Patent Description:
Automotive RADAR systems are increasingly used in human-operated vehicles as well as autonomous vehicles. These RADAR systems can be used for various control and/or safety mechanisms within the host vehicle. Thus, improved RADAR system performance can result in improved automotive control and/or increased safety. <CIT> discloses a CW radar generator, comprising a stable local oscillator, STALO, the output of which is provided to a quadrature up-converter mixer and to a frequency divider. A first DDS receiver an output from the divider, splits the signal into a first and second split signals, and sends them to the quadrature up-converter mixer. The output of this mixer is input to a frequency mixer, and then to an SSB upconverter.

A second DDS circuit receives the signal from the divider, and sends two split signals as a second input to the SSB upconverter. <CIT> discloses a radar unit, comprising a waveform generator with a local oscillator feeding a signal to a PLL and a DDS circuit. The DDS splits the signal into I and Q components, and sends these signals to an I/Q upconverter. This I/Q upconverter receives also an input from the PLL circuit. <CIT> discloses a radar transmission system with two DDS circuits, for I and Q components, respectively, and a PLL circuit, the outpu of which is multiplied with the output of the respective DDS circuits.

Current commercial automotive radar systems are based on phase locked loop (PLL) and voltage control oscillator (VCO) architectures. Design of systems based on the PLL and VCO combination involves a tradeoff between settling time (PLL bandwidth) and phase noise in the system. The result is that the PLL and VCO based automotive radar systems suffer from either high phase noise or slow settling times. This architecture results in sub-optimal performance.

In frequency-modulated continuous-wave (FMCW) radar systems, for example, phase noise can result in sidelobes. Sidelobes are areas of energy that are outside of the main beam of the radar detection after processing (e.g., range, velocity, angular data) the baseband signal. Detection sidelobes can cause false detections or can superimpose weak detections, making them undetectable. As discussed above, PLL and VCO based automotive radar systems can suffer from high phase noise, which can result in sidelobes.

Sidelobes of a strong target (e.g., a delivery truck) can shadow weaker targets (e.g., cyclist, pedestrian). Thus, for high-resolution radar systems (e.g., automotive radar systems), it is desirable to have low phase noise to reduce sidelobes and detect weak targets that are physically close to strong targets. As discussed above, in PLL and VCO based automotive radar systems, a tradeoff is required so that decreasing phase noise in an attempt to reduce sidelobes will result in slower frequency settling times, which limits FMCW repetition rates. Further, fast frequency hopping is not possible with PLL and VCO based systems. Preferred embodiments are listed in the dependent claims.

In the example systems described below, heterodyne combination of signals of a low phase noise oscillator signal and a direct digital synthesis (DDS) signal can function to decouple the relationship between settling time and phase noise and reduce or eliminate the shortcomings discussed above. The settling time of low-noise oscillator and DDS configuration diminishes in importance because the PLLs of the system remain at a single frequency point after power up. Other examples can include an all-digital PLL and digitally controlled oscillator (DCO) based architecture. The low phase noise frequency synthesizer based architecture and DDS (or DCO) can be utilized to generate a carrier signal. In an example, a small filter loop bandwidth can be used for a static PLL frequency to optimize phase noise performance. Additional phase noise from the DDS can be negligible and the digitally-generated ramp has no constraints regarding settling time, ramp slope and repetition rate.

In the description that follows, specific example circuits are provided that utilize a low phase noise oscillator and DDS circuit based architecture for use in automotive radar systems. The resulting automotive radar system architecture can provide improved resolution and a higher performance automotive radar system that could be archived utilizing a PLL and VCO based architecture.

<FIG> is a block diagram of an example vehicle having a RADAR system as described herein. In one example, vehicle <NUM> is an autonomous vehicle that has the functionality to navigate roads without a human driver by utilizing sensors <NUM> including RADAR systems and vehicle control systems <NUM>. As another example, vehicle <NUM> can be a human-operated vehicle having an advanced driver assistance system (ADAS) that can utilize vehicle control systems <NUM> including radar systems within vehicle <NUM>.

Vehicle <NUM> can include, for example, sensor systems <NUM> including any number of sensor systems (e.g., sensor system <NUM>, sensor system <NUM>). Sensor systems <NUM> can include various types of sensors that can be arranged throughout vehicle <NUM>. For example, sensor system <NUM> can be a camera sensor system. As another example, sensor system <NUM> can be a light detection and ranging (LIDAR) sensor system. As a further example, one of sensor systems <NUM> can be a radio detection and ranging (RADAR) sensor system, an electromagnetic detection and ranging (EmDAR) sensor system, a sound navigation and ranging (SONAR) sensor system, a sound detection and ranging (SODAR) sensor system, a global navigation satellite system (GNSS) receiver system, a global positioning system (GPS) receiver system, accelerometers, gyroscopes, inertial measurement unit (IMU) systems, infrared sensor systems, laser rangefinder systems, microphones, etc..

