SE542206C2 - Radar transponder detection - Google Patents

Radar transponder detection

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Publication number
SE542206C2
SE542206C2 SE1830149A SE1830149A SE542206C2 SE 542206 C2 SE542206 C2 SE 542206C2 SE 1830149 A SE1830149 A SE 1830149A SE 1830149 A SE1830149 A SE 1830149A SE 542206 C2 SE542206 C2 SE 542206C2
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SE
Sweden
Prior art keywords
range
radar
doppler
transponder
signal
Prior art date
Application number
SE1830149A
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SE1830149A1 (en
Inventor
Zijun Liang
Original Assignee
Qamcom Tech Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Qamcom Tech Ab filed Critical Qamcom Tech Ab
Priority to SE1830149A priority Critical patent/SE542206C2/en
Publication of SE1830149A1 publication Critical patent/SE1830149A1/en
Publication of SE542206C2 publication Critical patent/SE542206C2/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
    • G01S13/78—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe
    • G01S13/785—Distance Measuring Equipment [DME] systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G01S13/75—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors
    • G01S13/751—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors wherein the responder or reflector radiates a coded signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/40—Means for monitoring or calibrating
    • G01S7/4052—Means for monitoring or calibrating by simulation of echoes
    • G01S7/406—Means for monitoring or calibrating by simulation of echoes using internally generated reference signals, e.g. via delay line, via RF or IF signal injection or via integrated reference reflector or transponder

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

A method in a radar transceiver for detecting a radar transponder at a range, wherein the radar transponder is arranged to modulate a re-transmitted radar signal by a data signal over consecutive transponder frames, the method comprising;transmitting (S1) a radar signal,receiving (S2) a reflected radar signal,processing (S3) the received reflected radar signal to generate a range-Doppler representation of the received reflected radar signal comprising range-Doppler values, anddetecting a (S4) radar transponder at a range if a sum of range-Doppler values corresponding to the range is above a first threshold and a sample variance of range-Doppler values corresponding to the range is above a second threshold.

