design of Fig. 7 during the review period; Fig. 9 a different design, wherein the signal processing unit is a component of a spatially modified computing unit.

[0029] In this embodiment, the invention is used to test a gas detection device. This gas detection device is used, or can be used, to examine a spatial area for several different flammable target gases. In one embodiment, the concentration of each target gas is determined, and preferably, information about at least one determined target gas concentration is output in a form perceptible to a human. In another embodiment, an alarm is triggered if the measured concentration of at least one target gas exceeds a predetermined threshold.

[0030] The gas detection device under review utilizes a principle known from the prior art, namely the following: Various target gases attenuate electromagnetic and / or acoustic radiation. A measure of the attenuation is the spectral response, expressed as transmittance Tr in %, as a function of the wavelength λ of the radiation. The lower the transmittance Tr[λ], the more strongly the target gas attenuates the radiation.

[0031] Fig. Figure 1 shows an example of the spectral profile for the hydrocarbon methane. Fig. 2. The values ​​for propane are shown, each at an exemplary concentration of methane or propane. In this example, electromagnetic radiation penetrates a measuring chamber.

[0032] Fig. 3 and Fig. Figure 5 schematically shows the gas detection device 100 according to one embodiment of the exemplary embodiment. The gas detection device 100 comprises a measuring chamber 2 and a radiation source 1.

[0033] Measuring chamber 2 is at least temporarily in fluid contact with the spatial area B to be monitored via an opening Ö. This area B can contain at least one target gas Zg to be detected. A gas sample Gp Ref , GP Üb The gas sample Gp flows through opening Ö from area B into measuring chamber 2, for example by means of a pump or other fluid conveying unit. Ref , GP Üb aspirates and / or by taking the gas sample GP Ref , GP Üb diffused into measuring chamber 2.

[0034] Radiation source 1 emits radiation eW with a frequency band. In one implementation, radiation source 1 emits electromagnetic radiation, in particular infrared radiation; in another implementation, it emits acoustic radiation (sound or ultrasound). The term "radiation" used below is intended to include, in particular, electromagnetic radiation in the visible, infrared, or ultraviolet range, as well as sound and ultrasound.

[0035] This radiation eW penetrates measuring chamber 2 at least once, optionally several times. The gas detection device 100 employs a principle that is well known from the prior art. The target gas Zg, or at least one of the gases to be detected, in measuring chamber 2 attenuates the radiation eW in a frequency range, which, with reference to Fig. 1 and Fig. 2 was described. This frequency range typically differs from target gas to target gas and is known in advance. The intensity of the respective attenuation depends on the target gas concentration. The frequency range in which the attenuation occurs generally depends only on the target gas type, but not on the target gas concentration. A detector measures a measure of the intensity of the incident radiation after the emitted radiation eW has passed through the measuring chamber 2. This measure of intensity correlates with the target gas concentration.

[0036] In Fig. 3 and Fig. 5. The time-varying intensity of the emitted radiation eW is determined by a signal x. Ref (t), x Üb (t) described. This signal x Ref (t), x Üb (t) refers to a region upstream of measuring chamber 2 and is subsequently referred to as the input signal. The input signal x Ref (t), x Üb(t) is measured or predetermined by the control signal of the radiation source 1. If a control signal of the radiation source 1 is used as the input signal, the actual intensity may deviate from the control signal because the radiation source 1 is faulty. In some cases, thanks to the invention, an indication of such a fault in the radiation source 1 can also be detected.

[0037] Preferably, the radiation source 1 emits the radiation eW such that the input signal x Ref (t), x Üb (t) is sinusoidal with a frequency that varies over time (frequency sweep signal). In one realization, the radiation source 1 emits the radiation eW such that the input signal x Ref (t), x Üb(t) ideally is a white noise signal. In reality, white noise can only be approximated. To get close to a white noise signal, a broadband noise signal with limited energy is preferably emitted in practice.