The various radar systems of vehicle <NUM> can utilize the architecture described below with respect to, for example, <FIG>, <FIG> and <FIG>. Specifically, one or more of the radar systems of vehicle <NUM> can utilize the low phase noise oscillator and DDS circuit based architecture described herein. In general, the radar systems described herein are frequency-modulated continuous-wave (FMCW) radar systems. The FMCW radar systems transmit a chirp, or a pulse with a frequency that rises during transmission. The difference between the frequency of the chirp at transmission and the frequency of the received reflection is related to the distance to the reflecting object.

Vehicle <NUM> can further include mechanical systems to control and manage motion of vehicle <NUM>. For example, the mechanical systems can include vehicle propulsion system <NUM>, braking system <NUM>, steering system <NUM>, cabin system <NUM> and safety system <NUM>. Vehicle propulsion system <NUM> can include, for example, an electric motor, an internal combustion engine, or both. Braking system <NUM> can include an engine brake, brake pads, actuators and/or other components to control deceleration of vehicle <NUM>. Steering system <NUM> can include components that control the direction of vehicle <NUM>. Cabin system <NUM> can include, for example, cabin temperature control systems, in-cabin infotainment systems and other internal elements.

Safety system <NUM> can include various lights, signal indicators, airbags, systems that detect and react to other vehicles. Safety system <NUM> can include one or more radar systems. Automobiles can utilize different types of radar systems, for example, long-range radar (LRR), mid-range radar (MRR) and/or short-range radar (SRR). LRR systems can be used, for example, to detect objects that are farther away (e.g., <NUM> meters, <NUM> meters) from the vehicle transmitting the signal. LRR systems typically operate in the <NUM> band (e.g., <NUM>-<NUM>). SRR systems can be used, for example, for blind spot detection or collision avoidance. SRR systems typically operate in the <NUM> band. MRR systems can operate in either the <NUM> band or the <NUM> band. Other frequency bands can also be supported.

Vehicle <NUM> can further include internal computing system <NUM> that can interact with sensor systems <NUM> as well as the mechanical systems (e.g., vehicle propulsion system <NUM>, braking system <NUM>, steering system <NUM>, cabin system <NUM>, safety system <NUM>). Internal computing system <NUM> includes at least one processor and at least one memory system that can store executable instructions to be executed by the processor. Internal computing system <NUM> can include any number of computing sub-systems that can function to control vehicle <NUM>. Internal computing system <NUM> can receive inputs from passengers and/or human drivers within vehicle <NUM>.

Internal computing system <NUM> can include control service <NUM>, which functions to control operation of vehicle <NUM> via, for example, the mechanical systems as well as interacting with sensor systems <NUM>. Control service <NUM> can interact with other systems (e.g., constraint service <NUM>, communication service <NUM>, latency service <NUM>, internal computing system <NUM>) to control operation of vehicle <NUM>.

Internal computing system <NUM> can also include constraint service <NUM>, which functions to control operation of vehicle <NUM> through application of rule-based restrictions or other constraints on operation of vehicle <NUM>. Constraint service <NUM> can interact with other systems (e.g., control service <NUM>, communication service <NUM>, latency service <NUM>, user interface service <NUM>) to control operation of vehicle <NUM>.

Internal computing system <NUM> can further include communication service <NUM>, which functions to control transmission of signals from, and receipt of signals by, vehicle <NUM>. Communication service <NUM> can interact with safety system <NUM> to provide the waveform sensing, amplification and repeating functionality described herein. Communication service <NUM> can interact with other systems (e.g., control service <NUM>, constraint service <NUM>, latency service <NUM>, user interface service <NUM>) to control operation of vehicle <NUM>.

Internal computing system <NUM> can also include latency service <NUM>, which functions to provide and/or utilize timestamp information on communications to help manage and coordinate time-sensitive operations within internal computing system <NUM> and vehicle <NUM>. Thus, latency service <NUM> can interact with other systems (e.g., control service <NUM>, constraint service <NUM>, communication service <NUM>, user interface service <NUM>) to control operation of vehicle <NUM>.

Internal computing system <NUM> can further include user interface service <NUM>, which functions to provide information to, and receive inputs from, human passengers within vehicle <NUM>. This can include, for example, receiving a desired destination for one or more passengers and providing status and timing information with respect to arrival at the desired destination. User interface service <NUM> can interact with other systems (e.g., control service <NUM>, constraint service <NUM>, communication service <NUM>, latency service <NUM>) to control operation of vehicle <NUM>.

Internal computing system <NUM> can function to send and receive signals from vehicle <NUM> regarding reporting data for training and evaluating machine learning algorithms, requesting assistance from a remote computing system or a human operator, software updates, rideshare information (e.g., pickup, dropoff), etc..

