RADAR DEVICE AND METHOD FOR OPERATING A RADAR DEVICE

Abstract

A radar device including a transceiver unit and a signal processing unit. The transceiver unit detects a first measuring range including distances from the radar device in a first predefined distance range and outputs first sensor signals. The transceiver unit detects a second measuring range including distances from the radar device in a second predefined distance range and outputs second sensor signals. The signal processing unit evaluates the first and second sensor signals. The first distance range at least partially differs from the second distance range. The distances of the second distance range are greater than a predefined minimum distance.

Claims

1. A radar device, comprising: a transceiver unit configured to detect a first measuring range including distances from the radar device in a first predefined distance range and output first sensor signals, and to detect a second measuring range including distances from the radar device in a second predefined distance range and output second sensor signals; and a signal processing unit configured to evaluate the first sensor signals and the second sensor signals; wherein the first distance range at least partially differs from the second distance range; and wherein distances of the second distance range are greater than a predefined minimum distance.

2. The radar device as recited in claim 1, wherein the second measuring range adjoins the first measuring range or partially overlaps with the first measuring range.

3. The radar device as recited in claim 1, wherein the transceiver unit includes a first radar sensor component, which is configured to detect the first measuring range and output the first sensor signals, and includes a second radar sensor component, which is configured to detect the second measuring range and output the second sensor signals.

4. The radar device as recited in claim 3, wherein a distance resolution of the first radar sensor component differs from a distance resolution of the second radar sensor component.

5. The radar device as recited in claim 1, wherein the transceiver unit includes a radar sensor component which is operable in a first measuring mode to detect the first measuring range and output the first sensor signals and is operable in a second measuring mode to detect the second measuring range and output the second sensor signals.

6. The radar device as recited in claim 1, wherein the transceiver unit includes a bandpass filter, which is configured to suppress frequency components from a baseband signal generated by the transceiver unit to detect the second measuring range which are less than a predefined minimum frequency.

7. The radar device as recited in claim 6, wherein the transceiver unit includes an anti-aliasing filter, the anti-aliasing filter including the bandpass filter.

8. The radar device as recited in claim 6, wherein the predefined minimum frequency is an even-numbered divisor of a maximum frequency of the baseband signal.

9. The radar device as recited in claim 6, wherein the transceiver unit includes: an oversampling analog-to-digital converter, which is configured to provide the baseband signal; and a digital decimation filter, which includes the bandpass filter and is configured to filter the baseband signal provided by the analog-to-digital converter.

10. The radar device as recited in claim 1, wherein the transceiver unit is configured to shift frequencies from a baseband signal generated to detect the second measuring range toward lower frequencies.

11. A method for operating a radar device, comprising the following steps: detecting, using the radar device, a first measuring range including distances from the radar device in a first predefined distance range, and outputting first sensor signals; detecting, using the radar device, a second measuring range including distances from the radar device in a second predefined distance range, and outputting second sensor signals; and evaluating, using the radar device, the first sensor signals and the second sensor signals; wherein the first distance range at least partially differs from the second distance range; and wherein distances of the second distance range are greater than a predefined minimum distance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 shows a schematic top view of a radar device according to one specific embodiment of the present invention to explain measuring ranges.

[0027] FIG. 2 shows a schematic block diagram of the radar device illustrated in FIG. 1.

[0028] FIG. 3 shows a low-pass filter in the baseband as may be used in the related art, for example.

[0029] FIG. 4 shows a bandpass filter for use in a radar device according to the present invention.

[0030] FIG. 5 shows a flowchart of a method for operating a radar device according to one specific embodiment of the present invention.

[0031] In all figures, identical or functionally identical elements and devices are provided with the same reference numerals. The numbering of method steps is used for clarity and in general is not to imply a specific chronological sequence. In particular, multiple method steps may also be carried out at the same time.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0032] FIG. 1 shows a schematic top view of a radar device 100 to explain measuring ranges B1, B2. Radar device 100 is designed to detect both a first measuring range B1 and a second measuring range B2. An angle range of first measuring range B1 is preferably greater than an angle range of second measuring range B2. Furthermore, a maximum distance d1 of first measuring range B1 is less than a maximum distance d2 of second measuring range B2. Furthermore, second measuring range B2 adjoins first measuring range B1, and thus includes distances between maximum distance d1 of first measuring range B1 and maximum distance d2 of second measuring range B2. First measuring range B1 thus corresponds to a close-up range or medium distance range and second measuring range B2 corresponds to a far range.

[0033] The present invention is not restricted to the illustrated design of measuring ranges B1 and B2. According to other specific embodiments, second measuring range B2 may also partially overlap with first measuring range B1. Furthermore, a differing shape of the measuring ranges is also possible. In particular, the angle extension of the measuring ranges may also change with the distance.

[0034] FIG. 2 shows a schematic block diagram of radar device 100. The components of radar device 100 may be implemented in an MMIC (monolithic microwave integrated circuit).

[0035] Radar device 100 includes a transceiver unit 1, which detects first measuring range B1 shown in FIG. 1 and generates a first sensor signal and detects second measuring range B2 shown in FIG. 1 and generates a second sensor signal. Transceiver unit 1 includes a first radar sensor component 11 including first antenna arrangements for detecting first measuring range B1. Furthermore, transceiver unit 1 includes a second radar sensor component 12 including second antenna arrangements for detecting second measuring range B2. A separate antenna arrangement is accordingly provided for each measuring range.