[0038] The radiation eW penetrates measuring chamber 2 at least once. The intensity of the radiation eW that has penetrated measuring chamber 2 is determined by the signal s. Ref (t), s Üb (t) described.

[0039] The gas detection device 100 analyzes the gas sample Gp Ref , GP Üb in measuring chamber 2. For the duration of this analysis, the gas sample Gp Ref , GP Üb as a linear time-invariant system. This assumption is generally justified, in particular because neither the gas detection device 100 itself nor the chemical composition of the gas sample Gp is ​​variable. Ref , GP Übin measuring chamber 2 changes significantly, while the gas sample Gp Ref , GP Üb is being analyzed.

[0040] The gas detection device 100 further comprises a detector 4, which is arranged in or on the measuring chamber 2. The detector 4 is excited by incident radiation eW and provides a time-resolved signal. The signal x Ref (t), x Üb (t), which describes the intensity of the radiation eW incident on measuring chamber 2, is treated as the input signal for the linear time-varying system just described. The signal that detector 4 generates in response to excitation by the signal s Ref (t), S Üb (t) is treated as the output signal of this system and is represented by y Ref (t), y Üb (t) denotes. These two designations are explained below.

[0041] The gas detection device 100 is used in a reference period (Ref_ZR) and a verification period (Üb_ZR). It is assumed that the gas detection device 100 is functioning correctly during the reference period (Ref_ZR). During the verification period (Üb_ZR), it is to be checked whether the gas detection device 100 is still functioning correctly or has a fault – generally speaking, whether its condition has changed compared to its condition during the reference period (Ref_ZR). It is also possible that the reference period (Ref_ZR) lies after the verification period (Üb_ZR), and therefore the purpose of the verification period is to determine whether the gas detection device 100 was functioning correctly or faulty during the verification period (Üb_ZR).

[0042] In particular, the following errors can occur, which are detected by the invention: - Detector 4 becomes faulty, for example because harmful gases accumulate, or due to aging or a sudden external influence. - Radiation source 1 becomes faulty, for example also due to deposits or aging or due to a sudden failure. - One wall of measuring chamber 2 absorbs radiation eW, which is a particular error if the radiation is intended to pass through measuring chamber 2 several times to lengthen the optical path. - The voltage supply for voltage source 1 weakens, for example due to aging of an internal power supply unit or faults in a power supply network.

[0043] The output signal obtained by detector 4 in the reference period Ref_ZR is denoted by y Ref (t) denotes the output signal from the verification period Üb_ZR. Üb (t) denotes the input signal in the reference period Ref_ZR. Ref (t) denotes the input signal in the verification period Üb_ZR with x Üb(t). Accordingly, the measure for the intensity of the radiation eW that strikes detector 4 during the reference period Ref_ZR is given by s Ref (t) denotes and the measure for the intensity of the radiation incident during the review period Üb_ZR eW with s Üb (t). In Fig. 3 to Fig. Position 9 indicates whether the representation refers to the reference period Ref_ZR or to the review period Üb_ZR.

[0044] With a fault-free gas detection device 100 and matching input signals x Ref (t) and x Üb (t) the two signals match s Ref (t) and S Üb (t) and the two output signals y Ref (t) and y Üb (t) ideally match.

[0045] The input signal x Ref (t) and the output signal y Ref(t) refer to the same reference period Ref_ZR and to the same sampling times within this matching reference period Ref_ZR. Accordingly, the input signal x refers to Üb (t) and the output signal y Üb (t) refer to the same verification period Üb_ZR and to the same sampling times in this matching verification period Üb_ZR.

[0046] In the exemplary implementation, the following conditions are established in the reference period Ref_ZR and in the verification period Üb_ZR: - In both time periods Ref_ZR, Üb_ZR, the radiation source 1 emits radiation eW with a frequency band, where in this frequency band the intensity of the radiation eW is above a specified lower threshold. - The gas test Gp Üb, which is located in measuring chamber 2 during the verification period Üb_ZR, absorbs the radiation eW in this frequency band up to a specified tolerance, just like the gas sample Gp Ref within the reference period Ref_ZR. For example, the two gas samples are largely chemically identical.

