Patent ID: 12228680

In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. Connecting lines or connectors shown in the various figures presented are intended to represent example functional relationships and/or physical or logical couplings between the various elements.

DETAILED DESCRIPTION

To mitigate performance degradations resulting from, for example, temperature variations, radar RF/analog subsystem settings are varied based on operating parameters such as temperature. The radar RF/analog subsystem settings can be determined using calibration techniques. However, RF/analog subsystem settings changes resulting from calibration can instantaneously change a loopback response (e.g., a phase response, an amplitude response, etc.) of the radar RF/analog subsystem. Because tracking algorithms rely on phase information across time and/or across sets of chirps, calibration changes and attendant loopback response changes can disturb ongoing object tracking. Thus, calibration cannot be done during operation of some radar systems.

A loopback response represents the change in amount, type, shape, form, etc. of amplitude, phase, etc. a transmit signal undergoes between a first point in a transmit signal path and a second point in a receive signal path. In some examples, the first point is a point at which an analog transmit signal is generated, and the second point is the point at which an analog receive signal is converted to the digital domain. In disclosed examples, the first point and the second point are selected to encompass portions of a transmit path and a receive path that change sufficiently based on calibration changes to warrant compensation. For example, all of a transmit analog signal path and all of a receive analog signal path may be included in a loopback path.

To compensate for RF/analog subsystem response changes resulting from calibration, examples disclosed herein determine: (a) a current loopback response of the RF/analog subsystem for a current calibration, and (b) a new loopback response of the RF/analog subsystem for a new calibration. Differences between the current loopback response and the new loopback response are used to digitally compensate for the RF/analog response changes resulting from calibration changes. Having compensated for the RF/analog subsystem response changes resulting from calibration, the calibration setting can be changed without disturbing ongoing object tracking (e.g., without disturbing and/or resetting tracking filters).

An example digital compensation includes the adjustment of the coefficient(s) of a receive filter, a transmit filter, etc. such as those found in a radar system. In some examples, the coefficient(s) are trained so a particular QPSK symbol is received with a desired amplitude and phase. If a calibration change is made, the same QPSK symbol would instead be received with a different amplitude and phase. The difference(s) in amplitude and phase represent a change in loopback response resulting from the calibration change. An example digital compensation would be a change in the filter coefficient(s) so the same QPSK symbol is to be received with the desired amplitude and phase after the calibration change is made. An example compensation in a radar system modifies the amplitude and/or phase of a receiver output signal by determined amount. For example, by multiplying a receiver output by a factor A*exp(j*θ) to change the amplitude of the receiver output by an amount A, and the phase of the receiver output by a factor θ (e.g., expressed in radians, where 2*π radians is 360 degrees), and j=sqrt(−1). Another example compensation in a radar system modifies an amplitude and/or phase of a transmitter output signal by determined amount. For example, a transmitter input signal can be multiplied by a factor B*exp(j*θ) (e.g., to change the phase of the transmitter output by θ radians). The multiplications can be carried out in a digital domain, an RF-analog-digital-mixed domain, etc. In the digital domain, the multiplications may be expressed as:
(I+j*Q)*A*exp(j*θ)=A*I*cos(θ)−A*Q*sin(θ)+j*A*Q*cos(θ)+j*A*I*sin(θ).
where I and Q are, respectively the real and imaginary receiver outputs or transmitter inputs.

In some examples, the loopbacks are performed using an internal transmit (TX) to receive (RX) loopback path in a radar system-on-a-chip (SoC) device. In some examples, the loopbacks are performed across radar SoC devices to compensate for TX and/or common mode path changes. In some examples, the loopbacks are performed in a test mode. In some examples, loopbacks are performed continuously at a known intermediate frequency (IF) frequency above the IF used for object tracking to continuously track changes in the response of the radar RF/analog subsystem.

Reference will now be made in detail to non-limiting examples, some of which are illustrated in the accompanying drawings.

