METHOD AND APPARATUS FOR DETECTING A SPEED AND A DISTANCE OF AT LEAST ONE OBJECT WITH RESPECT TO A RECEIVER OF A RECEPTION SIGNAL

Abstract

An apparatus for detecting a speed and a distance of at least one object with respect to a receiver of a reception signal. The apparatus has at least one interface for reading in at least one in-phase component and one quadrature component of a plurality of temporally successive reception signals each representing a signal which is reflected to the receiver at the object and was emitted at a predefined transmission frequency. The apparatus also has a unit for forming a first detection value and a unit for determining a second detection value and a unit for determining a speed, corresponding to a reference speed, of the object with respect to the receiver and the reference distance as the distance of the object with respect to the receiver using the first and second detection values.

Claims

1. A method for detecting a speed and a range of at least one object in relation to a receiver of a received signal, the method comprising: reading in at least one inphase component and one quadrature component of a plurality of temporally successive received signals that each represent a signal reflected from on the object to the receiver, which signal was transmitted at a predefined transmission frequency; forming a first detection value using the inphase component and the quadrature component of a first of the received signals, wherein the first detection value corresponds to a predetermined reference speed and a predetermined reference range of the object from the receiver; ascertaining a second detection value using the inphase component and the quadrature component of a second of the received signals, wherein the second detection value corresponds to the predetermined reference speed and the predetermined reference range of the object from the receiver; and determining a speed, corresponding to the reference speed, of the object in relation to the receiver and the reference range as the range of the object in relation to the receiver using the first and second detection values.

2. The method as claimed in claim 1, wherein the step of determining involves the first and second detection values being added.

3. The method as claimed in claim 1, wherein the step of forming further involves a third detection value being formed using the inphase component and the quadrature component of the first of the received signals, wherein the third detection value corresponds to a further reference speed and to a further reference range of the object from the receiver, wherein the step of ascertaining further involves a fourth detection value being ascertained using the inphase component and the quadrature component of the second of the received signals, wherein the fourth detection value corresponds to the further reference speed and the further reference range of the object from the receiver, and wherein the step of determining a speed, corresponding to the reference speed, of the object in relation to the receiver and to the reference range as the range of the object in relation to the receiver involves being determined using the third and fourth detection values.

4. The method as claimed in claim 3, wherein the step of determining involves the reference speed as the speed of the object and the reference range as the range of the object in relation to the receiver being determined when a combined value comprising the first and second detection values is in a predetermined relationship with a combined value comprising the third and fourth detection values.

5. The method as claimed in claim 1, wherein a step of transmitting the signal to be reflected from the object, wherein a transmission frequency of the signal is chosen on the basis of a pseudorandom sequence.

6. The method as claimed in claim 1, wherein the step of reading in involves at least one inphase component and one quadrature component of a plurality of temporally successive antenna signals being read in, that each represent a signal reflected from on a further object to the receiver, which signal was transmitted at a predefined transmission frequency, wherein the step of forming involves a first identification value being formed using the inphase component and the quadrature component of a first of the antenna signals, wherein the first identification value corresponds to a predetermined further reference speed and to a predetermined further reference range of the further object from the receiver; wherein the step of ascertaining involves a second identification value being ascertained using the inphase component and the quadrature component of a second of the antenna signals, wherein the second identification value corresponds to the predetermined further reference speed and the predetermined further reference range of the further object from the receiver, and wherein the step of determining involves a speed, corresponding to the further reference speed, of the object in relation to the receiver and to a range, corresponding to the further reference range, of the further object in relation to the receiver being determined using the first and second identification values.

