EP3528224B1 - Device and method for detecting presence and/or movement by infrared measurement - Google Patents

Description

The present invention relates to the field of access control, surveillance, anti-intrusion and alarm protection devices and systems, more particularly the detection, signal processing and discrimination means implemented in such devices. and systems.

The subject of the invention is a device for detecting presence and / or movement by infrared, an alarm system comprising such a device and a method for detecting presence and / or movement implementing such a device.

Passive infrared (PIR) sensors and detectors, introduced in the mid-1970s, are well known and have been widely marketed since.

Generally, in these known devices, an optic divides the space to be monitored into zones and focuses on a pyroelectric sensor the variations in heat caused by the movements of people inside the protected volume. The sensor produces on its output a signal proportional to the power of infrared radiation collected and an alarm is normally generated when the amplitude of the output signal of the sensor reaches a predetermined threshold level called the detection threshold.

In the state of the art, methods which count the number of crossings of the detection threshold with a change of sign between two successive crossings in order to conclude that an alarm condition is present have already been proposed.

A general problem of detection is to decide on the presence or absence of a relevant signal in the noise. A second problem is to differentiate the signal resulting from an intrusion from a signal caused by a source of parasitic heat such as electromagnetic radiation or thermal convection for example. The optimization of a motion detection sensor consists in reducing these malfunctions (non detection of a target when it is present, and false alarm on noise) and in maximizing its probability of detection (probability of detecting a target when it is present, and 'she is here).

The document US 5,077,549 discloses a passive infrared detector and a method of integrating the sensor output signal which triggers an alarm when the integration result exceeds a predetermined threshold. The method provides an improvement in the sense that it makes it possible to reduce the risk of false alarms linked to short-term peaks. The weakness of this method lies in the fact that intrusion signals of low amplitude are rejected while a parasitic signal of sufficient duration is capable of triggering an alarm.

The document US 8,941,066 discloses a device and method which also utilizes signal integration.

Other known devices exploit two different signal sources to improve the quality and reliability of detection, namely infrared radiation and also, for example, video ( US 2016/006988 ), microwaves ( CN 10482 1054 ) or electromechanical or optical signals ( GB 2 528 703 ).

Nevertheless, such use of signals / radiations of various kinds requires a multiplication of acquisition and evaluation chains, resulting in complex and costly solutions.

The object of the present invention is to overcome at least the main drawbacks of the state of the art and to propose a solution which achieves presence and / or movement detection which only exploits the thermal radiation emitted by an intruder and makes it possible to improve the probability of detection by allowing the detection of intrusion signals of low amplitude and reduce the rate of false alarms by rejecting signals produced by radiation originating from parasitic sources.

The detection device of claim 1 and the detection method of claim 9 make it possible, in accordance with the invention, to achieve the aforesaid object.

• la figure 1 est une représentation synoptique d'un dispositif de détection de présence et/ou de mouvement selon l'invention ;
• la figure 2 est un ordinogramme illustrant un mode de réalisation du procédé de détection de présence et/ou de mouvement selon l'invention ;
• les figures 3 à 5 sont des représentations graphiques sous forme de courbes, d'une part, de l'amplitude du signal électrique de mesure à la sortie du capteur (figures 3A, 4A, 5A) et, d'autre part, de la puissance de variation de l'amplitude de ce signal (figures 3B, 4B, 5B), ledit signal représenté ayant été délivré dans trois situations différentes, à savoir :
  • au repos (absence d'événement ou de phénomène thermique particulier dans le champ d'acquisition du capteur - figures 3A et 3B) ;
  • en présence d'une intrusion générant un signal de faible amplitude (figure 4A), mais avec un rapport des niveaux de la puissance de variation de l'amplitude mesurée en I et en II (dans deux fenêtres temporelles différentes) de l'ordre de 5 environ (figure 4B) ;
  • en présence d'un mouvement de convection thermique générant un signal (figure 5A) de même ordre d'amplitude que celui de la figure 4A, avec toutefois un rapport des niveaux de puissance de variation de l'amplitude mesurés en I et II qui n'est que de l'ordre de 2 environ (figure 5B).

