AU2021203195B2

AU2021203195B2 - Wheel detector and method of detecting a rail-bound wheel

Info

Publication number: AU2021203195B2
Application number: AU2021203195A
Authority: AU
Inventors: Rainer Freise
Original assignee: Siemens Mobility GmbH
Current assignee: Siemens Mobility GmbH
Priority date: 2020-05-27
Filing date: 2021-05-18
Publication date: 2022-07-28
Anticipated expiration: 2041-05-18
Also published as: EP3916434A1; EP3916434B1; AU2021203195A1

Abstract

Wheel detector and method for detecting a rail-bound wheel ABSTRACT The invention relates to a method for detecting a rail-bound wheel, in which, in an inductive sensor arrangement installed in a rail-encompassing manner with a transmit coil (299) and a receive coil (324), a receive signal (308) is generated which represents a wheel influence. In addition, a measurement signal (309) which represents an interference is generated by a measurement coil (364). It is provided that the processing takes place in a computer-assisted manner, in that a modified receive signal (392) and a modified measurement signal (395) are generated, in which a useful frequency band, in which the receive signal lies, is suppressed within the measured bandwidth of the receive signal and the measurement signal, with which the interference can advantageously be assessed. For this, the signal strengths of the modified receive signal (392) and the modified measurement signal (395) are adjusted to one another. Subsequently, the interference in the adjusted receive signal (345) can be rectified or at least reduced by taking into consideration the adjusted measurement signal (385). The invention additionally relates to a wheel detector, as well as a computer program, with which the method can be performed. Fig. 3 2/3 Cl) CD) CY) cy)) F --- -- , F - - - -- - - - --- I 'LO CNJ LO L.O cy')) ccc CZ) CZ) co' L.A) cyf) A C n-- CY*I i -- N~* C-0 ' A I A I (-0 CC~) cyC-) CC-0 C l~) C-0C)

Description

2/3 Cl)

CD) CY)

cy))

F -- --- , F - - - -- - - - --- I 'LO CNJ LO L.O

cy')) ccc

CZ) CZ)

co' L.A) cyf) A C n-- CY*I i -- N~* C-0 ' A I A I (-0 CC~)

cyC-)

CC-0

C l~) C-0C)

Wheel detector and method for detecting a rail-bound wheel

[0001] This application relates to European Patent Application No. EP20176772, the content of which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to a method for detecting a rail-bound wheel, in which, * in an inductive sensor arrangement installed in a rail-encompassing manner with a transmit coil and a receive coil, a receive signal is generated which represents a wheel influence, * a measurement signal which represents an interference is generated by a measurement coil, * the receive signal and the measurement signal are processed.

[0003] The present disclosure additionally relates to a wheel detector, having • an inductive sensor arrangement for installation in a rail-encompassing manner with a transmit coil and a receive coil for generating a receive signal which represents a wheel influence, * a measurement coil for generating a measurement signal which represents an interference, • a processing unit for the receive signal and the measurement signal.

[0004] Furthermore, the present disclosure relates to a computer program product as well as to a provision apparatus for said computer program product, wherein the computer program product is equipped with program commands for performing said method.

[0005] Wheel detectors, or axle counting sensors, which operate in accordance with the system that encompasses rails with transmitter and receiver which lie opposite and are separated, are sufficiently known in track vacancy detection technology. There are various options for increasing the immunity to interference of wheel detectors. One option is the direct counter coupling of a receive coil of the same construction, which is interconnected such that in-phase interference fields, such as those which arise due to rail current at the operating frequency, for example, are subtracted from one another and are thus suppressed to the greatest possible extent. Due to the coils having the same construction and the same positioning on the rail in relation to the induction of the interference fields, a greatest possible suppression of interference fields is produced. One example of this is described in DE 10 2007 023 475 B4.