7. The method as claimed in claim 1, wherein the step of reading in involves at least one inphase component and one quadrature component of a plurality of temporally successive object signals that each represent a signal reflected from on the object to a further receiver, which signal was transmitted at a different transmission frequency, wherein the step of forming involves a first object detection value being formed using the inphase component and the quadrature component of the first of the object signals, wherein the first object detection value corresponds to the reference speed and the reference range of the object from the further receiver, wherein the step of ascertaining involves the second object detection value being formed using the inphase component and the quadrature component of a second of the object signals, wherein the second object detection value corresponds to the reference speed and to the reference range of the object from the further receiver, and wherein the step of determining involves a speed, corresponding to the reference speed, of the object in relation to the further receiver and to the reference range as the range of the object in relation to the further receiver being determined using the first and second object detection values.

8. The method as claimed in claim 7, wherein a step of detecting an angle between the object, the receiver and the further receiver, wherein the step of detecting involves the angle being provided using a distance between the receiver and the further receiver and/or an averaged frequency from those transmission frequencies that correspond to received signals that were used to determine the first and second detection values and the first and second object detection values.

9. An apparatus for detecting a speed and a range of at least one object in relation to a receiver of a received signal, wherein the apparatus has at least the following features: an interface for reading in at least one inphase component and one quadrature component of a plurality of temporally successive received signals that each represent a signal reflected from on the object to the receiver which signal was transmitted at a predefined transmission frequency; a unit for forming a first detection value using the inphase component and the quadrature component of a first of the received signals, wherein the first detection value corresponds to a predetermined reference speed and a predetermined reference range of the object from the receiver; a unit for ascertaining a second detection value using the inphase component and the quadrature component of a second of the received signals, wherein the second detection value corresponds to the predetermined reference speed and the predetermined reference range of the object from the receiver and a unit for determining a speed, corresponding to the reference speed, of the object in relation to the receiver and the reference range as the range of the object in relation to the receiver using the first and second detection values.

10. A computer program product having program code for performing the method as claimed in claim 1, when the program product is executed on an apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0036] FIG. 1 shows a traffic monitoring system having an apparatus according to an exemplary embodiment of the present invention;

[0037] FIG. 2 shows a block diagram of an apparatus for detecting a speed and a range of at least one object in relation to a receiver of a received signal according to an exemplary embodiment of the present invention;

[0038] FIG. 3 shows a 2D representation of absolute values on a map M.sub.tv from which a speed and a range of at least one object in relation to a receiver of a received signal is detectable; and

[0039] FIG. 4 shows a flowchart of a method according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

[0040] FIG. 1 shows a block diagram of an exemplary embodiment of the present invention in the form of a traffic monitoring system 100 having an apparatus for detecting a speed and a range of at least one object 105a in relation to at least one receiver 110a (for example in the form of a radar reception unit) of a received signal 120. The object 105a may, like the further object 105b, be a vehicle that is exposed to a signal 125 from a radar transmission antenna 130 as transmitter. Similarly, a further receiver 110b (for example likewise in the form of a radar reception unit) can receive into a further received signal 135 that is emitted from the object 105 to the further receiver 110b on account of a reflection of the signal 125. Additionally, a further object 105b can be exposed to the signal 125, from which object the signal 125 is reflected and is sent as an additional received signal 140 to the receiver 110a.

[0041] In the exemplary embodiment presented in FIG. 1, the frequency generation for the signal 125 is designed such that what is known as a VCO 145 (Voltage Controlled Oscillator) is used whose frequency is placed in proportion to the actuating voltage. So as now to realize pseudorandom frequency control, a digital/analog converter 150 is actuated using a pseudorandom digital sequence from a pseudo noise generator 155 (PRNG) that is converted into a pseudorandom frequency sequence.

