Radar transceiver device
By generating modulated multi-frequency chirp signals using a digital chirp generator and a digital-to-analog converter, the problems of high cost and insufficient flexibility of analog components in existing technologies are solved, and efficient and flexible radar signal generation and processing are achieved.
Patent Information
- Application Number
- CN202480023317.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-03-30
- Filing Date
- 2024-01-23
- Publication Date
- 2025-11-04
AI Technical Summary
Existing radar transceiver devices suffer from high cost and insufficient flexibility in generating modulated multi-frequency chirped signals, especially in MIMO systems where efficient frequency reuse and modulation are difficult to achieve.
At least two digital chirp generators and digital-to-analog converters are used to digitally generate and modulate the chirp signal, which is then converted to the radar band in an IQ mixer, reducing the use of analog components. At the receiving end, the reflected signal is processed by analog-to-digital conversion and digital mixing, reducing the analog complexity of the receiving path.
It achieves efficient and flexible generation and processing of multi-frequency tone chirped signals, reduces costs and improves the modulation flexibility of the system, especially simplifying the complexity of analog implementation in multi-frequency tone signals.
Smart Images
Figure CN120898150A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a radar transceiver device for generating a modulated multi-tone chirp signal (linear frequency modulated signal). BACKGROUND
[0002] Such radar transceiver devices are used, for example, in vehicles in order to implement driving assistance systems and driving safety systems.
[0003] It is also known from the prior art to combine the chirp sequence modulation method with MIMO (Multiple-Input Multiple-Output) radar systems. Here, the chirp signal is transmitted via a plurality of transmitting antennas and the reflected signal is received via a plurality of receiving antennas. In order to implement multiplexing of the plurality of transmitting antennas, various multiplexing methods are used, such as the TDM (Time-Division-Multiplexing), FDM (Frequency-Division-Multiplexing) or DDM (Doppler-Division-Multiplexing) method. Furthermore, there are radar sensors which enable transmit beam steering, in which the same modulated signal is transmitted on a plurality of transmitters, but with different phases and amplitudes.
[0004] The necessary chirp signals are usually generated with analog components, such as voltage-controlled oscillators, so-called VCOs (Voltage-Controlled Oscillator). In order to implement a modulation such as DDM or TX beam steering, analog phase shifters are used in order to modulate the phase of the analog chirp signal. The reflected signal is analog mixed with the transmitted chirp signal, low-pass filtered and then digitized. The thus digitized signal is then further processed with digital signal processing methods. SUMMARY
[0005] The radar transceiver device for generating a modulated multi-tone chirp signal enables an efficient and flexibly configurable implementation of a chirp sequence radar which enables different modulated chirp signals with frequency multiplexing in a MIMO system, having a transmitting device with at least two digital chirp generators which each generate a complex digital chirp signal with configurable parameters, having at least two transmitting paths, each of the chirp generators generating a signal for the transmitting path by combining the chirp signals, which is analog converted by a digital-to-analog converter in order to transmit a radar signal via a transmitting antenna.
[0006] An important aspect of the present application is to realize a hardware architecture for the efficient digital generation of a modulated multi-tone chirp signal and a hardware architecture related thereto for the efficient digital demodulation of a reflected chirp signal.
[0007] Furthermore, an important aspect of the present application is that the processing of the chirp signal is carried out digitally. This aspect relates to the purely digital generation of the modulation. Subsequently, the digital signal is converted by means of a digital-to-analog converter and converted into the radar frequency band in an IQ mixer. The share of analog components, which are cost-intensive and subject to tolerances, is kept to a minimum while achieving the greatest flexibility in the modulation beyond the conventional signal generation methods. This is particularly advantageous in the case of multi-tone signals, where an analog implementation would be very complex, while in a digital implementation the high degree of freedom can be well exploited.
[0008] According to an aspect of the present application, a receiving device is provided, which has at least two receiving antennas for receiving at least two reflected chirp signals at an object, which reflected chirp signals are each fed to an analog-to-digital converter and digitally mixed in at least one receiving path assigned to each receiving antenna with at least one of the transmitted chirp signals by means of a complex multiplier. In correspondence with the process at the signal transmission, the received reflected chirp signals are digitally mixed with the transmitted chirp signals in the complex baseband and further processed only after the analog-to-digital conversion. In this way, the complexity in the analog part of the receiving path is also reduced in the case of multi-tone signals compared to analog mixing, since only one analog quadrature mixer is required even if there are multiple tones.
[0009] Here, the configurable parameters at least include a start phase, a start frequency, a ramp slope and a ramp length.
[0010] The local oscillators required for mixing into the transmission band here usually work at one fixed frequency or run in several discrete frequency stages (usually 2 to 16). This makes it possible to increase the overall bandwidth of the radar transmission or, for example, to avoid interfering signals. However, the frequency of the local oscillators does not change during the transmission of the chirp signal.
