• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for the radiometric calibration of the radar backscatter cross section RCS j of a number N of radar targets, at least one radar target having a radar transmitter with a transmitting antenna and a radar receiver with a receiving antenna. The process includes the following steps. In a first step (101), a signal S is transmitted by a radar transmitter S k with a transmission power PT k, j, the signal S is received by another of the radar targets, the received signal S is transmitted or reflected by the other radar target and receiving the signal S emanating from the radar target by the radar receiver of the radar target with the received power PR k, j. In a second step (102) step (101) is carried out for N different pairings of radar targets. In a third step 103, based on known distances of the radar transponders when carrying out steps (101) and (102) and determined ratios PR k, j, / PT k, j, the radar backscatter cross sections RCS j of the radar transponders T j are determined based on following connection:
    公开号:CH709940B1
    申请号:CH01039/15
    申请日:2015-07-16
    公开日:2020-03-13
    发明作者:Döring Björn；Schwerdt Marco；Jirousek Matthias；Rudolf Daniel；Raab Sebastian；Reimann Jens
    申请人:Deutsch Zentr Luft & Raumfahrt；
    IPC主号:
    专利说明:

    The invention relates to a method for the absolute radiometric calibration of the radar backscatter cross section RCSj (English "Radar Cross Section" - RCS) of a number N of radar targets Ti, with i = 1, 2, N, and N ≥ 3. The invention takes place Use in the space and aviation industry for the absolute radiometric calibration of the radar backscatter cross-section, in particular of active reference targets, so-called transponders.
    As a result of the steadily increasing demand for remote sensing data from the earth, in particular remote sensing data that are obtained with the help of satellite-based SAR systems such as TerraSAR-X or Sentinel-1, the quality of the so-called SAR data products is becoming more and more important. Because only when the quality of the SAR data products is ensured, useful information for earth observation can be derived (e.g. for the observation of glacier movements, the pack ice or floods, the cutting down of tropical rainforests, the derivation of worldwide biomass etc.).
    However, a high quality of the SAR data products can only be achieved if the satellite-based SAR systems are precisely calibrated, and since future SAR systems are to be compared with a higher degree of accuracy, the accuracy of the reference targets required for this purpose and thus the sufficiently accurate calibration of these reference targets is becoming more and more important.
    The main application of the method described is initially in the absolute radiometric calibration of active reference targets, the so-called (radar) transponders, which are then used for the calibration of satellite-based SAR systems. In principle, the method can be used wherever radar backscatter cross sections RCS of active calibration targets in particular are to be measured. This also includes, for example, transponders such as those used to calibrate weather radars.
    At present there are basically three different method variants for determining the radar backscatter cross section RCS of active radar targets by measurement. In a first variant of the method, the individual transponder components, such as antennas and amplifiers, are measured in the laboratory and the resulting radar backscatter cross section RCS of the respective transponder is then calculated. One problem with this variant is the high systematic measurement uncertainty of the method, which results from the many individual measurements. In addition, there are uncertainties due to the series connection of the individual components of the transponder (antennas, converters, amplifiers, etc.) after the measurement, since the interfaces are not part of the original measurements.
    In a second variant of the method, the transponder is measured as a radar target in a suitable RCS measuring system (inside and outside). The transponder is viewed as a “black box”, the specific “inner workings” of which are irrelevant. In addition to the usual challenges, such as the suppression of undesired backscattering caused by the measurement environment, for example by brackets, a rotating tower, etc., a problem with this variant is in particular that this measurement is a comparative measurement, i.e. it becomes an additional measurement Reference target with known radar backscatter cross section RCS required. The uncertainty with which this last-mentioned radar backscatter cross-section RCS is known directly represents a limit for achieving even more accurate calibrations. In addition, transponders with a high radar backscatter cross-section RCS and thus a high gain can lead to unwanted oscillations when they are operated in a screen chamber will. This prevents an accurate absolute radiometric calibration of the transponders in a shielded chamber.
    In a third variant of the method, the transponder is operated as a radar device, i.e. with an active transmitter and receiver with which a reference target with a known radar backscatter cross section RCS is measured at a known distance. One problem with this variant is that, in addition to the same problems as with the previous second variant, filtering of the background in the time domain is not possible to a sufficient extent due to the typically limited transponder bandwidth.