<FIG> is a block diagram of an example automotive radar system having a signal generator with a low phase noise oscillator and a direct digital synthesis circuit, the automotive radar system also having an up converter. The radar system of <FIG> can be, for example, one of sensor systems <NUM>. The example automotive radar system of <FIG> can provide improved resolution and a higher performance automotive radar system than could be archived utilizing a PLL and VCO based architecture.

As described in greater detail below, signal generator <NUM> can utilize a stable local oscillator (STALO) circuit and a direct digital synthesis (DDS) circuit to generate a signal to be transmitted from, for example, a host platform (e.g., vehicle <NUM>). In one example, the host platform can be an autonomous vehicle. In another example, the host platform can be a human-operated vehicle having an advanced driver assistance system (ADAS).

In the example architecture of <FIG>, the heterodyne combination of a low phase noise PLL (e.g., a stable local oscillator) signal and a DDS signal within signal generator <NUM> decouples the relation between settling time and phase noise. Further, settling time of the PLL is no longer a limiting factor because the low phase noise PLL remains at a static frequency after power up.

The signal generated by signal generator <NUM> can be filtered, multiplied and amplified by up converter <NUM> to generate a radar frequency signal to be transmitted by transmit antenna <NUM> as transmitted radar signal <NUM>. One example architecture for signal generator <NUM> is provided in greater detail in <FIG>. One example architecture for up converter <NUM> is provided in greater detail in <FIG>. Other architectures based on the concepts illustrated in <FIG>, <FIG> and <FIG> to generate a radar frequency signal can also be utilized.

In contrast to the circuits of <FIG>, <FIG> and <FIG>, current FMCW automotive radar systems are based on a local voltage controlled oscillator (VCO) to generate a frequency modulated continuous wave signal (a chirp) that can be amplified and transmitted. As mentioned above, these VCO-based FMCW automotive radar systems require design tradeoffs that can result in less than optimal performance. The example architectures of <FIG>, <FIG> and <FIG> can provide a system that can overcome some or all of the shortcomings of current automotive radar systems.

Transmitted radar signal <NUM> can be reflected by a remote object, for example, remote vehicle <NUM>. Reflected radar signal <NUM> is detected by receive antenna <NUM>. The received reflected radar signal <NUM> from receive antenna <NUM> can be amplified by low-noise amplifier <NUM>. The amplified signal can be down converted by down converter <NUM> and filtered by low-pass filter <NUM>. The filtered signal can be amplified by amplifier <NUM> and the output of amplifier <NUM> can be digitized by analog-to-digital converter <NUM> and processed by signal processing unit <NUM> by performing fast Fourier transforms (FFTs) and other processing. The FFT processing can be utilized to, for example, calculate the distance from the time of flight that is indirectly given with the frequency offset of the transmitted and received ramp. The FFT processing can also calculate the velocity and angle.

<FIG> is a block diagram of a first example, not covered by the claims, signal generator having a low phase noise oscillator and a direct digital synthesis circuit that can be used in an automotive radar system. The example signal generator of <FIG> can function as signal generator <NUM> of <FIG>. As mentioned above, the lower-frequency (e.g., below radar frequency) use of a stable local oscillator <NUM> and direct digital synthesis circuit <NUM> to generate the radar signal can result in reduced phase noise without introduction of increased settling time. Thus, the architectures of <FIG> and <FIG> can provide an overall improvement in, for example, automotive radar systems.

In the examples that follow specific frequencies and frequency ranges are provided. These are merely examples and other frequencies and frequency ranges could be utilized. The illustrated approach can be utilized in other applications as well.

In one example, stable local oscillator <NUM> (STALO) functions to provide fixed, constant, low phase noise output signals of a selected frequency (i.e., lower-frequency signal <NUM>). In other examples, different low phase noise PLL circuits can be used. An input reference oscillator (not illustrated in <FIG>) can be used to produce the time domain pulse train. Lower-frequency signal <NUM> generated by stable local oscillator <NUM> is a significantly lower frequency than the final output radar signal (e.g., transmitted radar signal <NUM>). Lower-frequency signal <NUM> can be, for example, a selected fraction of the final radar signal. In an example, lower-frequency signal <NUM> can be in the range of <NUM>-<NUM> (e.g., <NUM>, <NUM>, <NUM>). As another example, lower-frequency signal <NUM> can be in the range of <NUM>-<NUM> (e.g., <NUM>, <NUM>, <NUM>). Lower-frequency signal <NUM> can be filtered by high-pass filter <NUM> and amplified by amplifier <NUM>, which is then filtered by low-pass filter <NUM>. The result can be intermediate oscillator signal <NUM>.