[0005A] According to an aspect of the present invention, there is provided a method for detecting a rail-bound wheel, in which, * in an inductive sensor arrangement installed in a rail-encompassing manner with a transmit coil and a receive coil, a receive signal is generated which represents a wheel influence, * a measurement signal which represents an interference is generated by a measurement coil, the receive signal and the measurement signal are processed, wherein the processing takes place in a computer-assisted manner, in that • a modified receive signal and a modified measurement signal are generated, in which a useful frequency band, in which the receive signal lies, is suppressed within the measured bandwidth of the receive signal and the measurement signal, * the signal strengths of the modified receive signal and the modified measurement signal are adjusted to one another, * the interference in the adjusted receive signal is rectified or at least reduced by taking into consideration the adjusted measurement signal; wherein the receive signal and the measurement signal, in order to suppress the useful frequency band in a signal adjustment path, each pass through a high-pass filter that is dimensioned such that the frequencies that can be generated by wheel influence are suppressed.

[0005B] According to another aspect of the present invention, there is provided a wheel detector, * having an inductive sensor arrangement for installation in a rail-encompassing manner with a transmit coil and a receive coil for generating a receive signal which represents a wheel influence, * a measurement coil for generating a measurement signal which represents an interference, • a processing unit for the receive signal and the measurement signal, wherein the processing unit is configured, in a computer-assisted manner, * to generate a modified receive signal and a modified measurement signal, in which a useful frequency band, in which the receive signal lies, is suppressed within the measured bandwidth of the receive signal and the measurement signal, * to adjust the signal strengths of the modified receive signal and the modified measurement signal to one another,

2a

to rectify or at least reduce the interference in the adjusted receive signal by taking into consideration the adjusted measurement signal; wherein the receive signal and the measurement signal, in order to suppress the useful frequency band in a signal adjustment path, each pass through a high-pass filter that is dimensioned such that the frequencies that can be generated by wheel influence are suppressed.

[0006] Aspects of the present disclosure increase the immunity to interference of wheel sensors that operate inductively with separated transmitter and receiver when faced with induced interference voltages caused by external magnetic interference fields, which are generated by rail current at operating frequency, for example, and make this increase in the immunity to interference independent of external parameters, such as rail type, rail wear, manufacturing and mounting tolerances of the sensor or also the variable conditions during wheel traversal, for example.

[0007] Aspects of the present disclosure provides a method as indicated in the introduction, in that the processing takes place in a computer-assisted manner, in that • a modified receive signal and a modified measurement signal are generated, in which a useful frequency band, in which the receive signal lies, is suppressed within the measured bandwidth of the receive signal and the measurement signal, * the signal strengths of the modified receive signal and the modified measurement signal are adjusted to one another, and an adjusted receive signal is generated from the modified receive signal and an adjusted measurement signal is generated from the modified measurement signal (wherein the signal adjusted in each case may be identical to the associated modified signal if an adjustment is not necessary or the other modified signal is changed for the adjustment in each case), * the interference in the adjusted receive signal is rectified or at least reduced by taking into consideration the adjusted measurement signal.

[0008] The aforementioned problem of variable results depending on the mounting situation is, in other words, therefore solved or ameliorated by an independently readjusting interference field compensation as a function of the instantaneous state of the sensor (coils) in the wheel detector or the degree to which an interference field is coupled in. This has the significant advantage that manufacturing tolerances, installation tolerances, interference field magnitudes or a drift of the signal generation due to wear do not have to be known, as these can be

2b

immediately compensated during the measurement of the receive voltage as receive signal, taking into consideration the measured measurement voltage as measurement signal.

[0009] An additional sensor coil, the measurement coil, is dimensioned and positioned, or oriented, such that it generates as little receive voltage or excess signal increase as possible during wheel traversal, but generates interference voltages induced by rail currents at operating frequency. The measurement coil serves to measure the interference emanating from the rail current or from another source of interference. The measurement voltage (measurement signal) of said coil or said resonant circuit is taken into consideration, preferably subtracted from or added to the receive voltage (receive signal), in order for the interference to be rectified or at least reduced in the adjusted receive signal by taking into consideration the adjusted measurement signal, depending on the phase angle and orientation of the coils on the rail. The phase angle may depend upon the geometry of the measurement apparatus in the polarity of the coils used. Additionally, this may be influenced by the wheel passage.

[0010] "Computer-assisted" or "computer-implemented", in conjunction with the invention, may be understood to mean, for example, an implementation of the method in which a computer/processor or a plurality of computers/processors carries/carry out at least one method step of the method.

