IMAGING RADAR SYSTEM HAVING A RECEIVING ARRAY FOR DETERMINING THE ANGLE OF OBJECTS IN TWO DIMENSIONS BY MEANS OF A SPREAD ARRANGEMENT OF THE RECEIVING ANTENNAS IN ONE DIMENSION

Abstract

The present invention relates to an apparatus for determining the position of objects in two-dimensional space having a first dimension and a second dimension, the direction vector of which is orthogonal to the direction vector of the first dimension, containing at least one transmitter (I) having at least one transmitting antenna (3) and an imaging receiver circuit (2) having at least one receiving antenna array (Rx Array) with rows (6) of receiving antennas for scanning the first dimension by means of digital beam shaping, wherein the receiving antenna array has a linear array, a sparse array or an array with an enlarged aperture, and wherein the rows (6) of receiving antennas in the receiving antenna array of the receiver circuit (2) are linearly arranged in the first dimension according to a curve function or according to the contour of a two-dimensional geometric object and are spread out in the second dimension, and to a method using the apparatus.

Claims

1-15. (canceled)

16. A radar system comprising: a transmitter antenna; a first row of receiver antennas, where the first row of receiver antennas has a first phase center at a first position along the first row of receiver antennas; a second row of receiver antennas, where the second row of receiver antennas has a second phase center at a second position along the second row of receiver antennas, where the first row of receiver antennas is offset from the second row of receiver antennas in a first dimension, where the first row of receiver antennas and the second row of receiver antennas extend in parallel with one another along a second dimension, and further where the first position of the first phase center is offset from the second position of the second phase center in the second dimension; and processing circuitry that is in communication with the first antennas and the second antennas, where the processing circuitry is configured to perform acts comprising: obtaining a first signal from the first row of receiver antennas, where the first signal is based upon a radar signal emitted into an environment by the transmitter antenna, and further where the environment includes an object; obtaining a second signal from the second row of receiver antennas, where the second signal is based upon the radar signal emitted into the environment by the transmitter antenna; digitizing the first signal and the second signal to form first digitized data and second digitized data, respectively; performing digital beamforming based upon the first digitized data and the second digitized data; and computing a position of the object in the environment in both azimuth and elevation.

17. The radar system of claim 16, further comprising a third row of receiver antennas that has a third phase center that has a third position along the third row of receiver antennas, where the third row of receiver antennas is offset from both the first row of receiver antennas and the second row of receiver antennas in the first dimension, where the third row of receiver antennas extends in parallel with the first row of receiver antennas and the second row of receiver antennas along the second dimension, and further where third position of the third phase center is offset from the first position of the first phase center and the second position of the second phase center in the second dimension; wherein the acts performed by the processing circuitry further comprise: obtaining a third signal from the third row of receiver antennas, where the third signal is based upon the radar signal emitted into the environment by the transmitter antenna; and digitizing the third signal to form third digitized data, wherein the digital beamforming is performed based further upon the third digitized data.

18. The radar system of claim 16 comprising eight rows of receiver antennas, where the eight rows of receiver antennas include the first row of receiver antennas and the second row of receiver antennas, and further where the digital beamforming is performed based upon signals obtained from the eight rows of receiver antennas.

19. The radar system of claim 16 comprising sixteen rows of receiver antennas, where the sixteen rows of receiver antennas include the first row of receiver antennas and the second row of receiver antennas, and further where the digital beamforming is performed based upon signals obtained from the eight rows of receiver antennas.

20. The radar system of claim 16, where the first row of receiver antennas includes first planar antennas coupled to one another in series, and further where the second row of receiver antennas includes second planar antennas coupled to one another in series.

21. The radar system of claim 16 mounted on an automobile.

22. The radar system of claim 16, further comprising a row of transmitter antennas that extend in the second dimension in parallel with the first row of receiver antennas and the second row of receiver antennas, where the row of transmitter antennas is offset from the first row of receiver antennas and the second row of receiver antennas in the first dimension, and further where the row of transmitter antennas includes the transmitter antenna.

23. The radar system of claim 16, wherein a random function is employed to set the first position and the second position.

24. The radar system of claim 16, further comprising a second transmitter antenna that is offset from the transmitter antenna in the second dimension, where the transmitter antenna and the second transmitter antenna are switchable.

25. The radar system of claim 16 being a pulse radar system.

26. The radar system of claim 16, where the first dimension is orthogonal to the second dimension.

27. The radar system of claim 16, where the first row of receiver antennas and the second row of receiver antennas are oriented linearly on a straight line in the first dimension.