    Overall, for the calibration of SAR systems mentioned, the measurement uncertainty in the calibration of a reference transponder has a direct influence on the achievable radiometric accuracy of the SAR systems to be calibrated. The more accurate the calibration standard, the more accurately the SAR system can then be calibrated.
    The object of the invention is to provide an improved method for the absolute radiometric calibration of the radar backscatter cross-sections of three or more radar calibration targets.
    [0010] The invention results from the features of the independent claims. The dependent claims relate to advantageous developments and refinements. Further features, possible applications and advantages of the invention emerge from the following description and the explanation of exemplary embodiments of the invention which are shown in the figures.
    The object is achieved with a method for the absolute radiometric calibration of the radar backscatter cross section RCSieiner number N of radar targets Timit i = 1, 2, ..., N, and N ≥ 3. The proposed method is based on the fact that at least one radar target Ti = 1 has a radar transmitter S1 with a transmitting antenna SA1 and a radar receiver E1 with a receiving antenna EA1, the radar receiver E1 and the radar transmitter S1 working independently of one another. The radar target T1 can thus be operated in a radar mode in which the radar target T1 can transmit radar signals and receive radar signals independently thereof.
    The proposed method is also based on the fact that a second radar target Tj = 2 is present, which has a radar transmitter S2 with a transmitting antenna SA2, a radar receiver E2 with a receiving antenna EA2, and a unit D2 with which the radar transmitter S2 in a transponder mode TM des Radar target T2 is connected to the radar receiver E2, so that a signal S received by the radar receiver E2 is (actively) transmitted again by the radar transmitter S2 (largely immediately), and with which the radar transmitter S2 in a radar mode RM of the radar target T2 is not connected to the radar receiver E2, so that the radar transmitter S2 and the radar receiver E2 work independently of one another.
    The proposed method is also based on the fact that a third radar target Ti = 3 is present, which has a radar transmitter S3 with a transmitting antenna SA3, a radar receiver E3 with a receiving antenna EA3, and a unit D3, with which the radar transmitter S3 can be connected to the radar receiver E3, so that a signal S received by the radar receiver E3 is re-transmitted by the radar transmitter S3, or the radar target T3 is a passive radar target that reflects an incident signal S. In the present case, a passive radar target Ti and a radar target Ti operated in transponder mode have in common that they reflect an impinging radar signal (in the first case this takes place passively, in the second case actively and possibly with a time delay).
    The aforementioned properties of the at least three radar targets Ti are minimum requirements. For example, all three of the Tiderart radar targets can be designed so that they can be operated both in radar mode and in transponder mode and thus have the properties of the aforementioned second radar target T2.
    The proposed method comprises the following steps.
    The method begins with the transmission of a signal S by the radar transmitter Skdes radar target Tk with a transmission power PTk, jan a different radar target Tj. The transmitted signal S is received by the other radar target Tj. This radar target Tj sends or reflects the received signal S back to the radar target Tk. The signal S emanating from the radar target Tj is received by the radar receiver Ek of the radar target Tk with the received power PRk, j, where: k, j {1, 2, ..., N} and k ≠ j. These processes are summarized as the “first step” of the procedure for the following explanations.
    Furthermore, in a second step, the step previously defined as the “first step” is carried out for N different pairings TkTj of radar targets Tkund Tj, the pairings TkTj and TjTkals being identical. The following variables are recorded in each case: transmit power PTk, j and receive power PRk, j. Furthermore, the distances Dk, j = | (Pk-Pj) | the radar targets Tkund Tjer detected or exactly determined.
    In a third step, based on known distances Dk, jder radar targets Tkund Tj during the implementation of the first and second step, as well as based on determined ratios of PRk, j / PTk, jder radar backscatter cross-sections RCSjder radar targets Tjbased on the following relationship:
    with GR: antenna gain of the receiver antenna EAk, GT: antenna gain of the transmitter antenna SAk, and λ wavelength of the radar signal S.
    The main beam direction of the radar transmitter Skexakt to the radar target Tjbzw is advantageous to carry out the "first step". its receiving antenna aligned. This alignment can take place, for example, by means of laser measurement.
    The distances Dk, j result advantageously from an accurate detection of the positions Pkund Pj of the radar targets Tkund Tj during the measurements: Dk, j = | (Pk-Pj) |, each of which is measured from the phase center of the respective antenna. The exact detection of these positions takes place, for example, by means of a differential GPS device. The distances Dk can advantageously also be recorded by means of a laser distance measuring device.
