EP1378865A1 - Method for controlling access to a determined space by a personalized portable object, and personalized portable object for carrying out the method - Google Patents

Abstract

The vehicle access control procedure uses wireless transmission of a coded identification signal. When an identification signal is received within the vehicle this is verified, by comparison with an analogue signature which is stored in memory. The procedure for controlling access to a vehicle (2) is effected by wireless transmission of a coded identification signal. An electronic system is provided with a processing unit (26) connected to units for transmission (22,28) and reception (21,27) of signals. The processing unit includes a memory (25), a microprocessor (24) and an analogue-digital converter (23). When an identification signal is received within the vehicle this is verified, by comparison with an analogue signature which is stored in memory. The analogue signature includes a variation in amplitude which is obtained by an over-modulation of the coded signal envelope.

Description

The invention relates to a method for controlling access to a portable object customized to a specific space, such as a vehicle, by wireless transmission of a coded identification signal. To do this, electronic means are provided for in space. These electronic means include, in particular, management means accesses connected to reception means and / or signal transmission means. The portable object for access control comprises a processing unit connected to transmission means and / or signal receiving means. The process of access control to space consists first of all to transmit a coded signal identification by the transmission means of the portable object or respectively by the transmission means provided in the determined space. This coded signal is then received by the receiving means in space or respectively by means of receiving the portable object, when the object is in a restricted area around reception means and / or transmission means provided in the space. A verification of the received coded signal is performed in the access management means or in the processing unit to allow access to the space.

The invention also relates to a personalized portable object for access to the determined space. This portable object comprises in particular a processing unit connected signals and transmission means and / or reception means of signals to transmit or receive a coded identification signal for access to the determined space.

Using the access control method, it is possible to authorize access to a person with the personalized portable object in a specific space after verification of the coded identification signal of the object and the space to be accessed. The encoded signal transmission can be started automatically as soon as the presence the object in a restricted area around the transmitting means and / or the means received in the space has been detected. This transmission of the coded signal can also be started manually by activating control means of the object or space. This transmission of the coded signal can therefore be realized from the object the means of reception provided in the space or vice versa means emission in space to the object. As soon as the received coded signal has been recognized in the access management means of the space or in the processing unit of the object, it is then possible to access the space.

The determined space can be a security enclosure, a safe, a secure room or building with an access door controlled by the portable object, a vehicle, or any other space in which entry is permitted only to persons authorized. Access authorization allows for example to open or close a door the enclosure, the safe or a secure building. Preferably, the space is defined by a road vehicle, such as a passenger car, including the doors and the safe can be locked or unlocked by remote control using a custom portable object.

The personalized portable object can be an electronic key, a watch, a cell phone, smart card, badge or other portable device. Of preferably, this portable object is an electronic key for controlling access to a vehicle. This portable object may include an own source of energy for the power supply of its electronic components. In this case, the portable object is active type. The power supply of said electronic components can also from a signal with a determined carrier frequency that is transmitted by transmission means provided in the space and which is received in the portable object. In this case, the portable object is of the passive type. However with a portable object of type passive, it is necessary to transmit a high frequency signal from the means in space to provide sufficient power to the electronic components of the object. That's why in the field of remote control of parts or functions of a vehicle, the portable object, which is an electronic key, is preferably of the active type.

The electronic key includes in particular a microcontroller connected to storage means in which an encryption algorithm is stored and / or a vehicle access code. As soon as a button is pressed of the key is operated, the microcontroller calculates a coded identification signal to transmitting by means of transmitting signals towards the vehicle. After recognition of the coded signal received by the vehicle, a lock command or unlocking parts or functions of the vehicle is performed.

To facilitate access to the vehicle without having to handle the electronic key, it has already been proposed an electronic key whose response signal is transmitted automatically to the vehicle based on an interrogation signal received from the vehicle. For this, the key must be in a restricted area around the vehicle for receive this interrogation signal from the vehicle. In addition, the key transmits a signal to the vehicle only if the interrogation signal has been recognized by the key. This response signal thus makes it possible to control the locking or unlocking of parts or functions of the vehicle.