FIGS.1A and1Bare a block diagram of an example radar system100configured to compensate for configuration changes resulting from calibration. The radar system100includes an example RF/analog subsystem102, an example digital signal processor (DSP) subsystem104, and an example processor106. In the illustrated example, the RF/analog subsystem102, and the DSP subsystem104are part of a radar SoC device. The processor106, which may be part of a radar SoC device, is a processor on which a customer can implement customer-specific functionality.

To generate transmit signals, the RF/analog subsystem102includes an example RF synthesizer108. The RF synthesizer108ofFIG.1Bgenerates an RF transmit signal110from chirp control data112received from an example timing engine114and, in some examples, from chirp control data116received from a transmitter118. Based on chirp parameter values for a sequence of chirps in a radar frame, the timing engine114generates chirp control signals that control the transmission and reception of the chirps in a frame based on the parameter values. In some examples, the RF synthesizer108includes a phase locked loop (PLL) and a voltage controlled oscillator (VCO).

To transmit the RF transmit signal110, the RF/analog subsystem102includes one or more transmit channels, one of which is designated at reference numeral120, and one or more antennas for respective ones of the transmit channels120, one of which is designated at reference numeral122. The transmit channels120each include an example pre-power amplifier (PPA)124, an example transmit programmable shifter126, and an example power amplifier (PA)128. The PPA124ofFIG.1Ais coupled to the RF synthesizer108ofFIG.1Bto receive the RF transmit signal110, and forms an amplified signal130. The programmable shifter126ofFIG.1Ais coupled to the PPA124to receive the amplified signal130, and forms a shifted signal132. The PA128ofFIG.1Ais coupled to the programmable shifter126to receive the shifted signal132, and forms a radar transmit signal134. The radar transmit signal134is emitted (e.g., transmitted) by the example antenna122ofFIG.1A. In some examples, the programmable shifter126is configurable for both frequency and phase shifting. For example, the shifted signal132may have a frequency equal to the input frequency of the amplified signal130plus a programmable offset frequency, and a phase equal to the input phase of the amplified signal130plus a programmable offset phase. In some examples, the transmit signal used to measure a loopback is an RF signal (e.g., near 80 GHz) modulated by a sinusoidal oscillating signal (e.g., near 1 MHz), a square wave signal (e.g., near 1 MHz), etc. Loopback measurements are performed during time intervals when normal transmitting and receiving is performed.

To receive an RF signal, the RF/analog subsystem102includes one or more receive channels, one of which is designated at reference numeral136, and one or more antennas for respective ones of the receive channels136, one of which is designated at reference numeral138. The receive channels136each include an example low-noise amplifier (LNA)140, an example mixer142, an example intermediate frequency amplifier (IFA)144, and an example analog-to-digital converter (ADC)146. The LNA140ofFIG.1Aamplifies a radar return signal148received from the antenna138ofFIG.1Ato form an RF receive signal150. The mixer142ofFIG.1Bmixes the RF transmit signal110generated by transmission generation circuitry (e.g., the RF synthesizer108and the timing engine114) with the RF receive signal150to generate an analog IF output signal152. The mixer142is a down converter that generates the output signal152with a frequency equal to the difference between the frequency of the signal150received from the LNA140and the frequency of the signal110received from the transmission generation circuitry, both of which are RF signals. The IFA144ofFIG.1B(e.g., a combined bandpass filter (BPF) and variable amplitude amplifier (VAA)) amplifies the analog IF output signal152to form an amplified analog IF signal154. The ADC146ofFIG.1Bconverts the amplified analog IF signal154to the digital domain as a digital IF signal156(output signal156of the ADC146).