[0011] Unless otherwise specified in the subsequent description, the terms "create", "calculate", "compute", "ascertain", "generate", "configure", "modify" and the like preferably refer to actions and/or processes and/or processing steps that change and/or generate data and/or convert data into other data. In this context, the data is present in particular as physical variables, for example as electrical pulses or also as measurement values. The necessary instructions/program commands are consolidated in a computer program as software. Furthermore, the terms "receive", "transmit", "read in", "read out", "transfer" and the like refer to the interaction of individual hardware components and/or software components via interfaces. The interfaces may be implemented as hardware, for example in a cable-bound manner or as a wireless connection, and/or as software, for example as an interaction between individual program modules or program parts of one or more computer programs.

[0012] The expression "computer" is to be interpreted broadly, covering all electronic devices with data processing properties. Computers may therefore be, for example, personal computers, servers, handheld computer systems, pocket PC devices, mobile radio devices and other communication devices that process data in a computer-assisted manner, processors and other electronic devices for data processing, which preferably may also be combined to form a network. A "memory unit", in conjunction with the invention, may be understood to mean, for example, a computer-readable memory in the form of random access memory (RAM) or data storage (hard drive or a data carrier).

[0013] A "processor", in conjunction with the invention, may be understood to mean, for example, a machine, for example, a sensor for generating measurement values or an electronic circuit. The processor may involve, in particular, a central processing unit (CPU), a microprocessor or a microcontroller, for example an application-specific integrated circuit or a digital signal processor, possibly in combination with a memory unit for storing program commands, etc. A processor may also involve, for example, an IC (integrated circuit), in particular an FPGA (field-programmable gate array) or an ASIC (application-specific integrated circuit), or a DSP (digital signal processor). A processor may also be understood to mean a virtualized processor or a soft CPU. It may also involve, for example, a programmable processor, which is equipped with a configuration for carrying out a computer-assisted method.

[0014] "Cloud" is to be understood as meaning an environment for "cloud computing". This means an IT infrastructure which is made available via a network such as the Internet. As a general rule, it contains storage space, computing capacity or application software as a service, without these having to be installed on the local computer using the cloud. These services are supplied and utilized exclusively by way of technical interfaces and protocols, such as by means of a web browser. The range of services offered as part of cloud computing comprises the entire spectrum of information technology and contains inter alia infrastructure, platforms and software.

[0015] "Program modules" are to be understood as meaning individual functional units that enable the program sequence according to the invention. These functional units may be implemented in a single computer program or in a plurality of computer programs that communicate with one another. The interfaces realized here may be implemented as software within a single processor or as hardware, if a plurality of processors are used.

[0016] The measurement signals of the measurement coil and receive signals of the receive coil are preferably aligned to be synchronous with the transmit frequency. This has the advantage that a shared processing of the receive signal and the measurement signal is simplified. These may be directly compared with one another, in particular for the purpose of eliminating the interference, and also added to or subtracted from one another (more on this in the following).

[0017] The preferably (previously) aligned receive voltage and the measurement voltage, in order to suppress the useful frequency band, in accordance with an advantageous embodiment of the invention, pass through a high-pass filter that is dimensioned such that the frequencies that can be generated due to wheel traversals are advantageously suppressed. The signal change of the wheel traversal is therefore suppressed. At the same time, interference signals close to the operating frequency that determines the useful frequency band (preferably lying in the middle of the useful frequency band) are therefore also suppressed. A high-pass filtering therefore advantageously represents a simple option for suppressing the useful frequency band. It can be accepted that, in this context, some of the interference signals close to the operating frequency are also suppressed, because sufficient interference is available in the measurement signal and in the receive signal for adjusting the receive signal and measurement signal outside the useful frequency band.

[0018] The dynamic compensation of interference fields is based on the interfering rail currents and other sources of interference normally being generated in a wideband manner, for example by spark breakaways. In addition to the interference frequency precisely at the operating frequency of the transmitter, voltages are therefore also induced in the adjacent frequency ranges due to rail currents in the coils. The two signal processing paths of the receive signal and the measurement signal have at least identical frequency components, preferably an at least largely identical frequency response.