Description

TITLE RADAR TRANSPONDER DETECTION TECHNICAL FIELD The present disclosure relates to detection of radar transponders by a radar transceiver. The disclosure focuses on detection of modulating radar transponders arranged to modulate a retransmitted radar signal by a data signal over consecutive transponder frames.
BACKGROUND Radio detection and ranging (radar) systems are sensor systems arranged to produce output comprising a series of reflection points as measured by radar receiver sensors. A radar transmitter and receiver together implement a radar transceiver. Reflection points can be treated as separate detections or grouped if they relate to the same object. Reflection points or groups of reflection points observed over time can be used to track the motion of an object over time. Such a determination over time is referred to as the track of an object. Radar systems may, e.g., be used to detect objects in a vicinity of a vehicle by means of radar signal reflections.
A Doppler radar is a radar which monitors a Doppler shift of the received radar signal. Doppler radars are able to determine not only a range to a reflecting object but also a velocity of the object due to the Doppler shift generated on the received radar waveform compared to the transmitted radar waveform. Doppler radars in general are known.
A radar transponder is a device which receives radar signals and re-transmits the radar signals. Some radar transponders apply a modulation to the signal before re-transmission. This modulation may comprise, e.g., changing a phase or an amplitude of the signal. By applying a modulation, the radar transponder may communicate an information signal or a data quantity back to the radar transceiver. This data quantity may, e.g., comprise an identification code or similar. The radar transceiver can then extract the data quantity from the received radar signal and thus receive the information. Modulating radar transponders are known from, e.g., US5486830A.
There is always a need for improved methods of detecting objects by means of radar signals, and in particular for detecting radar transponders.
SUMMARY It is an object of the present disclosure to provide methods, radar transceivers, control units, infrastructure surveillance systems, and vehicles for improved transponder detection.
This object is obtained by a method in a radar transceiver for detecting a radar transponder at a range, wherein the radar transponder is arranged to modulate a re-transmitted radar signal by a data signal over consecutive transponder frames. The method comprises transmitting a radar signal, receiving a reflected radar signal, processing the received reflected radar signal to generate a range-Doppler representation of the received reflected radar signal comprising range-Doppler values, and detecting a radar transponder at a range if a sum of range-Doppler values corresponding to the range is above a first threshold and a sample variance of range-Doppler values corresponding to the range is above a second threshold.
There is also disclosed herein a control unit for a radar transceiver comprising processing circuitry and an interface module, wherein the processing circuitry is arranged to transmit a radar signal via the radar transceiver, to receive a reflected radar signal via the radar transceiver, to process the received reflected radar signal to generate a range-Doppler representation of the received reflected radar signal comprising range-Doppler values, and to detect a radar transponder at a range if a sum of range-Doppler values corresponding to the range is above a first threshold and a sample variance of range-Doppler values corresponding to the range is above a second threshold.
Traditional radar transceivers can have difficulty detecting a modulating transponder. Since energy in the re-transmitted radar signal is spread over Doppler by the modulation, there is no longer a distinct peak in the range-Doppler representation of the received radar signal. However, by accounting for the spreading effect in the detection routine, detection of modulating transponders can be improved. In other words, the disclosed methods, control units, radar transceivers, infrastructure systems and vehicles improve detection performance for detecting modulating radar transponders in that the spread over Doppler caused by the modulation is accounted for. The energy received by the radar transceiver due to the re transmission by the transponder is integrated by the summing, and the check on variance makes sure that there actually is a spreading phenomenon as opposed to a more focused energy.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will now be described more in detail with reference to the appended drawings, where: Figure 1 schematically illustrates a system comprising a radar transceiver and a radar transponder; Figure 2 is a graph illustrating an amplitude modulation of a re-transmitted radar signal; Figures 3-5 are graphs illustrating range-Doppler representations of reflected received radar signals; Figure 6 schematically illustrates a control unit; Figure 7 is a flowchart illustrating methods according to the present disclosure; DETAILED DESCRIPTION Figure 1 illustrates a communication arrangement 100 comprising a radar transceiver 110 and a transponder 120, for communicating information to the radar transceiver. The radar transceiver is arranged to illuminate the transponder by a radar signal 130 in order to detect a position of the transponder in relation to the radar transceiver by means of radar signals reflected and/or re-transmitted by the transponder. The transponder is arranged to receive the radar signals, and to modulate information onto the received radar signals, and to retransmit the modulated radar signals 131 towards the radar transceiver 110. The radar transceiver 110 is arranged to receive the modulated re-transmitted radar signals from the transponder, thereby receiving the information.
The radar transceiver comprises a control unit 115 arranged to control functions of the radar transceiver, such as radar signal transmission and reception, and signal processing of radar signals in general. A Doppler radar transceiver processes the received signal to generate a range-Doppler representation of the received signal. Range-Doppler representations are often generated using Fast Fourier Transform (FFT) processing. The range-Doppler representation illustrates how power is distributed in the received radar signal. A reflection from an object at a distance will give rise to a peak in the range-Doppler representation at the distance. The peak will be located at the Doppler shift value corresponding to the relative velocity of the object in relation to the radar transceiver. Some range-Doppler representations will be exemplified below and discussed in connection to Figures 3-5.
The radar transceiver may operate according to different principles. For instance, the radar transceiver may operate using frequency modulated continuous wave (FMCW) transmission, or pulsed transmissions.
The radar transponder also comprises a control unit 125 arranged to control the function of the radar transponder, including receiving radar signals, modulating information signals onto the radar signals, and re-transmitting the modulated radar signals back towards the radar transponder. The information signals may, e.g., comprise an identification unique to the transponder, or a location in absolute coordinates.