With the use of such an electronic key automatically controlled by the interrogation signal from the vehicle, there is the risk of allowing the opening the vehicle through intermediate relays without the knowledge of the key holder electronic. As a result, it gives the possibility to malicious people to use these intermediary relays between the vehicle and the holder of the electronic key to open the vehicle and turn it on. Said relays are able to copy to the key or the vehicle, the signal interrogation respectively the response signal which each include a sequence of binary data.

FIG. 1 schematically represents the principle of relay attack intermediate. The two relays are placed respectively close to an object portable, such as an electronic key with automatic control, and the vehicle associated.

In a normal situation without the relays, the carrier of the portable object 2 must to be in a restricted area around the vehicle 1 to order the opening of the closed vehicle, because the interrogation signal 6, 8 transmitted by a antenna 11 means of transmitting signals 14 of the vehicle, can not be detected only at short distance. This interrogation signal has a low carrier frequency frequency LF, for example of the order of 125 kHz. A sequence of binary data in the interrogation signal is for example generated by amplitude modulation of the carrier. An antenna 21 for receiving means of the object 2 can not detect this low-frequency interrogation signal only in an area around the vehicle that does not exceed, for example, not 2 m. Once the interrogation signal could be controlled by the portable object, an antenna 22 means for transmitting the object portable transmits a response signal 9, 10. This signal response has a frequency high frequency carrier UHF, for example of the order of 433 MHz. This signal response is picked up by an antenna 12 of receiving means 15 of the vehicle. of the access management means 13 connected to the transmission means and the means of receipt of the vehicle will order including the opening of doors and trunk the vehicle upon receipt of the response signal.

FIG. 2 represents a flowchart of the steps of the control method access to a portable object, such as an electronic key, personalized to the vehicle of way to control the locking or unlocking including doors and of the trunk of said vehicle.

First at step 50, the electronic key in the possession of the user of the vehicle is in the waiting position. Once the vehicle handle has been seized by the user in step 51, an interrogation signal LF is transmitted by the means transmission in step 52 under the control of the access management means of the vehicle. In step 53, the key, placed in the restricted area around the vehicle, receives the interrogation signal and verifies the identity of the vehicle by this received signal. If this signal coded query is not recognized by the key, the key is placed again in the waiting position in step 50. On the other hand, if this interrogation signal is recognized by the key, then a response signal is calculated by a processing unit of the key to step 54. This high frequency response signal is transmitted by the antenna means key issue in step 55. Finally, the means for receiving the vehicle captures this response signal to enable the access management means of order the opening or closing of the vehicle at step 56.

As shown in FIG. 1, when the wearer of the electronic key moves away of the vehicle beyond the restricted area, the key is no longer able to receive a interrogation signal from the vehicle. So, through the relays intermediaries 3 and 4, it is possible to make a bridge at a distance between the carrier of the portable object 2 and the vehicle 1 to open. These intermediate relays are used in general rule by malicious people to easily steal the vehicle without the knowledge of the vehicle user. The opening of the vehicle can thus be performed without having to steal said key and without forcing the locks of the vehicle.

The first intermediate relay 3, placed in the restricted zone 5 around the vehicle, is able to receive by an antenna 31 an interrogation signal 6 to low frequency. This first relay converts the low frequency signal LF to transmit an RF radio signal 7 by an antenna 32 to a second relay 4 near the carrier of the portable object 2. This second relay converts the RF radiofrequency signal received by the antenna 42 in a low frequency signal LF, which is the image of the interrogation signal transmitted by the vehicle. This low signal frequency 8 is transmitted by the antenna 41 to the portable object 2. This object portable receives by the antenna 21 the interrogation signal 8 provided by the second relay 4. After receiving the interrogation signal, a high frequency response signal UHF 9 is transmitted by the antenna 22, if the identity of the vehicle has been recognized. The second relay picked up by the antenna 43 this high frequency signal. The second relay converts the signal high frequency received by the portable object into a radiofrequency signal that is transmitted by the antenna 42. The first relay receives the high frequency signal and converts it to a UHF high frequency signal, which is the image of the response signal calculated by the object portable. This high frequency response signal 10 is transmitted by the antenna 33 to destination of the vehicle so that the antenna 12 of the receiving means 15 receives the response signal 10. Access management means 13 connected to the transmission means and the means of reception of the vehicle will control in particular the opening of the doors and trunk of the vehicle as soon as the response signal is received.

