Key tracking

Abstract

Tracking device with multiple tracking modules (1, 2, 3, 4, 5) for locating a key (51; 52) for a motor vehicle (80), characterized in that, that the tracking device (1, 2, 3, 4, 5) has at least one measuring device (12) for measuring the field strength (F1, F2, F3, F4; F5; F6) of at least one RF signal (F3, F4, F5, F6) sent by a tracking module (1, 2, 3, 4; 5) in the motor vehicle (7) or in the key (51; 52) and received by another tracking module (5; 1, 2, 3, 4) in the key (51; 52) or in the motor vehicle (7), and that at least each measured (12) RF signal (F1; F2; F3, F4, F5, F6) for locating a key (51; 52) has a frequency in the range above 300kHz, characterized by the fact that it has a decision device (8) configured to locate a key (51; 52) at least on the basis of an analysis (S4) by low-pass filtering of several field strengths (F1, F2; F3, F4, F5, F6) of a radio frequency signal received in a location module (1, 2, 3, 4; 5) at different times (t1, t2, t3) and at different positions ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) of certain field strengths (F1, F2; F3, F4, F5, F6).

Description

[0001] The invention relates to methods and devices for locating a key, in particular by means of an RF radio link for passive access systems for a motor vehicle.

[0002] Various approaches already exist for locating a key in different areas, such as in DE100 329 36 A1, DE10 2012 201 385 A1, WO 2012 / 076 389 A1, DE 199 41 351 A1, DE 10 2012 216 843 B3, US 5 689 431 A, and DE 10 2011 088 917 A1, DE 10 2013 221 936 A1, WO 2011 / 019 406 A2, US 2013 / 0 281 111 A1.

[0003] One object of the invention is to optimize a tracking device for a key, particularly for a motor vehicle. This object is achieved by the subject matter of the independent claims. Some particularly advantageous embodiments of the invention are specified in the dependent claims and the description. Embodiments of the invention can also enable efficient and / or cost-effective localization as alternatives to existing solutions. According to embodiments of the invention, for example, locating a key (for a motor vehicle) based on (the field strength of) at least one RF signal from the key can advantageously also dispense with the evaluation of an LF signal.

[0004] Further features and advantages of some advantageous embodiments of the invention will become apparent from the following description of some exemplary embodiments of the invention with reference to the drawing.

[0005] To illustrate some possible embodiments of the invention, the following are shown in simplified schematic form: Fig. 1 a vehicle with a tracking device comprising a transmitter and a receiver for locating a key, Fig. 2 a vehicle equipped with a tracking device with multiple transmitters and / or multiple receivers for locating a key, Fig. 3 a tracking module with a receiver and an evaluation device of a tracking device in a key or vehicle (for locating a key relative to a motor vehicle), Fig. 4. A process for locating a key, Fig. 5 Some examples of spatial distributions of field strengths in the vicinity of a car.

[0006] Fig. Figure 1 shows, by way of example, a tracking module 3 of a tracking device, which tracking module 3 is located in a motor vehicle 80, e.g. within the interior of a motor vehicle 80, e.g. in the area of ​​a car radio etc., as well as schematically a tracking module 5 of a tracking device, which is located in a key 51 outside or in a key 52 inside the motor vehicle 80.

[0007] At least one tracking module 3 or 5 shall determine, based on at least one field strength measured by it, at least one (HF and / or RF) field F1, F2, F3, F4, F5, F6 transmitted by the key 51 or 52 or by a tracking module in the motor vehicle 80. whether the (for location in Fig. 1 a field F1 sending or a field F3 receiving) key 51 is located outside (the passenger compartment) of the motor vehicle 80 or the (for location in Fig. 1. Key F2 (transmitting field F2 or receiving field F3) is located inside (the passenger compartment) of the motor vehicle 80. e.g. by analyzing one or, in particular, several (temporarily stored) measured values ​​of the field strength F1, F2; F3, F4, F5, F6, e.g. with a trend analysis (d / dt) and / or with a time low-pass filter and / or with threshold values ​​(d / dt) etc.