This way, a signal processing device connected to the radar transponder may obtain knowledge of the geometry of the surrounding infrastructure by means of the received radar reflections. The transponder re-transmission may be a strong signal in comparison to other reflections from passive objects in the infrastructure. A system may associate the information received from the transponder with a strong radar detection, and thus relate the received information to a specific location in three dimensions corresponding to the location of the transponder. However, the modulation imposed by the transponder may cause the range-Doppler representation to exhibit a ridge shape instead of a peak. This ridge shape is due to the modulation, in that the modulation changes the appearance of the re-transmission over time, e.g., between different frequency chirps of an FMCW radar transceiver. Such ridge shapes will be discussed in more detail below.
The radar transceivers discussed herein are applicable in a wide range of different systems and scenarios. For instance, the radar transceivers may be comprised in infrastructure systems arranged to monitor, e.g., railway crossings, in vehicles such as trucks and cars, in tank radar systems, and in construction equipment, just to name a few examples.
A basic application may comprise a transponder modulating information onto a received radar signal comprising a location in absolute coordinates. The transponder then re-transmits the modulated radar signal to the radar transceiver. The radar transceiver, or a system arranged to receive input from the radar transceiver, may then associate a relative position of the transponder, relative to the radar transceiver, such as, e.g., a range and a bearing, obtained by radar detection of the re-transmitted transponder signal, with the information about absolute coordinates of the transponder received via the modulated re-transmitted signal. Thus, an association between relative and absolute coordinates is obtained, which enables, e.g., calibration of positioning systems.
The applied modulation may, e.g., comprise amplitude or phase modulation. A two-level amplitude modulation 200 is illustrated in Figure 2, where the re-transmitted signal varies between two levels, i.e., level A 220 and level B 210. This type of modulation is sometimes referred to as pulse amplitude modulation (PAM). PAM may comprise any number of amplitude levels, thus communicating different number of bits per amplitude shift, or information symbol.
Phase modulation may also be applied, such as phase shift keying (PSK). Here a number of distinct phase shifts are applied to modulate the signal in order to carry the information signal.
PAM and PSK may be combined to generate, e.g., a quadrature amplitude modulated signal, (QAM). PAM, PSK, and QAM are known and will not be discussed in detail here.
Energy is spread over Doppler frequencies by the modulation applied at the transponder. Thus, a modulating transponder appears differently from a non-modulating transponder in a range-Doppler representation of the received signal. A non-modulating transceiver may appear as a peak in the range-Doppler representation, while the modulating transponder will not always be associated with a distinct peak in the range-Doppler representation. Instead, it has been discovered that the modulating transponder will be associated with a ridge over several Doppler frequencies, or over a Doppler frequency band, due to the modulation applied by the transponder to the radar signal. This is because the modulation affects the frequency representation of the re-transmitted signal.
According to aspects, the re-transmitted radar signal is arranged in frames. A frame is a signal portion delimited by a start and a stop time. The information signal, or data, which is modulated onto the radar signal may change between consecutive frames. This change in information also alters the frequency representation, i.e., perceived Doppler shift, of the retransmitted signal.
This ridge characteristic of the received modulated radar signal is exemplified in Figures 3 and 4, where a range-Doppler representation of a received modulated transponder signal is illustrated.
Figure 3 shows a range-Doppler representation corresponding to a received modulated radar signal from a transceiver located close to the radar transceiver. It can be seen that the range-Doppler representation has been spread out over a range of Doppler frequencies due to the modulation applied by the transponder. However, in this example there is still a peak 310 visible corresponding to the range and relative velocity of the transponder in relation to the radar transceiver.
Figure 4 shows the same transponder signal, but now the transponder is further away from the radar transceiver, i.e., at a larger distance. Still the energy is spread out over a range of Doppler frequencies. However, also in this example there is a peak 410 visible corresponding to the range and relative velocity of the transponder in relation to the radar transceiver.
The phenomenon of a radar transponder spreading the signal over a range of Doppler frequencies can be used to detect this type of modulating radar transponder, as will now be explained.
Figure 5 shows the results of applying a threshold to the range-Doppler representation in Figure 4. Values above the threshold are called detections and are illustrated by small circles 510.lt is appreciated that the detections exhibit a ridge like shape. The detections have a variance over Doppler, i.e., they are not focused around a single Doppler value as would have been the case with a non-modulating transponder or a passive object.
Traditional radar transceivers can have difficulty detecting the modulating transponder since energy is spread over Doppler, there is no longer a distinct peak in the range-Doppler representation of the received radar signal. However, by accounting for the spreading effect in the detection routine, detection of modulating transponders can be improved.
Figure 6 schematically illustrates a control unit 115 for a radar transceiver 110. The control unit 115 comprises processing circuitry 610 and an interface module 620.
The methods and techniques discussed herein can be performed by the control unit 115 illustrated in Figure 6. The processing circuitry 610 is arranged to transmit a radar signal via the radar transceiver, to receive a reflected radar signal via the radar transceiver, to process the received reflected radar signal to generate a range-Doppler representation of the received reflected radar signal comprising range-Doppler values, and to detect a radar transponder at a range if a sum of range-Doppler values corresponding to the range is above a first threshold and a sample variance of range-Doppler values corresponding to the range is above a second threshold.
The processing circuitry 610 is provided using any combination of one or more of a suitable central processing unit CPU, multiprocessor, microcontroller, digital signal processor DSP, etc., capable of executing software instructions stored in a computer program product, e.g. in the form of a storage medium 630. The processing circuitry 610 may further be provided as at least one application specific integrated circuit ASIC, or field programmable gate array FPGA.