In one example, direct digital synthesis circuit <NUM> functions to produce analog waveform <NUM> by generating a time-varying signal in digital form and then performing a digital-to-analog conversion on the digital signal to generate analog waveform <NUM>. Analog waveform <NUM> is also a significantly lower frequency than the final output radar signal. In one example, analog waveform <NUM> is in the range of <NUM> to <NUM>. In alternate examples, other frequency ranges (e.g., <NUM> to <NUM>, <NUM> to <NUM> or other frequency ranges) can be supported.

Because operations within direct digital synthesis circuit <NUM> are primarily digital, direct digital synthesis circuit <NUM> can provide fast switching between output frequencies, good frequency resolution and operation over a broad range of frequencies. In one example, analog waveform <NUM> from direct digital synthesis circuit <NUM> can be filtered by band-pass filter <NUM> and provided to image rejection mixer <NUM>.

In one example, image rejection mixer <NUM> provides image rejection and mixing of signals generated by stable local oscillator <NUM> and by direct digital synthesis circuit <NUM>. In an example, image rejection mixer <NUM> is a sideband rejection mixer that can mix intermediate oscillator signal <NUM> and filtered analog waveform <NUM>. The output signal from image rejection mixer <NUM> can be filtered by band-pass filter <NUM> to generate output signal to up converter <NUM> to be further processed by, for example, the up converter architecture of <FIG>. In an example, output signal to up converter <NUM> is a higher-frequency signal than either lower-frequency signal <NUM> or analog waveform <NUM>.

<FIG> is a block diagram of a second example, falling onto the scope of the claims, signal generator having a low phase noise oscillator and a direct digital synthesis circuit that can be used in an automotive radar system. The example signal generator of <FIG> can function as signal generator <NUM> of <FIG>. As mentioned above, the lower-frequency (e.g., below radar frequency) use of stable local oscillator <NUM> and direct digital synthesis integrated circuit <NUM> to generate the radar signal can result in reduced phase noise without introduction of increased settling time. Thus, the architectures of <FIG> and <FIG> can provide an overall improvement in, for example, automotive radar systems.

In one example, stable local oscillator <NUM> (STALO) functions to provide fixed, constant, low phase noise output signals of a selected frequency (i.e., lower-frequency signal <NUM>). In other examples, different low phase noise PLL circuits can be used. In one example, stable local oscillator <NUM> includes a comb generator that uses a timer periodic sequence of pulses to produce a frequency domain periodic sequence. An input reference oscillator (not illustrated in <FIG>) can be used to produce the time domain pulse train. In an example, lower-frequency signal <NUM> can be in the range of <NUM>-<NUM> (e.g., <NUM>, <NUM>, <NUM>). As another example, lower-frequency signal <NUM> can be in the range of <NUM>-<NUM> (e.g., <NUM>, <NUM>, <NUM>). Lower-frequency signal <NUM> can be filtered by high-pass filter <NUM> and amplified by amplifier <NUM>, which is then filtered by low-pass filter <NUM>. The result can be intermediate oscillator signal <NUM>.

In one example, direct digital synthesis integrated circuit <NUM> functions to produce analog waveform <NUM> by generating a time-varying signal in digital form and then performing a digital-to-analog conversion on the digital signal to generate analog waveform <NUM>. Analog waveform <NUM> is also a significantly lower frequency than the final output radar signal. In one example, analog waveform <NUM> is in the range of <NUM> to <NUM>. In alternate examples, other frequency ranges (e.g., <NUM> to <NUM>, <NUM> to <NUM>) can be supported.

Because operations within direct digital synthesis integrated circuit <NUM> are primarily digital, direct digital synthesis integrated circuit <NUM> can provide fast switching between output frequencies, good frequency resolution and operation over a broad range of frequencies. In one example, analog waveform <NUM> from direct digital synthesis integrated circuit <NUM> can be filtered by band-pass filter <NUM> and provided to <NUM>-degree hybrid coupler <NUM>.

In one example, <NUM>-degree hybrid coupler <NUM> can function to equally split the filtered signal from band-pass filter <NUM> into two split signals (first split signal <NUM> and second split signal <NUM>) with a <NUM>-degree phase shift between the two split signals. First split signal <NUM> and second split signal <NUM> from <NUM>-degree hybrid coupler <NUM> can be provided to I/Q mixer <NUM>, which also receives intermediate oscillator signal <NUM>.

While the example of <FIG> utilizes an image rejection mixer (e.g., image rejection mixer <NUM>) that takes as one input filtered analog waveform <NUM> from band-pass filter <NUM>, the example of <FIG> utilizes I/Q mixer <NUM>, which can be, in an example, a single sideband mixer that takes first split signal <NUM> and second split signal <NUM> as inputs. Utilization of I/Q mixer <NUM> can relax the requirements for band-pass filter <NUM>.