[0042] The approach presented here is based on pseudorandom actuation such that down conversion of the signal 120, 135 (also referred to as object signal) or 140 (also referred to as antenna signal) received by one at one of the receivers 110 entails the amplitude and the phase of the low frequency mixed signal being digitized. This normally involves what is known as an IQ mixer 157 for each path from one of the receivers 110 to a processing unit being used as an apparatus 160 for detecting a speed and a range of at least one object 105a, which IQ mixer is capable of digitizing the inphase (I1, I2) and quadrature (Q1, Q2) components, as depicted in FIG. 1 using an example of one transmission and two reception antennas or units. In this case, each of the IQ mixers 157 is provided with the signal provided by the VCO (which corresponds to the transmission signal along with amplitude and phase), a signal phase-shifted through 90 provided by the VCO and the received signal 120, 135 or 140 received by the receiver 110 respectively connected to the relevant IQ mixer 157. Each of the inphase outputs 11 and 12 and quadrature outputs Q1 and Q2 are connected via an ND converter 165 to the processing unit 160, in this case a microcontroller, in which the data delivered from the IQ mixers 157 are processed in accordance with the description below, for example. From this processing, it is then possible to determine the desired targets 170 that correspond to a range and speed of the objects 105a and 105b.

[0043] In the exemplary embodiment presented here, a concept is therefore proposed for how to use frequency actuation limited to a relatively narrow bandwidth to discover multiple targets simply and systematically. The method proposed here improves the options by virtue of the pseudorandom actuation of the frequency generation. There is therefore a technically simple and numerically simply implemented opportunity for multiple resolution of objects with regard to relative speed and range relative to the radar using a small bandwidth (250 MHz max.). In this case, it is also possible for objects at the same objective speed but a different range can to be resolved. In addition, the approach presented here can also be used to resolve objects at the same range but different relative speed.

[0044] The frequency selection of the existing radar systems (FST3/TR6000) is modified, by way of example, such that a pseudorandom frequency is produced per sampling time. A discrete speed/range transformation accumulates the sampled values into a speed/range space. The range and relative speed of multiple objects can be read off directly in the measurement space.

[0045] As is known for the FSK method, the frequency is kept stable for a short period, e.g. one hundred thousandth of a second, by virtue of appropriate action of the VCO 145, in order to measure phase and amplitude for said frequency. On the basis of this actuation, a number of amplitude and phase valuesscattered over timeof the received signals 120, 135 and 140 are therefore obtained, for which, in each case, the transmission frequency of the signal 125 at which this value of the received signals 120, 135 and 140 was measured is known.

[0046] For each sampled value, the underlying transmission frequency f is therefore known. In addition, the time t at which this frequency f was generated by the VCO 145 is known. For each individual sample value (i.e. of a value of the IQ mixer 157 delivered by the A/D converter 165) for that one of the received signals 120, 135 and 140 to be evaluated as appropriate, the following transformation is now performed:

[0047] The speed is quantized into N.sub.v fine stages (which are subsequently referred to as reference speeds), e.g. from 0 to 100 m/s in 0.2 m/s steps. For each quantization point (that is to say for each reference speed), the measured phase and amplitude of the received signal 120, 125, 135 or 140 currently read in is modulated such that it corresponds to a time t.sub.0 at the corresponding (reference) speed. For a sample x of the frequency f at the time t, the modulated value x.sub.v is obtained as follows:

[00001]$x_v=x.Math.e^{i.Math.4.Math..Math.v.Math.\left(t-t_0\right).Math.\frac{f}{c_0}}$

where c.sub.0=speed of light and v=(reference) speed. A modulated value of such kind that is ascertained on the basis of the different reference speeds is subsequently referred to as a speed value. The time t.sub.0 can be chosen arbitrarily. At the end of this transformation, by way of example, for all N.sub.t sampled values (e.g. 1024 delivered values from the A/D converters 165) are therefore associated with all potential (reference) speeds, so that the (speed) values are accommodated in a matrix A.sub.tv of magnitude N.sub.tN.sub.v.

[0048] The range is quantized into N.sub.r fine stages (subsequently also referred to as reference ranges), e.g. from 0 to 200 m in 0.25 m steps. For each point of the matrix A.sub.tv, the phase and the amplitude are modulated such that they correspond to the respective range of the fine stages and reference ranges. For a value x.sub.v (i.e. for each speed value) of the frequency f, the modulated value x.sub.vr, is obtained as follows:

[00002]$x_{\mathrm{vr}}=x_v.Math.e^{i.Math.4.Math..Math.r.Math.\frac{f}{c_0}}$

where r =range. This modulated value is referred to as a range value in the description below. That is to say that each point of the matrix A.sub.tv is augmented by a vector of length N.sub.r. The volume V.sub.tvr, with the dimensions samples, speed and range is obtained.