[0011] According to an aspect of the present application, the chirp signals are each weighted with an individualized complex parameter before the chirp signals are combined in the transmission path. Here, the configurable parameters can include these individualized complex parameters.
[0012] According to an aspect of the present application, the mixing of the at least two reflected chirp signals with the transmitted chirp signal is provided after the reversal of the frequency.
[0013] According to a further aspect of the application, the mixed signal is low-pass filtered and the sampling rate is reduced.
[0014] Instead of at least a second chirp generator, a complex sinusoidal wave generator and at least one additional frequency mixer can also be provided.
[0015] According to an aspect of the application, in each reception path, the received chirp signals are separated in a filter bank provided for this purpose. BRIEF DESCRIPTION OF DRAWINGS
[0016] Embodiments of the application are illustrated in the drawings and are described in detail below.
[0017] Figure 1 A transmitting device according to the application with at least two digital chirp generators is shown.
[0018] Figure 2 A receiving device according to the application with at least two receiving antennas for receiving at least two chirp signals reflected at an object is shown.
[0019] Figure 3 An extension of the transmitting device according to the application with three digital chirp generators is shown.
[0020] Figure 4 A cascade structure for generating a plurality of frequency-shifted chirp signals is shown.
[0021] Figure 5 An extension of the receiving device according to the application for demodulating reflected radar signals with more than two tones is shown.
[0022] Figure 6 Separation of individual tones of a multi-tone chirp signal by means of a "multi-channel demodulator" is shown. DETAILED DESCRIPTION
[0023] In Figure 1 A basic form of a hardware architecture for generating a modulated multi-tone chirp signal composed of two tones is shown in Fig. 1. Two digital chirp generators 110, 120 are provided. These two digital chirp generators are capable of generating complex digital chirp signals with configurable parameters independently of each other. These configurable parameters can be, for example, a start frequency, a start phase, a ramp slope or a ramp length. Each of these chirp signals can be associated with a complex parameter , The multiplication is carried out as shown by the multipliers 111, 112, 121, 122. For this purpose, complex multipliers are provided whose number is the number of transmit antennas multiplied by two. In this way, for each transmit antenna two chirp signals with configurable amplitude and phase are obtained. Depending on the modulation desired, it is sufficient for the complex parameters to change only from ramp to ramp (for example DDM beamforming or TX beamforming), or the complex parameters can also change during the transmit ramp for other modulation methods (for example code division multiplexing, CDM) in the case of the respective design. In this way, in principle all modulation methods based on modulation of the amplitude and / or phase of the chirp signals can be implemented. For each of the transmit antennas TX1, TX2, the modulated chirp signals are added. For this purpose, adders 130, 140 are provided. In this way, for each transmit antenna TX1, TX2, an individual modulated multitone chirp signal is obtained. These digital multitone chirp signals are converted into analog signals by digital-to-analog converters 150, 160. In this way, for each of the transmit antennas TX1, TX2, there are two analog signals each, which represent the in-phase component (I) and the quadrature component (Q) of the multitone chirp signal, respectively. These signals are converted to the desired radar frequency band using quadrature mixers 155, 165 (for this purpose a local oscillator 170 is used), amplified by means of amplifiers 157, 167 and transmitted by means of antennas TX1, TX2.
[0024] The receive path is shown in Figure 2 In the receive path, the reflected analog radar signals received by the receive antennas RX1, RX2 are amplified by means of amplifiers 201, 202 and converted into the complex baseband for each receive antenna RX1, RX2 using quadrature mixers 210, 220. The mixing is done by means of a local oscillator 270. Subsequently, the signals are converted into digital signals by means of analog-to-digital converters 215, 225. Now, the receive path of each receive antenna RX1, RX2 branches into two paths each. Each of these paths comprises a complex multiplier 232, 234 or 242, 244, which mixes the receive signal with one of the chirp signals generated on the transmit side (but with negated frequency), respectively. The negated frequency is achieved, for example, by inverting the sign of the imaginary part. The signals are then digitally low-pass filtered by means of the respective low-pass filters 252, 254 or 262, 264 and the sampling rate is reduced by means of decimators 272, 274 or 282, 284. In this way, for each receive antenna RX1, RX2 and for each individual transmit tone, a separate signal is obtained, which can be further processed using the methods known per se for digital radar signal processing.
[0025] In Figure 3 and Figure 5 extensions in more than two tones are shown. Here, the same elements are shown with the same reference signs as in Figure 1 and Figure 2 . Here, extensions to three tones are shown in Figure 3 and Figure 5 , respectively. For this, three digital chirp generators 310, 320, 330 are provided in Figure 3 , wherein the number of multipliers is increased to three, namely 311, 321, 331 or 312, 322, 332, respectively. For each transmit antenna TX1, TX2, the three modulated chirp signals are added in adders 130, 140 and further processed as described in connection with Figure 1 .