[0047] A signal processing unit 50 receives the input signal x Ref (t), x Üb (t) and the output signal y Ref (t), y Üb (t) processes these signals and delivers a result that includes state information (Zust) about the state of the gas detection device 100. This state information (Zust) refers to the state during the verification period (Üb_ZR). In the configuration according to Fig. 3 and Fig. The signal processing unit 50 is a component of the gas detection device 100, and the gas detection device 100 further includes an output unit 14. The output unit 14 outputs the status information visually and / or acoustically and / or haptically (by vibrations).

[0048] The following section describes this signal processing unit 50 in more detail, with reference to Fig. 4 and Fig. 6.

[0049] In the exemplary embodiment, the signal processing unit 50 comprises at least one processor, a data storage device 11 and the following functional components, which are preferably designed as software programs that run on the processor while the gas detection device 100 is in use: - a cross-correlator 6, - an optional smoothing unit 7, - a transformer 8, - an optional filter unit 9 and - one analysis unit 10.

[0050] The cross-correlator 6 calculates a measure of the cross-correlation ρ. xy,Ref = ρ xy,Ref (τ) and ρ xy,Üb = p xy,Üb (τ) between input signal x Ref (t), x Üb (t) and the output signal y Ref (t), y Üb (t). The cross-correlation ρ xy (τ) describes the similarity between two signals x(t) and y(t). As is well known, the cross-correlation ρ xy (τ) in the time domain according to the formula ρxy(τ)=T→∞ lim1T∫−T / 2+T / 2x(t)y(t+τ)dt The output signal y(t) of a linear time-invariant system is known to be related to the input signal x(t) by the so-called impulse response g(t), namely according to the formula y(t)=g(t)*x(t)=∫−∞+∞g(u) x(t−u)du

[0051] Here, g(t) * x(t) is the convolution between the two signals g and x.

[0052] The cross-correlation ρ xy(τ) is known to be related to the impulse response g(t) according to the formula ρxy(τ)=∫−∞+∞g(u)ρxx(τ−u)du together. Here, ρ xx the autocorrelation of the input signal x(t).

[0053] In the following, the index Ref denotes a quantity that is calculated using the output signal y. Ref (t) was generated from the reference period Ref_ZR, the index Üb a quantity that was determined using the output signal y Üb (t) was generated from the review period Üb_ZR.

[0054] Based on the relationships just presented, extractor 7 generates from the cross-correlation ρ xy,Ref (τ) the impulse response g Ref (t) and from the cross-correlation ρ xy,Üb (τ) the impulse response g Üb (t).

[0055] The Transformer 8 transforms the impulse responses g Ref (t) and g Üb(t) from the time domain to the frequency domain, in this exemplary embodiment by a Laplace transform. This Laplace transform yields the transfer function G Ref (s) of the impulse response g Ref (t) and the transfer function G Üb (s) of the impulse response g Üb (t) calculated.

[0056] As is known, the transfer function G(s) in the complex of an impulse response g(t) is calculated by a Laplace transform according to the following calculation rule: G(s)=L{g(t)}=∫−∞+∞g(t)exp(−st)dt with s = σ+jω, where σ is the real part, j is the imaginary number and ω = 2πf is the angular frequency.

[0057] In an alternative implementation, the following relationship is used to determine the transfer functions G. Ref (s) and G Üb (s) to calculate: GRef(s)=L{yRef(t)}L{xRef(t)} and GU¨b(s)=L{yU¨b(t)}L{xU¨b(t)}

[0058] In this configuration, the Laplace transforms of the input signals x are used. Ref (t), x Üb (t) and the Laplace transform of the output signals y Ref (t), y Üb (t) is calculated. The design avoids the need to calculate a cross-correlation.