[0019] In the one signal path (signal conditioning path), the wheel signal components in the receive signal of the receive coil and (where present) in the measurement signal of the measurement coil are preferably suppressed by a downstream high-pass filter and thus a modified measurement signal and a modified receive signal are generated. The interference signal levels present at the end are compared with one another. The relationship between said interference voltages is used to track the signal amplification of the measurement signal (alternatively, the adjustment may also take place in a different manner, for example by amplifying the receive signal).

[0020] Another signal path (signal processing path) does not contain the high-pass filter. Wheel signals are therefore not suppressed. The signal level of the measurement coil conditioned by the interference voltage relationship is eliminated from the actual receive signal, preferably by subtracting it. The wheel signal is therefore obtained from the receive signal, adjusted for interference (ascertained by way of the measurement signal).

[0021] No wheel signal is generated in the measurement coil, due to its geometry and orientation. In this context, a wheel signal is to be understood as meaning a signal component that is induced by the influence of a passing wheel. In the context of the invention, this means that interference signals, which are not suppressed by the subsequent high-pass filter and still lie within the input bandwidth of the receive resonant circuit, generate a signal level that corresponds to the interference variable. These levels vary, depending on the shape and position of the coils. The signal level relationship between receive coil and measurement coil, however, is constant for the usable frequency range, i.e. the pass band. This means that it is possible to calculate, from this relationship, the amplification factor (greater than, equal to or less than 1) by which the actual compensation signal of the measurement coil has to be changed, in order to thus compensate for the adjusted interference signal, obtained by adjusting the receive signal and measurement signal, in the receive signal. As complete a compensation as possible is achieved, while interference signal levels remain the same.

[0022] In a particularly simple manner, it is advantageously possible for the amplification factor, as described above, to be ascertained for the measurement signal. An adjustment may also take place, however, by an amplification factor being ascertained solely for the receive signal or for the receive signal and the measurement signal. Ultimately, it is only important that the receive signal and the measurement signal are adjusted to one another, in order to enable a compensation of the interference signal level. Regardless of which of the two signals is changed, after applying this process, both signals are referred to as adjusted signals, i.e. adjusted receive signal and adjusted measurement signal.

[0023] The conditioned signal level of the measurement coil (adjusted measurement signal) is added to or subtracted from the actual adjusted receive signal, depending on the phase angle, wherein no high passes are present in the signal processing path in this context, since the actual useful signal, i.e. the wheel signal, is to be processed. Since the interference signals may also involve individual, brief interference pulses, a signal preprocessing in the form of a temporal expansion of said pulses, e.g. in the form of a holding element (S&H element), a peak value sampling or also averaging of the interference signals is sensible, depending on the processing speed and processing type, e.g. digital or analog.

[0024] Aspects of the present disclosure provides a wheel detector as indicated in the introduction, in that the processing unit is configured, in a computer-assisted manner,

• to generate a modified receive signal and a modified measurement signal, in which a useful frequency band, in which the receive signal lies, is suppressed within the measured bandwidth of the receive signal and the measurement signal, * to adjust the signal strengths of the modified receive signal and the modified measurement signal to one another, * to rectify or at least reduce the interference in the adjusted receive signal by taking into consideration the adjusted measurement signal.

[0025] The advantages associated with the wheel detector or the use thereof have already been stated as part of the explanation of the above method, and will not be repeated once again at this point.

[0026] Both coils, the measurement coil and the receive coil, are preferably designed as wideband resonant circuits with the same frequency response. For example, this could be achieved by damped resonant circuits. This input signal bandwidth is greater than that which is required by the actual useful signal, i.e. the wheel traversal.

[0027] Furthermore, a computer program product with program commands for performing the stated method according to the invention and/or exemplary embodiments thereof is claimed, wherein the method according to the invention and/or exemplary embodiments thereof in each case can be performed by means of the computer program product.

[0028] Moreover, a provision apparatus for storing and/or providing the computer program product is claimed. The provision apparatus is, for example, a data carrier which stores and/or provides the computer program product. As an alternative and/or in addition, the provision apparatus is, for example, a network service, a computer system, a server system, in particular a distributed computer system, a cloud-based computer system and/or virtual computer system, which preferably stores and/or provides the computer program product in the form of a data stream.