In one example, I/Q mixer <NUM> functions to provide image rejection and mixing of intermediate oscillator signal <NUM>, first split signal <NUM> and second split signal <NUM>. The output signal from I/Q mixer <NUM> can be filtered by band-pass filter <NUM> to generate output signal to up converter <NUM> to be further processed by, for example, the up converter architecture of <FIG>. In an example, output signal to up converter <NUM> is a higher-frequency signal than either lower-frequency signal <NUM> or analog waveform <NUM>.

<FIG> is a block diagram of an example direct digital synthesis circuit. The example direct digital synthesis circuit as illustrated in <FIG> can be analogous to direct digital synthesis circuit <NUM> or direct digital synthesis integrated circuit <NUM>. The example architecture of <FIG> is one type of direct digital synthesis circuit that can be utilized in the systems of <FIG>. Other direct digital synthesis circuit architectures can also be used.

In general, direct digital synthesis circuit <NUM> generates an output signal (e.g., analog waveform <NUM>), which can be, for example, a sine wave at a selected frequency. Direct digital synthesis circuit <NUM> can also generate other waveforms, for example, square, triangular, etc. The frequency of analog waveform <NUM> depends on a reference clock signal provided to direct digital synthesis circuit <NUM> (not illustrated in <FIG>) and a number represented by tuning word <NUM>. In an example, tuning word <NUM> is a frequency register.

Phase accumulator <NUM> receives input signals from tuning word <NUM> and from digital ramp accumulator <NUM> to provide phase step information to sine table <NUM>. In an example, digital ramp accumulator <NUM> provides digital waveform ramp information to cause phase accumulator <NUM> to generate the desired waveform shape.

Phase accumulator <NUM> provides an intermediate signal to sine table <NUM>, which can be, for example, a sine look-up table that provides phase-to-amplitude conversion functionality. Sine table <NUM> generates digital waveform <NUM>, which is a digital waveform having the characteristics determined by tuning word <NUM>, digital ramp accumulator <NUM> and phase accumulator <NUM>. Digital-to-analog converter <NUM> converts digital waveform <NUM> to corresponding analog waveform <NUM> to be used as, for example, described in <FIG>.

<FIG> is a block diagram of an example up converter that can be used in an automotive radar system. The example up converter of <FIG> can be analogous to up converter <NUM> of <FIG>. The up converter of <FIG> can function to receive input signal from signal generator <NUM> (e.g., corresponding to output signal to up converter <NUM> or output signal to up converter <NUM>), which can be in a frequency range lower than the final radar signal frequency.

The received signal (input signal from signal generator <NUM>) is amplified by amplifier <NUM>, filtered by low-pass filter <NUM> and the frequency is increased (e.g., doubled) by frequency multiplier <NUM>. The signal is then filtered again by band-pass filter <NUM>. In one example, intermediate up converter signal <NUM> has a frequency in the range of <NUM> to <NUM>. In other example configurations, different frequency ranges can be supported.

Intermediate up converter signal <NUM> can be provided to frequency multiplier <NUM> where the frequency increased again (e.g., doubled again) by frequency multiplier <NUM>. Any number of stages of filtering and multiplying can be provided to convert the received signal (e.g., input signal from signal generator <NUM>) to the desired output frequency having the desired signal characteristics. In one example, final radar frequency signal <NUM> is in the range of <NUM> to <NUM>. In other example configurations, other frequency ranges can be supported. This is just one example, frequency range and multiplier configuration. Other examples generating different frequencies could be based on different local oscillator (e.g., stable local oscillator <NUM>, stable local oscillator <NUM>), which could be filtered, amplified, and/or multiplied to achieve the desired radar frequency signal.

The output signal from frequency multiplier <NUM> (e.g., final radar frequency signal <NUM>) can be sent to transmitter <NUM> to be transmitted (e.g., like transmitted radar signal <NUM>) from the host platform (e.g., vehicle <NUM>). A reflected signal (e.g., reflected radar signal <NUM>) can be received by the host platform and processed as described above with respect to <FIG>.

<FIG> is a flow diagram for one technique for generating a radar-frequency signal to be utilized by a host platform. The technique of <FIG> can be utilized by a host platform, for example, an autonomous vehicle (e.g., vehicle <NUM>) having various sensors (e.g., sensors <NUM>) and control systems (e.g., control service <NUM>). In an example, the techniques described can be provided utilizing the circuits and architectures as described with respect to <FIG>, <FIG> and <FIG>. A corresponding technique for utilizing the architectures of <FIG>, <FIG> and <FIG> would be adjusted to function with an image rejection mixer that receives a single input signal from the DDS branch (i.e., without a <NUM>-degree hybrid coupler). This architecture does not fall onto the scope of the claims.

A low phase noise oscillating signal is generated, <NUM>. In an example, the low phase noise oscillating signal can be generated by a stable local oscillator (e.g., stable local oscillator <NUM>) that generates a lower-frequency signal (e.g., lower-frequency signal <NUM>). The lower-frequency signal has a frequency that is less than a radar-frequency signal. In an example, the lower-frequency signal is in the range of <NUM> and can be used in a heterodyne combination of signals to generate a radar-frequency signal. In some examples, the low phase noise oscillating signal can be filtered (e.g., high-pass filter <NUM>, low-pass filter <NUM>) and/or amplified (e.g., amplifier <NUM>) before being combined with other signals.