[0059] The optional filter unit 9 generates from the transfer function G Ref (s) the filtered transfer function G f,Ref (s) and from the transfer function G Üb (s) the filtered transfer function G f,Üb (s).

[0060] The transfer function G Ref (s) or the filtered transfer function G f,Ref (s) from the reference period Ref_ZR is stored in data storage 11 and read back from data storage 11 for verification.

[0061] The comparison unit 10 compares the transfer function G. Üb(s) from the review period Üb_ZR with the transfer function G Ref (s) from the reference period Ref_ZR, optionally the two filtered transfer functions G f,Üb (s) and G f,Ref (s) with each other. Ideally, these two transfer functions match each other in a properly functioning gas detection device 100. A deviation above a predefined tolerance indicates a fault. Preferably, the comparator unit 10 determines the phase response and the amplitude response. In many cases, the phase response provides an indication of the frequencies at which a fault occurs, and thus with which target gases.

[0062] Fig. 7 and Fig. Figure 8 shows an alternative design, whereby Fig. 7 in turn refers to the reference period Ref_ZR and Fig. 8 to the review period Üb_ZR. The same reference symbols have the same meanings as in Fig. 3 to Fig. 6.

[0063] According to this embodiment, the gas detection device 100 comprises, in addition to the measuring chamber 2, a reference chamber 3. The reference chamber 3 is filled with a reference gas Rg, which is free of the target gas(es) to be detected. The radiation source 1 emits radiation eW into both the measuring chamber 2 and the reference chamber 3, and both chambers 2 and 3 are arranged parallel to the radiation source 1. The signal describing the time-varying intensity of the emitted radiation eW before this radiation reaches the chambers 2 and 3 is denoted by e Ref (t) or e Üb (t) denotes the intensity of the radiation eW that has penetrated measuring chamber 2 at least once. 2,Ref (t) or s 2,Üb (t) denotes the intensity of the radiation eW that has penetrated the reference chamber 3 at least once. 1,Ref (t) or s 1,Üb (t) denotes.

[0064] Just as with the design according to Fig. 3 to Fig. 6. The detector 4 also generates this in the configuration according to Fig. 7 and Fig. 8 an output signal y Ref (t), y Üb (t), which is of intensity s 2,Ref (t) or s 2,Üb (t) depends on the incident radiation eW. A reference detector 5 generates a signal depending on the incident radiation eW. This signal depends on the intensity s. 1,Ref (t) or s 1,Üb (t) of the radiation eW that has penetrated the reference chamber 3 at least once and strikes the reference detector 5. This signal, generated by the reference detector 5, is referred to as the input signal x. Ref (t), x Üb (t) is used. The hypothetical system whose system behavior is being calculated is thus connected to the signal x. Ref (t), x Üb (t) is excited by the reference detector 5 and generates the output signal y in response to this excitation. Ref (t), yÜb (t). The further steps in the review are the same as those described above with reference to Fig. 3 to Fig. 6 were described.

[0065] In the design according to Fig. 3 to Fig. 8 The signal processing unit 50 is a component of the gas detection device 100. Fig. Figure 9 shows an alternative design.