Particularly, the processing circuitry 610 is configured to cause the control unit 115 to perform a set of operations, or steps. For example, the storage medium 630 may store the set of operations, and the processing circuitry 610 may be configured to retrieve the set of operations from the storage medium 630 to cause the control unit 115 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 610 is thereby arranged to execute methods as herein disclosed, such as the methods discussed below in connection to Figure 7.
The storage medium 630 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.
The control unit 115 further comprises an interface 620 for communications with at least one external port of, e.g., a radar transceiver. As such the interface 620 may comprise one or more transmitters and receivers, comprising analogue and digital components and a suitable number ports for wireline or wireless communication.
The processing circuitry 610 controls the general operation of the control unit 115 e.g. by sending data and control signals to the interface 620 and the storage medium 630, by receiving data and reports from the interface 620, and by retrieving data and instructions from the storage medium 630. Other components, as well as the related functionality, of the control unit 115 are omitted in order not to obscure the concepts presented herein.
Figure 7 is a flow chart showing methods. There is illustrated a method in a radar transceiver for detecting a radar transponder at a range, wherein the radar transponder is arranged to modulate a re-transmitted radar signal by a data signal over consecutive transponder frames. The method comprises transmitting S1 a radar signal, receiving 52 a reflected radar signal, processing S3 the received reflected radar signal to generate a range-Doppler representation of the received reflected radar signal comprising range-Doppler values, and detecting a 54 radar transponder at a range if a sum of range-Doppler values corresponding to the range is above a first threshold and a sample variance of range-Doppler values corresponding to the range is above a second threshold.
The new transceiver proposed herein detects the transponder by integrating over Doppler for a given range bin or bins and also requiring spread of Doppler values. It is appreciated that the received signal may be spread also over range. Therefore, it may be appropriate in some cases to consider range intervals where the transponder is located with high probability, instead of considering single range bins. The size of the range intervals can be pre-configured according to operating scenario.
Advantageously, a strong peak in the range-Doppler representation is not detected as a modulating transponder since there is no sample variance associated with the peak, even though the energy is large.
Advantageously, background signals which are relatively flat in the range-Doppler representation are not detected as a modulating transponder since there is not enough sum energy in a flat background signal.
According to aspects, the radar transponder is arranged to amplitude modulate the retransmitted radar signal.
According to aspects, a data signal associated with a first transponder frame is different from a data signal associated with a second transponder frame adjacent in time to the first transponder frame.
This type of modulation provides for a large spread over Doppler, and a more pronounced ridge like characteristic such as exemplified in Figures 3 and 4.
According to other aspects, the data signal is the same for each transponder frame. This way, advantageously, a received end portion of a frame can be combined with a start portion of another frame to a complete data signal frame. It is appreciated that this type of modulation, i.e., using the same data signal for each frame, also generates a spread over Doppler. For instance, in FMCW radar transmissions, Doppler is spread since portions of the data signal changes between chirps of the radar signal.
According to aspects the processing comprises Fourier transform processing S31 to generate the range-Doppler representation.
According to aspects, a range-Doppler value represents a signal energy value, or a signal power value associated with the received reflected radar signal at a given delay range and Doppler frequency shift range.
According to aspects, a sample variance of range-Doppler values is determined by counting the number of range-Doppler values above a third threshold. Thus, a low complex implementation of the method is obtained.
According to aspects, a sample variance of range-Doppler values is determined as Image available on "Original document" where N is the number of range-Doppler values corresponding to the range or a range interval around the range, x, is the i-th range-Doppler value, and m is a mean value of the range-Doppler values corresponding to the range. This sample variance represents a spread over Doppler and can therefore be used to detect the presence of a modulating transponder. It is appreciated that the range interval allows for a limited spread also in range by the applied modulation. The range interval size can be pre-configured based on measurements or computer simulations.
According to aspects, the first threshold is determined as a function of a background radar reflection reception level. The first threshold can be fixed or dynamically adjusted. It can be determined based on laboratory experiments, computer simulation, or measurement campaigns.
According to aspects, the second threshold is determined as a function of a number of Doppler bins in the range-Doppler representation. Similar to the first threshold, the second threshold can be fixed or dynamically adjusted. It can be determined based on laboratory experiments, computer simulation, or measurement campaigns.
A potential problem related to modulating Doppler transponders is that the actual Doppler shift resulting from relative motion of the transponder with respect to the radar transceiver is harder to detect due to the ridge-like appearance of the transponder signal in the range-Doppler representation. To measure actual Doppler, the method optionally comprises detecting and removing S5 the modulation from the received waveform. The detecting and removing results in a new received reflected radar signal which is not affected by the modulation. Consequently, following detecting and removing the modulation, a new range-Doppler representation can be generated. In this range-Doppler representation the transponder will be more clearly visible as a peak at a distance corresponding to the distance between transponder and radar transceiver and also at a Doppler value corresponding to the relative velocity of the transponder with respect to the radar transceiver.
Detecting a PAM, PSK, or QAM modulation is known and will not be discussed in more detail here.
Removing a modulation comprises applying an inverse modulation to the received signal. For instance, in case of a PAM modulation between level A and level B, removing modulation comprises compensating for the different levels in order to generate a received signal without modulation.
In case of a PSK modulation, removing modulation comprises phase shifting the received signal opposite the modulation phase shifts to compensate for the applied modulation. This way a received signal without modulation is obtained.
The method optionally also comprises detecting the presence of a transponder over several frames. Doppler value corresponding to relative motion may then be determined based on the detections over different frames by, e.g., comparing phases of corresponding range-Doppler representations.