An analog waveform is generated based on a time-varying digital signal, <NUM>. In an example, the analog waveform (e.g., analog waveform <NUM>) can be generated by a direct digital synthesis circuit (e.g., direct digital synthesis circuit <NUM>). In an example, the analog waveform has a frequency that is less than the final radar-frequency signal and can be used in the heterodyne combination of signals to generate the radar-frequency signal. In some examples, the analog waveform can be filtered (e.g., band-pass filter <NUM>) before being combined with other signals.

In one example, falling onto the scope of the claims, (e.g., utilizing an architecture analogous to that of <FIG>), the analog waveform (e.g., analog waveform <NUM>) is split into multiple split signals having phase shifts between the split signals, <NUM>. In an example, the analog waveform is split by a <NUM>-degree hybrid coupler (e.g., <NUM>-degree hybrid coupler <NUM>) into two signals (e.g., first split signal <NUM>, second split signal <NUM>) having a <NUM> degree phase difference. In another example (e.g., utilizing an architecture analogous to that of <FIG>), the analog waveform (e.g., analog waveform <NUM>) is not split into two signals having a phase difference.

In the architecture having the <NUM>-degree hybrid coupler, the split signals and the low phase noise oscillating signal (after filtering and/or amplifying) are mixed, <NUM>. In an example, an I/Q mixer (e.g., image rejection mixer <NUM>) can be utilized to mix the signals and provide image rejection. The mixed signal can be further filtered (e.g., band-pass filter <NUM>) to provide a signal generator output signal (e.g., output signal to up converters <NUM>). In the architecture without the <NUM>-degree hybrid coupler, the filtered analog waveform and the low phase noise oscillating signal (after filtering and/or amplifying) can be mixed.

Up conversion can be performed on the mixed output signal to generate a radar-frequency output signal, <NUM>. The up conversion includes filtering (e.g., low-pass filter <NUM>, band-pass filter <NUM>), amplification (e.g., amplifier <NUM>) and frequency multiplication (e.g., frequency multiplier <NUM>, frequency multiplier <NUM>). The level of frequency multiplication to be used can be based on the relationship between the low-frequency signals in the signal generator and the desired radar-frequency output signal.

The radar-frequency output signal can be transmitted, <NUM>. In an example, the radar-frequency output signal can be transmitted from a host platform (e.g., vehicle <NUM>) to gather information related to other objects (e.g., remote vehicle <NUM>) in an operating environment of the host platform. The transmitted radar-frequency signal can be reflected by one or more remote objects and the reflected signal can be received (e.g., via receive antenna <NUM>), <NUM>.

Signal processing can be performed on the received signal, <NUM>. The signal processing can be used to determine various characteristics about remote objects including, for example, location, direction of travel, size, speed.

<FIG> is a block diagram of one example of a processing system that can generate a radar-frequency signal to be utilized by a host platform. In one example, system <NUM> can be part of an autonomous vehicle (e.g., vehicle <NUM> as part of internal computing system <NUM>) that utilizes various sensors including radar sensors. In other examples, system <NUM> can be part of a human-operated vehicle having an advanced driver assistance system (ADAS) that can utilize various sensors including radar sensors. In an example, the processing system as described with respect to <FIG> can include and/or control the circuits and architectures as described with respect to <FIG>, <FIG> and <FIG>. This architecture does not fall onto the scope of the claims.

In an example, system <NUM> can include processor(s) <NUM> and non-transitory computer readable storage medium <NUM>. Non-transitory computer readable storage medium <NUM> may store instructions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> that, when executed by processor(s) <NUM>, cause processor(s) <NUM> to perform various functions. Examples of processor(s) <NUM> may include a microcontroller, a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), a data processing unit (DPU), an application-specific integrated circuit (ASIC), an field programmable gate array (FPGA), a system on a chip (SoC), etc. Examples of a non-transitory computer readable storage medium <NUM> include tangible media such as random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, a hard disk drive, etc..

Instructions <NUM> cause processor(s) <NUM> to cause a low phase noise oscillating signal to be generated. In an example, the low phase noise oscillating signal can be generated by a stable local oscillator (e.g., stable local oscillator <NUM>) that generates a lower-frequency signal (e.g., lower-frequency signal <NUM>). The lower-frequency signal has a frequency that is less than a radar-frequency signal. In an example, the lower-frequency signal is in the range of <NUM> and can be used in a heterodyne combination of signals to generate a radar-frequency signal. In some examples, the low phase noise oscillating signal can be filtered (e.g., high-pass filter <NUM>, low-pass filter <NUM>) and/or amplified (e.g., amplifier <NUM>) before being combined with other signals.