[0029] The provision takes place, for example, as a download in the form of a program data block and/or command data block, preferably as a file, in particular as a download file, or as a data stream, in particular as a download data stream, of the complete computer program product. This provision may also, however, take place as a partial download, for example, which consists of a plurality of parts and in particular is downloaded via a peer-to-peer network or provided as a data stream. Such a computer program product is read into a system, for example using the provision apparatus in the form of the data carrier, and carries out the program commands, so that the method according to the invention is made to be carried out on a computer.

[0030] In particular, a wheel detector may be equipped with a processing unit, wherein the processing unit has a provision apparatus which stores and/or provides the mentioned computer program product. In this case, it is possible to have the method according to the invention carried out in full or in part by a computer, wherein the individual functional modules for the method are implemented in full or in part by software in a digital manner, and not by hardware components in an analog manner. This advantageously makes it easier to modify the method. As a result, the method may come to be used, for example, with different parameters for different wheel detectors, without modified hardware components having to be provided.

[0031] Further details of the invention are explained below, making reference to the drawing. Identical or corresponding drawing elements are provided with the same reference characters in each case and are explained multiple times only insofar as differences arise between the individual figures.

[0032] The exemplary embodiments set out in the following involve preferred embodiments of the invention. The components of the embodiments as described in the exemplary embodiments each represent individual features of the invention that are to be regarded as independent of one another and each also develop the invention independently of one another and are thus also to be considered individually, or in a different combination from that shown, as a constituent part of the invention. Furthermore, the embodiments described can also be enhanced by others of the previously described features of the invention.

[0033] Fig. 1 shows the fundamental signal-voltage curve Ue over the frequency f of a damped resonant circuit consisting of receive coil and measurement coil in a coordinate system,

[0034] Fig. 2 shows, for clarification, pulse-like interference signals in a diagram corresponding to Fig. 1,

[0035] Fig. 3 shows the possible signal processing in an exemplary embodiment of the method according to the invention as a flow diagram with functional elements in the manner of a block diagram, wherein the blocks may represent analog functional modules or program modules of an exemplary embodiment of the computer program according to the invention,

[0036] Fig. 4 schematically shows a sectional view of a coil position on the rail with a traversing wheel in an exemplary embodiment of the wheel detector according to the invention,

[0037] Fig. 5 shows a view of an exemplary embodiment of the wheel detector according to the invention from the side.

[0038] Fig. 1 shows the fundamental signal voltage curve Ue over the frequency f of a damped resonant circuit 325 with receive coil and a damped resonant circuit 365 with measurement coil (see also Fig. 3). A largely symmetrical receiving range 327, 367, with decreasing sensitivity as a function of the distance of the frequency f involved from the operating frequency f res, is present around the operating frequency f res 100 with synchronous alignment.

[0039] In Fig. 2, exemplary interference signals 120 are furthermore shown for clarification. The relationship between the interference voltage levels of the receive coil and measurement coil is constant in the receiving range 327, 367 of the input frequencies of the damped resonant circuits 325, 365 (see Fig. 3), in which the receive coil and the measurement coil are installed. Only the range 130 omitted by a high-pass filter 340, 380 is excluded from consideration for the interference variables. Here, the wheel traversal would distort the signal relationship, as it generates a signal level in the receive coil, but not in the measurement coil.

[0040] Fig. 3 shows a possible signal processing. Located in an opposing manner on a rail 303 are a transmitter resonant circuit 300, having the transmit coil 299 and a capacitor 298, in a housing 301 and a damped receive resonant circuit 325, having the receive coil 324, a capacitor 323 and a damping resistor 322 for generating a receive signal 308, together with the measurement resonant circuit 365, having the receive coil 364, a capacitor 363 and a damping resistor 362 for generating a measurement signal 309. The latter two resonant circuits are accommodated in a shared housing 360 here, due to their spatial proximity.