    It should be noted here that the radar backscatter cross section RCSj is only meaningfully defined for a far field. Based on an antenna dimension D, the far field condition applies to a distance Dk, jfrom>, where λ is the wavelength of the signal S.
    If, for example, radar transponders with two antennas (transmitting antenna, receiving antenna) are used as radar targets, the antenna apertures of which each have a diameter of 20 cm and the antenna feed lines are separated from each other by approximately 40 cm, then the result is a D of 60 cm and one Wavelength λ = 5.6 cm means that the far field begins at distances of Dk, j> 13 m.
    If N> 3, the further radar targets Ti> 3 can be implemented as desired, i.e. they can be passive radar targets, radar targets operating as transponders, radar targets operating as radar or alternatively radar targets that can be operated in radar or transponder mode.
    For absolute calibration, the proposed method requires, for example, the radar backscatter cross-sections RCSi = 1,2,3 three generic radar targets Ti = 1,2,3 so only the measurement of the ratio PRk, j / PTk, j for three radar target combinations, e.g. T1T2, T1T3 and T2T3 at known distances D1,2, D1,3, and D2,3. These data are inserted into a linear and easily solvable system of equations with three equations and three unknowns (radar backscatter cross-sections RCSi = 1,2,3) resulting from equation (1).
    It follows that to determine the radar backscatter cross sections of N radar targets Tim at least N measurements for N different pairings are required.
    An advantageous development of the method is characterized in that the radar target T1 has a unit D1 with which the radar transmitter S1 is connected to the radar receiver E1 in a transponder mode TM of the radar target T1, so that a signal S received by the radar receiver E1 is re-transmitted by the radar transmitter S1 and with which the radar transmitter S1 is not connected to the radar receiver E1 in a radar mode RM of the radar target T1, so that the radar receiver E1 and the radar transmitter S1 operate independently of one another. In other words, the radar target T1 in this development can be used both in transponder mode and in radar mode, so that a total of two of the minimum three radar targets Ti can be operated in both modes, while the third radar target T3 can only be operated as a transponder or a passive one Represents radar target.
    An advantageous development of the method is characterized in that the radar target T3 has a unit D3 with which the radar transmitter S3 is connected to the radar receiver E3 in a transponder mode TM of the radar target T3, so that a signal S received by the radar receiver E3 is re-transmitted by the radar transmitter S3 and with which the radar transmitter S3 is not connected to the radar receiver E3 in a radar mode RM of the radar target T3, so that the radar receiver E3 and the radar transmitter S3 work independently of one another. This variant of the method, together with the above development, includes the combination that all three radar target Ti can be operated in both modes (transponder mode or radar mode).
    An advantageous further development of the method is characterized in that the entire method, i.e. the first to third step, for different transmission frequencies f the radar transmitter Sibzw. of the signal S, the result being that the radar backscatter cross sections RCSj of the radar targets Tj are determined as frequency-dependent radar backscatter cross sections RCSj (f). This results in absolutely calibrated frequency-dependent radar backscatter cross-sections RCSj (f) as the method result.
    Furthermore advantageously the whole process, i. The first to third step is carried out for each pairing TkTj for different distances Dk, j of the radar targets Tkund Tj, whereby the measured distance-dependent ratios (PRk, j / PTk, j) (Dk, j) are used to correct multipath effects when determining the radar backscatter cross-sections RCSj . Disturbances or inaccuracies due to multipath propagation of the signals S or due to standing waves can thereby be largely compensated, which ultimately improves the accuracy of the determined radar backscatter cross-sections RCSj.
    Furthermore advantageously the whole process, i. The first to third step are carried out for different polarizations P of the signal S, the result being that the radar backscatter cross sections RCSj of the radar targets Tjals are determined as radar backscatter cross sections RCSj (P) which are dependent on the polarization P.
    The entire method (first to third step) is advantageously carried out q times repeatedly, the radar backscatter cross sections RCSials mean values <RCSj> q being determined, with q ε {2, 3, 4 ...}. It is also advantageous that only the “first step” for pairing radar targets Tkund Tjq-fold is carried out repeatedly, with the measured transmit powers PTkj and received powers PRk, j being averaged, and the mean values generated: <PTk, j> q and <PRk, j> q can be used to determine the ratio PRk, j / PTk, j = <PRj, k> q / <PTk, j> q and accordingly to determine the radar backscatter cross-section RCSj.