FIG. 3 represents a flowchart of the steps of the control method access of a portable object, such as an electronic key, to the vehicle through intermediary relays for locking or unlocking, particularly doors and of the trunk of said vehicle. It should be noted that the steps in this Figure 3, which corresponding to that of Figure 2, bear identical reference signs.

After the person carrying the first intermediary relay has entered the vehicle handle in step 51, the interrogation signal is transmitted by the vehicle in step 52. This interrogation signal is therefore picked up by the first relay in step 60 to convert it to a radio frequency signal. This conversion into a signal Radio frequency is necessary for long distance transmission. The second relay captures the radio frequency signal from the first relay in step 61 in order to convert it into a signal that is the image of the interrogation signal. This signal interrogation is transmitted to the electronic key.

In step 53, the key near the second relay receives the interrogation signal and verify the identity of the vehicle by this received signal. If this coded interrogation signal is not recognized by the key, the key is placed in the waiting position again In contrast, if this interrogation signal is recognized by the key, then a response signal is calculated by a key processing unit in step 54. This signal high frequency response is transmitted by the antenna means of issuing the key in step 55. In step 62, the second relay captures this response signal to convert it again in a radiofrequency signal. This radiofrequency signal is transmitted from the second relay to the first relay. At step 63, the first relay, having received the radiofrequency signal, converts it into a high frequency signal which is the image response signal transmitted by the key. This high frequency signal is transmitted to the vehicle so that in step 56, the access management means control the opening or closing the vehicle.

We therefore understand the need to implement an access control method which prohibits the use of such intermediary relays for controlling the locking or unlocking parts or functions of the vehicle.

A solution to avoid the use of such intermediary relays is mentioned in WO 01/25060. This document describes a detection system that prevents an intermediate relay attack for unlocking a vehicle to unbeknownst to the user of said vehicle. To do this, a frequency comparison of signals transmitted and received by the car is operated in the car so as to estimate the remote response time of the key. The frequency of the signal received by the key is used to define the operations processed in the key and the frequency of the signal answer of the key. The frequency of the response signal is for example more than 1000 times greater than the frequency of the received signal.

Once the car has transmitted the interrogation signal at a frequency determined, the frequency is varied in the car until the moment the signal response from the key is received. The frequency of the response signal is divided to correspond to the frequency of the signal initially transmitted. So, a comparison between the frequency of the response signal and the frequency changed over time in the car is operated. The greater the distance between the key and the car, the more frequency of signals in the car will have changed. We can detect by this measurement of frequency change, if intermediate relays have been used to the unexpected opening of the car.

A disadvantage of the solution proposed in this document is in particular the complexity of creating this frequency variation in the car in order to be able to accurately estimate the distance between the key and the car. It is necessary that give a distance value from which the electronic means estimate Intermediate relays could be used to unlock the car.

The object of the invention is therefore to provide an access control method of a custom portable object to a specific space preventing the use of relays intermediate and overcoming the disadvantages of the cited prior art.

This and other purposes are achieved by the above-mentioned process characterized in that the encoded identification signal transmitted and received comprises a analog signature defined by at least one amplitude variation of the envelope of the encoded signal, said analog signature being specific to either the portable object or the electronic means provided in the space, that is to say the pair formed by the object custom notebook and electronic means provided in the space so as to allow access to the space in case of recognition of the said signature.

An advantage of the method is that with the use of an analog signature in the coded signal, this prevents any intermediate relays held by ill-intentioned people to serve as a bridge between the object and the means provided in the space to be accessed. These possible relays are not as to reproduce digital type signals, that is, in which a sequence of binary data is transmitted. By adding to these signals a specific analog coding for example to the pair constituted by the portable object and the electronic means provided for in the space to be accessed, the relays can not more accurately reproduce the coded signals. The analog signature, which depends characteristics of the transmitting means and / or receiving means, may be at least one amplitude variation of the coded signal envelope. It could be over-modulation of the envelope of the coded signal. This analog signature can also be defined according to a growth time and / or a time of amplitude decrease of the coded signal envelope at the beginning or at the end of the signal code. If the coded signal comprises a sequence of binary data, this signature can be defined according to a time of growth and / or decay of amplitude between two bits of different value of the sequence of data. The amplitude variation during the growth time and / or decay being linear or hyperbolic or random.