The invention will be better understood, thanks to the description below, which relates to a preferred embodiment, given by way of non-limiting example, and explained with reference to the appended schematic drawings, in which:

• the figure 1 is a block diagram of a presence and / or movement detection device according to the invention;
• the figure 2 is a flowchart illustrating an embodiment of the method for detecting presence and / or movement according to the invention;
• the figures 3 to 5 are graphical representations in the form of curves, on the one hand, of the amplitude of the electrical measurement signal at the output of the sensor ( figures 3A, 4A, 5A ) and, on the other hand, the power of variation of the amplitude of this signal ( figures 3B, 4B, 5B ), said signal represented having been delivered in three different situations, namely:
  • at rest (no event or particular thermal phenomenon in the sensor's acquisition field - figures 3A and 3B );
  • in the presence of an intrusion generating a weak signal amplitude ( figure 4A ), but with a ratio of the levels of the power of variation of the amplitude measured in I and in II (in two different time windows) of the order of approximately 5 ( figure 4B );
  • in the presence of a thermal convection movement generating a signal ( figure 5A ) of the same order of amplitude as that of the figure 4A , however with a ratio of the dimming power levels of the amplitude measured in I and II which is only about 2 ( figure 5B ).

• au moins un capteur 2 de rayonnement infrarouge ou pyroélectrique délivrant un signal électrique de mesure SEM,
• un moyen 3 de détection et de déclenchement apte et destiné à détecter le dépassement par l'amplitude du signal électrique de mesure SEM d'une première valeur seuil PVS, dit seuil de sensibilité, et à déclencher sélectivement une fenêtre temporelle de traitement FTT,
• une unité de traitement 4 comprenant des moyens 5, 5' d'exploitation dudit signal électrique de mesure SEM, ainsi qu'un moyen 6 de vérification des critères qualifiant une intrusion ou une présence non autorisée et de commande, de délivrance ou de génération sélective d'un signal d'alarme, ce moyen 6 évaluant les résultats des opérations réalisées par les moyens d'exploitation 5, 5'.

The figure 1 illustrates a device 1 for detecting presence and / or movement by infrared or pyroelectric measurement, comprising:

• at least one infrared or pyroelectric radiation sensor 2 delivering an electrical measurement signal SEM,
• a detection and triggering means 3 capable of and intended to detect the overshoot by the amplitude of the electrical measurement signal SEM of a first threshold value PVS, called the sensitivity threshold, and to selectively trigger an FTT processing time window,
• a processing unit 4 comprising means 5, 5 'for using said electrical measurement signal SEM, as well as a means 6 for verifying the criteria qualifying an intrusion or an unauthorized presence and for command, delivery or selective generation an alarm signal, this means 6 evaluating the results of the operations carried out by the operating means 5, 5 '.

According to the invention, the processing unit 4 comprises two separate operational means 5 and 5 'for exploiting the electrical measurement signal SEM, namely, on the one hand, a first operational means 5 capable and intended to determine, over an FTT time window, the value of the peak amplitude AC and the occurrences of exceeding the first or another threshold value PVS, PVS 'by the electrical signal SEM and, on the other hand, a second operational means 5 'capable and intended to determine, by time window FTT, FTT', a quantity VQ1, VQ2 depending on the variation of the amplitude of the electrical signal SEM, the checking and control means 6 evaluating the data supplied by the first operational means 5, and where appropriate those provided by the second operational means 5 ', to selectively decide on the command, generation or delivery, or not, of an alarm signal.

By infrared or pyroelectric sensor is meant in the present any means, normally directional and having an acquisition field, capable of converting a collected infrared radiation into an electrical quantity.

The invention thus provides a device 1 with two separate evaluation means 5 and 5 ′, both exploiting the same electrical measurement signal SEM but implementing processing different, which makes detection more reliable while limiting constructive complexity.

In addition, the first evaluation means 5 itself provides two distinct values allowing the application by the checking and control means 6 of two different discriminating criteria for event recognition, easily individually adjustable, to determine the occurrence. or not of an intrusion or an unwanted presence of an individual. The two types of criteria chosen for this first method make it possible to easily rule out a large number of situations generating false alarms when only one of the two criteria is applied.