    An advantageous development of the method is characterized in that the units DjTransponder mode of the radar target Tj amplify and / or filter and / or time-delay signals S received by the radar receiver Ej before they are forwarded to the radar transmitter Sj for transmission. Disturbing effects of multipath signals and other environment-dependent effects such as oscillation can be largely excluded, in particular by delayed transmission.
    An advantageous further development of the method is characterized in that the distances Dk, jder radar targets Tkund Tivon each meet the following condition: (2) Dk, j> (2 * D <2>) / λ with D: antenna diameter of the transmitting antenna SAjund λ: wavelength of the signal S. This corresponds to the far-field condition already mentioned.
    The transmitting antenna SAk of the radar target T and the receiving antenna EAj of the radar target Tjkopolar are advantageously aligned.
    The at least three measurements of transmit powers PTk, j and received powers PRk, allow the establishment of a system of equations from which the radar backscatter cross section RCS of each radar target Tje can be calculated unambiguously, provided that the distance Dk, j between the radar targets Tkund Tj is known with sufficient accuracy.
    In contrast to the known methods, no additional radar target with a known backscatter cross section is necessary for this, so that higher calibration accuracies are possible. In addition, the radar targets Tjin are measured in their final configuration (as a black box), i.e. cable connections and corresponding internal interfaces do not have to be changed again after the measurement, which would subsequently falsify the radar backscatter cross-section RCS. In addition, radar targets Tj, which work as transponders with a digital delay, allow the transmission and reception of signals to be decoupled in time. This prevents oscillation, as can happen with previous measurements of transponders in a shielded chamber. Another advantage is that no additional high-frequency measurement equipment, such as a network channel analyzer, is necessary to carry out the measurements. This not only saves costs, but also avoids their additional measurement uncertainty. Finally, the traceability of the proposed RCS calibration is limited to standards for a comparatively simple length measurement, while the radar backscatter cross section RCS was previously determined either by a detour via another calibrated reference target or by measuring the individual components of a respective radar target. Thus, with the present method, a simple traceability of the calibration to different standards is possible.
    A computer system with a data processing device can be used, the data processing device being designed in such a way that partial steps of the method, as stated above, are carried out on the data processing device.
    Furthermore, a computer program product, i. a machine-readable carrier with program code stored thereon can be used to carry out sub-steps of the method when the program code is executed on a data processing device.
    Such a computer program with the program code as stated above can run on a data processing device which is designed as any computer system known from the prior art.
    Further advantages, features and details emerge from the following description, in which - if necessary with reference to the drawing - at least one exemplary embodiment is described in detail. Identical, similar and / or functionally identical parts are provided with the same reference symbols.
    1 shows a schematic and exemplary representation of a radar target that is operated only as a radar and of a radar target that is operated in the present case in transponder mode and that can be switched between transponder mode and radar mode, and FIG. 2 shows a schematic flow chart of an exemplary embodiment of the proposed method.
    An exemplary embodiment of the proposed method is described in detail below, in which the radar backscatter cross sections RCS1, RCS2, and RCS3 are absolutely calibrated for three radar targets T1, T2, and T3. Two of the three radar targets, namely T1 and T2, can be operated both in radar mode and in transponder mode, i.e. they have a unit that can switch between these two modes. In the present case, the radar target T3 can only be operated as a radar, i.e. the reception and transmission of radar signals S take place independently of one another.
    A radar target 201, which is operated only as a radar, and a radar target 220, which is operated in the present case in transponder mode and which can be switched between transponder mode and radar mode, are shown schematically and by way of example.
    The radar target 201 comprises a radar transmitter 202 with an amplifier 204 (which operates in the digital domain), a digital-to-analog converter 205 and a transmission unit 206 with a transmission antenna 207. The radar transmitter 202 is provided with a signal at the amplifier 204 that is ultimately emitted as signal S via the transmitting antenna 207. The radar target 201 further comprises a radar receiver 203 with a receiving antenna 210, an amplifier 209 and an analog-digital converter 208. A signal S received by the radar receiver reaches the analog-digital converter via the signal path shown from the receiving antenna 210 and is there made available for further processing. It can easily be seen that the radar transmitter 202 is not connected to the radar receiver 203, i. a signal S received by the radar receiver 203 is not made available to the radar transmitter 202 for transmission.