[0008] Based on the decision of the tracking device or one of its tracking modules 3 or 5 (whether a key 51 or 52 is located outside or inside the (passenger compartment of the) motor vehicle 80), can a device (11 in Fig. 3) be informed and make decisions based on that information, e.g. whether starting the engine of the motor vehicle 8 is permitted and / or initiated, whether opening a door of the motor vehicle is permitted and / or initiated, etc.

[0009] In Fig. 1. A key 51 is located outside a motor vehicle, which can be determined based on measured field strengths and / or temporal and / or spatial profiles of RF signals received in at least one location module; and a key 52 is located at three times t1, t2, t3 at three positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) inside a motor vehicle 80, which is due to measurements taken at times t1, t2, t3 and at the corresponding positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) (as Fig. 5 shows different) field strengths and / or profiles (because the key is located at different places at three times t1, t2, t3) of RF signals received in at least one locating module 3 or 5 can be determined.

[0010] Fig. Figure 2 shows an example of a further embodiment of the invention. several tracking modules 1, 2, 3, 4; 5 of a tracking system, of which tracking modules 1, 2, 3, 4, 5 one or more (1, 2, 3, 4) are located in a motor vehicle 80 and e.g. one (5) in the key 51 or 52, e.g. with tracking modules 3, 4 inside the interior of a motor vehicle 80 and / or with tracking modules 1, 2 outside the (interior of a) motor vehicle 80 in one of the exterior mirrors 801, 802 and / or bumper and / or engine compartment etc.

[0011] The tracking modules 1, 2, 3, 4 of the tracking device in the motor vehicle 80 can also be connected to each other and / or to an evaluation device, e.g. via cable and / or radio, for the purpose of exchanging measurement results concerning field strengths.

[0012] A tracking module 3 or 5, which evaluates and / or analyzes measured field strengths (e.g., low-pass filtering) and / or makes decisions, can be located, for example, in the motor vehicle 80 and / or in the key 51, 52; it can also communicate a decision to another tracking module or a control system, e.g., via (e.g., RF) radio.

[0013] The frequency of a field F1, F2, F3, F5, F6 which transmits a tracking module 5 in the key 51, 52 and / or (at least) one tracking module 1, 2, 3, 4 in the motor vehicle 80 is in particular a high frequency (e.g., also referred to as RF or radio frequency), e.g., an HF frequency and / or RF frequency and / or frequency above 300 kHz, especially in a band around 900 MHz or 2.4 GHz (Bluetooth). Accordingly, a receiving device and / or a filter, etc., can be provided in (each) a tracking module 1, 2, 3, 4, 5, 6 of the tracking device for reception in this frequency range; A decision (whether a key 51 or 52 is located inside or outside an interior of a vehicle 80) can be made generally or for a specific key (e.g. further identified by identification signals) based on received field strength(s) in this frequency range.

[0014] A measuring device 12 can, in particular, be a measuring device for an RF frequency and / or frequency above 300 kHz, especially in a band around 900 MHz or 2.4 GHz (Bluetooth). Locating a key (for a motor vehicle) based on (the field strength of) at least one RF or HF signal from a locating module 1, 2, 3, 4; 5 can advantageously, for example, dispense with the evaluation of an LF signal and thus also with its generation. With regard to measuring the field strength F1, F2, F3, F4, F5, F6, a so-called (e.g., measurable) RF_RSSI or RSSI value of at least one received RF signal can, in particular, be provided.

[0015] Data exchange, e.g. concerning location tracking, between a tracking module 1, 2, 3, 4, 5 of the tracking device, e.g. in a key 51, 52 or in the motor vehicle 80, and another tracking module 1, 2, 3, 4, 5 of the tracking device, e.g. in a key 51, 52 or in the motor vehicle 80, can also take place, e.g. via radio using an HF frequency and / or RF frequency and / or frequency above 300 kHz, in particular in a band around 900 MHz or 2.4 GHz (Bluetooth).