Claims (10)

1. A method in a radar transceiver for detecting a radar transponder at a range, wherein the radar transponder is arranged to modulate a re-transmitted radar signal by a data signal over consecutive transponder frames, the method comprising; transmitting (S1) a radar signal, receiving (S2) a reflected radar signal, processing (S3) the received reflected radar signal to generate a range-Doppler representation of the received reflected radar signal comprising range-Doppler values, and detecting a (S4) radar transponder at a range if a sum of range-Doppler values corresponding to the range is above a first threshold and a sample variance of range-Doppler values corresponding to the range is above a second threshold.
2. The method according to claim 1, wherein a data signal associated with a first transponder frame is different from a data signal associated with a second transponder frame adjacent in time to the first transponder frame.
3. The method according to any previous claim, wherein the processing comprises Fourier transform processing (S31) to generate the range-Doppler representation.
4. The method according to any previous claim, wherein a sample variance of range-Doppler values is determined by counting the number of range-Doppler values above a third threshold.
5. The method according to any previous claim, wherein a sample variance of range-Doppler values is determined as Image available on "Original document" where N is the number of range-Doppler values corresponding to the range or a range interval around the range, x, is the i-th range-Doppler value, and m is a mean value of the range-Doppler values corresponding to the range.
6. The method according to any previous claim, wherein the first threshold is determined as a function of a background radar reflection reception level.
7. The method according to any previous claim, wherein the second threshold is determined as a function of a number of Doppler bins in the range-Doppler representation.
8. The method according to any previous claim, comprising removing the modulation from the received reflected radar, and detect Doppler shift by generating a new range-Doppler representation.
9. A control unit (115) for a radar transceiver (110) comprising processing circuitry (610) and an interface modulate (620), wherein the processing circuitry is arranged to transmit a radar signal via the radar transceiver, to receive a reflected radar signal, to process the received reflected radar signal to generate a range-Doppler representation of the received reflected radar signal comprising range-Doppler values, and to detect a radar transponder at a range if a sum of range-Doppler values corresponding to the range is above a first threshold and a sample variance of range-Doppler values corresponding to the range is above a second threshold.
10. A radar transceiver comprising the control unit (115) according to claim 9.
SE1830149A 2018-05-02 2018-05-02 Radar transponder detection SE542206C2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4155769A1 (en) * 2021-09-23 2023-03-29 2pi-Labs GmbH Radar-based target identification, position detection and / or positioning

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4155769A1 (en) * 2021-09-23 2023-03-29 2pi-Labs GmbH Radar-based target identification, position detection and / or positioning

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