Instructions <NUM> cause processor(s) <NUM> to cause an analog waveform to be generated based on a time-varying digital signal. In an example, the analog waveform (e.g., analog waveform <NUM>) can be generated by a direct digital synthesis circuit (e.g., direct digital synthesis circuit <NUM>). In an example, the analog waveform has a frequency that is less than the final radar-frequency signal and can be used in the heterodyne combination of signals to generate the radar-frequency signal. In some examples, the analog waveform can be filtered (e.g., band-pass filter <NUM>) before being combined with other signals.

Instructions <NUM> cause processor(s) <NUM> to cause the analog waveform to be split into multiple signals having phase shifts between the split signals. In one example (e.g., utilizing an architecture analogous to that of <FIG>), the analog waveform (e.g., analog waveform <NUM>) is split into multiple split signals having phase shifts between the split signals, <NUM>. In an example, the analog waveform is split by a <NUM>-degree hybrid coupler (e.g., <NUM>-degree hybrid coupler <NUM>) into two signals (e.g., first split signal <NUM>, second split signal <NUM>) having a <NUM> degree phase difference. In another example (e.g., utilizing an architecture analogous to that of <FIG>), the analog waveform (e.g., analog waveform <NUM>) is not split into two signals having a phase difference.

In the architecture having the <NUM>-degree hybrid coupler, the split signals and the low phase noise oscillating signal (after filtering and/or amplifying) are mixed. In an example, an I/Q mixer (e.g., image rejection mixer <NUM>) can be utilized to mix the signals and provide image rejection. The mixed signal can be further filtered (e.g., band-pass filter <NUM>) to provide a signal generator output signal (e.g., output signal to up converters <NUM>). In the architecture without the <NUM>-degree hybrid coupler, the filtered analog waveform and the low phase noise oscillating signal (after filtering and/or amplifying) can be mixed.

Instructions <NUM> cause processor(s) <NUM> to cause the split signals and the low phase noise oscillating signal (after filtering and/or amplifying) to be mixed. In an example, an I/Q mixer (e.g., image rejection mixer <NUM>) can be utilized to mix the signals and provide image rejection. The mixed signal can be further filtered (e.g., band-pass filter <NUM>) to provide a signal generator output signal (e.g., output signal to up converters <NUM>). In the architecture without the <NUM>-degree hybrid coupler, the filtered analog waveform and the low phase noise oscillating signal (after filtering and/or amplifying) can be mixed.

Instructions <NUM> cause processor(s) <NUM> to cause up conversion to be performed on the mixed output signal to generate a radar-frequency output signal. The up conversion can include filtering (e.g., low-pass filter <NUM>, band-pass filter <NUM>), amplification (e.g., amplifier <NUM>) and/or frequency multiplication (e.g., frequency multiplier <NUM>, frequency multiplier <NUM>). The level of frequency multiplication to be used can be based on the relationship between the low-frequency signals in the signal generator and the desired radar-frequency output signal.

Instructions <NUM> cause processor(s) <NUM> to cause the radar-frequency output signal to be transmitted. In an example, the radar-frequency output signal can be transmitted from a host platform (e.g., vehicle <NUM>) to gather information related to other objects (e.g., remote vehicle <NUM>) in an operating environment of the host platform.

Instructions <NUM> cause processor(s) <NUM> to receive reflected radar-frequency signals via, for example, a receive antenna (e.g., receive antenna <NUM>). Instructions <NUM> cause processor(s) <NUM> to perform signal processing on the received signal. The signal processing can be used to determine various characteristics about remote objects including, for example, location, direction of travel, size, speed.

In one example, a RADAR system includes at least a signal generator (e.g., signal generator <NUM>), an up converter (e.g., up converter <NUM>) and a transmitter (e.g., transmitter <NUM>). In an example, the signal generator includes at least a stable oscillator (e.g., stable local oscillator <NUM>) that outputs a first lower-frequency signal (e.g., lower-frequency signal <NUM>). The signal generator can further include a direct digital synthesis circuit (e.g., direct digital synthesis circuit <NUM>) that outputs an analog waveform (e.g., analog waveform <NUM>) by generating a time-varying signal in digital form and performing a digital-to-analog conversion to produce the analog waveform.

The RADAR system further includes an up converter (e.g., up converter <NUM>) coupled with the signal generator to receive the signal generator output signal. The up converter is configured to filter the signal generator output signal and to increase frequencies of the signal generator output signal to generate a filtered and frequency multiplied signal (e.g., final radar frequency signal <NUM>).

The RADAR system further includes a transmitter (e.g., transmitter <NUM>) coupled with the up converter to receive the filtered and frequency multiplied signal. The transmitter can transmit a corresponding radar output signal (e.g., transmitted radar signal <NUM>) toward a remote target (e.g., remote vehicle <NUM>).