[0016] Various technologies can be used for the RF connection. An RF connection can be, for example, a so-called sub-GHz connection and / or a connection in one or more ISM bands and / or a Bluetooth connection (e.g., Bluetooth Low Energy). In particular, but not exclusively, in the case of an RF connection in the form of a Bluetooth connection, the key 51; 52 can also be a smartphone. Generally, the key 51; 52 can be any key for a motor vehicle 80, e.g., in the form of a card and / or a smartphone and / or with a mechanical key and / or with a receiver and / or transmitter for, e.g., at least one key ID.

[0017] For example, only at least one HF (or RF) connection can be provided or evaluated, i.e. without considering or using an LF connection (e.g. to the key).

[0018] Fig. Figure 3 schematically and in a simplified manner shows an example of a tracking module 3 of a tracking system 1, 2, 3, 4, 5 with an antenna 6 for receiving a field F1, F2; F3, F4, F5, F6 emitted from or to, for example, a key 51 located at a position, wherein the field strength of the (possibly total) field F(x,y,z) at the location of the tracking module 3 or 5 of a tracking system (measured by a measuring device 12) can be evaluated (20) by an evaluation device 7 (e.g., on a circuit board, etc., with a controller and / or circuit) at one or more times based on, for example, at least one threshold value S (e.g., stored in a memory 9 in the evaluation device) (and / or time profiles, low-pass filters, averaging, etc.). The evaluation device 7 transmits a result 10 of this, for example, to a device 11.

[0019] Depending on the signaled (10) decision communicated to it by a tracking module 3 or 5 in the motor vehicle 80 or key 51, 52, the device 11 (e.g. a motor vehicle locking device or door locking device etc.) can, for example, permit and / or initiate the starting of the motor vehicle 8 or permit and / or initiate the opening of a door of the motor vehicle, etc.

[0020] ZB, the device 11 (e.g., a motor vehicle locking device or door locking device, etc.) can, when signaled to it by the evaluation device 7 as a decision (10) that a key 51 is located at (e.g., any) position (x51, y51, z51) outside the motor vehicle 80, e.g., allow and / or initiate or prevent the starting of the motor vehicle 80's engine and / or allow and / or initiate or prevent the opening of a door of the motor vehicle (e.g., if the measured field strength is below a threshold and thus the distance d13 of the key 51 from the motor vehicle 80 is too great).

[0021] Furthermore, the device 11 (e.g., a vehicle locking device or door locking device, etc.) can, for example, when signaled by the evaluation device 7 as a decision (10) that a key 52 is located at (e.g., any) position (x52, y52) inside the vehicle 80, allow the engine of the vehicle 80 to be started and / or allow or prevent a door of the vehicle to be opened or locked. An evaluation unit of a tracking device can, for example, be arranged in (only or at least) one of the tracking modules 1, 2, 3, 4, 5, each of which measures (and signals to the evaluation device) a field strength of at least one (or an entire) field F1, F2, F3, F4; F5, F6, or in another tracking module of the tracking device, e.g., also in a module in / on the car radio, etc.

[0022] An evaluation of a field F1, F2, F3, F4, F5, F6 received at (each) a tracking module 1, 2, 3, 4 of an RF signal from a key 51 or 52 or tracking module 1, 2, 3, 4 by the motor vehicle 80 can be carried out in different ways, e.g. at least one measured field strength of the field F(x,y) at the location of (at least) a tracking module 1, 2, 3, 4;5 of the tracking system can be analyzed for a decision of the decision device 8.

[0023] If a decision device 8 for locating a key 51; 52 performs an analysis (e.g. by comparison or mean comparison) of several field strengths of at least one received RF signal F1, F2, F3, F4; F5; F6 (i.e., a signal waveform) with at least one threshold value S etc. transmitted by a key 51; 52 or locating module 1, 2, 3, 4 in the motor vehicle 80 with at least one measuring device 12 at several times, the field strengths of one or more RF signals F1, F2, F3, F4; F5; F6 measured for such dynamic locating can be temporarily stored in a memory 9 of a module of the locating device 3 or 5.

