Slow time modulation for multiple radar channels

Abstract

This document describes techniques and systems for slow time modulation of multiple radar channels. One set of transmit channels is modulated using a code sequence to phase modulate the transmit signal. A second set of transmit channels is modulated using the same code for phase modulation and using a frequency phase shift. Demodulation is achieved by multiplying the received signal by the code sequence. A Fast Fourier Transform (FFT) is applied to the received signal to generate a range Doppler map for each receive channel. A non-coherent integration is performed on the range Doppler map to form a range Doppler average map. The range Doppler average map is shifted by a frequency phase shift and the minimum values ​​in the range Doppler average map and the shifted range Doppler average map are retained. These techniques can reduce the effects of signal residues and improve angular resolution by enabling the use of multiple transmit channels.

Description

Background Art

[0001] Multiple-input multiple-output (MIMO) radar systems may have multiple transmit and receive channels. A greater number of channels results in better angular resolution. However, increasing the number of channels also has disadvantages, such as reduced signal-to-noise ratio (SNR), reduced Doppler coverage, and in some cases, negatively affecting Doppler dynamic range and limiting the number of simultaneously transmitting channels. Radar systems are the basis for some advanced safety and autonomous driving systems that are becoming standard equipment in today's modern cars. Low-cost radar systems that can handle multiple high-resolution channels simultaneously are desirable for improving driving safety. Summary of the invention

[0002] This document describes techniques and systems for slow time modulation of multiple radar channels. One set of transmit channels is modulated using a code sequence to phase modulate the transmit signal. A second set of transmit channels is modulated using the same code for phase modulation and using a frequency phase shift. Demodulation is achieved by multiplying the received signal by the code sequence. A Fast Fourier Transform (FFT) is applied to the received signal to generate a range Doppler map for each receive channel. A non-coherent integration is performed on the range Doppler map to form a range Doppler average map. The range Doppler average map is shifted by a frequency phase shift and the minimum values ​​in the range Doppler average map and the shifted range Doppler average map are retained. These techniques can reduce the effects of signal residues and improve angular resolution by enabling the use of multiple transmit channels.

[0003] In one example, a method includes modulating, by a radar system, a first group of transmit channels based on a first group of code sequences to transmit a plurality of chirp signals having a phase modulation defined by the first group of code sequences. The method further includes modulating, by the radar system, a second group of transmit channels based on: based on the first group of code sequences, the second group of transmit channels for transmitting a plurality of chirps having a phase modulation defined by the first group of code sequences; and based on a first group of frequency phase shift sequences, the second group of transmit channels for transmitting a plurality of chirp signals having a frequency phase shift defined by the first group of frequency phase shift sequences. The method further includes: in response to transmitting a plurality of chirp signals associated with the first group of transmit channels and a plurality of chirp signals associated with the second group of transmit channels, receiving a plurality of chirp returns from one or more receive channels. The method further includes: in response to demodulating the plurality of chirp returns based on the first group of code sequences, outputting, by the radar system to the automotive system, radar data identifying an object inferred from the demodulated plurality of chirp returns.

[0004] In another example, in addition to describing a system configured to perform the method outlined above and other methods described herein, a radar system includes a first set of transmit channels, a second set of transmit channels, one or more receive channels, and at least one processor configured to perform this method and other methods described herein.

[0005] This Summary introduces a simplified concept of slow-time modulation for multiple radar channels. This Summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used to determine the scope of the claimed subject matter. That is, one problem solved by the described technology is to increase the number of channels that can be used with minimal negative impact. Thus, while primarily described in the context of increasing the functionality of automotive radar systems, slow-time modulation for multiple radar channels may be applied to other applications where improved angular resolution is desired. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Details of one or more aspects of slow time modulation for multiple radar channels are described in this document with reference to the following figures. The same numbers are generally used throughout the figures to reference similar features and components:

[0007] Figure 1 An example environment in which slow-time modulation for multiple radar channels may be applied is shown in accordance with techniques of this disclosure;

[0008] Figure 2 An example automotive system configured to perform slow-time modulation for multiple radar channels in accordance with techniques of this disclosure is shown;

[0009] Figure 3 An example modulation scheme according to the techniques of this disclosure is shown that may be used to perform slow-time modulation for multiple radar channels;

[0010] Figure 4 An example demodulation scheme according to the techniques of this disclosure is shown that can be used to perform slow-time modulation for multiple radar channels;

[0011] Figure 5-1 and Figure 5-2 an example Doppler graph showing a range-Doppler graph generated by slow-time modulation for multiple radar channels in accordance with the techniques of this disclosure; and