[0066] According to this alternative embodiment, the signal processing unit 50 is a component of a computing unit 110, which is spatially separated from the gas detection device 100 and maintains a data connection with it, at least temporarily. The data connection can be established via cable or radio waves. This embodiment facilitates the implementation of the signal processing unit 50 on a high-performance computer. In the illustrated embodiment, the gas detection device 100 comprises a communication unit 15, which exchanges messages via radio waves with a communication unit 16 of the computing unit 110. During the reference period Ref_ZR, the gas detection device 100 transmits the input signal x. Ref (t) and the output signal y Ref (t) and, during the verification period Üb_ZR, the input signal x Üb (t) and the output signal y Üb(t) to the processing unit 110. The analysis unit 10 generates a result Erg with a status information Zust. In the example shown, this status information Zust is displayed on an output computer 55 of the processing unit 110. The status information Zust is also transmitted back to the gas detection device 100 and displayed there on the output unit 14. Reference symbol list 1 Radiation source, emitted into the measuring chamber 2 electromagnetic or acoustic radiation eW, the intensity of which is determined by the input signal x Ref (t), x Üb (t) or e Ref (t), e Üb (t) is described 2 measuring chamber, takes the gas sample Gp Ref , GP Üb on 3 Reference chamber, receives the reference gas Rg 4 Detector at measuring chamber 2, delivers the time-resolved output signal y in the reference period Ref_ZR. Ref(t) and during the verification period Üb_ZR the time-resolved output signal y Üb (t) 5 Reference detector at reference chamber 3, delivers the time-resolved input signal x during the reference period Ref_ZR. Ref (t) and during the verification period Üb_ZR the time-resolved input signal x Üb (t) 6 Cross-correlator, calculates the cross-correlation ρ in the reference period Ref_ZR. xy,Ref (t) between the input signal x Ref (t) and the output signal y Ref (t) and in the review period Üb_ZR the cross-correlation ρ xy,Üb (t) between the input signal x Üb (t) and the output signal y Üb (t) 7 extractors, generated in the reference period Ref_ZR from the cross-correlation ρ xy,Ref (t) the impulse response g Ref (t) and in the review period Üb_ZR from the cross-correlation ρ xy,Üb (t) the impulse response g Üb (t) 8 Transformer, transforms the impulse response gRef (t), g Üb (t) from the time domain to the frequency domain yields the transformation result G Ref (S), G Üb (s) 9 Filter unit, generated from the transfer function G Ref (s) the filtered transfer function G f,Ref (s) and from the transfer function G Üb (s) the filtered transfer function G f,Üb (s) 10. Comparison unit, compares the two measurements G f,Ref (s), G f,Üb (s) for the system behavior with each other, provides as a result information about the current state of the gas detection device 100 11 Data storage in which the measure G is stored in the reference period Ref_ZR f,Ref (s) is stored for the reference system behavior 12 Housing of the gas detection device 100 14. Output unit of the gas detection device 100 or the computing unit 110, outputs the status information "Status of the gas detection device 100" visually and / or audibly and / or haptically. 15 Communication unit of the gas detection device 100 16 Communication unit of the computing unit 110 50 Signal processing unit, comprising the cross-correlator 6, the smoothing unit 7, the transformer 8, the optional filter unit 9 and the comparator unit 10, has read access to the data storage 11, in one embodiment a component of the gas detection device 100 and in another embodiment a component of the computing unit 100 55 Output computer with screen, displays the status information. 