[0024] The field strength (at least) of a signal F1; F2, F3, F4; F5, F6 emitted by a tracking module 1, 2, 3, 4 in the motor vehicle 80 or (5) in the key 51; 52 can, for example, decrease approximately quadratically with the distance of a receiver 1 / 2 / 3 / 4 of the signal F1, F2, F3, F4; F5; F6 to the tracking module 5; 1, 2, 3, 4 and / or exhibit other profiles at obstacles.

[0025] ZB, the distance d11, d12, d13, d14 of receiver 1 / 2 / 3 / 4 to the key 51 or tracking module 1, 2, 3, 4 in the vehicle 80 emitting signal F1, or the current position of the receiver, can be deduced from the field strength of the signal received at a receiver on a tracking module 1 / 2 / 3 / 4. Similarly, the distance d21, d22, d23, d24 of receiver 1 / 2 / 3 / 4 to the key 52 or tracking module 1, 2, 3, 4 in the vehicle 80 emitting signal F2 can be deduced from the field strength F2 of the signal received at a receiver on a tracking module 1 / 2 / 3 / 4.

[0026] It is also possible (dynamically) to deduce the last position of a tracking module (e.g., the last position of the key in the vehicle) from the field strengths of several signals received at multiple times t1, t2, t3 (and thus at different positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) at a receiver on a tracking module 1 / 2 / 3 / 4 / 5 received signals, e.g., t3), e.g., using a low-pass filter or averaging, etc.

[0027] If multiple receivers on a tracking module 1 / 2 / 3 / 4 each receive one or more signals, the signals can be evaluated together.

[0028] For example, the following results for the in Fig. 1 and Fig. 2. Position x51, y51 of key 51 shown represents a decision that key 51 is located outside the motor vehicle 80 and / or for the purpose of Fig. 1 and Fig. The positions of the key 52 shown in the diagram ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) at times t1, t2, t3 make a decision that the key 52 was last located (e.g. after t3) inside the motor vehicle 80 (i.e., in particular inside the passenger compartment of the vehicle 80).

[0029] Fig. Figure 4 shows an example of the sequence of a location tracking S1-S7 of a key 51 or 52. (52 could, for example, be the same key as the one at position 51 but at a different time, or another key.)

[0030] In Fig. In step S1, a decision device initiates a so-called polling process in a so-called access zone, i.e., for example, a key 51; 52 is requested (at least) to send an RF signal or to receive an RF signal (from the vehicle 80) by a radio signal (e.g., from at least one tracking module 1, 2, 3, 4 of the tracking device in the motor vehicle 80) and / or at least one tracking module 1, 2, 3, 4 in the motor vehicle 80 is requested to send an RF signal or to receive one (from the key).

[0031] In step S2, a measuring device measures the field strengths of one or more RF signals received with at least one antenna at several times t1, t2, t3 (and thus at different positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) in the form of RF-RSSI or HF-RSSI values ​​at several times t1, t2, t3 etc. (and temporarily stores them, for example, in a memory).

[0032] In step S3, RF-RSSI or HF-RSSI values ​​measured at several times t1, t2, t3 etc. (and thus at different positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3) etc.) relating to field strengths of one or more RF signals received with at least one antenna are evaluated, i.e. filtered (e.g. with a low-pass TP or LP) and / or differentiated.

[0033] In step S4, a decision device uses the RF-RSSI or HF-RSSI values ​​measured at several time points t1, t2, t3, etc. (and thus at different positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) and analyzed in step S3, and if applicable.

[0034] Analysis-based decision made regarding the location of a key 52; 53.

[0035] If, for example, at several times t1, t2, t3, etc. (and thus at different positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)), received and then filtered RF-RSSI or HF-RSSI values ​​(all or predominantly or on average or low-pass filtered, etc.) are below a stored threshold (possibly under further condition(s) that, for example, a (possibly averaged) time derivative is greater than zero), a decision device can decide in step S5 to reject a signal (10 in Fig. 3) to another device (11 in Fig. 3) to send, indicating that the key (51, 51 in Fig. 1, Fig. 2) outside (e.g. the passenger compartment of the) motor vehicle (80 in Fig. 1, Fig. 2) is located (e.g. as flag “loc_flag ID outside”).