[0012] Figure 6 An example method for slow-time modulation of multiple radar channels in accordance with the techniques of this disclosure is shown. DETAILED DESCRIPTION

[0013] Overview

[0014] Radar systems are utilized in many applications, including autonomous vehicles. Multiple-input, multiple-output (MIMO) radar systems are particularly well suited for vehicles because MIMO radar systems are able to detect and track multiple objects well. However, MIMO radar systems still have room for improvement. It is expected that MIMO radar systems will be able to process a large number of channels simultaneously with high angular resolution. Manufacturers are continually working to improve MIMO radar technology by increasing angular resolution and reducing or at least minimizing the effects of signal remnants. Achieving these goals may ultimately improve the safety of vehicles using improved radar systems.

[0015] MIMO radar systems utilize multiple transmit and receive channels, which are essentially signal paths that propagate signals between antennas and transmitters or receivers. Increasing the number of channels in a MIMO radar system can improve angular resolution. One advantage of higher angular resolution is the ability to detect smaller objects next to larger objects. However, in general, increasing the number of channels may increase the signal residual, which is the distributed energy from the suppressed signal present in the recovered signal experienced by each receive channel. Higher signal residuals may reduce Doppler dynamic range.

[0016] Since MIMO radar requires that all transmit channels are orthogonal to each other, several methods for achieving orthogonality have been used. One method is time multiplexing, which uses a different time slot for each transmitter channel. The time multiplexing method increases the pulse repetition period and therefore reduces the Doppler coverage. This method also reduces the signal-to-noise ratio (SNR) due to the reduced duty cycle for each transmitter channel.

[0017] Another method used to achieve orthogonality is to apply binary phase modulation (BPM). BPM enables the radar sensor to transmit on multiple channels simultaneously. While BPM does not degrade Doppler coverage or signal-to-noise ratio, it has some negative effects on Doppler dynamic range and limits the number of channels that can transmit simultaneously. Signal residues present during demodulation can degrade the Doppler dynamic range. The degradation is more severe as the number of transmit channels increases. The degradation of Doppler dynamic range can make it difficult to detect smaller objects next to larger objects. For example, the radar may not be able to detect a pedestrian next to a car.

[0018] To overcome some of the challenges and shortcomings of previous modulation methods, this document describes a slow time modulation process to improve both signal-to-noise ratio and angular resolution. As described herein, this proposed modulation method combines code division multiplexing (CDM) and frequency division multiplexing (FDM) to increase the number of channels that can be utilized in a MIMO radar scheme. The proposed modulation technique maintains a residual level similar to time division multiplexing (TDM). In addition, the signal-to-noise ratio is improved relative to TDM and approaches the signal-to-noise ratio level achieved by CDM. In this way, the angular resolution can be increased and the maximum Doppler dynamic range can be maintained.

[0019] Example Environment

[0020] Figure 1 An example environment 100 is shown in which slow time modulation for multiple radar channels may be applied in accordance with the techniques of the present disclosure. Vehicle 102 is equipped with radar system 104, which is configured to perform slow time modulation on multiple radar channels. Although depicted as a car, vehicle 102 may represent other types of vehicles and machinery (e.g., motorcycles, buses, tractors, semi-trailer trucks, watercraft, aircraft, or other heavy equipment), including manned or unmanned systems that may be used for a variety of purposes. Vehicle 102 is traveling on road 112. Moving or stationary objects (e.g., vehicles 114 and pedestrians 116) may also be similarly in or near road 112.

[0021] The radar system 104 includes at least one radar sensor 106, a first group of transmit channels 108-1, a second group of transmit channels 108-2, and one or more receive channels 110. More groups of transmit channels 108 may also be included. The radar system 104 may detect objects in a field of view (FOV) based on radar signals transmitted by the first group of transmit channels 108-1 and the second group of transmit channels 108-2, which are reflected from objects (such as vehicles 114 and pedestrians 116) and received by the group of receive channels 110. The radar system 104 may be able to detect vehicles 114 and pedestrians 116 even if the vehicles 114 and pedestrians 116 are very close to each other. This may be due to the increased angular resolution due to maximizing the number of transmit channels used.

[0022] In general, a manufacturer may mount radar system 104 to any mobile platform that can travel on road 112. For example, a manufacturer may integrate features of a radar system (such as one or more radar sensors) into a side mirror, a roof, a bumper, or any other interior or exterior location (where the FOV includes road 112 and any objects, moving or stationary, near road 112). In this example, a portion of radar system 104 is mounted near the front bumper of vehicle 102.