100 gas detection device to be tested, comprising the measuring chamber 2, the detector 4, the radiation source 1, the housing 12, the data storage 11, and in one embodiment the signal processing unit 50 and in another embodiment the communication unit 15 110 computing unit, comprising the signal processing unit 50, the output computer 55 and the communication unit 16, wirelessly connected to the gas detection device 100 The spatial area to be monitored (B) can contain at least one target gas (Zg). The result of the comparison unit 10 includes the state information. e Ref (t) Intensity of the radiation eW before passing through the two chambers 2, 3 in the reference period Ref_ZR e Üb (t) Intensity of radiation eW before penetration of the two chambers 2, 3 during the verification period Üb_ZR eW electromagnetic or acoustic radiation emitted from radiation source 1 into measuring chamber 2 has an intensity x before passing through measuring chamber 2. Ref (t), x Üb (t) and after the passage the intensity s Ref (t), S Üb (t) on GP Ref Gas sample flows from the monitored area B into measuring chamber 2 before or during the reference period Ref_ZR. GP Üb Gas sample, flows from the monitored area B into measuring chamber 2 before or during the monitoring period Üb_ZR. G Ref (t) Impulse response in the time domain, is extracted from the cross-correlation ρ by extractor 7 in the reference period Ref_ZR. xy,Ref (t) generates G Üb (t) Impulse response in the time domain, is extracted from the cross-correlation ρ by extractor 7 during the verification period Üb_ZR. xy,Üb (t) generates G Ref(s) Transfer function of the system responding to excitation by the input signal x Ref (t) the output signal y Ref (t) describes the system behavior in the reference period Ref_ZR and is supplied by transformer 8. G Üb (s) Transfer function of the system responding to excitation by the input signal x Üb (t) the output signal y Üb (t) delivers, describes the system behavior during the verification period Üb_ZR, and is delivered by transformer 8. G f,Ref (s) filtered transfer function in the frequency domain, supplied by filter unit 9 in the reference period Ref_ZR G f,Üb (s) filtered transfer function in the frequency domain, supplied by filter unit 9 during the verification period Üb_ZR ρ xy,Ref (t) Cross-correlation in the time domain between the input signal x Ref (t) and the output signal y Ref(t) in the reference period Ref_ZR, calculated by cross-correlator 6 ρ xy,Üb (t) Cross-correlation in the time domain between the input signal x Üb (t) and the output signal y Üb (t) in the review period Üb_ZR, calculated by cross-correlator 6 Ref_ZR Reference period during which the gas detection device 100 is intact Rg reference gas in reference chamber 3, free of any target gas s Ref (t) Signal describing the intensity of the radiation eW after passing through measuring chamber 2 in the reference period Ref_ZR S Üb (t) Signal describing the intensity of the radiation eW after passing through measuring chamber 2 during the verification period Üb_ZR Üb_ZR Review period during which the gas detection device 100 may be faulty x Ref(t) time-resolved input signal, describes the intensity of the radiation eW emitted by the radiation source 1 into the measurement chamber 2 during the reference period Ref_ZR x Üb (t) time-resolved input signal, describes the intensity of the radiation eW emitted by radiation source 1 into measuring chamber 2 during the verification period Üb_ZR y Ref (t) Time-resolved output signal from detector 4 in response to input signal x Ref (t) delivered in the reference period Ref_ZR y Üb (t) Time-resolved output signal from detector 4 in response to input signal x Üb (t) delivered during the review period Üb_ZR Status Information - Information about the current status of the gas detection device 100