    The radar target 220 comprises a radar transmitter 222 with an amplifier 225 (which operates in the digital domain), a digital-to-analog converter 224 and a transmission unit 223 with a transmission antenna 226. The radar target 220 furthermore comprises a radar receiver 221 with a reception antenna 227 , an amplifier 228 and an analog-to-digital converter 229. Furthermore, the radar target 220 comprises a unit 230 with which the radar transmitter 222 is connected to the radar receiver 221 in the illustrated transponder mode TM of the radar target 220, so that one of the radar receiver 221 received signal S from the radar transmitter 222 is re-transmitted, and with which the radar transmitter 222 is not connected to the radar receiver 221 in a radar mode RM (not shown) of the radar target 220, so that the radar transmitter 222 and the radar receiver 221 are independent of one another, ie work as a radar.
    The present three radar targets of the exemplary embodiment each correspond in their basic structure to the radar targets 201 and 220 generally presented above.
    For the absolute radiometric calibration of the radar backscatter cross-section RCSj = 1,2,3 of the radar targets Ti defined above, with i = 1, 2, 3, the following measurements are carried out for the following pairings: T3T1, T3T2 and T1T2, with the first two pairings: T3T1, T3T2, the radar targets T1 and T2 are operated in the transponder mode, so that the radar target T3 each sends signals S to the radar targets or T2 and detects the signals coming back from there. When pairing T1, T2, one of the two radar targets T1 or T2 must work in radar mode and the other in transponder mode. It is assumed here that T1 works in radar mode and T2 works in transponder mode.
    For each of these pairings, a signal S is transmitted by the radar transmitter Skeines of the radar targets Tk with a transmission power PTk, j, the signal S is received by the respective other radar target Tj of the pairings, and the received signal S is transmitted by the other radar target Ti , and receiving the signal S emanating from the radar target Tj by the radar receiver Ek of the radar target Tk with the received power PRk, jmit k, j ε {1, 2, N} and k ≠ j.
    The measurements are each carried out at the same frequency of the signal S, for example using a sinusoidal signal. The measurements are then preferably repeated for frequencies f of the signal S that are changed step-by-step in order to determine the frequency-dependent radar backscatter cross section RCSj (f).
    For each measurement, the transmission power PTk, j and the received power PRk, jam are measured in each case as a radar operated radar target Tk. Overall, according to the measurements, there are the following transmission powers: PTk = 3, j = 1, PTk = 3, j = 2 and PTk = 1, j = 2 and the following reception powers PRk = 3, j = 1, PRk = 3, j = 2, and PRk = 1, j = 2vor. Furthermore, the distance Dk, j present between the respective radar targets T and Tj during the measurement is determined for each pairing by means of laser distance measurement.
    Furthermore, based on known distances Dk, j the radar targets Tkund Tj during the measurements and determined ratios PRk, j / PTk, j: PRk = 3, j = 1 / PTk = 3, j = 1, PRk = 3, j = 2 / PTk = 3, j = 2 and PRk = 1, j = 2 / PTk = 1, j = 2, a determination of the radar backscatter cross-sections RCSider radar targets Tj based on the radar equation:
    with GR: antenna gain of the receiver antenna EAk, GT: antenna gain of the transmitter antenna SA and λ wavelength of the radar signal.
    This equation (1) describes the received power PRk received by a radar target Tk, j with an antenna gain GR of the receiving antenna EAk as a function of the radar backscatter cross section RCSj, of the radar target Tj in a distance / distance Dk, j, and the transmission power PTk, j of the radar transmitter Sk with a transmitting antenna SAk, which has an antenna gain GT, for a wavelength λ of the transmitted signal S.
    The radar backscatter cross section RCSj can also be expressed by the total gain Gl (“loop gain”) of the radar target Tj. This results in:
    where the "loop gain" can typically be represented as follows: Gl = Gs * Ge * Gr, i.e. as the product of the antenna gain Gs of the transmitting antenna SAj of the radar target Tj, the antenna gain Gr of the receiving antenna EAj of the radar target Tj, and the gain G of the electronic amplification of the received signal in the radar target Tj.
    The equation can thus also be written:
    where Gtx and Grx are the gains of the transmission path and the reception path in the radar target Tj, i.e. are a combination of antenna gain and gain from electronic amplification in the respective paths. The transmission path or the reception path is given in relation to FIG. 1 by the signal path in the radar receiver 221, for example in the radar transmitter 222.