Preferably, the determined space is a vehicle and the portable object is a personalized electronic key to the vehicle to order. Components key electronics are powered by power supply means that include a standard battery or accumulator or photovoltaic cells or an oscillating mass generator.

The analog signature is preferably inserted in the coded signal interrogation transmitted by the vehicle to the electronic key. This signal interrogation comprises a data sequence obtained by modulation amplitude of the determined carrier frequency signal. This carrier frequency can be of the order of 125 kHz. Each bit of the sequence is set to a time period greater than the reverse of the carrier frequency. At the reception the coded interrogation signal, when the key is in a restricted area around the means of emission of the vehicle, an indicator of the amplitude of the means of receiving signals from the key provides dynamic values of amplitude of the envelope of the coded signal. With these amplitude values of the signal envelope received code, it is possible to check the analog signature of the coded signal. This verification is performed in a microcontroller by comparing the values digitized amplitude with stored reference values.

As the interrogation signal transmitted by the vehicle is low Frequency, most of the computing operations in the microcontroller of the key is also low frequency which reduces the consumption compared to a high frequency treatment. In a sleep mode, the operation is also low frequency. However, once the analog signature has been recognized, a high frequency response signal shall be transmitted to the vehicle for controlling the locking or unlocking of parts or functions of the vehicle. This high carrier frequency can be of the order of 433 MHz, which makes it possible to order the vehicle at a distance between 10 to 30 m. Like the electronics of the Key generating this high frequency signal only operates sporadically, the power consumption remains low. This power consumption can be the order of 10 mA for a period of 100 ms.

The invention also aims to provide a portable object for the implementation of implementation of the access control method.

This goal, as well as others, is achieved through the above-mentioned object which is characterized in that the processing unit is arranged to control the means transmission and / or receiving means for transmitting and / or receiving a encoded identification signal with an analog signature, which is defined by least a variation of amplitude of the envelope of the coded signal, said signature analogue being specific to either the portable object or the electronic means in space, or to the couple formed by the object and the space to be accessed, such than a vehicle.

la figure 1 déjà citée représente schématiquement des relais intermédiaires placés entre l'objet portable et le véhicule pour l'ouverture ou la fermeture non autorisée du véhicule,

la figure 2 déjà citée représente un organigramme des étapes du procédé de contrôle d'accès d'une clé électronique personnalisée au véhicule de l'art antérieur pour verrouiller ou déverrouiller des parties on fonctions du véhicule,

la figure 3 déjà citée représente un organigramme des étapes du procédé de contrôle d'accès d'une clé électronique personnalisée au véhicule de l'art antérieur par le biais de relais intermédiaires pour le verrouillage ou le déverrouillage des parties on fonctions du véhicule,

la figure 4 représente schématiquement les composants électroniques de l'objet portable pour la mise en oeuvre du procédé de contrôle d'accès selon l'invention,

la figure 5 représente un organigramme des étapes du procédé de contrôle d'accès d'un objet portable, tel qu'une clé électronique, à un espace, tel qu'un véhicule selon l'invention,

les figures 6a à 6c représentent des graphiques montrant plusieurs types de signature analogique par variation d'amplitude dans le temps de l'enveloppe du signal codé, qui comprend une séquence de données binaires pour le procédé de contrôle d'accès selon l'invention, et

la figure 7 représente un graphique montrant de manière plus détaillée la porteuse du signal codé se terminant par une signature analogique reflétée par décroissance d'amplitude de l'enveloppe du signal codé comme illustrée à la figure 6a.