The receive channels136are coupled to an example digital front end (DFE)158of the example DSP subsystem104. The DFE158ofFIG.1Bperforms decimation filtering on the digital IF signal156, DC offset removal, digital compensation of non-idealities in the receive channel136(e.g., an inter-RX amplitude imbalance non-ideality, an inter-RX phase imbalance non-ideality, etc.), etc. The DFE158transfers decimated digital IF signals160to a main processing unit162when the radar system100is in normal mode. In a loopback mode, the DFE158transfers the decimated digital IF signals160to an example loopback measurer164.

To measure loopback responses, the DSP subsystem104ofFIG.1Bincludes the loopback measurer164. The loopback measurer164ofFIG.1Bmeasures the phase and amplitude response of a loopback path. An example loopback path for the radar system100includes the transmit channel120, an example loopback channel166, and the receive channel136. The loopback measurer164ofFIG.1Bimplements any number and/or type(s) of methods, algorithms, etc. to determine the response (e.g., amplitude and phase) of the loopback path based on changes to a known RF transmit signal110as the RF transmit signal110passes through the transmit channel120, the loopback channel166, the receive channel136, and is received as the receive signal156. Because the loopback measurer164receives the RF transmit signal110as a reference, the loopback measurer164can determine what changes the RF transmit signal110underwent prior to becoming the receive signal156. Example methods and apparatus to measure loopback responses are disclosed in U.S. patent application Ser. No. 14/870,129, entitled “Measurement of Transceiver Performance Parameters In a Radar System,” and filed on Sep. 30, 2015. U.S. patent application Ser. No. 14/870,129 is hereby incorporated herein by reference in its entirety.

The loopback channel166ofFIGS.1A and1Bincludes an example combiner168, an example frequency shifter170, and an example splitter172. The combiner168ofFIG.1Areceives the shifted signal134output by each of the PAs128, and forms a combined signal174from the shifted signals134. The combiner168provides the combined signal174to the frequency shifter170. The frequency shifter170ofFIG.1Aapplies a frequency shift to the combined signal174using, for example, an on-off keying (OOK) modulator or a binary phase shift keying (BPSK) modulator to form a shifted combined signal176. The frequency shifter170is coupled to the splitter172to provide the shifted combined signal176to the splitter172. The splitter172ofFIG.1Ais coupled to each of the receive channels136. The splitter172splits the shifted combined signal176to provide signals of equal power and phase to each of the receive channels136. In some examples, the splitter172splits the shifted combined signal176so the amplitude, attenuation, and/or delay on the signal from the splitter input178to the LNAs140of each of the receive channels136are significantly similar.

To determine the range, angle, and/or velocity of an object, the example DSP subsystem104includes an example tracking system180. The tracking system180ofFIG.1Bimplements any number and/or type(s) of methods, algorithms, etc. to determine the range, angle, and/or velocity of an object based on the radar return signal148processed through the receive channel136. In the illustrated example, the tracking system180is implemented as machine readable instructions executed on the main processing unit162.

To calibrate the RF/analog subsystem102, the example DSP subsystem104includes an example calibrator182. The example calibrator ofFIG.1Bimplements any number and/or type(s) of methods, algorithms, etc. to take calibration measurements that characterize the RF/analog subsystem102based on the chirp control data112,116, and to determine calibration settings for the RF/analog subsystem102based on the measurements. The calibrator182can compute new calibration settings as temperature changes occur to track temperature-based changes to circuit characteristics. In some examples, the calibrator182periodically and/or aperiodically determines calibration settings. Additionally, and/or alternatively, the calibrator182determines calibration settings under the control of the main processing unit162and/or the processor106. In the illustrated example, the calibrator182is implemented as machine readable instructions executed on the main processing unit162. In a calibration mode, the DFE158transfers the decimated digital IF signals160to the calibrator182.

To configure the RF/analog subsystem102, the example DSP subsystem includes an example configurer184. The configurer184writes configuration (e.g., calibration) data, parameters, settings, etc. stored in a configuration data store186to the RF/analog subsystem102to change the configuration of the RF/analog subsystem102. The configuration data store186may be any number and/or type(s) of non-transitory computer-readable storage device or disk.