    The equations (1) and (3) can be combined into one equation. As explained above, it is assumed that the radar target Tkal's radar and the radar target Tial's radar transponder are operated. This results in:
    For the total of three proposed pairings, three equations thus result. These equations can always be transformed into a linear system of equations by means of a logarithmic transformation. This is possible because all expressions are greater than zero.
    For the sake of simplicity, the same symbols are used below for the radar backscatter cross section RCSj, but it is pointed out that after the logarithmic transformation: 10log (...) they now relate to values that are given in decibels.
    The equation (5) can therefore be expressed as follows:
    with Pk, j: Ratio10log (PRk, j / PTk, j) in which the radar target Tk acts as a radar and the radar target Tials a transponder, the latter being measured.
    For C we get: (7) C = 2 · 10log (4πDk, j <2>)
    It should be noted that in equation (7) only one length measurement (Dk, j) needs to be traced back to a national standard in order to make the calibration traceable.
    The system of linear equations can be written in matrix form as follows:
    Fig. 2 shows a highly schematic flow chart of an embodiment of the proposed method for radiometric calibration of the radar backscatter cross-section RCSie a number N of radar targets Ti, with i = 1, 2, N, ..., N and N ≥ 3, with at least one radar target T1 Radar transmitter S1 with a transmitting antenna SA1 and a radar receiver E1 with a receiving antenna EA, the radar receiver E1 and the radar transmitter S1 working independently of one another, a radar target T2, a radar transmitter S2 with a transmitting antenna SA2, a radar receiver E2 with a receiving antenna EA2, and a unit D2 with which the radar transmitter has S2 is connected to the radar receiver E2 in a transponder mode TM of the radar target T2, so that a signal S received by the radar receiver E2 is re-transmitted by the radar transmitter S2, and with which the radar transmitter S2 in a radar mode RM of the radar target T2 is not connected to the radar receiver E2, so that the Radar transmitter S2 and the radar receivers E2 work independently of one another, and a radar target T3 has a radar transmitter S3 with a transmitting antenna SA3, a radar receiver E3 with a receiving antenna EA3, and a unit D3 with which the radar transmitter S3 is connected to the radar receiver E3, so that a signal S received by the radar receiver E3 is re-transmitted by the radar transmitter S3 , or the radar target T3 is a passive radar target that reflects an incident signal S. The process consists of the following steps.
    In a first step 101, a signal S is transmitted by the radar transmitter Skeines of the radar targets Tk with a transmission power PTk, j, the signal S is received by another of the radar targets Tj, the received signal S is transmitted or reflected by the other Radar target Tj, and the radar receiver Ek of the radar target Tk receives the signal S emanating from the radar target Tj with the received power PRj, k, with k, j ε {1, 2, ..., N} and k ≠ j.
    In a second step 102, step 101 is carried out for N different pairings TkTj of radar targets Tkund Tj, the pairings TkTj and TjTkals being identical.
    In a third step 103, based on known distances Dk, j the radar transponder Tkund Tj when performing steps 101 and 102 and determined ratios PRj, k / PTk, j, the radar backscatter cross-sections RCSider radar transponder Tibased based on the following relationship:
    with GR: antenna gain of the receiver antenna EAk, GT: antenna gain of the transmitter antenna SAk, and λ wavelength of the radar signal.
    Although the invention has been illustrated and explained in detail by preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that there is a multitude of possible variations. It is also clear that embodiments cited by way of example really only represent examples that are not to be interpreted in any way as a limitation, for example, of the scope of protection, the possible applications or the configuration of the invention. Rather, the preceding description and the description of the figures enable the person skilled in the art to specifically implement the exemplary embodiments, with the person skilled in the art being able to make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, with knowledge of the disclosed inventive concept, without the To leave the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.