The aims, advantages and characteristics of the access control method and of the portable object for its implementation will appear better in the following description of at least one embodiment illustrated by the drawings in which:

FIG. 1 already cited schematically represents intermediary relays placed between the portable object and the vehicle for unauthorized opening or closing of the vehicle,

FIG. 2 already cited represents a flowchart of the steps of the access control method of a personalized electronic key to the vehicle of the prior art for locking or unlocking parts or functions of the vehicle,

FIG. 3, already cited, represents a flowchart of the steps of the access control method of a personalized electronic key to the vehicle of the prior art by means of intermediate relays for locking or unlocking the parts or functions of the vehicle,

FIG. 4 diagrammatically represents the electronic components of the portable object for the implementation of the access control method according to the invention,

FIG. 5 represents a flowchart of the steps of the access control method of a portable object, such as an electronic key, to a space, such as a vehicle according to the invention,

FIGS. 6a to 6c show graphs showing several types of analog signatures by time amplitude variation of the envelope of the coded signal, which comprises a binary data sequence for the access control method according to the invention, and

FIG. 7 represents a graph showing in more detail the carrier of the coded signal ending with an analog signature reflected by amplitude decay of the envelope of the coded signal as illustrated in FIG. 6a.

A preferred embodiment of the control method will be described below. access to a specific space, such as a vehicle with a portable object consisting of preferably by an electronic key of active type. Of course, all electronic components of the vehicle and the portable object, which are known to the skilled person in this technical field will not be described so Detailed.

As indicated above with reference to FIG. 1, the portable object 2 must be find in a restricted area 5 around the electronic means of the vehicle 1 for implementing the access control method according to the invention. These means electronic means include transmitting means 11, 14 and / or means for receiving 12, 15 signals.

The portable object 2 is preferably an active electronic key in which power supply means can supply all the components which contains the key. These feeding means may comprise a battery, accumulator, photovoltaic cells, mass generator oscillating or other well-known source of electrical energy.

The electronic components of the key are shown schematically in Figure 4. As explained above, it is necessary that the key has its own source of energy because it must be able to respond with a encoded high frequency signal which may be of the order of 433 MHz. A diet by a polling signal received at low frequency of the order of 125 kHz for example, in the case of a passive key, is not sufficient to allow the generation of the high frequency coded signal transmitted by the key.

The electronic key 2 essentially comprises a processing unit of signals 26 connected to signal receiving means 21, 27, and to means 22, 28. The power consumption of the key is of the order of 5 μA in standby mode 99% of the time, and in the order of 10 mA during a 100 ms period when transmitting the high frequency coded signal.

The reception means are composed of a receiving antenna 21 for receive a low frequency coded signal from the vehicle, and a receiver 27. The coded interrogation signal, received by the reception means, comprises a sequence of binary data. The receiver LF 27, receiving the coded signal, provides the sequence of binary data to a microcontroller 24 of the processing unit 26. This LF receiver 27 also includes an amplitude indicator (RSSI, Received Signal Strength Indicator in English terminology) providing values dynamic analog amplitude of the coded signal envelope received at a digital analog converter 23 of the processing unit 26. This converter digital analog 23 digitizes amplitude values provided by the indicator clocked by a clock signal of the order of 125 khZ. Scored values of amplitude, partially defining the analog signature, are compared with amplitude reference values. These reference values are stored in the storage means 25 of the processing unit 26, which are connected to the microcontroller.

As the amplitude of the coded signal is dependent on the distance between the vehicle and the key, it is rather the derivatives of the coded signal envelope or the amplitude differences, which are digitized and compared in the microcontroller 24 with stored reference values. After sampling at a frequency determined in the converter 23, it is possible to evaluate these derivatives or these deviations to identify the torque formed by the key and the vehicle.

The LF receiver 27, which includes the amplitude indicator, may be the electronic component referenced EM4083 produced by the company EM Microelectronic-Marin SA located in Marin, Switzerland. The microcontroller 24, used in particular for the comparison of the amplitude values and for the calculation of a signal answer, can be the electronic component referenced EM6640 also produced by EM Microelectronic-Marin SA in Marin, Switzerland.