[0036] Transceiver unit 1 includes an oversampling analog-to-digital converter 13 to provide a baseband signal on the basis of the signals emitted and received by second radar sensor component 12. Furthermore, transceiver unit 1 includes a digital decimation filter 14, which includes a bandpass filter 141 and is designed to filter the baseband signal provided by analog-to-digital converter 13. The bandpass filter suppresses frequency components of the baseband signal which are less than a predefined minimum frequency. The predefined minimum frequency is preferably an even-numbered divisor of a maximum frequency of the baseband signal.

[0037] An analog-to-digital converter (not shown) for providing a baseband signal and a low-pass filter for filtering the baseband signal may also be provided for first radar sensor component 11. Alternatively, analog-to-digital converter 13 and filter 141 (preferably operated as a low-pass filter for first radar sensor component 11) may also be provided for processing the emission signals generated by first radar sensor component 11. For example, the sensor signals of first radar sensor component 11 and second radar sensor component 12 may be processed alternately.

[0038] The distance resolution of first radar sensor component 11 may differ from a distance resolution of second radar sensor component 12. The design of bandpass filter 141 is not linked to the maximum baseband frequency of the close-up range. Rather, the selection of the band limits of the filter, in combination with the frequency deviation, may result in a correspondence of the distance ranges at the corresponding limits.

[0039] Furthermore, radar device 100 includes a signal processing unit 2, which evaluates the first sensor signals and the second sensor signals. In particular, signal processing unit 2 may carry out a data fusion of the first sensor signals and the second sensor signals.

[0040] However, the present invention is not restricted to this design. In particular, it may also be provided that transceiver unit 1 only includes a single radar sensor component including antenna elements. Transceiver unit 1 is operable in two different measuring modes. In the first measuring mode, first measuring range B1 is detected and in the second measuring mode, second measuring range B2 is detected.

[0041] Furthermore, transceiver unit 1 may also include an anti-aliasing filter, the anti-aliasing filter including bandpass filter 141.

[0042] Bandpass filter 141 may be implemented in the high-frequency component of the MMIC and preferably in spatial proximity to the analog-to-digital converter. Bandpass filter 141 may be designed as an analog filter before analog-to-digital converter 13 or (as shown in FIG. 2) as a digital filter after analog-to-digital converter 13. If an analog-to-digital converter 141 including oversampling and digital decimation filters is used, new bandpass filter 141 may be integrated easily. A frequency shift may also be integrated in the case of digital filters, so that the aliasing effect does not have to be implicitly used. Such bandpass filters 141 may be implemented easily and cost-effectively using RF CMOS (radio frequency complementary metal-oxide semiconductor) technology.

[0043] Finally, transceiver unit 1 may also be designed to shift frequencies of the baseband signal generated to detect second measuring range B2 toward lower frequencies.

[0044] FIG. 3 shows a typical low-pass filter in the baseband as may be used in the related art, for example. The magnitude (in decibels) is plotted as a function of a normed frequency f.sub.norm (in radiant per sample). Small frequencies which correspond to small distances of the object from the radar device are completely detected and taken into consideration further during the following data evaluation. A radar system according to the related art thus samples baseband signals from 0 Hz up to the maximum frequency with the aid of an analog-to-digital converter. A microcontroller has to process and also store all data for a Doppler FFT (fast Fourier transform).

[0045] In a real receiving system, the analog-to-digital converter including anti-aliasing filter may be designed in such a way that the sampling rate corresponds to approximately twice the maximum occurring frequency, so that the available and transferred baseband extends from 0 Hz to Fs/2, Fs denoting the sampling frequency. However, due to the real signals, this corresponds to the range from −Fs/2 to Fs/2. In IQ mixers, a single sideband processing may take place so that the baseband effectively extends from 0 Hz to Fs/2. However, due to the required complex-valued numbers, the same amount of data is required.

[0046] FIG. 4 shows a bandpass filter for use in a radar device 100 according to the present invention. The filtering in the MMIC takes place in such a way that the entire baseband is no longer sampled and transferred, but only parts of the baseband. One possible embodiment is to only transfer the upper half of the baseband. In IQ systems, this corresponds to the range from Fs/4 to Fs/2. Bandpass filter 141 thus suppresses all signals having a frequency below Fs/4. According to the Nyquist sampling theorem, the sampling rate may thus be reduced. The sampling rate is dependent in this case on the bandwidth of the signals. Higher frequencies may be transformed by aliasing into the lower range, which is unproblematic since the signals located there earlier were suppressed by the filtering.

[0047] In real systems, the sampling rate may be reduced after the filtering and the aliasing effect may also be used.

[0048] FIG. 5 shows a flowchart of a method for operating a radar device, in particular above-described radar device 100.

[0049] In a first method step S1, a first measuring range B1 including distances from radar device 100 in a first predefined distance range is detected by radar device 100. First sensor signals are output. The first distance range at least partially differs from the second distance range. All distances of the second distance range are greater than a predefined minimum distance.

[0050] In a second method step S2, a second measurement range B2 including distances from radar device 100 in a second predefined distance range is detected with the aid of radar device 100. Second sensor signals are output.

[0051] In a third method step S3, radar device 100 evaluates the first and second sensor signals. In particular, a data fusion of the first sensor signals and the second sensor signals may be carried out.