    权利要求:
    Claims (10)
    [1]
    1. Method for the radiometric calibration of the radar backscatter cross section RCSie a number N of radar targets Ti, with i = 1, 2, ..., N, and N ≥ 3, where at leastA radar target T1 has a radar transmitter S1 with a transmitting antenna SA1 and a radar receiver E1 with a receiving antenna EA1, the radar receiver E1 and the radar transmitter S1 being able to operate independently of one anotherA radar target T2 has a radar transmitter S2 with a transmitting antenna SA2, a radar receiver E2 with a receiving antenna EA2, and a unit D2 with which the radar transmitter S2 is connected to the radar receiver E2 in a transponder mode TM of the radar target T2, so that a signal S received by the radar receiver E2 from the radar transmitter S2 is re-transmitted, and with which the radar transmitter S2 is not connected to the radar receiver E2 in a radar mode RM of the radar target T2, so that the radar transmitter S2 and the radar receiver E2 work independently of one another, andA radar target T3 has a radar transmitter S3 with a transmitting antenna SA3, a radar receiver E3 with a receiving antenna EA3, and a unit D3 with which the radar transmitter S3 can be connected to the radar receiver E3, so that a signal S received by the radar receiver E3 is re-transmitted by the radar transmitter S3, or the radar target T3ein is a passive radar target that reflects an incident signal S,with the following steps:1.1. Transmission of a signal S by the radar transmitter Skeines of the radar target Tk with a transmission power PTk, j, reception of the signal S by another of the radar targets Tj, transmission or reflection of the received signal S by the other radar target Tj, and reception of the signal S emanating from the radar target Tj by the radar receiver Ek of the radar target Tk with the received power PRk, j, with k, j ε {1, 2, ..., N} and k ≠ j,1.2. Performing step 1.1. for N different pairings TkTjof radar targets Tkund Tj, where the pairings TkTjand TjTkals apply to be identical1.3. based on known distances Dk, each of the radar targets Tkund Tj when performing steps 1.1. and 1.2 and determined ratios PRk, j / PTk, j, determination of the radar backscatter cross-sections RCSj of the radar targets Tj based on the following relationship:
    with GR: antenna gain of the receiver antenna EAk, GT,: antenna gain of the transmitter antenna SAk, and λ wavelength of the radar signal.
    [2]
    2. The method according to claim 1,in which the radar target T1 has a unit D1, by means of which the radar transmitter S1 is connected to the radar receiver E1 in a transponder mode TM of the radar target T1, so that a signal S received by the radar receiver E1 is re-transmitted by the radar transmitter S1, while the radar transmitter S1 is in a radar mode RM of the Radar target T1 is not connected to the radar receiver E1, so that the radar receiver E1 and the radar transmitter S1 work independently of one another.
    [3]
    3. The method according to claim 1 or 2,in which the unit D3 is designed such that the radar transmitter S3 is connected to the radar receiver E3 in a transponder mode TM of the radar target T3, so that a signal S received by the radar receiver E3 is re-transmitted by the radar transmitter S3, and with the radar transmitter S3 in a radar mode RM of the radar target T3 is not connected to the radar receiver E3, so that the radar receiver E3 and the radar transmitter S3 work independently of one another.
    [4]
    4. The method according to any one of claims 1 to 3,where steps 1.1. until 1.3. for different transmission frequencies f of the radar transmitter S, the radar backscatter cross-sections RCSj of the radar targets Tj are determined as frequency-dependent radar backscatter cross-sections RCSj (f).
    [5]
    5. The method according to any one of claims 1 to 4,where steps 1.1. until 1.3. for each pairing TkTj for different distances Dk, j of the radar targets Tkund Tj, the measured distance-dependent ratios (PRk, j / PTk, j) (Dk, j) being used to correct multipath effects when determining the radar backscatter cross-sections RCSj.
    [6]
    6. The method according to any one of claims 1 to 5,where steps 1.1. until 1.3. for different polarizations P of the signal S, the radar backscatter cross sections RCSj of the radar targets Tj as radar backscatter cross sections RCSj (P) dependent on the polarization P being determined.
    [7]
    7. The method according to any one of claims 1 to 6,where steps 1.1. until 1.3. are repeated q times and the radar backscatter cross sections RCSj are determined as mean values <RCSj> q.
    [8]
    8. The method according to any one of claims 1 to 7,in each of which the unit Di in the transponder mode TM of the radar target Tidas amplifies and / or filters and / or delays the signal S received by the radar receiver E1 before it is forwarded to the radar transmitter Si.
    [9]
    9. The method according to any one of claims 1 to 8,where the distances Dk, each of the radar targets T and Tj from one another satisfy the following condition:Dk, j> (2 * D <2>) / λWithD: antenna diameter of the transmitting antenna SAiλ: wavelength of the signal S
    [10]
    10. The method according to any one of claims 1 to 9,in which the transmitting antenna SAk of the radar target T and the receiving antenna EAj of the radar target Tjkopolar are aligned.