[0023] The radar system 104 includes machine-readable instructions that, when executed by a processor or other logic of the radar system 104, cause the processor or other logic to modulate, transmit, receive, and demodulate radio frequency (RF) energy to detect and identify targets. The radar system 104 may include a combination of hardware, software, and / or firmware for detecting and identifying targets for an automotive system.

[0024] The first group of transmit channels 108-1 is modulated based on a set of code sequences, each code sequence corresponding to a single transmit channel in the first group of transmit channels 108-1. The code sequences are unique relative to each other and can be generated by a random number generator. The code sequences are applied to a plurality of chirp signals to be transmitted by the first group of transmit channels 108-1. An example of such a modulation scheme is BPM.

[0025] The second group of transmit channels 108-2 is modulated by two modulation schemes. The first modulation scheme of the two modulation schemes is the same as the scheme used on the first group of transmit channels 108-1. Then, the second modulation scheme of the two modulation schemes includes a frequency phase shift, which is applied to the chirp signal to be transmitted by the second group of transmit channels 108-2. The phase shift may be a rotator phase shift. By further modulating the second group of transmit channels 108-2 with the second modulation scheme, the impact of the signal residual experienced by each individual channel can be reduced, thereby enabling the radar system 104 to use a greater number of transmit channels without degrading the Doppler dynamic range of the radar system 104.

[0026] One or more receive channels 110 receive chirp returns associated with the first group of transmit channels 108-1 and the second group of transmit channels 108-2. Once the chirp returns are demodulated, radar data can identify objects inferred from the chirp returns and can be output to the automotive system. The automotive system can use the radar data to assist in driving operations, which can improve the safety of operating the vehicle 102.

[0027] Figure 2 An example automotive system 200 is shown that is configured to perform slow-time modulation for multiple radar channels in accordance with techniques of this disclosure. The automotive system 200 may be integrated within the vehicle 102 .

[0028] The automotive system 200 includes a controller 202 and a radar system 104-1, which is an example of a radar system 104. The radar system 104-1 includes a radar sensor 106-1, however, any number of radar sensors 106-1 may be used. The controller 202 and the radar system 104-1 communicate via a link 204. The link 204 may be a wired or wireless link, and in some cases includes a communication bus. The controller 202 performs operations based on information received from the radar system 104-1 via the link 204, such as data output from the radar system 104-1, including information indicating one or more objects identified and tracked in the FOV.

[0029] The controller 202 includes a processor 206 and a computer readable storage medium (CRM) 222 (e.g., memory, long-term storage, short-term storage) that stores instructions for the automotive module 208. Similarly, the radar system 102 includes processing hardware that may include a processor 212 and a computer readable storage medium (CRM) 214. The processors 206 and 212 may be two separate microprocessors, or a single microprocessor, or a pair of systems on a chip or a single system on a chip of a computing device, controller, or control unit. The processors 206 and 212 execute computer executable instructions stored in the CRMs 222 and 214.

[0030] Processor 206 may execute automobile module 220 to perform driving functions or other operations of automobile system 200, which may include using output from radar system 104-1 to help determine driving decisions. For example, automobile module 220 may provide automatic cruise control and monitor radar system 104-1 for output indicating the presence of objects in the FOV, for example, to reduce speed and prevent collisions with vehicles 114 or pedestrians 116. When data obtained from radar module 104-1 indicates that one or more objects are crossing in front of vehicle 102, automobile module 220 may provide an alert or perform a specific maneuver.

[0031] The CRM 214 stores a modulation and demodulation module 216 associated with the radar system 104-1. Similarly, the CRM stores a code sequence 218-1 and a frequency phase shift 218-2 used by the modulation and demodulation module 216 to modulate radar signals transmitted by the first set of transmit channels 208-1 and the second set of transmit channels 208-2, and demodulate signal returns received by the receive channel 210. Objects in the FOV may be inferred based on the demodulated signal returns obtained from a plurality of different sensors 106 of the vehicle 102. The automobile module 220, when executed at the processor 206, may receive an indication of one or more objects detected by the radar system 104-1 in response to the radar system 104-1 combining and analyzing sensor data generated at each of the sensors 106 (e.g., the radar sensor 106-1).

[0032] Also like Figure 2 As shown, radar system 104 includes at least first and second groups of transmit channels 208-1 and 208-2, and a group of receive channels 210. Radar system 104 is not limited to two groups of transmit channels 208, and may include more groups of transmit channels than depicted.