[0049] Each point in the volume V.sub.tvr now corresponds to a hypothesis for a sample of one of the received signals 120, 125, 135 and 140 on the basis of an assumed speed (reference speed) and an assumed range (reference range).

[0050] Following the transformation, the multiple target resolution can be achieved as follows.

[0051] If a ray is placed through the volume V.sub.tvr along the dimension of the samples and the complex values of the volume along this ray are summed, then, for a determined speed/range hypothesis, a complex value is obtained whose absolute value is a measure of the probability of occurrence of an object 105a or 105b. In practice, the volume along the dimension of the samples can be summed. A 2D map M.sub.tv is obtained regarding probabilities of occurrence of objects at a particular speed and a particular range.

[0052] FIG. 2 shows a block diagram of an exemplary embodiment of an apparatus 200 for detecting a speed and a range of at least one object in relation to a receiver of a received signal. This apparatus 200 may, for example, be part of the processing unit 160 from FIG. 1, which is depicted as a microcontroller. In FIG. 2, the apparatus 200 is depicted merely connected to a reception unit 110a.

[0053] The apparatus 200 comprises at least one interface 210 for reading in at least one inphase component 11 and one quadrature component Q1 of a plurality of temporally successive received signals 120 that each represent a signal 125 that is reflected from on the object 105a to the receiver 110a and that was transmitted at a predefined transmission frequency f. Further, the apparatus 160 comprises a unit 220 for forming a first detection value x.sub.vr using the inphase component I1 and the quadrature component Q1 of a first of the received signals 120, wherein the first detection value x.sub.vr corresponds to a predetermined reference speed v and a predetermined reference range r of the object 105a from the receiver 110a. The apparatus 160 also comprises a unit 230 for ascertaining a second detection value x.sub.vr using the inphase component I1 and the quadrature component Q1 of a second of the received signals 120, wherein the second detection value x.sub.vr corresponds to the predetermined reference speed v and the predetermined reference range r of the object 105a from the receiver 110a. Finally, the apparatus 160 comprises a unit for determining 440 a speed v, corresponding to the reference speed v, of the object 105a in relation to the receiver 110a and the reference range v as the range of the object 105a in relation to the receiver 110a using the first and second detection values x.sub.vr.

[0054] FIG. 3 shows a 2D depiction of absolute values on a map M.sub.tv in which seven objects 105 are discernible as light points at speeds of 0, 15, 30 and 45 m/s and ranges of 20 m, 50 m, 60 m and 75 m. In this case, instead of the two objects 105a and 105b depicted in FIG. 1, seven objects 105 have been sensed, the respective ranges and speeds of the objects 105 relative to the receiver 110a having been entered in the map from FIG. 2.

[0055] If more than one reception antenna or reception unit 110a is used (as portrayed in FIG. 1 by the depicted further reception unit 110b), then a corresponding map M.sub.tv.sup.i can be determined for each reception antenna or reception unit i, for example in accordance with the procedure described above, using a received signal 135 or 140 from this reception unit i. From the phase difference =(M.sub.tv.sup.1(t, v))(M.sub.tv.sup.2(t, v)) for a measurement points t,v in two maps M.sub.tv.sup.1 and M.sub.tv.sup.2, it is possible, for example, to measure the angle at which the object is situated

[00003]$=\arcsin \left(\frac{.Math..Math..Math.}{2.Math..Math.d}\right),$

where is the average wavelength of the frequencies used and d is the distance between the reception antennas under consideration. Alternatively, the 3D samples/speed/range space can also be expanded by the fourth dimension angle. In this case, an appropriate modulation of the amplitudes and phases is performed on the basis of an angle quantized into fine stages (which can also be referred to as reference angles) (e.g. 18 to 18 in 0.01 steps). A summation using the samples dimension delivers a speed/range angle space. This approach allows objects to be separated with regard to their speed, their range and their angle.