    类似技术:
    公开号 | 公开日 | 专利标题
    CH709940B1|2020-03-13|Absolute radiometric calibration of the radar backscatter cross section of radar targets.
    DE102017100272A1|2017-07-13|System and method for measuring a plurality of RF signal paths
    EP2799898B1|2019-07-10|Weather radar
    DE102006058852B4|2014-01-02|Method and device for correcting non-ideal intermediate frequency signals in distance measuring devices according to the FMCW principle
    DE102014008670A1|2015-02-05|RADAR CALIBRATION SYSTEM FOR VEHICLES
    EP2101279A2|2009-09-16|Adjustable circuit and RFID reader unit
    DE102006029317A1|2007-12-27|Polarization modulated transmitter
    CN107219526B|2020-04-28|Calibration system and method in double-star Ka FMCW SAR and imaging system
    DE102014225830A1|2016-06-16|Method for calibrating a radar system
    DE102013113859A1|2014-06-12|Compensating slowly varying intermediate frequency DC voltage offsets in receivers
    DE102013111512A1|2015-04-23|Radar device and method for operating a radar device
    DE102016005058B4|2020-02-06|Method for operating a radar sensor in a motor vehicle and motor vehicle
    DE102014118683A1|2015-06-25|CIRCUIT AND METHOD FOR A CIRCUIT
    DE102012016637A1|2014-05-15|Method and apparatus for determining a relative alignment of two GPS antennas to each other
    WO2017134028A1|2017-08-10|Method for calibrating an active sensor system
    DE102015219612A1|2017-04-13|System architecture for a MIMO level radar
    DE102017125171B3|2019-02-07|RADAR SENSOR WITH DIGITAL SIGNAL PROCESSING UNIT
    EP2875381B1|2017-09-20|Method for determining the functionality of a switchable receiving amplifier
    CH634927A5|1983-02-28|CIRCUIT ARRANGEMENT FOR SHIFTING THE CLUTTER SPECTRUM IN THE RECEIVER OF A PULSE DOPPLER RADAR.
    EP2293096A2|2011-03-09|Method and device for providing a reflection signal
    EP2746812B1|2020-03-25|Method and receiver for processing a navigation satellite signal
    DE102012218730B4|2017-10-26|Gain measurement circuit, gain measurement method and communication device
    DE102018206200A1|2019-10-24|Method for detecting a channel impulse response in a system, in particular for communication, system, transmitting device and receiving device
    DE102020115709B3|2021-10-28|AUTOMOTIVE RADAR ARRANGEMENT AND METHOD OF OBJECT DETECTION BY A VEHICLE RADAR
    DE102018132739A1|2020-06-18|Method for FMCW-based distance measurement
    同族专利:
    公开号 | 公开日
    DE102014110079B3|2015-07-09|
    CH709940A2|2016-01-29|
    CA2897569A1|2016-01-17|
    GB2529934A|2016-03-09|
    GB2529934B|2018-11-14|
    GB201512481D0|2015-08-19|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    GB2221590B|1987-12-02|1991-11-27|Plessey Co Plc|Radar system calibration apparatus|
    JP2004361155A|2003-06-03|2004-12-24|Fujitsu Ten Ltd|Target discriminating apparatus, target determining apparatus, and discrimination auxiliary equipment|
    US8947295B2|2012-06-27|2015-02-03|The United States Of America As Represented By The Secretary Of The Air Force|Low clutter method for bistatic RCS measurements|CN105466365B|2015-11-12|2017-11-17|中国科学院光电研究院|The method for obtaining radar corner reflector RCS precision|
    DE102016101898B3|2016-02-03|2017-04-13|Deutsches Zentrum für Luft- und Raumfahrt e.V.|Method for calibrating an active sensor system|
    CN110146859B|2019-05-30|2021-07-06|中国人民解放军63921部队|Method and device for radar scattering cross section RCS calibration|
    CN111551904A|2020-04-03|2020-08-18|北京无线电计量测试研究所|Method and device for measuring radar scattering cross section parameter field calibration|
    CN113534150A|2021-06-08|2021-10-22|国家卫星海洋应用中心|Satellite-borne synthetic aperture radar ocean scene observation radar gain setting method and system|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    DE102014110079.4A|DE102014110079B3|2014-07-17|2014-07-17|Method for absolute radiometric calibration of the radar backscatter cross section of radar targets|
    [返回顶部]