Once the analog signature has been verified in the microcontroller 24, a calculation of a response signal is performed in said microcontroller to control the transmission of this response signal to the transmitting means 22, 28. These means are composed of a UHF transmitter 28 and an antenna 22. As the component parts of the transmitter are well known in this technical field, they do not will not be explained below. However for high response signal transmission frequency, a voltage-controlled oscillator of the transmitter is in principle used, which consumes a lot of electrical energy. Thus, the UHF transmitter 28 is not continuously snapped into the dongle to avoid unloading too quickly the source of energy that includes the key. This transmitter is not engaged only if the microcontroller 24 has recognized the analog signature of the signal interrogation received. This analog signature specifically defines the couple constituted by the personalized key and the vehicle, because it depends on characteristics transmission means and means for receiving the key and the vehicle.

The coded interrogation signal transmitted by the vehicle comprises a carrier at a frequency of 125 kHz on which a sequence of binary data is obtained by amplitude modulation of the envelope of the carrier. Each element binary of the sequence is thus defined over a time period greater than the opposite of the carrier frequency. Each binary element takes the value 1, respectively 0, when the amplitude level of the envelope of the bit element of the encoded signal is greater or less than a threshold amplitude level determined. At this low frequency, the coded interrogation signal is only captured at a distance of less than 2 m which defines the restricted area around the vehicle.

Of course, the carrier frequency of the coded signal transmitted by the vehicle may be different from 125 kHz. It may be considered to fix this frequency carrier for example at 90 kHz.

The response signal transmitted by the key to the vehicle comprises a carrier at a frequency of the order of 433 MHz. Normally at this frequency, the coding of the response signal is not obtained by amplitude modulation, because of the problems Well-known Multiple Paths Would Influence Coding Recognition transmitted.

As in the case of the low frequency coded signal, the carrier frequency of this response signal may be different from 433 MHz. The value of this frequency signal carrier response may be dependent on certain country requirements where the access control method is applied. With such a carrier frequency, it It is possible to order parts or functions of the vehicle up to distance of 30 m.

FIG. 5 represents a flowchart of the steps of the control method access of a personalized electronic key to the vehicle for locking or unlocking including doors and trunk of said vehicle according to the invention. he it should be noted that the steps of this FIG. 5, which correspond to that of FIG. bear identical reference signs.

In step 50, the electronic key carried by the user of the vehicle is in waiting position. Once the vehicle handle has been grasped by the hand of the user in step 51, an interrogation signal LF is transmitted by the means transmission in step 52 under the control of the access management means of the vehicle. The electronic key, placed in the restricted area around the vehicle, receives the coded interrogation signal in step 70. At this step 70, the amplitude indicator of the RF receiver provides analog amplitude values to the converter. The converter digitizes these amplitude values in order to control these digitized amplitude values in the microcontroller, defining the signature analogue of the received signal, with stored values of reference. If the signature analog is not recognized, the electronic key goes to step 50 of setting waiting. On the other hand, if the analogue signature is recognized, the vehicle is identified step 53. If the vehicle is not recognized, the key is placed again in position waiting time in step 50. In case of recognition of the vehicle to be controlled, a signal response is calculated by a key processing unit in step 54. This signal high frequency response is transmitted by the antenna means of issuing the key in step 55. Finally, the vehicle reception means receives this response signal to enable the access management means to control the opening or the closing of the vehicle at step 56. It may also be planned to order this step 56, the function of starting the vehicle. In the latter case, instead of grasping the handle as explained above, it is for example the pommel of speed that is touched by the user's hand.

Of course, it is not mandatory for example to enter the handle of the vehicle for the access control method to be activated. He can be considered any other means of detecting the presence of the key near the vehicle to instruct the vehicle to transmit a coded interrogation signal with an analog signature. Acoustic or optical means for example can be used to order the transmission of the coded interrogation signal of the vehicle.

As mentioned above, the analog signature of the coded signal is defined by at least one amplitude variation of the coded signal envelope. Several non-limiting examples of analog signatures are represented on the Figures 6a to 6c. The signals represented in these FIGS. 6a to 6c are for example those provided by the amplitude indicator.