[0033] Example Modulation and Demodulation Schemes

[0034] Figure 3 An example modulation scheme 300 is shown that can be used to perform slow time modulation for multiple radar channels according to the techniques of this disclosure. The modulation scheme 300 is composed of Figure 2 The modulation and demodulation module 216 is performed by the radar system. The example modulation scheme 300 includes transmissions by the radar system using a first set of transmit channels 302 and a second set of transmit channels 304. For simplicity, the modulation scheme 300 is described as resulting in transmissions from only two sets of transmit channels; however, more than two sets of transmit channels may be used.

[0035] The first group of transmit channels 302 includes transmit channels Tx1 to TxN, which can transmit a series of chirps 306. The first group of transmit channels 302 can be modulated by CDM (e.g., BPM) and use a series of codes (code 1 to code N) to combine with and modulate the chirps 306. Each code in the code sequence can be generated using a random number generator and is unique relative to other codes in the sequence.

[0036] The second group of transmit channels 304 may use the same code sequence and frequency shift sequence as the first group of transmit channels 302 (e.g., [1, exp exp …,exp ], where K is the number of chirps in the series, and If more than two transmission channels are used, There can be a different value for each set of transmit channels that is being frequency shifted.

[0037] Figure 4 An example modulation scheme 400 is shown that can be used to perform slow time modulation for multiple radar channels in accordance with the techniques of this disclosure. The example modulation scheme 400 is composed of Figure 2 The modulation and demodulation module 216 is performed by the radar system. The example modulation scheme 400 includes receiving using a set of receive channels 402 (eg, receive channels 402-1 to 402-M).

[0038] When the receive channel 402 receives the chirp return, the chirp return is formatted for further processing (e.g., the analog signal is digitized into a digital version representing the chirp return received over time), and a range FFT is applied to the chirp return at 404. The chirp return 306 is demodulated by multiplying the chirp return by the code sequence used to modulate the chirp, and a Doppler FFT is applied to the chirp return at 406. As a result of the previous steps, at 408, each receive channel 402 has generated a number of range-Doppler maps equivalent to the number (N) of transmit channels in each group of transmit channels (e.g., the first group of transmit channels 302 and the second group of transmit channels 304).

[0039] At 410, a non-coherent integration is performed on all range-Doppler maps to form a single range-Doppler average map. At 412, the rotator is shifted (e.g., frequency shifted) ) is applied to the range-Doppler average map, thereby creating a shifted range-Doppler average map. The range-Doppler average map 414 and the shifted range-Doppler average map 416 are compared, and the minimum is selected at 418. The radar system further uses the minimum range-Doppler map 420 as radar data output to a tracking system or automotive system to identify and avoid targets.

[0040] Example Implementation

[0041] Figure 5-1 and Figure 5-2 Example Doppler graphs (500-1, 500-2) of range Doppler graphs generated by slow time modulation for multiple radar channels according to the techniques of the present disclosure are shown. To generate the example range Doppler graph 500-1, three BPM code sequences and one frequency shift may be used. The frequency shift may be set to radians. After executing Figure 4After step 410, the range Doppler map is generated. In the range Doppler map, the number of peaks is twice the number of targets. For example, a target may be located at Doppler bin 101, and the range Doppler map generated may include two peaks, one of which is located at Doppler bin 101, and the other is located at Doppler bin 349, as shown by the solid curve in Doppler graph 500-1. After the rotator shifts at step 412, as shown by the dotted line in Doppler graph 500-1, Doppler bin 249-512 shifts to Doppler bin 1-263, and Doppler bin 1-248 shifts to Doppler bin 264-512. After taking the minimum value between the solid line and the dotted line, a single curve is shown in Doppler graph 500-2. Compared with other modulation schemes using the same example parameters, the example implementation for creating Doppler graphs 500-1 and 500-2 may have advantages. For example, using a TDM scheme may result in an SNR loss of approximately 3 decibels (dB) compared to the scheme described in the exemplary implementation. The Doppler dynamic range degradation may be less than that with a BPM scheme. In addition, the exemplary implementation may require less processing to compensate for the signal residual.

[0042] Example Method

[0043] Figure 6 An example method 600 for slow time modulation of multiple radar channels according to the techniques of the present disclosure is shown. At 602, a first set of transmit channels for transmitting multiple chirp signals is modulated based on a first set of code sequences. The code sequence defines a phase modulation. For example, from Figure 2 The first set of transmit channels 208-1 is modulated by the modulation and demodulation module 216 using the code sequence 218-1 and the CDM scheme. The chirp signal associated with each transmit channel is combined with the code sequence of each transmit channel. The code sequence can be a binary code sequence (e.g., BPM) that, when combined with the chirp signal, shifts the phase of the single chirp signal by π or does not shift the phase of the chirp signal.