[0036] If, for example, filtered RF-RSSI or HF-RSSI values ​​(all, predominantly, or on average, etc.) at several time points t1, t2, t3 (and thus at different positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) or their mean value or low-pass filtering, etc., correspond exactly or sufficiently closely to the last value or (sample / ) set of values, and / or if the RF-RSSI or HF-RSSI values, differentiated (derived over time), result in zero exactly or (according to a specification) sufficiently closely (because they do not change or hardly change), Can a decision device decide in step S6 to retain the last decision where key 51; 52 was and / or send a signal (10 in Fig. 3) to another device (11 in Fig. 3) to send, indicating that the last decision where key 51; 52 was (inside or outside (e.g. the passenger compartment) of the motor vehicle) will be retained.

[0037] If, for example, filtered RF-RSSI or HF-RSSI values ​​at several time points t1, t2, t3, and thus at different positions ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3) (all or predominantly or on average, etc.) are at or above a stored threshold (possibly with the further condition that RRSI values ​​(possibly after averaging) are differentiated (derived) and not equal to zero), a decision device can decide in step S7 to receive a signal (10 in Fig. 3) to another device (11 in Fig. 3) to send, indicating that the key (51, 51 in Fig. 1, Fig. 2) inside (e.g. the passenger compartment) of the motor vehicle (80 in Fig. 1, Fig. 2) is located (e.g. as “flag “loc_flag ID inside”).

[0038] A decision device 8 can, for the purpose of locating a key (51; 52), at least also take into account an analysis of an acceleration of the object (51; 52) to be located, measured in the object to be located, in particular the key (51; 52), e.g. with acceleration sensors B in the object to be located 51; 52, which transmit (B) data concerning an acceleration detected by them (B) to the decision device 8 (in the object or in the motor vehicle) e.g. via the (e.g. HF) radio interface, e.g. for (improved) determination of small changes in position in the motor vehicle etc.

[0039] Fig. Figure 5 shows some examples of spatial distributions of field strengths F (of signals sent by location modules 1, 2, 3, 4 or 5 in the area of ​​motor vehicles 80, top left in a top view from above of a motor vehicle 8080, top center a rear view of the rear of a motor vehicle 80, top right a side view of a motor vehicle 80, top left in a top view from above of a motor vehicle 80 (without showing the motor vehicle), top center a rear view of the rear of a motor vehicle 80 (without showing the motor vehicle), top right a side view of a motor vehicle 80 (without showing the motor vehicle).

[0040] Fig. Figure 5 shows examples of spatial distributions of field strengths F (i.e., field strengths F(x,y)) with scale markings, in the directions (to the right) x, (towards) y, and (forwards / backwards in the motor vehicle 80°). In some applications or situations, spatially and / or temporally irregular distributions of field strengths F(x,y) may occur. Therefore, multiple spatially and / or temporally irregular measurements and evaluations of field strengths F may be necessary (as in...). Fig. 1) one or (as in Fig. 2) to make several tracking device modules 1, 2, 3,4 of a tracking device advantageous (e.g. connected to an evaluation device via cable and / or radio).