Finally, the conditional implementation of the exploitation of the values VQ1 and VQ2 provided by the second evaluation means 5 ′ makes it possible, on the one hand, to limit the resources used (no systematic implementation) and, to on the other hand, to discriminate between different event situations but which appear equivalent when using the values provided by the first evaluation means 5.

In accordance with a preferred embodiment of the invention, the two operational means 5 and 5 ′ for exploiting the electrical signal SEM are in the form of analog components or of software implemented by the processing unit 4 of the type processor, and comprise a first operational means 5 for repeatedly measuring the amplitude of the electrical measurement signal SEM, determining the peak AC amplitude, counting the number of exceedances of the first PVS or of another PVS 'value threshold during a time window FTT and, on the other hand, a second operational means 5 'calculating a quadratic function of the variation in the amplitude of the electrical signal SEM during a time period FTT, FTT'.

The processing unit 4 is advantageously in the form of a signal processing microprocessor, programmed to perform the various tasks and functions of the means 5, 5 'and 6 in particular.

According to another aspect of the invention, it can be advantageously provided that the verification and control means 6 consist of software means, preferably implemented by the processing unit 4, capable and intended to evaluate, from a on the one hand, firstly and systematically, the results provided by the first operational means 5 active during a time window FTT triggered by the detection and triggering means 3 and, on the other hand, conditionally, the results provided by the second operational means 5 'active during two consecutive time windows FTT and FTT', the first of which corresponds to the aforementioned FTT time window. The second operational means 5 'is only activated during this second consecutive FTT' time window when the criteria qualifying an intrusion are not verified after comparative analysis by the means 6 for checking and controlling the results supplied by the first operational means 5. at the end of the first FTT time window.

In accordance with a preferred practical embodiment of the invention, the second operational means 5 'consists of a quadratic adder determining, over a time window FTT, FTT', the variation power of the electrical measurement signal SEM, for example by carrying out the sum of the squares of the amplitude differences of the electrical signal SEM taken two by two.

avec

• SEM_t(i) : valeur du signal électrique de mesure à l'instant t (i) = i.FTT/n et
• SEM_t(_i-1) : valeur du signal électrique de mesure à l'instant t (i-1) = (i-1).FTT/n

The quadratic adder 5 'can for example be based on the following calculation formula to determine the magnitude calculated for a given time window: $$\mathrm{QV}={\mathrm{\Sigma }}_{\left(\mathrm{i}=1\mathrm{at}\mathrm{not}\right)}{\left[{\mathrm{SEM}}_{\mathrm{t}\left(\mathrm{i}\right)}-{\mathrm{SEM}}_{\mathrm{t}\left(\mathrm{i}-1\right)}\right]}^2$$

with

• SEM _{t (i)} : value of the electrical measurement signal at time t (i) = i.FTT / n and
• SEM _t ( _i-1 ): value of the electrical measurement signal at time t (i-1) = (i-1) .FTT / n

The implementation of such a second operational means 5 ′ and the specific comparative interpretation carried out by means 6 of the results provided by this second means 5 ′, in particular make it possible to distinguish the two situations illustrated by the figures 4 and 5 , and to determine which one corresponds to an intrusion (situations which cannot be differentiated by the exploitation of the results provided by the first operational means 5).

Although it is not specifically represented, the device 1 advantageously comprises a sampling circuit, for example a sample-and-hold (or a sampler integrated into the unit 4), processing the electrical signal SEM output from the sensor 2 to deliver , at a predetermined frequency, discrete measured amplitude values at the detection and triggering means 3 and to the first and second operational operating means 5 and 5 '.

• le moyen 3 de détection et de déclenchement et l'unité de traitement 4 constituent un module fonctionnel externe, analogique ou numérique, associé à un capteur 2, ou
• le moyen 3 de détection et de déclenchement et l'unité de traitement 4 soient intégrés directement au capteur 2, plus précisément dans un circuit intégré du type microprocesseur ou circuit hybride faisant partie dudit capteur 2.

In terms of practical construction of the device 1, two variants can be envisaged. Thus, it can be expected that:

• the detection and triggering means 3 and the processing unit 4 constitute an external functional module, analog or digital, associated with a sensor 2, or
• the detection and triggering means 3 and the processing unit 4 are integrated directly into the sensor 2, more precisely in an integrated circuit of the microprocessor or hybrid circuit type forming part of said sensor 2.