[0044] At 604, a second set of transmit channels for transmitting a plurality of chirp signals is modulated based on the first set of code sequences. The second set of transmit channels is also modulated based on the first set of frequency phase shift sequences defining frequency phase shifts. Similarly, in the same example, Figure 2 The second set of transmit channels 208-2 is modulated by modulation and demodulation module 216 using code sequence 218-1 and additional frequency phase shift 218-2. Using a combination of CDM and FDM on the second (and subsequent) set of transmit channels 208-2 enables more channels to be utilized while minimizing the negative effects of the increased number of channels.

[0045] At 606, in response to transmitting a chirp signal associated with a first group of transmit channels and a second group of transmit channels, one or more receive channels receive a plurality of chirp returns. In the example, one or more receive channels 210 may receive a plurality of chirp returns associated with a first group of transmit channels 208-1 and a second group of transmit channels 208-2. One or more receive channels 210 demodulate the chirp returns by applying both the code sequence 218-1 and the frequency phase shift 218-2. In this example, the demodulation process may further include applying a range FFT and a Doppler FFT to the chirp returns. At this step, the chirp returns are demodulated based on the code sequence 218-1, and a range Doppler map is generated for each receive channel. Non-coherent integration is performed on the range Doppler map generated by each receive channel to generate a single range Doppler average map. The range Doppler average map may be frequency shifted using the frequency phase shift 218-2 to create a shifted range Doppler average map. The range-Doppler average map and the shifted range-Doppler average map may be compared and the smallest map may be selected to be used by the radar system 104 - 1 or the car module 220 .

[0046] At 608, in response to demodulating the plurality of chirp returns, the radar system outputs radar data identifying an object inferred from the demodulated plurality of chirp returns to the automotive system. In an example, radar system 104-1 may output radar data inferred from the demodulated plurality of chirp returns to automotive module 220 of automotive system 200 via link 204. Because radar system 104-1 uses multiple transmit channels, the radar data may have sufficient Doppler dynamic range to detect large objects as well as small objects (e.g., objects from a vehicle) even if the large objects and the small objects are very close to each other. Figure 1 The vehicle module 200 may initiate a maneuver (e.g., slow down, turn) or alert the operator of the host vehicle (e.g., vehicle 102) of any object identified by the radar data. In this scenario, the pedestrian 116 may be walking behind the vehicle 114 and crossing the road 112. The vehicle 102, which is equipped with a radar system 104 using slow time modulation for multiple radar channels, detects both the vehicle 114 and the pedestrian 116. When the pedestrian 116 steps out into the road 112 in front of the vehicle 102, the vehicle 102 is able to brake the vehicle and avoid the pedestrian 116. In this way, collisions and injuries can be avoided because the Doppler dynamic range has an angular resolution that enables the radar to track large and small objects in the field of view even if they are close to each other.

[0047] Additional Examples

[0048] Example 1: A method, the method comprising: modulating a first group of transmit channels by a radar system based on a first group of code sequences to transmit a plurality of chirp signals having a phase modulation defined by the first group of code sequences; modulating a second group of transmit channels by the radar system based on: based on the first group of code sequences, the second group of transmit channels are used to transmit a plurality of chirps having the phase modulation defined by the first group of code sequences; and based on a first group of frequency phase shift sequences, the second group of transmit channels are used to transmit a plurality of chirp signals having a frequency phase shift defined by the first group of frequency phase shift sequences; in response to transmitting the plurality of chirp signals associated with the first group of transmit channels and the plurality of chirp signals associated with the second group of transmit channels, receiving a plurality of chirp returns from one or more receive channels; and in response to demodulating the plurality of chirp returns based on the first group of code sequences, outputting radar data by the radar system to an automotive system, the radar data identifying an object inferred from the demodulated plurality of chirp returns.

[0049] Example 2: The method of Example 1 further includes: demodulating multiple chirp returns based on the first group of code sequences in the following manner: digitizing the multiple chirp returns received by the one or more receiving channels by the radar system for application of a range fast Fourier transform (FFT); and in response to digitizing the multiple chirp returns received by the one or more receiving channels: applying the range FFT to the multiple chirp returns received by the one or more receiving channels by the radar system; multiplying the multiple chirp returns received by the one or more receiving channels by the radar system by the first group of code sequences; and applying a Doppler FFT to the multiple chirp returns received by the one or more receiving channels by the radar system.