[0041] The synchronous rectification is controlled by way of synchronous rectifiers 311, 361 via a transmit frequency 310. The optional low-pass filters 326, 366 are used to adjust the damping curves, i.e. the receiving ranges, if, for example, the frequency ranges of the receive resonant circuit 325 and measurement resonant circuit 365 do not match precisely due to the different coils.

[0042] Both signal levels 327, 367 are amplified by amplifiers 330, 370, wherein the signal level of the measurement signal may be amplified in a variable manner (controlled via feedback 375). This makes it possible to adjust the two signal levels (and thus the measurement signal and the receive signal). The amplified signals, i.e. the adjusted receive signal 345 and the adjusted measurement signal 385, are guided one time directly to a further-processing unit as U_1 (receive voltage) and U s (measurement voltage), i.e. to a microcontroller 390, for example. At the same time, the two signals are also guided via high-pass filters 340, 380 and reach the microcontroller as U_h (filtered receive voltage) 392 and U_sh (filtered measurement voltage) 395. These represent a measure of the interference voltages.

[0043] The relationship U_1h/U_sh, i.e. the relationship between the interference voltages, produces the amplification factor as feedback 375. It is amplified or also reduced, so that the interference variables are as equal as possible: U_1h = Ush.

[0044] With these adjusted interference variables, the signal Us is subtracted from or added to the receive signal U_1, depending on the coil orientation and phase angle.

[0045] Here, the two optional signal processing units 391, 394 represent the signal preprocessing mentioned above, such as S&H elements, for example, which in turn are routed to a hardware adder/subtractor 393, which directly sets the amplification factor as feedback 375 to the variable amplifier 370.

[0046] As is generally common, an analog or digital wheel signal is available for further processing as an output signal 399 of the complete signal processing. In principle, it is also possible to transfer the entire signal processing to a computer or microcontroller. The units shown above would then be dispensed with in hardware form and would be emulated in the computer or microcontroller. In particular, the components 311, 361, 326, 366, 330, 370, 340, 380, 391, 394, 393 and 390 are then implemented by suitable program modules. In this regard, the signal path shown in Fig. 3 is only used to illustrate the program structure for this exemplary embodiment.

[0047] Fig. 4 shows a coil position on the rail 303 with traversing wheel 306 and wheel flange 307. The transmit coil 299 (the associated resonant circuit 300 is not shown for reasons of clarity: see Fig. 3) is accommodated in a housing 301. The orientation of the receive coil 324 (the associated resonant circuit 325 is not shown here for reasons of clarity) is approximately horizontal here, for example, so that concentric magnetic field lines generated by rail current only induce low interference voltage levels. Located in a housing 360 in the vicinity of the receive coil 324 is the measurement coil 365 (the associated resonant circuit 365 is not shown here for reasons of clarity). Here, the position is only arranged below the receive coil for illustrative purposes, and may also be arranged at the same height. The measurement coil may also be tilted from the horizontal position (preferably by 900, such that a vertical orientation is produced), in order to reduce the signal influence during wheel traversal and to increase that of the interference.

[0048] Fig. 5 shows a view of the sensor from the side. This time, the design has two channels, i.e. a second receive coil 525 is located next to the one receive coil 324 in the housing 360. Two-channel sensors are used for detecting the direction of travel and are sufficiently known. The measurement coil 365 is arranged therebetween. In principle, a measurement coil may be used for interference field compensation for a plurality of receive coils. Therefore, one measurement coil would be used for both receive signals here. However, each receive coil may also be equipped with its own measurement coil.

[0049] List of reference characters

100 Operating frequency f_res 120 Pulse-like interference signals 130 Range omitted 298 Capacitor 299 Transmit coil 300 Transmitter resonant circuit 301 Housing 303 Rail 306 Wheel 307 Wheel flange 308 Receive signal 309 Measurement signal 310 Transmit frequency 311,361 Synchronous rectifier 324 Receive coil 322 Damping resistor 325 Receive resonant circuit 326,366 Low-pass filter 327,367 Signal level 327,367 Symmetrical receiving range 330,370 Amplifier 335 Signal conditioning path 336 Signal processing path 340,380 High-pass filter 345 Adjusted receive signal 360 Housing 362 Damping resistor 364 Measurement coil 365 Measurement resonant circuit 375 Feedback 385 Adjusted measurement signal 390 Microcontroller