28. The radar system of claim 16, where a distance between the first row of receiver antennas and the second row of receiver antennas along the first dimension is 2200 μm.

29. A method for forming a radar system, the method comprising: providing a transmitter, where the transmitter includes a transmitter antenna; providing a receiver circuit, where the receiver circuit comprises: a first row of receiver antennas, where the first row of receiver antennas has a first phase center at a first position along the first row of receiver antennas; a second row of receiver antennas, where the second row of receiver antennas, where the second row of receiver antennas has a second phase center at a second position along the second row of receiver antennas, where the first row of receiver antennas is offset from the second row of receiver antennas in a first dimension, where the first row of receiver antennas and the second row of receiver antennas extend in parallel with one another along a second dimension, and further where the first position of the first phase center is offset from the second position of the second phase center in the second dimension; operably coupling processing circuitry to the receiver circuitry; and programming the processing circuitry to perform acts comprising: obtaining a first signal from the first row of receiver antennas, where the first signal is based upon a radar signal emitted into an environment by the transmitter antenna, and further where the environment includes an object; obtaining a second signal from the second row of receiver antennas, where the second signal is based upon the radar signal emitted into the environment by the transmitter antenna; digitizing the first signal and the second signal to form first digitized data and second digitized data, respectively; performing digital beamforming based upon the first digitized data and the second digitized data; and computing a position of the object in the environment in both azimuth and elevation.

30. The method of claim 29, wherein the acts further comprise: prior to performing the digital beamforming, performing a range Fast Fourier Transform (FFT) and a velocity FFT with respect to the first digitized data and the second digitized data.

31. The method of claim 30, wherein the acts further comprise: employing a peak search function over frequencies in signals generated based upon the range FFT and the velocity FFT.

32. The method of claim 29, wherein the receiver circuit further comprises: a third row of receiver antennas that has a third phase center that has a third position along the third row of receiver antennas, where the third row of receiver antennas is offset from both the first row of receiver antennas and the second row of receiver antennas in the first dimension, where the third row of receiver antennas extends in parallel with the first row of receiver antennas and the second row of receiver antennas along the second dimension, and further where third position of the third phase center is offset from the first position of the first phase center and the second position of the second phase center in the second dimension; where the acts further comprise: obtaining a third signal from the third row of receiver antennas, where the third signal is based upon the radar signal emitted into the environment by the transmitter antenna; and digitizing the third signal to form third digitized data, wherein the digital beamforming is performed based further upon the third digitized data.

33. The method of claim 29, where the first row of receiver antennas includes first antennas and the second row of receiver antennas includes second antennas, the method further comprising: prior to providing the receiver circuit: utilizing a random function to determine positions of the first antennas in the first row of receiver antennas; and utilizing the random function to determine positions of the second antennas in the second row of receiver antennas.

34. The method of claim 29, wherein the radar system is a pulse radar system.

35. A method performed by a radar system to compute a position of an object in an environment, the method comprising: obtaining a first signal from a first row of receiver antennas of the radar system, where the first signal is based upon a radar signal emitted into an environment by a transmitter antenna of the radar system, where the environment includes an object, and further where the first row of receiver antennas has a first phase center at a first position along the first row of receiver antennas; obtaining a second signal from a second row of receiver antennas of the radar system, where the second signal is based upon the radar signal emitted into the environment by the transmitter antenna, where the second row of receiver antennas has a second phase center at a second position along the second row of receiver antennas, where the first row of receiver antennas is offset from the second row of receiver antennas in a first dimension, where the first row of receiver antennas and the second row of receiver antennas extend in parallel with one another along a second dimension, and further where the first position of the first phase center is offset from the second position of the second phase center in the second dimension; digitizing the first signal and the second signal to form first digitized data and second digitized data, respectively; performing digital beamforming based upon the first digitized data and the second digitized data; and computing a position of the object in the environment in both azimuth and elevation.

Description

[0041] In the figures:

[0042] FIG. 1 shows a front end having 16 Rx antennas and one Tx antenna. Arrangement of the Rx antennas in the 2.sup.nd dimension by rand( )*Max. deviation;

[0043] FIG. 2 shows an antenna pattern in the 2.sup.nd dimension with three shaped beams by virtue of different positionings of the phase center in the 2.sup.nd dimension;

[0044] FIG. 3 shows an antenna pattern in the first dimension for the antenna positions listed in table 1 (1.sup.st dim. linear, 2.sup.nd dimension randomly generated) and for a linear array of the antenna positions without a deviation in the second dimension;

[0045] FIG. 4 shows a signal flow diagram of the 2D location determination with the use of FMCW; and

[0046] FIG. 5 shows an elliptic array arrangement having 2 Tx and 8 Rx.