[0050] Example 3: The method of any of the preceding examples, wherein applying the range FFT to the multiple chirp returns received by the one or more receive channels further comprises: applying, by the radar system, a window function to the multiple chirp returns before applying the range FFT.

[0051] Example 4: The method of any of the preceding examples, wherein applying the Doppler FFT to the plurality of chirp returns received by the one or more receive channels further comprises: applying, by the radar system, a window function to the plurality of chirp returns prior to applying the Doppler FFT.

[0052] Example 5: The method of any of the preceding examples, further comprising: generating, by the radar system, a range Doppler map for each of the one or more receive channels for incoherent integration of the one or more receive channels.

[0053] Example 6: The method of any of the preceding examples, further comprising: performing, by the radar system, the non-coherent integration of all of the range-Doppler maps generated for the one or more receive channels to form a single average range-Doppler map.

[0054] Example 7. The method of any of the preceding examples, further comprising: generating, by the radar system, a rotator-shifted range-Doppler average map by shifting the frequency phase of the range-Doppler map; and selecting, by the radar system, a minimum value between the range-Doppler average map and the shifted range-Doppler average map.

[0055] Example 8: The method of any of the preceding examples, wherein the first set of code sequences comprises binary codes.

[0056] Example 9: The method of any of the preceding examples, further comprising: generating each code sequence in the first set of code sequences by the radar system using a random number generator, the random number generator providing a unique code to each code sequence in the first set of code sequences relative to each other code sequence from the first set of code sequences.

[0057] Example 10: The method of any one of the preceding examples, further comprising: modulating at least a third group of transmission channels based on: based on the first group of code sequences, the at least third group of transmission channels is used to transmit a plurality of chirps having a phase modulation defined by the first group of code sequences; and based on at least a second group of frequency phase shift sequences, the at least third group of transmission channels is used to transmit a plurality of chirp signals having a frequency phase shift defined by the at least second group of frequency phase shift sequences.

[0058] Example 11: A radar system comprising: a first group of transmit channels; a second group of transmit channels; one or more receive channels; and at least one processor, the at least one processor being configured to: modulate the first group of transmit channels based on a first group of code sequences to transmit a plurality of chirp signals having a phase modulation defined by the first group of code sequences; modulate the second group of transmit channels based on: based on the first group of code sequences, the second group of transmit channels are used to transmit a plurality of chirps having the phase modulation defined by the first group of code sequences; and based on a first group of frequency phase shift sequences, the second group of transmit channels are used to transmit a plurality of chirp signals having a frequency phase shift defined by the first group of frequency phase shift sequences; in response to transmitting the plurality of chirp signals associated with the first group of transmit channels and the plurality of chirp signals associated with the second group of transmit channels, receive a plurality of chirp returns from one or more receive channels; and in response to demodulating the plurality of chirp returns based on the first group of code sequences, output radar data to an automotive system, the radar data identifying an object inferred from the demodulated plurality of chirp returns.

[0059] Example 12: A radar system of any of the preceding examples, wherein the at least one processor is further configured to demodulate the multiple chirp returns based on the first group of code sequences in the following manner: digitizing, by the radar system, the multiple chirp returns received by the one or more receiving channels for application of a range fast Fourier transform (FFT); and in response to digitizing the multiple chirp returns received by the one or more receiving channels: applying, by the radar system, the range FFT to the multiple chirp returns received by the one or more receiving channels; multiplying, by the radar system, the multiple chirp returns received by the one or more receiving channels by the first group of code sequences; and applying, by the radar system, a Doppler FFT to the multiple chirp returns received by the one or more receiving channels.

[0060] Example 13: The radar system of any of the preceding examples, wherein applying the range FFT to the multiple chirp returns received by the one or more receive channels further comprises: applying, by the radar system, a window function to the multiple chirp returns before applying the range FFT.

[0061] Example 14: The radar system of any of the preceding examples, wherein applying the Doppler FFT to the multiple chirp returns received by the one or more receive channels further comprises: applying, by the radar system, a window function to the multiple chirp returns before applying the Doppler FFT.

[0062] Example 15: The radar system of any of the preceding examples, wherein the at least one processor is further configured to demodulate the plurality of chirp returns at least by generating, by the radar system, a range Doppler map for each of the one or more receive channels for incoherent integration of the one or more receive channels.