The invention also relates to a surveillance and / or anti-intrusion alarm system (not shown) comprising a central unit, at least one control and programming interface, at least one sound and / or light warning means and sensor means. , and which is characterized in that at least one of the sensor means consists of a detection device 1 as described above.

• au moins un capteur 2 de rayonnement infrarouge ou pyroélectrique délivrant un signal électrique de mesure SEM,
• un moyen 3 de détection et de déclenchement apte et destiné à détecter le dépassement par l'amplitude du signal électrique de mesure SEM d'une première valeur seuil PVS, dit seuil de sensibilité, et à déclencher sélectivement une fenêtre temporelle de traitement FTT,
• une unité de traitement 4 comprenant des moyens 5, 5' d'exploitation dudit signal électrique de mesure SEM, ainsi qu'un moyen 6 de vérification des critères qualifiant une intrusion ou une présence non autorisée et de commande, de délivrance ou de génération sélective d'un signal d'alarme, ce moyen 6 évaluant les résultats des opérations réalisées par les moyens d'exploitation 5, 5'.

Finally, the invention also relates to a method for detecting presence and / or movement by infrared or pyroelectric measurement, by means of a device 1 comprising:

• at least one infrared or pyroelectric radiation sensor 2 delivering an electrical measurement signal SEM,
• a detection and triggering means 3 capable of and intended to detect the overshoot by the amplitude of the electrical measurement signal SEM of a first threshold value PVS, called the sensitivity threshold, and to selectively trigger an FTT processing time window,
• a processing unit 4 comprising means 5, 5 'for using said electrical measurement signal SEM, as well as a means 6 for verifying the criteria qualifying an intrusion or an unauthorized presence and for command, delivery or selective generation an alarm signal, this means 6 evaluating the results of the operations carried out by the operating means 5, 5 '.

This method is characterized in that it consists, on the one hand, by virtue of a first operational operating means 5, in determining over a time window FTT, the value of the peak amplitude AC and the occurrences of exceeding of the first or another PVS threshold value, PVS 'by the electrical signal SEM and, on the other hand, by a second operational operating means 5 'to determine, during the aforementioned FTT time window, and where appropriate a consecutive FTT' time window, a quantity VQ1, VQ2 depending on the variation in the amplitude of the electrical signal SEM, the means 6 of verification and control evaluating the data supplied by the first operational means 5, and where appropriate those supplied by the second operational means 5 ', this over two successive time windows FTT and FTT', to decide selectively on the order, on the generation or the issue, or not, of an alarm signal.

The device 1 used for implementing the method may also have, where appropriate, one or more of the other characteristics mentioned above.

• a) comparer, à intervalles temporels réguliers, l'amplitude du signal de mesure électrique SEM délivré par le capteur 2 à une première valeur seuil PVS, prédéterminée,
• b1) si l'amplitude mesurée est inférieure à ladite première valeur seuil PVS, revenir à l'étape a) et répéter la comparaison précitée après écoulement de l'intervalle temporel,
• b2) si l'amplitude mesurée est supérieure à ladite première valeur seuil PVS, effectuer les étapes c), d) e) et f1) ou f2) suivantes durant une fenêtre temporelle FTT prédéterminée d'une durée inférieure à l'intervalle temporel,
• c) déterminer l'amplitude crête AC du signal électrique SEM et comptabiliser le nombre de dépassements de la première PVS ou d'une autre PVS' valeur seuil par l'amplitude dudit signal SEM, avec changement de signe entre deux franchissements successifs,
• d) calculer une fonction quadratique de la variation de l'amplitude du signal électrique SEM,
• e) vérifier si l'amplitude crête AC et le nombre total de dépassements répondent à des premiers critères qualifiant une intrusion, et,
• f1) soit délivrer un signal d'alarme, dans l'affirmative,
• f2) soit calculer une fonction quadratique de la variation de l'amplitude du signal électrique SEM pendant une seconde fenêtre temporelle FTT' consécutive à la première FTT, puis comparer les résultats VQ1 et VQ2 des deux fonctions quadratiques effectuées sur les variations d'amplitude des deux fenêtres temporelles FTT et FTT' et vérifier si le résultat de cette comparaison répond à des seconds critères qualifiant une intrusion pour ensuite, soit délivrer un signal d'alarme dans l'affirmative, soit attendre la fin de l'intervalle temporel pour retourner à l'étape a).