In one example, the transmitted radar output signal is a frequency-modulated continuous-wave (FMCW) radar signal. In one example, the signal generator, the up converter and the transmitter reside within a vehicle (e.g., vehicle <NUM>).

In an example, the RADAR system can further include a receiver (e.g., receive antenna <NUM>) to receive a reflected RADAR signal (e.g., reflected radar signal <NUM>) corresponding to the transmitted radar output signal. The RADAR system can further include a down converter (e.g., down converter <NUM>) coupled to receive the reflected RADAR signal and to convert the reflected RADAR signal to a lower-frequency signal. The RADAR system can further include a digital-to-analog converter (e.g., analog-to-digital converter <NUM>) coupled to receive the lower-frequency signal and to convert the received lower-frequency signal to a digital equivalent signal. The RADAR system can further include a signal processing unit (e.g., signal processing unit <NUM>) coupled with the digital-to-analog converter to perform digital signal analysis on the digital equivalent signal.

In an example, an autonomous vehicle (e.g., vehicle <NUM>) can include a sensor system (e.g., sensor systems <NUM>) including at least a signal generator (e.g., signal generator <NUM>) further comprising, which can include a stable oscillator (e.g., stable local oscillator <NUM>) that outputs a first lower-frequency signal (e.g., lower-frequency signal <NUM>). The signal generator can further include a direct digital synthesis circuit (e.g., direct digital synthesis circuit <NUM>) that outputs an analog waveform (e.g., analog waveform <NUM>) by generating a time-varying signal in digital form and performing a digital-to-analog conversion to produce the analog waveform.

The signal generator can further include a <NUM>-degree coupler (e.g., <NUM>-degree hybrid coupler <NUM>) coupled to receive the analog waveform from the direct digital synthesis circuit. The <NUM>-degree coupler can split the analog waveform into a first split signal (e.g., first split signal <NUM>) and a second split signal (e.g., second split signal <NUM>) with a <NUM>-degree phase shift between the first split signal and the second split signal.

The signal generator can further include a mixer (e.g., image rejection mixer <NUM>) coupled to receive the first lower-frequency signal from the stable oscillator, and the first split signal and the second split signal from the direct digital synthesis circuit, the mixer to mix the first lower-frequency signal, the first split signal and the second split signal to generate a signal generator output signal (e.g., output signal to up converter <NUM>).

The autonomous vehicle further includes an up converter (e.g., up converter <NUM>) coupled with the signal generator to receive the signal generator output signal. The up converter to filter and to increase frequencies of the signal generator output signal to generate a filtered and frequency multiplied signal (e.g., final radar frequency signal <NUM>).

The autonomous vehicle further includes a transmitter (e.g., transmitter <NUM>) coupled with the up converter to receive the filtered and frequency multiplied signal. The transmitter is configured to transmit a corresponding radar output signal (e.g., transmitted radar signal <NUM>) toward a remote target (e.g., remote vehicle <NUM>).

The autonomous vehicle further includes an internal control system (e.g., internal computing system <NUM>) having a control service (e.g., control service <NUM>) coupled with the sensor system, the control system to control functionality of the autonomous vehicle based on signals from the sensor system.

Various examples may include various processes. These processes may be performed by hardware components or may be embodied in computer program or machine-executable instructions, which may be used to cause processor or logic circuits programmed with the instructions to perform the processes. Alternatively, the processes may be performed by a combination of hardware and software.

Claim 1:
A RADAR system comprising:
a signal generator (<NUM>) comprising
a stable local oscillator (<NUM>) that outputs a first lower-frequency signal (<NUM>, <NUM>),
a direct digital synthesis circuit (<NUM>) that outputs an analog waveform <NUM>) by generating a time-varying signal in digital form and performing a digital-to-analog conversion to produce the analog waveform,
a mixer (<NUM>) coupled to receive the first lower-frequency signal from the stable oscillator, and a first split signal and a second split signal with a <NUM>-degree phase shift between the first split signal and the second split signal, from the direct digital synthesis circuit, the mixer to mix the first lower-frequency signal, the first split signal and the second split signal to generate an intermediate signal having a first frequency as a signal generator output signal (<NUM>, <NUM>);
an up converter (<NUM>) coupled with the signal generator to receive the signal generator output signal, the up converter to filter and to increase frequencies of the signal generator output signal to generate a filtered and frequency multiplied signal (<NUM>), wherein the signal generator output signal is amplified by an amplifier (<NUM>), filtered by a low-pass filter (<NUM>), a frequency is increased by a frequency multiplier (<NUM>), and filtered by a band-pass filter (<NUM>); and
a transmitter (<NUM>) coupled with the up converter to receive the filtered and frequency multiplied signal, the transmitter to transmit a corresponding radar output signal (<NUM>) toward a remote target.