[0041] In Fig.5, for example, a key 52 is located at three times t1, t2, t3 successively at the several (here three) locations ((x52t1, y52t1, z52t1) and (x52t2, y52t2, z52t2) and (x52t3, y52t3, z52t3)) within the vehicle 80, at which locations (and times) the field strength of several HF signals F1, F2, F3, F4 is determined. Reference symbol list 1 tracking module of a tracking system (in or on the motor vehicle) 2. Location module of a tracking system (in or on the motor vehicle) 3. Location module of a tracking system (in or on the motor vehicle) 4. Location module of a tracking system (in or on the motor vehicle) 5 Location module of a location system (alternative in the key) 51 keys 52 keys 6 antennas on a tracking module 1 / 2 / 3 / 4 7 Evaluation device / circuit board 8 Decision device (F1 / 2 > S?) 9 Memory for threshold(s) S 10. Result of a comparison (F1 / 2 > S?, d / dt curves, etc.) 11 Device (vehicle locking device etc.) 12 Measuring device (in 1, 2, 3, 4 for measuring F1 or F2) 13 Comparison device (F1 / 2 > S?, d / dt curves, etc.) 80 motor vehicles 801 Rearview mirrors (out of 80) 802 rearview mirrors (out of 80) S Threshold of received field strength(s) for key acceptance in the vehicle (x51, y51) Position of a key 51 (x52, y52) Position of a key 52 F1 field, sent from key S1 F1 (x, y) Field at position (x, y), sent from key S1 F2 field, sent from key S2 F2(x, y) Field at position (x, y), sent from key S2 F3, F4, F5, F6 fields, sent by tracking modules 1, 2, 3, 4 in S1 Step of starting polling (in the access zone) S2 step of receiving RF RSSI values S3 Step of filtering and / or differentiating HF RSSI values S4 Step of deciding whether to use the key inside or outside S5 Step of deciding and / or reporting that key inside S6 Step of deciding and / or reporting that the key is where it was before (either outside as before or inside as before) S7 step of deciding and / or reporting that key outside B. Accelerometers (in the object)