[0063] Example 16: The radar system of any of the preceding examples, wherein the at least one processor is further configured to demodulate multiple chirp returns at least by performing the non-coherent integration of all of the range Doppler maps generated for the one or more receive channels by the radar system to form a single average range Doppler map.

[0064] Example 17: The radar system of any of the preceding examples, wherein the at least one processor is further configured to demodulate the multiple chirp returns at least by: generating a rotator-shifted range Doppler average map by the radar system by shifting the frequency phase of the range Doppler map; and selecting, by the radar system, a minimum value between the range Doppler average map and the shifted range Doppler average map.

[0065] Example 18: The radar system of any of the preceding examples, wherein the first set of code sequences comprises binary codes.

[0066] Example 19: The radar system of any of the preceding examples, wherein the at least one processor is further configured to: generate each code sequence in the first set of code sequences by the radar system using a random number generator, the random number generator providing a unique code to each code sequence in the first set of code sequences relative to each other code sequence from the first set of code sequences.

[0067] Example 20: The radar system of any of the preceding examples, further comprising at least a third group of transmit channels, and the at least one processor is further configured to modulate the at least third group of transmit channels based on: based on the first group of code sequences, the at least third group of transmit channels is used to transmit a plurality of chirps having a phase modulation defined by the first group of code sequences; and based on at least a second group of frequency phase shift sequences, the at least third group of transmit channels is used to transmit a plurality of chirp signals having a frequency phase shift defined by the at least second group of frequency phase shift sequences.

[0068] Conclusion

[0069] Although various embodiments of the present disclosure are described in the foregoing description and shown in the accompanying drawings, it should be understood that the present disclosure is not limited thereto, but may be implemented into practice in various ways within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the present disclosure as defined by the following claims. Problems associated with increasing the number of radar channels may occur in other systems. Therefore, although described as a way to improve slow time modulation techniques for multiple radar channels, the techniques described above may be applied to other problems that depend on MIMO signal propagation.

[0070] Unless the context clearly dictates otherwise, the use of "or" and grammatically related terms represents unlimited, non-exclusive alternatives. As used herein, a phrase referring to "at least one" of a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover: a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

Claims

1. A method for a radar system, the method comprising: modulating, by the radar system, a first set of transmit channels based on a first set of code sequences to transmit a plurality of chirp signals having a phase modulation defined by the first set of code sequences; A second set of transmit channels is modulated by the radar system based on: Based on the first set of code sequences, the second set of transmission channels is used to transmit a plurality of chirps having the phase modulation defined by the first set of code sequences; as well as Based on a first set of frequency phase shift sequences, the second set of transmit channels is used to transmit a plurality of chirp signals having frequency phase shifts defined by the first set of frequency phase shift sequences; receiving a plurality of chirp returns from one or more receive channels in response to transmitting the plurality of chirp signals associated with the first set of transmit channels and the plurality of chirp signals associated with the second set of transmit channels; as well as Wherein, the method further comprises: Demodulating the plurality of chirp returns based on the first set of code sequences in the following manner: digitizing, by the radar system, the plurality of chirp returns received by the one or more receive channels for application of a range fast Fourier transform (FFT); and In response to digitizing the plurality of chirp returns received by the one or more receiving channels: applying, by the radar system, the range FFT to the plurality of chirp returns received by the one or more receive channels; returning, by the radar system, the plurality of chirps received by the one or more receive channels to the first set of code sequences; and applying, by the radar system, a Doppler FFT to the plurality of chirp returns received by the one or more receive channels; and Radar data identifying an object inferred from the demodulated plurality of chirp returns is output by the radar system to a vehicle system.

2. The method according to claim 1, characterized in that Applying the range FFT to the plurality of chirp returns received by the one or more receive channels further comprises: A window function is applied, by the radar system, to the plurality of chirp returns prior to applying the range FFT.

3. The method according to claim 1, characterized in that Applying the Doppler FFT to the plurality of chirp returns received by the one or more receive channels further comprises: A window function is applied, by the radar system, to the plurality of chirp returns prior to applying the Doppler FFT.

4. The method according to claim 1, characterized in that Further including: A range-Doppler map is generated by the radar system for each of the one or more receive channels for incoherent integration of the one or more receive channels.

5. The method according to claim 4, characterized in that Further including: The non-coherent integration is performed by the radar system on all of the range-Doppler maps generated for the one or more receive channels to form a single average range-Doppler map.

6. The method according to claim 5, characterized in that Further including: generating, by the radar system, a rotator-shifted range-Doppler average map by shifting a frequency phase of the range-Doppler map; as well as A minimum value between the range-Doppler average pattern and the shifted range-Doppler average pattern is selected by the radar system.