Claims

[1] Testing method for testing a gas detection device (100), wherein the gas detection device (100) to be tested - a measuring chamber (2), - a detector (4) and - comprises a radiation source (1), wherein the measuring chamber (2) is designed to contain a gas sample to be examined (Gp Üb , GP Ref ), wherein the method comprises the automatically performed steps of both in a reference period (Ref_ZR) and in a review period (Üb_ZR) different from the reference period (Ref_ZR) - the radiation source (1) emits radiation (eW) into the measuring chamber (2), in particular electromagnetic radiation, where a respective input signal [x Ref (t), x Üb (t)] a measure of the intensity of the emitted radiation (eW) is specified or measured, - at least a part of the emitted radiation (eW) passes through the measuring chamber (2) at least once and is reflected by a radiation source [x Ref (t), x Üb (t)] dependent intensity [s Ref (t), s Üb (t)] hits the detector (4), - the detector (4) depending on the intensity [s Ref (t), s Üb (t)] of the incident radiation (eW) an output signal [y Ref (t), y Üb (t)] and - in the time domain or in the frequency domain a measure [G Ref (s), G Üb (s)] is calculated for the system behavior of an imaginary system, where this imaginary system is connected to the input signal [x Ref (t), x Üb (t)] and this system, in response to this excitation, produces the output signal [y Ref (t), y Üb (t)], wherein the radiation source (1), the measuring chamber (2) and the detector (4) are intact in the reference period (Ref_ZR) and the method comprising the further automatically performed steps of - the verification system behavior, which is the system behavior of the system that is in the verification period (Üb_ZR) with the input signal [x Üb (t)] and in response the output signal [y Üb (t)], with - the reference system behavior, which is the system behavior of the system that is in the reference period (Ref_ZR) with the input signal [x Ref (t)] and in response the output signal [y Ref (t)] using the two measures [G Ref (s), G Üb (s)] and Depending on the result of the comparison between the two system behaviors, status information (Zust) is derived about the status of the gas detection device (100) in the verification period (Üb_ZR). [2] Verification method according to claim 1, characterized by , that both in the reference period (Ref_ZR) and in the review period (Üb_ZR) the step, the measure [G Ref (s), G Üb (s)] for the system behavior, each includes the step that a measure of the cross-correlation [ρ xy,Ref (t), ρ xy,Üb (t)] between the input signal [x Ref (t), y Üb (t)] and the output signal [y Ref (t), y Üb (t)] is calculated. [3] Verification method according to claim 2, characterized by , that both in the reference period (Ref_ZR) and in the review period (Üb_ZR) the step, the measure [G Ref (s), G Üb (s)] for the system behavior, each includes the additional steps that - a transformation of the cross-correlation [ρ xy,Ref (t), ρ xy,Üb (t)] into the frequency domain, in particular by a Laplace transformation or a Fourier transformation, and - the measure [G Ref (s), G Üb (s)] for the system behavior using the result of the transformation of the cross-correlation [ρ xy,Ref (t), ρ xy,Üb (t)] in the frequency domain. [4] Verification method according to claim 3, characterized by , that the radiation source (1) in both time periods (Ref_ZR, Üb_ZR) each measures the radiation (eW) with an input signal [x Ref (t), x Üb (t)] is emitted in the form of white noise into the measuring chamber (2), using the cross-correlation transformation [ρ xy,Ref (t), ρ xy,Üb (t)] in the frequency domain the respective transfer function [G Ref (s), G Üb (s)] of the imaginary system when excited by the input signal [x Ref (t), x Üb (t)] is calculated and the measure [G Ref (s), G Üb(s)] for the system behavior using the transfer function. [5] Verification method according to one of the preceding claims, characterized by , that the intensity of the emitted radiation (eW) in a frequency band is greater than or equal to a lower threshold and the measuring chamber (2) in the reference period (Ref_ZR) with a reference gas sample (Gp Ref ) and during the inspection period (Üb_ZR) with a verification gas sample (Gp Üb ) is or is filled, where the two gas samples (Gp Ref , GP Üb ) in the frequency band, the radiation (eW) is attenuated equally up to a given tolerance and in particular the respective chemical composition of the two gas samples (Gp Ref , GP Üb ) differ from each other by at most a given composition tolerance. [6] Verification method according to one of the preceding claims, characterized by , that a quantity with at least one target gas (Zg) to be detected is or will be specified, preferably with several target gases, and the frequency band of the radiation (eW) emitted by the radiation source (1) covers a target gas frequency band for the or each target gas of the set, where the target gas (Zg) absorbs radiation (eW) in the target gas frequency band more strongly than a given lower limit. [7] Verification method according to one of the preceding claims, characterized by , that the verification method is carried out using a signal processing unit (50), wherein the signal processing unit (50) is spatially spaced from the gas detection device (100) and wherein the