391,394 Signal processing units 392 Modified receive signal 395 Modified measurement signal 393 Hardware adder/subtractor 399 Output signal 525 Second receive coil

Claims

CLAIMS:

1. A method for detecting a rail-bound wheel, in which, * in an inductive sensor arrangement installed in a rail-encompassing manner with a transmit coil and a receive coil, a receive signal is generated which represents a wheel influence, * a measurement signal which represents an interference is generated by a measurement coil, * the receive signal and the measurement signal are processed, wherein the processing takes place in a computer-assisted manner, in that • a modified receive signal and a modified measurement signal are generated, in which a useful frequency band, in which the receive signal lies, is suppressed within the measured bandwidth of the receive signal and the measurement signal, * the signal strengths of the modified receive signal and the modified measurement signal are adjusted to one another, * the interference in the adjusted receive signal is rectified or at least reduced by taking into consideration the adjusted measurement signal; wherein the receive signal and the measurement signal, in order to suppress the useful frequency band in a signal adjustment path, each pass through a high-pass filter that is dimensioned such that the frequencies that can be generated by wheel influence are suppressed.

2. The method as claimed in claim 1, wherein the measurement signal of the measurement coil and the receive signal of the receive coil are aligned to be synchronous with the transmit frequency of the transmit coil.

3. The method as claimed in claim 1, wherein the interference is rectified or at least reduced in a signal adjustment path that runs in parallel with the signal processing path.

4. The method as claimed in claim 3, wherein the adjusted measurement signal is added to or subtracted from the adjusted receive signal, depending on the phase shift.

5. The method as claimed in claim 4, wherein the adjusted measurement signal is subtracted in the case of previous rectification in accordance with claim 2.

6. The method as claimed in any one of the preceding claims, wherein a signal preprocessing takes place for the measurement signal and the receive signal in the form of a temporal expansion of the pulses arising due to the interference.

7. The method as claimed in claim 6, wherein the signal preprocessing takes place for the measurement signal and the receive signal in the form of using a holding element and/or a peak value sampling and/or an averaging of the measurement signals.

8. The method as claimed in any one of the preceding claims, wherein the measurement coil is excited at the installation site such that a minimum wheel signal is generated in the measurement coil by a wheel influence.

9. A wheel detector, having • an inductive sensor arrangement for installation in a rail-encompassing manner with a transmit coil and a receive coil for generating a receive signal which represents a wheel influence, * a measurement coil for generating a measurement signal which represents an interference, • a processing unit for the receive signal and the measurement signal, wherein the processing unit is configured, in a computer-assisted manner, * to generate a modified receive signal and a modified measurement signal, in which a useful frequency band, in which the receive signal lies, is suppressed within the measured bandwidth of the receive signal and the measurement signal, * to adjust the signal strengths of the modified receive signal and the modified measurement signal to one another, * to rectify or at least reduce the interference in the adjusted receive signal by taking into consideration the adjusted measurement signal; wherein the receive signal and the measurement signal, in order to suppress the useful frequency band in a signal adjustment path, each pass through a high-pass filter that is dimensioned such that the frequencies that can be generated by wheel influence are suppressed.

10. The wheel detector as claimed in claim 9, wherein the measurement coil and the receive coil are designed as resonant circuits, which are wideband compared to the useful frequency band, with the same frequency response.

11. The wheel detector as claimed in claim 9 or 10,wherein the measurement coil is oriented in the wheel detector at the installation site such that a minimum wheel signal is generated in the measurement coil by a wheel influence.

12. A computer program product with program commands for performing the method as claimed in one of claims 1 - 8.

13. A provision apparatus for the computer program product as claimed in claim 12, wherein the provision apparatus stores and/or provides the computer program product.

14. The wheel detector as claimed in any one of claims 9 - 11, wherein a provision apparatus in accordance with claim 13 is integrated in the processing unit or is connected thereto.

Siemens Mobility GmbH Patent Attorneys for the Applicant/Nominated Person SPRUSON&FERGUSON