7. The method according to claim 1, characterized in that The first group of code sequences includes binary codes.

8. The method according to claim 1, characterized in that Further including: Each code sequence in the first set of code sequences is generated by the radar system using a random number generator that provides each code sequence in the first set of code sequences with a unique code relative to each other code sequence from the first set of code sequences.

9. The method according to claim 1, characterized in that Further including: At least a third set of transmit channels are modulated based on: Based on the first set of code sequences, the at least a third set of transmit channels is used to transmit a plurality of chirps having the phase modulation defined by the first set of code sequences; as well as Based on at least a second set of frequency phase shift sequences, the at least a third set of transmit channels is used to transmit a plurality of chirp signals having frequency phase shifts defined by the at least a second set of frequency phase shift sequences.

10. A radar system comprising: A first group of transmit channels; A second group of transmission channels; one or more receiving channels; as well as at least one processor configured to: modulating the first set of transmit channels based on a first set of code sequences to transmit a plurality of chirp signals having a phase modulation defined by the first set of code sequences; The second set of transmit channels is modulated based on: Based on the first set of code sequences, a second set of transmission channels is used to transmit a plurality of chirps having the phase modulation defined by the first set of code sequences; as well as Based on a first set of frequency phase shift sequences, the second set of transmit channels is used to transmit a plurality of chirp signals having the frequency phase shifts defined by the first set of frequency phase shift sequences; receiving a plurality of chirp returns from one or more receive channels in response to transmitting the plurality of chirp signals associated with the first set of transmit channels and the plurality of chirp signals associated with the second set of transmit channels; Wherein, the at least one processor is further configured to: Demodulating the plurality of chirp returns based on the first set of code sequences in the following manner: digitizing, by the radar system, the plurality of chirp returns received by the one or more receive channels for application of a range fast Fourier transform (FFT); and In response to digitizing the plurality of chirp returns received by the one or more receiving channels: applying, by the radar system, the range FFT to the plurality of chirp returns received by the one or more receive channels; returning, by the radar system, the plurality of chirps received by the one or more receive channels to the first set of code sequences; and applying, by the radar system, a Doppler FFT to the plurality of chirp returns received by the one or more receive channels; and Radar data identifying an object inferred from the demodulated plurality of chirp returns is output by the radar system to a vehicle system.

11. The radar system according to claim 10, characterized in that Applying the range FFT to the plurality of chirp returns received by the one or more receive channels further comprises: A window function is applied, by the radar system, to the plurality of chirp returns prior to applying the range FFT.

12. The radar system according to claim 10, characterized in that Applying the Doppler FFT to the plurality of chirp returns received by the one or more receive channels further comprises: A window function is applied, by the radar system, to the plurality of chirp returns prior to applying the Doppler FFT.

13. The radar system according to claim 10, characterized in that The at least one processor is further configured to demodulate the plurality of chirp returns by at least: A range-Doppler map is generated by the radar system for each of the one or more receive channels for incoherent integration of the one or more receive channels.

14. The radar system according to claim 13, characterized in that The at least one processor is further configured to demodulate the plurality of chirp returns by at least: The non-coherent integration is performed by the radar system on all of the range-Doppler maps generated for the one or more receive channels to form a single average range-Doppler map.

15. The radar system according to claim 14, characterized in that The at least one processor is further configured to demodulate the plurality of chirp returns by at least: generating, by the radar system, a rotator-shifted range-Doppler average map by shifting a frequency phase of the range-Doppler map; and A minimum value between the range-Doppler average pattern and the shifted range-Doppler average pattern is selected by the radar system.

16. The radar system according to claim 10, characterized in that The first group of code sequences includes binary codes.

17. The radar system according to claim 10, characterized in that The at least one processor is further configured to: Each code sequence in the first set of code sequences is generated by the radar system using a random number generator that provides each code sequence in the first set of code sequences with a unique code relative to each other code sequence from the first set of code sequences.

18. The radar system of claim 10, further comprising at least a third set of transmit channels, and the at least one processor is further configured to modulate the at least third set of transmit channels based on: Based on the first set of code sequences, the at least a third set of transmit channels is used to transmit a plurality of chirps having the phase modulation defined by the first set of code sequences; and Based on at least a second set of frequency phase shift sequences, the at least a third set of transmit channels is used to transmit a plurality of chirp signals having frequency phase shifts defined by the at least a second set of frequency phase shift sequences.

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