Advantageously, and as illustrated by way of example figure 2 , the detection method may consist more precisely in carrying out the following steps:

• a) comparing, at regular time intervals, the amplitude of the electrical measurement signal SEM delivered by the sensor 2 with a first predetermined threshold value PVS,
• b1) if the measured amplitude is less than said first PVS threshold value, return to step a) and repeat the aforementioned comparison after the time interval has elapsed,
• b2) if the measured amplitude is greater than said first PVS threshold value, perform the following steps c), d) e) and f1) or f2) during a predetermined FTT time window of a duration less than the time interval,
• c) determining the peak AC amplitude of the electrical signal SEM and counting the number of exceedances of the first PVS or of another PVS 'threshold value by the amplitude of said SEM signal, with change of sign between two successive crossings,
• d) calculate a quadratic function of the variation in the amplitude of the electrical signal SEM,
• e) check whether the peak AC amplitude and the total number of exceedances meet the first criteria qualifying an intrusion, and,
• f1) or issue an alarm signal, if so,
• f2) or calculate a quadratic function of the variation in the amplitude of the electrical signal SEM during a second time window FTT 'consecutive to the first FTT, then compare the results VQ1 and VQ2 of the two quadratic functions performed on the amplitude variations of the two time windows FTT and FTT 'and check whether the result of this comparison meets second criteria qualifying an intrusion and then either deliver an alarm signal in the 'affirmative, or wait for the end of the time interval to return to step a).

• de fournir des valeurs d'amplitude mesurées discrètes par échantillonnage du signal électrique à une fréquence donnée, les deux moyens opérationnels d'exploitation 5 et 5' traitant les valeurs de mesure échantillonnées simultanément et en parallèle durant la première fenêtre temporelle FTT ;
• que, à l'issue de la première fenêtre temporelle FTT, le moyen 6 de vérification et de commande décide que les critères d'une intrusion sont remplis lorsque sont réalisées simultanément les conditions relatives à la valeur de l'amplitude crête AC, par exemple au moins double de la première valeur seuil PVS, et au nombre de dépassements de la première valeur seuil PVS, comptabilisés sous forme d'impulsions par exemple ;
• que, à l'issue de la seconde fenêtre temporelle FTT', le moyen 6 de vérification et de commande décide que les critères d'une intrusion sont remplis lorsque le rapport entre les résultats de la fonction quadratique effectuée sur la variation de l'amplitude lors des première FTT et seconde FTT' fenêtres temporelles est supérieur à une valeur donnée, par exemple supérieure à environ 3 et éventuellement comprise entre 3 et 10 ;
• que l'unité de traitement 4 est en mode veille en dehors des fenêtres temporelles FTT et FTT', dont la première FTT est déclenchée par le moyen 3 de détection et de déclenchement.

By way of additional characteristics or possible variants, the method according to the invention can also provide:

• to supply discrete measured amplitude values by sampling the electrical signal at a given frequency, the two operational operating means 5 and 5 'processing the measured values sampled simultaneously and in parallel during the first time window FTT;
• that, at the end of the first time window FTT, the checking and control means 6 decide that the criteria for an intrusion are fulfilled when the conditions relating to the value of the peak amplitude AC are simultaneously fulfilled, for example at least double of the first PVS threshold value, and the number of exceedances of the first PVS threshold value, counted in the form of pulses for example;
• that, at the end of the second time window FTT ', the checking and control means 6 decide that the criteria of an intrusion are met when the ratio between the results of the quadratic function performed on the variation of the amplitude during the first FTT and second FTT 'time windows is greater than a given value, for example greater than approximately 3 and possibly between 3 and 10;
• that the processing unit 4 is in standby mode outside the time windows FTT and FTT ', the first FTT of which is triggered by the detection and triggering means 3.

By way of example, the time windows FTT and FTT 'can have durations of between 500 ms and 2500 ms, while the time interval between two consecutive activation phases of the means 3 can be of the order of ~ 0 ms to 5000 ms.

The detection means 3 can also be permanently activated and continuously monitor the level of the signal SEM.