[0047] FIG. 1 shows such an exemplary implementation of a radar front end consisting of a transmitter (1) having a transmitting antenna (3) and a receiver circuit (2) having 16 rows of receiving antennas (6), wherein the rows of receiving antennas (6) are oriented linearly on a straight line along the first dimension. The array is spread out in the second dimension, which is orthogonal to the first dimension, with the aid of a random function. The associated positions of the linear array having the row spacing 2200 μm in the first dimension and randomly determined positions in the second dimension are presented in table 1:

TABLE-US-00001 TABLE 1 Positioning of the rows of receiving antennas of the array illustrated in FIG. 1 with a linear arrangement in dimension 1 with a row spacing of 2200 μm and a randomly produced arrangement of the antennas in dimension 2. Dim 1 (μm) Dim 2 (μm) −1260    0 R × 1 −1620   2200 R × 2 1490   4400 R × 3 −1650   6600 R × 4 −530   8800 R × 5 1610 11 000 R × 6 890 13 200 R × 7 −190 15 400 R × 8 −1830 17 600 R × 9 −1860 19 800 R × 10 1370 22 000 R × 11 −1880 24 200 R × 12 −1830 26 400 R × 13 60 28 600 R × 14 −1200 30 800 R × 15 1430 33 000 R × 16

[0048] FIG. 2 shows three resulting beams in the second dimension for the front end having one transmitter and 16 receiving channels as illustrated in FIG. 1. In this case, the spreading of the position of the phase center results in an angle offset of the viewing direction of the beams and thus also allows an evaluation in the second dimension. In this case, the maximum deviation of the spreading from the mean value must be defined in such a way that for a finite number of receiving rows, the beamforming in the first dimension is not critically influenced.

[0049] FIG. 3 shows by way of example the antenna pattern produced by digital beamforming for a main beam direction of 0° in a comparison between a linear array without and with a spread-out second dimension. It is evident here that the effects of the spreading in the second dimension are manifested only marginally in the antenna pattern, principally at the sidelobes.

[0050] FIG. 4 shows the signal processing for calculating the two-dimensional target position in the form of a signal flow diagram on the basis of the example of an FMCW radar. After the measurement, that is to say the transmission, reception and digitization of a ramp, the basis for the subsequent digital beamforming is firstly established by means of a range FFT and a velocity FFT. The target detection is carried out firstly in the first dimension, e.g. by means of an OSCFAR or a Peak search function, followed by beamforming in the second dimension on the basis of the FFT data at the positions of the targets previously found in the first dimension. The further position determination in the second dimension is carried out as described above. Finally, the two-dimensional data of the so-called range-velo cells are calculated from the combination of both beamformers.

[0051] FIG. 5 illustrates an exemplary arrangement of a MIMO-on-TX radar system based on an elliptic arrangement of the antennas. In the arrangement shown, the phase centers of the eight rows of receiving antennas (6) lie on the contour of the ellipse described by the angle-dependent radius r thereof:

[00001]${r(\partial )}^2=\frac{a^2{b}^2}{a^2\sin (\partial )+b^2\cos (\partial )},$

[0052] wherein the maximum radius is defined by a and the minimum radius of the ellipse is defined by b. In the arrangement shown, here the radius forms the first dimension, the random distribution being applied to the angle, which accordingly represents the second dimension. The MIMO-on-TX is made possible by means of two switchable transmitting antennas (3), which are positioned in different positions relative to the ellipse.

Reference Signs

[0053] 1 Transmitter

[0054] 2 Receiver circuit

[0055] 3 Transmitting antenna

[0056] 4 Phase center

[0057] 5 Row spacing

[0058] 6 Row of receiving antennas

[0059] 7 Viewing direction (deviation 1)

[0060] 8 Directivity characteristic dim. 2 (deviation 1)

[0061] 9 Viewing direction (deviation 2)

[0062] 10 Directivity characteristic dim. 2 (deviation 2)

[0063] 11 Viewing direction (deviation 3)

[0064] 12 Directivity characteristic dim. 2 (deviation 3)

[0065] 13 Sidelobes