[0056] FIG. 4 shows a flowchart of an exemplary embodiment of the approach presented here as a method 400 for detecting a speed and a range of at least one object in relation to a receiver of a received signal. The method 400 comprises a step 410 of reading in at least one inphase component and on quadrature component of a plurality of temporally successive received signals that each represent a signal that is reflected from on the object to the receiver and that was transmitted at a predefined transmission frequency. Further, the method 400 comprises a step of forming 420 a first detection value x.sub.vr using the inphase component of the quadrature component of a first of the received signals, wherein the first detection value corresponds to a predetermined reference speed and a predetermined reference range of the object from the receiver. The method 400 also comprises a step of ascertaining 430 a second detection value using the inphase component and the quadrature component of a second of the received signals, wherein the second detection value corresponds to the predetermined reference speed and the predetermined reference range of the object from the receiver. Finally, the method 400 comprises a step of determining 440 a speed, corresponding to the reference speed, of the object in relation to the receiver and the reference range as the range of the object in relation to the receiver using the first and second detection values.

[0057] The approach presented here affords some advantages over the known approaches according to the prior art. In this context, it is firstly possible to cite the option of being able to perform a resolution for multiple objects both at the same range and at the same relative speed, current approaches being able to resolve only on the basis of relative speed. In addition, it is also possible for stationary objects to be measured, and for multiple operation of radars to be effected in the same frequency band on the basis of the pseudorandom modulation of the transmission signals of the signal transmitted by an apparatus in accordance with an exemplary embodiment described here. Also, stochastic sampling through pseudorandom modulation means that no systematic errors as a result of overlaps can arise (e.g. roaming of unprocessed targets, cancelations, etc.). Finally, the approach presented here makes it possible to prevent overreaches by the transmission signals used from causing interference in other apparatuses that are likewise provided for detecting a speed and range of an object.

[0058] In summary, it can therefore be noted that the approach presented here, in contrast to methods existing hitherto, allows very good resolution of speed and range to be achieved both for vehicles that start at the same range and travel at different speeds and for objects that travel at the same speed but at different ranges. In addition, if necessary and if at least two reception antennas or reception units are present, it is also possible for separation to be effected on the basis of object angle. Therefore, objects that exist in the measurement area at the same speed and the same range can also be resolved. The approach presented here is therefore superior to conventional methods of modulation technology as have been used hitherto. Conventional FSK and FMCW modulation techniques use deterministic frequency profiles, which is why simultaneous use of multiple radars results either in mutual interference or in reduction of the bandwidth. The use, proposed by way of example, of a pseudorandom frequency within the chosen frequency band allows many radars to be operated in parallel at the same time without significantly interfering with one another. In this case, a variable seed value of the random number generator can minimize the probability of the same frequencies arising for different radars at the same time. A further great advantage of the use of pseudorandom frequencies is the elimination of systematic measurement errors, which can arise as a result of aliasing and interference effects and can significantly interfere with radar measurements, which is known as stochastic sampling.

[0059] The approach presented here can also be used for measurements outside road safety. In particular, the method also allows improved spatial resolution when surveying general 3-dimensional objects.

[0060] The exemplary embodiments described and shown in the figures are chosen merely by way of example. Different exemplary embodiments can be combined with one another fully or in respect of individual features. It is also possible for one exemplary embodiment to be augmented by features from a further exemplary embodiment.

[0061] Further, method steps according to the invention can be performed repeatedly and in an order other than the one described.

[0062] Where an exemplary embodiment comprises an and/or conjunction between a first feature and a second feature, this is intended to be read to mean that the exemplary embodiment has both the first feature and the second feature in accordance with one embodiment and either just the first feature or just the second feature in accordance with a further embodiment.

[0063] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.