A possible embodiment of the invention is described in more detail below in relation to the figures of the accompanying drawings.

A detection device 1 according to the invention is shown schematically on the figure 1 .

This device 1 comprises a means 2 capable of converting the collected IR radiation into an electrical quantity (electrical measurement signal SEM); a first amplitude detection means 3 which produces a trigger signal when the electrical quantity reaches a first level called the sensitivity threshold; a processing module 4 activated for a period of time (FTT time window) by the signal from the detection means 3, for example applied to a conditional supply means 3 ′.

The processing module 4 comprises a first operational means 5 integrating a second amplitude detection means 7, which produces a pulse when the electrical quantity (signal SEM) reaches a second level called the detection threshold and a pulse counter 7 ' which counts the pulses generated by the detection means 7. Said module 4 also comprises a second operational means 5 'for establishing the power of the variation of the electrical quantity SEM over a time window and an event recognition means 6 which decides whether or not the electrical quantity SEM is significant of an intrusion signal by verifying the results produced by the first or the first and second operational means 5, 5 '. With this means 6 can be associated an alarm transmission means 6 'supervised by said means 6 and controlled by the latter.

The mode of operation of this device 1 is described by way of example below.

As long as the amplitude of the signal SEM is less than the PVS sensitivity threshold of the detection means 3, the acquisition time window FTT remains closed and the processing unit 4 is maintained in energy saving or standby mode.

When the amplitude of the SEM signal reaches or exceeds the PVS sensitivity threshold of the detection means 3, the processing unit 4 is activated and processes the SEM signal in parallel according to two methods during a first time window FTT.

According to the first method, when the amplitude of the signal SEM exceeds a detection threshold (either PVS or another PVS threshold), the pulse counter 7 'is incremented by one unit. The counter 7 'only counts the number of crossings of the detection threshold (PVS or PVS') with change of sign between two successive crossings. Means 6 of event recognition decides that there is an intrusion when on the time window FTT the pulse counter 7 'has counted the necessary number of pulses and the maximum amplitude or AC peak of the signal SEM reaches a sufficient level. By sufficient level is meant, for example, once or twice the level of the detection threshold PVS or PVS ', this example not being limiting.

According to the second method, and in parallel with the progress of the first method, a quadratic adder 5 ′ determines, over the first time window FTT, the power VQ1 of variation of the signal SEM by summing the squares of the differences in amplitude of the signal SEM measured by sampling. If at the end of this FTT time window, the event recognition means 6 is not able to decide on an intrusion according to the criteria of the first method (number of pulses and peak amplitude of the signal), a new FTT 'time window is initiated during which the second operating means 5' carries out a second determination VQ2 of the variation power of the signal SEM. The event recognition means 6 decides that there is an intrusion when the comparison of the first power measurement VQ1 to the second power measurement VQ2 is in a determined relationship. The determined ratio can be 3 or 4 for example, without being limited to these values.

When the event recognition means 6 decides that there is an intrusion, it can for example activate an alarm transmission means 6 ′.

When the first time window FTT, or possibly the second time window FTT ', has elapsed, the processing unit 4 is reconfigured in energy saving mode.

The motion detection method according to the invention is summarized schematically on the figure 2 .

1. a) mesurer l'amplitude crête AC de la grandeur électrique SEM et comptabiliser les dépassements de seuil de détection sur une fenêtre temporelle FTT (premier moyen opérationnel 5),
2. b) mesurer la puissance de variation de la grandeur électrique sur la même fenêtre temporelle FTT (second moyen opérationnel 5'),
3. c) si à l'issue de la première fenêtre temporelle FTT, le moyen 6 ne reconnaît pas un signal d'intrusion, le second moyen 5' procède sur une seconde fenêtre temporelle FTT' à une seconde mesure de la puissance de variation de la grandeur électrique (signal SEM).

In summary, the main steps of the process consist of:

1. a) measure the peak AC amplitude of the electrical quantity SEM and count the detection threshold overruns over an FTT time window (first operational means 5),
2. b) measure the power of variation of the electrical quantity over the same FTT time window (second operational means 5 '),
3. c) if at the end of the first FTT time window, the means 6 does not recognize an intrusion signal, the second means 5 'proceeds on a second time window FTT 'to a second measurement of the power of variation of the electrical quantity (signal SEM).