[0026] The receive path basically corresponds to that shown in Figure 2 , wherein, however, three complex multipliers 532, 534, 536 or 542, 544, 546, respectively, are provided and low-pass filtered in three low-pass filters 552, 554, 556 or 562, 564, 566, respectively. After the low-pass filters, three decimators 582, 584, 586 or 572, 574, 576, respectively, are connected for reducing the sampling rate.
[0027] When a very large number of tones has to be generated, a reduction of the hardware effort can be meaningful and a cascade structure can be used as it is shown, for example, in Figure 4 . Here, only one chirp signal is generated by one digital chirp generator 410 and a complex sinusoid with a fixed frequency is generated by means of a Numerically Controlled Oscillator (NCO) 405. These signals are digitally mixed with each other several times by means of multipliers 420, 421, 422, 423, 424, 425, 426 and 427. This multiple digital mixing is done to obtain a plurality of chirp signals with the same bandwidth and slope gradient which are equally spaced in frequency. In this case, only one digital chirp generator 410 and one complex sinusoid generator (Numerically Controlled Oscillator, NCO) 405 are needed at all times, regardless of the number of tones, wherein, however, the number of multipliers 420 to 427 required increases with the number of tones. Further signal processing is done as described in connection with Figure 1 .
[0028] In Figure 5The receiver side, schematically shown—as previously explained—can process a higher number of frequencies, with a path containing a mixer and a low-pass filter replicated for each frequency. Each path is then individually mixed with the frequencies that need to be separated.
[0029] Apart from Figure 5 In addition to the circuit shown, the individual frequencies of the multi-frequency chirp signal can be separated using so-called multi-frequency converters 650 and 660, such as in... Figure 6 As illustrated in the diagram, the same elements utilize the same... Figure 2 The same reference numerals are used in the accompanying drawings, so that the description of these elements refers to the description of the elements in relation to the figures. Figure 2 The description states that the imaginary part is inverted as described above in multipliers 630 and 640, and the individual frequencies are separated in the aforementioned multi-frequency converters 650 and 660.
Claims
1. A radar transceiver device for generating modulated multi-frequency tone chirped signals, characterized in that... The transmitter includes a transmitting device and at least two transmission paths. The transmitting device has at least two digital chirp generators (110, 120; 310, 320, 330), each of which generates a complex digital chirp signal with configurable parameters. Each chirp generator (110, 120; 310, 320, 330) generates a signal for the at least two transmission paths by combining the chirp signals. The signal is then converted to analog signal by a digital-to-analog converter (150, 160) to transmit a radar signal through a transmitting antenna (TX1, TX2).
2. The radar transceiver device according to claim 1, characterized in that... A receiving device having at least two receiving antennas (RX1, RX2) for receiving at least two chirped signals reflected at an object, the reflected chirped signals being respectively sent to analog-to-digital converters (215, 225) and digitally mixed with at least one of the transmitted chirped signals in at least one receiving path associated with each receiving antenna (RX1, RX2) by means of a complex multiplier.
3. The radar transceiver device according to claim 1 or 2, characterized in that, In the transmitting and receiving devices, the signal is converted between the complex baseband and the radar band by quadrature mixers (155, 165; 210, 220) and local oscillators (170; 270).
4. The radar transceiver device according to claim 1, characterized in that, The configurable parameters include at least: starting phase, starting frequency, slope gradient, and slope length.
5. The radar transceiver device according to claim 1, characterized in that, Before combining the chirped signals in the transmission path, each chirped signal is weighted with an individualized complex parameter.
6. The radar transceiver device according to claims 4 and 5, characterized in that, The configurable parameters include individualized complex parameters.
7. The radar transceiver device according to claim 2, characterized in that, After reversing the frequency, at least two reflected chirped signals are mixed with the transmitted chirped signal.
8. The radar transceiver device according to claim 2, characterized in that, A low-pass filter (252, 254, 262, 264; 552, 554, 556, 562, 564, 566) and a decimator (272, 274, 282, 284; 572, 574, 576, 582, 584, 586) are configured in the receiving path. The mixed signal is low-pass filtered in the low-pass filter, and the sampling rate is reduced in the decimator.
9. The radar transceiver device according to claim 1, characterized in that, Instead of at least one second chirp generator, a complex sine wave generator (405) and at least one additional mixer (420, 423, 426) are provided.
10. The radar transceiver device according to claim 2, characterized in that, In each receiving path, the received chirped signal is separated in a filter bank (650, 660) configured for this purpose.