In these FIGS. 6a to 6c, a coded interrogation signal transmitted by the vehicle comprises a data sequence obtained by amplitude modulation of the envelope of the coded signal. This data sequence is defined by a succession of binary elements. A binary element represents the value 1 when the amplitude of the envelope is above the threshold amplitude level As, while this binary element represents the value 0 when the amplitude of the envelope is below As a rule, the amplitude of the envelope defining the element binary 0 is close to 0. Simplified in these figures, the sequence of data includes a succession of bits of different value. The sequence 10101010 is shown in these figures 6a to 6c. Normally this sequence of data may represent a vehicle identification code.

In FIG. 6a, the analog signature transmitted and received in the coded signal identification is defined according to a growth time and / or a time of amplitude decrease Δt of the coded signal envelope of the passage between two binary elements of different value from the data sequence. Variation amplitude during the growth and / or decay time can be linear or hyperbolic or random so as to specifically represent the couple consisting of the vehicle and the personalized key. As previously described, digitized values provided by the converter of the processing unit allow to define derivatives of the curve of growth and / or decay of the envelope of the coded signal to be compared with stored reference values.

It should be noted that this analog signature depends in particular on specific characteristics of the transmitting means and the receiving means of the key and the vehicle. Amplitude growth or decay of the envelope defining the signature can be obtained by an RC type resonator.

In the case of a signal whose coding is not generated by modulation amplitude, the analog signature can be defined at the beginning or the end of the signal encoded, as a function of a growth time and / or amplitude decrease of the envelope of the coded signal.

In FIG. 6b, the analog signature transmitted and received in the coded signal identification is defined by over-amplitude modulation of the signal envelope code. This over-modulation is applied for example to the binary elements representing the value 1 of the data sequence. Amplitude growth of bits 1 is shown in this figure. However, it is also possible to predict a decrease in amplitude of the envelope of the series of said binary elements equal to 1 of the data sequence.

In FIG. 6c, the analog signature transmitted and received in the coded signal identification is defined by over-modulation of each bit. Of preferably, this over-amplitude modulation is applied only to the binary elements worth 1 of the data sequence. Thus, several variations of amplitude by binary element equal to 1 is found after passing through the converter and comparison in the microcontroller of the processing unit. This over-modulation of each binary element equal to 1 may be a sinusoidal or pulsed variation rectangular amplitude of the envelope.

As the data sequence is defined by amplitude modulation of a coded signal carrier, Figure 7 more precisely represents the shape of the encoded signal in the case of an analog signature shown in Figure 6a.

From the description that has just been made, multiple variants of realization of the access control method and the portable object can be designed by those skilled in the art without departing from the scope of the invention. The principle of signing analog signal on a coded signal transmitted by a transmitter to a receiver may also apply to a space, such as a safe or an access door of a place secret. In this case, the portable object may be a watch, a badge, a telephone portable, a smart card with or without a power source. Similarly, the analog signature can as well be transmitted in a response signal transmitted by the portable object.

Claims (13)