Of course, the invention is not limited to an embodiment described and shown in the accompanying drawings. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without thereby departing from the scope of protection of the invention.

Claims (14)

1. Device for detecting presence and/or movement by infrared or pyroelectric measurement, comprising:

   - at least one pyroelectric or infrared radiation sensor (2) delivering an electric measurement signal (SEM),

   - a detection and triggering means (3) able and intended to detect the crossing by the amplitude of the electric measurement signal (SEM) of a first threshold value (PVS), referred to as the sensitivity threshold, and to selectively trigger a processing time window (FTT),

   - a processing unit (4) comprising processing means (5, 5') for processing said electric measurement signal (SEM), and a means (6) for verifying the criteria qualifying an intrusion or an unauthorized presence and for controlling, delivering or generating, selectively, an alarm signal, this means (6) evaluating the results of the operations performed by the processing means (5, 5'),

   which device (1) is characterized in that the processing unit (4) comprises two distinct operational processing means (5 and 5') for processing the electric measurement signal (SEM), namely, on one hand, a first operational means (5) able and intended to determine, over a time window (FTT), the value of the peak amplitude (AC) and the occurrences of crossing of the first or of another threshold value (PVS, PVS') by the electric signal (SEM) and, on the other hand, a second operational means (5') able and intended to determine, per time window (FTT, FTT'), a quantity (VQ1, VQ2) corresponding to a quadratic function of the variation of the amplitude of the electric signal (SEM), the verification and control means (6) evaluating the data provided by the first operational means (5), and where appropriate those provided by the second operational means (5'), in order to selectively decide whether or not to control, to generate or to deliver an alarm signal, and the second operational means (5') being activated during the second consecutive time window (FTT') only when the criteria qualifying an intrusion are not verified after comparative analysis by the verification and control means (6) of the results provided by the first operational means (5) at the end of the first time window (FTT).
2. Device according to Claim 1, characterized in that the two operational processing means (5 and 5') for processing the electric signal (SEM) are in the form of analogue components or software implemented by the processing unit (4) of processor type, and comprise a first operational means (5) for repeatedly measuring the amplitude of the electric measurement signal (SEM), for determining the peak amplitude (AC), for counting the number of crossings of the first (PVS) or of another (PVS') threshold value during a time window (FTT) and, on the other hand, a second operational means (5') calculating a quadratic function of the variation of the amplitude of the electric signal (SEM) during a time period (FTT, FTT').
3. Device according to Claim 1 or 2, characterized in that the verification and control means (6) consists of a software means, preferably implemented by the processing unit (4), able and intended to evaluate, on one hand, firstly and systematically, the results provided by the first operational means (5) active during a time window (FTT) triggered by the detection and triggering means (3) and, on the other hand, conditionally, the results provided by the second operational means (5') active during two consecutive time windows (FTT and FTT'), the first of which corresponds to the aforementioned time window (FTT).
4. Device according to any one of Claims 1 to 3, characterized in that the second operational means (5') consists of a quadratic summer determining, over a time window (FTT, FTT'), the power of variation of the electric measurement signal (SEM), for example by summing the squares of the differences in amplitude of the electric signal (SEM) taken pairwise.
5. Device according to any one of Claims 1 to 4, characterized in that it comprises a sampling circuit, for example a sample-and-hold circuit, processing the output electric signal (SEM) of the sensor (2) in order to deliver, at a predefined frequency, discrete measured amplitude values to the detection and triggering means (3) and to the first and second operational processing means (5, 5').
6. Device according to any one of Claims 1 to 5, characterized in that the detection and triggering means (3) and the processing unit (4) constitute an analogue or digital external functional module associated with a sensor (2).
7. Device according to any one of Claims 1 to 4, characterized in that the detection and triggering means (3) and the processing unit (4) are integrated directly into the sensor (2).
8. Surveillance and/or anti-intrusion alarm system comprising a central unit, at least one control and programming interface, at least one sound and/or light alert means and sensor means, characterized in that at least one of the sensor means consists of a device (1) according to any one of Claims 1 to 7.
9. Method for detecting presence and/or movement by infrared or pyroelectric measurement, by means of a device (1) comprising:

   - at least one pyroelectric or infrared radiation sensor (2) delivering an electric measurement signal (SEM),

   - a detection and triggering means (3) able and intended to detect the crossing by the amplitude of the electric measurement signal (SEM) of a first threshold value (PVS), referred to as the sensitivity threshold, and to selectively trigger a processing time window (FTT),

   - a processing unit (4) comprising processing means (5, 5') for processing said electric measurement signal (SEM), and a means (6) for verifying the criteria qualifying an intrusion or an unauthorized presence and for controlling, delivering or generating, selectively, an alarm signal, this means (6) evaluating the results of the operations performed by the processing means (5, 5'),

   which method is characterized in that it consists, on one hand, by virtue of a first operational processing means (5), in determining, over a time window (FTT), the value of the peak amplitude (AC) and the occurrences of crossing of the first or of another threshold value (PVS, PVS') by the electric signal (SEM) and, on the other hand, by virtue of a second operational processing means (5'), in determining, during the aforementioned time window (FTT), and where appropriate a consecutive time window (FTT'), a quantity (VQ1, VQ2) corresponding to a quadratic function of the variation of the amplitude of the electric signal (SEM), the verification and control means (6) evaluating the data provided by the first operational means (5), and where appropriate those provided by the second operational means (5'), and this over two successive time windows (FTT and FTT'), in order to selectively decide whether or not to control, to generate or to deliver an alarm signal,
   the second operational means (5') being activated during the second consecutive time window (FTT') only when the criteria qualifying an intrusion are not verified after comparative analysis by the verification and control means (6) of the results provided by the first operational means (5) at the end of the first time window (FTT).
10. Method according to Claim 9, characterized in that it consists more precisely in performing the following steps:

    a) comparing, at regular time intervals, the amplitude of the electric measurement signal (SEM) delivered by the sensor (2) with a predefined threshold value (PVS),

    b1) if the measured amplitude is below said first threshold value (PVS), returning to step a) and repeating the aforementioned comparison after the time interval has elapsed,

    b2) if the measured amplitude is above said first threshold value (PVS), carrying out the following steps c), d), e) and f1) or f2) during a predefined time window (FTT) the length of which is shorter than the time interval,

    c) determining the peak amplitude (AC) of the electric signal (SEM) and counting the number of crossings of the first (PVS) or of another (PVS') threshold value by the amplitude of said signal (SEM), with the sign changing between two successive crossings,

    d) calculating a quadratic function of the variation of the amplitude of the electric signal (SEM),

    e) verifying whether the peak amplitude (AC) and the total number of crossings satisfy first criteria qualifying an intrusion, and

    f1) either delivering an alarm signal, if so,

    f2) or calculating a quadratic function of the variation of the amplitude of the electric signal (SEM) during a second time window (FTT') consecutive to the first (FTT), then comparing the results of the two quadratic functions carried out on the amplitude variations of the two time windows (FTT and FTT') and verifying whether the result of this comparison satisfies second criteria qualifying an intrusion in order to then either deliver an alarm signal if so, or await the end of the time interval to return to step a).
11. Method according to Claim 9 or 10, characterized in that it consists in providing discrete measured amplitude values by sampling of the electric signal at a given frequency, and in that the two operational processing means (5 and 5') process the sampled measurement values simultaneously and in parallel during the first time window (FTT).
12. Method according to any one of Claims 9 to 11, characterized in that, at the end of the first time window (FTT), the verification and control means (6) decides that the criteria for an intrusion are fulfilled when the conditions relating to the value of the peak amplitude (AC) are met simultaneously, for example at least double the first threshold value (PVS), and to the number of crossings of the first threshold value (PVS), counted in the form of pulses for example.
13. Method according to any one of Claims 9 to 11, characterized in that, at the end of the second time window (FTT'), the verification and control means (6) decides that the criteria for an intrusion are fulfilled when the ratio between the results of the quadratic function carried out on the variation of the amplitude during the first (FTT) and second (FTT') time windows is above a given value, for example above approximately 3 and potentially between 3 and 10.
14. Method according to any one of Claims 9 to 13, characterized in that the processing unit (4) is in standby mode outside the time windows (FTT and FTT') .

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