verification procedure comprises the additional steps of checking the respective input signal [x Ref (t), x Üb (t)] and the respective output signal [y Ref (t), y Üb (t)] are transmitted from the gas detection device (100) to the signal processing unit (50) and the signal processing unit (50) carries out the steps, - to calculate the measures for the verification system behavior and the reference system behavior, - to compare them with each other and - to derive the state information (Zust). [8] Verification method according to one of the preceding claims, characterized by , that the gas detection device (100) additionally comprises a reference chamber (3) and a reference detector (5), wherein the reference chamber (3) is filled with a reference gas (Rg) which is free of the or each target gas, where the radiation source (1) emits radiation [eW, e Ref (t), e Üb (t)] into both the measuring chamber (2) and the reference chamber (3), so that emitted radiation [eW, e Ref (t), e Üb (t)] penetrates both chambers (2, 3) at least once each, where the two chambers (2, 3) are in relation to the radiation [eW, e Ref (t), e Üb (t)] are arranged in parallel, wherein the reference detector (5) generates a time-resolved signal [x Ref (t), x Üb (t)] and where the imaginary system is used as a system which is operated with the signal from the reference detector (5) as the input signal [x Ref(t), x Üb (t)] and in response to this excitation the output signal [y Ref (t), y Üb (t)] is generated. [9] Verification method according to one of the preceding claims, characterized by , that both in the reference period (Ref_ZR) and in the verification period (Üb_ZR) the detector (4) outputs the output signal [y Ref (t), y Üb (t)] depending on the intensity [s Ref (t), s Üb (t)] of the incident radiation (eW) and the value of a parameter used, wherein several possible values ​​are specified for the parameter and wherein the method comprises the further automatically performed steps that during the review period (Üb_ZR) - for each possible value of the parameter, the measure of the verification system behavior resulting from this possible parameter value is calculated and compared with the reference system behavior and - a measure of the deviation between the verification system behavior resulting from this possible parameter value and the reference system behavior [G Ref (s)] is determined and depending on the deviation measures for the possible parameter values, a value for the parameter is determined and used. [10] Testing device (50, 110) for testing a gas detection device (100), wherein the gas detection device (100) to be checked - a measuring chamber (2), - a detector (4) and - comprises a radiation source (1), wherein the measuring chamber (2) is designed to contain a gas sample to be examined (Gp Üb , GP Ref ), wherein the radiation source (1) is designed to emit radiation (eW) into the measuring chamber (2), wherein the gas detection device (100) is designed such that at least a part of the emitted radiation (eW) penetrates the measuring chamber (2) at least once and impinges on the detector (4), wherein the detector (4) is designed to be dependent on the intensity [s Ref (t), s Üb (t)] of the incident radiation (eW) an output signal [y Ref (t), y Üb (t)] to generate wherein the checking device (50, 110) - comprises a signal processing unit (50) and - is at least temporarily in a data connection with the gas detection device (100), wherein the checking device (50, 110) is designed to both in a reference period (Ref_ZR) and in a review period (Üb_ZR) different from the reference period (Ref_ZR), the steps are to be triggered that - the radiation source (1) radiation with an input signal [x Ref (t), x Üb (t)] as a measure of the respective intensity of the radiation (eW), where an input signal [x Ref (t), x Üb (t)] a measure of the respective intensity of the emitted radiation (eW) is specified or measured, - emitted radiation (eW) hits the detector (4) and - the detector (4) each has an output signal [y Ref (t), y Üb (t)], wherein the radiation source (1), the measuring chamber (2) and the detector (4) are intact in the reference period (Ref_ZR), wherein the signal processing unit (50) is designed to calculate a measure of a system behavior of an imaginary system in the time domain or in the frequency domain, where this imaginary system with the input signal [x Ref (t), x Üb (t)] and this system, in response to this excitation, produces the output signal [y Ref (t), y Üb (t)], wherein the signal processing unit (50) is designed to - the verification system behavior, which is the system behavior of the system that is in the verification period (Üb_ZR) with the input signal [x Üb (t)] and in response the output signal [y Üb (t)], with - the reference system behavior, which is the system behavior of the system that is in the reference period (Ref_ZR) with the input signal [x Ref (t)] and in response the output signal [y Ref (t)], using the two dimensions [G Ref (s), G Üb (s)] and wherein the signal processing unit (50) is further configured to derive, depending on the result of the comparison between the two system behaviors, a state information item (Zust) about the state of the gas detection device (100) in the verification period (Üb_ZR).

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