Claims

[1] Locating device with multiple locating modules (1, 2, 3, 4, 5) for locating a key (51; 52) for a motor vehicle (80), characterized by , that the tracking device (1, 2, 3, 4, 5) has at least one measuring device (12) for measuring the field strength (F1, F2, F3, F4; F5; F6) of at least one RF signal (F3, F4, F5, F6) sent by a tracking module (1, 2, 3, 4; 5) in the motor vehicle (7) or in the key (51; 52) and received by another tracking module (5; 1, 2, 3, 4) in the key (51; 52) or in the motor vehicle (7), and that at least each measured (12) RF signal (F1; F2; F3, F4, F5, F6) for locating a key (51; 52) has a frequency in the range above 300kHz, characterized by , that it has a decision device (8) configured to locate a key (51; 52) at least on the basis of an analysis (S4) by low-pass filtering of several field strengths (F1, F2; F3, F4, F5, F6) of a radio frequency signal received in a location module (1, 2, 3, 4; 5) at different times (t1, t2, t3) and at different positions ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) of a certain field strength (F1, F2; F3, F4, F5, F6). [2] Locating device (1, 2, 3, 4, 5) according to claim 1, characterized by , that it has exactly one tracking module (3) in a motor vehicle (7) or exactly one tracking module (3) intended for arrangement in a motor vehicle (7) which sends an RF signal (F3) to a key (51; 52) and / or receives an RF signal (F1, F2) from a key (51; 52). Fig. 1) [3] Locating device (1, 2, 3, 4, 5) according to claim 1, characterized by , that it has several tracking modules (1, 2, 3, 4) in a motor vehicle (7) or several tracking modules (1, 2, 3, 4) intended for arrangement in a motor vehicle (7), each sends an RF signal (F3, F4, F5, F6) to a key (51; 52). and / or receive an RF signal (F1, F2) from a key (51; 52). Fig. 2) [4] Locating device according to one of the preceding claims, characterized by , that they include one or more measuring devices (12), in particular each in a locating module (1, 2, 3, 4; 5) of the locating device in (5) key (51, 52) or (1, 2, 3, 4) in the motor vehicle (80) having a measuring device (12) in each case designed to measure the field strength (F1, F2; F3, F4, F5, F6) of at least one received RF signal (F1, F2; F3, F4, F5, F6). [5] Locating device according to one of the preceding claims, characterized by, that a measuring device (12) is designed to measure the field strength in the form of an RF_RSSI or RSSI value of at least one RF signal (F1, F2; F3, F4, F5, F6) transmitted and received by at least one locating device (1, 2, 3, 4; 5). [6] Locating device according to one of the preceding claims, characterized by , that it has a decision device (8) which is configured to locate (S1-S7) a key (51; 52) at least on the basis of an analysis (S3; S4) of a temporal (t1, t2, t3) and / or spatial ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) progression (t1, (x52t1, y52t1, z52t1)); t2, (x52t2, y52t2, z52t2)); (t3, (x52t3, y52t3, z52t3))) (d / dt) of a field strength of an RF signal (F3, F4, F5, F6, F1, F2) (S4-S7). [7] Locating device according to one of the preceding claims, characterized by, that it has a decision device (8) configured to locate a key (51; 52) at least on the basis of an analysis of several field strengths of an RF signal (F1, F2; F3, F4, F5, F6) (S4-S7) measured with at least one measuring device (12) in the key (52) at several times (t1, t2, t3) and / or at several positions ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) where the key (52) is located successively (t1, t2, t3). [8] Locating device according to one of the preceding claims, characterized by , that it has a decision device (8) configured to locate a key (51; 52) at least on the basis of a comparison (S4) of the temporal (d / dt) derivative of several with at least one measuring device (12) at several times of certain field strengths of at least one RF signal (F1; F2; F3, F4, F5, F5) with at least one threshold of in particular zero (S4). [9] Locating device according to any one of the preceding claims, characterized by , that it has a decision device (8) which, when used in a temporal (d / dt) derivation of several field strengths at several times with at least one measuring device (12) at several times, selects at least one of a key (51; 52) to decide on the received or transmitted RF signal (F1, F2; F3, F4, F5, F6) at several times (t1, t2, t3) and / or at several locations ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) within a threshold of, in particular, zero, to retain the last result of the decision device (8), in particular to the effect that the key (51; 52) is still assumed to be outside the vehicle (80) or that the key (51; 52) is still assumed to be inside the vehicle (80) (S6). [10] Locating device according to any one of the preceding claims, characterized by, that it has a decision device (8), which is trained to, for a given value of, in particular, zero at several times (t1, t2, t3) and / or at several locations ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) where the key (52) is successively located (t1, t2, t3) to decide based on a certain field strength(s) (F1; F2) of at least one RF signal (F1, F2; F3, F4, F5, F6), that no key (51; 52) is inside the vehicle (80) and / or that no key (51; 52) is located outside the vehicle (80) or near the vehicle (80). [11] Locating device according to any one of the preceding claims, characterized by that they a device (11) in particular in the form of an engine start control or door opener control which is designed to determine, based on the location of a key (51; 52), whether the key (51; 52) is inside or outside a vehicle (80), decides on an action, in particular on instigating or carrying out or authorizing a start of the engine of the motor vehicle (80) and / or opening a door of the motor vehicle (80). [12] Locating device according to any one of the preceding claims, characterized by , that at least one or each measured (12) RF signal (F1; F2; F3, F4, F5, F6) for locating a key (51; 52) has a frequency in a band around 900 MHz or 2.4 GHz (Bluetooth). [13] Locating device according to one of the preceding claims, characterized by, that it has a decision device (8) which is designed to locate (S1-S7) an object (51; 52) at least also on the basis of taking into account an analysis of an acceleration of the object to be located (51; 52) measured in the object to be located, in particular key (51; 52). [14] Method for locating a key (51; 52), for a motor vehicle (80) with a tracking device (1, 2, 3, 4, 5) according to one of the preceding claims, wherein the tracking device has one or more tracking modules (1, 2, 3, 4) of the tracking device at several times (t1, t2, t3) and / or at several locations ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) where the key (52) is located successively (t1, t2, t3) measured (12) field strengths of RF signals (F1; F2) for locating (12) the key (51; 52) are taken into account (S1-S7), in particular without using low-frequency signals sent by a key for locating, characterized by , that a decision device (8) is used which is configured to locate a key (51; 52) at least on the basis of an analysis (S4) by low-pass filtering of several specific field strengths (F1, F2; F3, F4, F5, F6) of an RF signal received in a locating module (1, 2, 3, 4; 5) at different times (t1, t2, t3) and at different positions ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)) received at different times (t1, t2, t2, t3) and at different positions ((x52t1, y52t1, z52t1), (x52t2, y52t2, z52t2), (x52t3, y52t3, z52t3)).

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