A method of controlling access of a personalized portable object (2) to a determined space (1) by wireless transmission of an encoded identification signal, electronic means, which includes access management means (13) ) connected to receiving means (12, 14) and / or signal transmitting means (11, 15) being provided in the space, and the portable object comprising a processing unit (26) connected to transmitting means (22, 28) and / or signal receiving means (21, 27), the method comprising steps of: transmission of a coded identification signal by the transmission means of the portable object or respectively by the transmission means provided in the determined space, receiving the coded identification signal by the receiving means provided in the space or respectively by the receiving means of the portable object, when the object is in a restricted area (5) around the electronic means provided in the space, and checking the coded signal in the access management means (13) or respectively in the processing unit (26) to allow access to the space, the method being characterized in that the coded identification signal transmitted and received comprises an analog signature defined by at least one amplitude variation of the envelope of the coded signal, said analog signature being specific either to the electronic means provided in the space (1) or to the portable object (2) or to the pair constituted by the personalized portable object and the electronic means provided in the space so as to allow access to the space in the event of recognition of said signature. Method according to claim 1, characterized in that the amplitude variation defining the analog signature is obtained by over-modulating the envelope of the coded signal. Method according to claim 1, characterized in that the coded identification signal is defined by a binary data sequence obtained by amplitude modulation of the determined carrier frequency signal, each binary element of the sequence being defined over a longer period of time. in contrast to the carrier frequency, and in that each bit takes the value 1, respectively 0, when the amplitude level of the envelope of the bit of the coded signal is greater, respectively less than one level. threshold determined. Method according to claim 3, characterized in that an amplitude over-modulation of the envelope of the coded signal is applied to the bits of the data sequence corresponding to the value 1 by amplitude growth or decay. the envelope of the series of said bit elements of the sequence, or by several amplitude variations of the envelope of said bit elements equal to 1, and in that the amplitude level of the envelope of the signal coded for a corresponding bit element the value 0 is close to 0. Method according to one of claims 1 or 3, characterized in that the analog signature transmitted and received in the coded identification signal is defined as a function of a growth time and / or an amplitude decay time of envelope of the coded signal at the beginning or end of the coded signal, or as a function of a growth time and / or amplitude decrease of the envelope of the coded signal of the passage between two bits of value different from the sequence of data, the amplitude variation during the growth and / or decay time being linear or hyperbolic or random. Method according to one of the preceding claims, of access control of a personalized portal object (2), such as an electronic key, to a vehicle (1) so as to control the locking or unlocking of parts or functions. of the vehicle (1), the method being characterized in that it comprises steps of: transmission by transmission means (11, 15) of the vehicle of a first coded signal defined as an interrogation signal (6, 8) with an analog signature specific to the pair formed by the personalized object and the vehicle, receiving the interrogation signal by receiving means (21, 27) of the object, when the object is in a restricted area (5) around the transmission means (11, 15) of the vehicle (1) , comparing the received analog signature with a reference signature stored in the processing unit (26) of the object, calculating a second coded signal defined as a response signal in the processing unit of the object in case of recognition of the specific analog signature, and transmission of the response signal (9, 10) for controlling the locking or unlocking of parts or functions of the vehicle. A method according to claim 6, characterized in that an analog signature specific to the pair consisting of the vehicle and the personalized portable object is transmitted with the first and second coded signals. Method according to one of the preceding claims, characterized in that an amplitude indicator (27) of the envelope of the coded signal provided in the receiving means (21, 27) of the object, such as a electronic key, or space, such as a vehicle, provides dynamic amplitude values of the coded signal envelope to the management means (13) or the processing unit (26) to compare the signature analogue received with a memorized reference signature. A method according to claim 8, wherein the object processing unit and / or the space management means comprise an analog digital converter (23), a signal processing microcontroller (24) and storage (25) which comprise in particular an encryption algorithm and a reference signature, characterized in that the amplitude values provided by the indicator are digitized by the analog-digital converter (23), in that the converter clocked by a clock signal provides digitized amplitude values of the coded signal envelope received at the microcontroller (24), and in that the microcontroller makes a comparison between the digitized amplitude values with amplitude values of the signature reference memory. Personalized portable object (2) for implementing the method according to one of the preceding claims, the object comprising a processing unit (26) connected to transmission means (22, 28) and / or means for receiving (21, 27) signals, characterized in that the processing unit is arranged to control the transmitting means and / or the receiving means for transmitting and / or receiving a coded signal of identification with an analog signature, which is defined by at least one amplitude variation of the coded signal envelope, said analog signature being specific either to the electronic means provided in the space or to the portable object (2), the pair formed by the object and the electronic means provided in the space to be accessed, such as a vehicle. Object according to Claim 10, characterized in that it comprises means for transmitting high frequency signals (22, 28) and means for receiving low frequency signals (21, 27), and in that the reception means include an amplitude indicator (21) of the received coded signal envelope for providing dynamic amplitude values of the coded signal envelope to the processing unit (26) for comparing the received analog signature with a signature reference stored in storage means (25) of the processing unit. An object according to claim 11, characterized in that the processing unit comprises an analog-to-digital converter (23) for digitizing the amplitude values provided by the indicator, and a signal processing microcontroller (24) for comparing the values digitized amplitude provided by the converter with amplitude values of the stored reference signature. Object according to claim 10, characterized in that the object is an electronic key having power supply means of the integrated electronic components, the power supply means comprising a battery or a battery or photovoltaic cells or an oscillating weight generator .

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