As shown inFIG.1B, the configuration data store186includes settings for a current (e.g., old) calibration configuration for the transmit channel TX_OLD, a new calibration configuration for the transmit channel TX_NEW, a current (e.g., old) calibration configuration for the receive channel RX_OLD, and a new calibration configuration for the receive channel RX_NEW. The calibration configurations TX_OLD, TX_NEW, RX_OLD and RX_NEW can be determined by the calibrator182. In examples disclosed herein, calibration configurations may include parameters such as gain and/or phase jumps to be applied. The new calibration configurations TX_NEW and RX_NEW can be associated with a different temperature than the other calibration configurations TX_OLD and RX_OLD.

Changes in configuration (e.g., calibration) data, parameters, settings, etc. applied to the RF/analog subsystem102can cause changes (e.g., instantaneous changes) in the responses, characteristics, performance, etc. of the RF/analog subsystem102. An example configuration change is from a first calibration configuration to a second calibration configuration. Because such changes in calibration configuration can change loopback response, such changes can disrupt the ability to track one or more objects and/or the performance of object tracking performed by the tracking system180. In some examples, such changes can require a reset of the tracking system180, which could disrupt the ongoing operation of a system including the radar system100.

To compensate for changes in the RF/analog subsystem102resulting from, for example, calibration changes, the example DSP subsystem104includes an example compensator188. The compensator188changes the settings, coefficients, etc. of transmit and/or receive components at a change in calibration configuration so other receive components are not impacted by the change in calibration configuration that occurred. The compensator188ofFIG.1Bcontrols the configurer184to configure the RF/analog subsystem102with a first calibration configuration C1, and controls the loopback measurer164to compute a first loopback response L1for the first calibration configuration C1. The compensator188ofFIG.1Bthen controls the configurer184to configure the RF/analog subsystem102with a second calibration configuration C2, and controls the loopback measurer164to compute a second loopback response L2for the second calibration configuration C2. The compensator188computes the instantaneous change in loopback response by computing, for example, a difference between the loopback response L1and the loopback response L2. To compensate for the difference, the compensator188adjusts the parameters, settings, variables, etc. of the programmable shifters126, the DFE158, and/or the tracking system180. Table 1 shows example combinations to compensate for TX and/or RX calibration configuration changes. For example, to compensate for an RX amplitude and/or phase difference resulting from a calibration change: a first loopback L1is determined for a TX_OLD, RX_OLD calibration configuration, and a second loopback L2is determined for a TX_OLD, RX_NEW calibration configuration, and compensation is performed by digitally changing settings of the DFE158and/or the tracking system180based on a difference of L1and L2.

TABLE 1Loopback ConfigurationsConfigurationLoopbackRX or TXWhere to compensateTX_OLD, RX_OLDL1RX ΔA and/or ΔθDFE 158, and/or trackingTX_OLD, RX_NEWL2system 180TX_OLD, RX_OLDL1TX ΔA and/or ΔθProgrammable shifters 126,TX_NEW, RX_OLDL2DFE 158, and/or trackingsystem 180

In some examples, compensation is not applied during loopback measurements and, as a result, the raw analog gain/phase change factors for the section is measured. Example methods and apparatus to measure loopback responses are disclosed in U.S. patent application Ser. No. 14/870,129, entitled “Measurement of Transceiver Performance Parameters In a Radar System,” and filed on Sep. 30, 2015. U.S. patent application Ser. No. 14/870,129 is hereby incorporated herein by reference in its entirety.

In some examples, an output156of the ADC146is expressed as I+jQ, and digital compensation is performed by multiplying the output156of the ADC146by a compensation factor A*exp(j*θ). If the compensation factor was A1*exp(j*θ1) for a previous (e.g., old) calibration setting, the compensation factor after a calibration setting change would be A1*ΔA*exp(j*θ1+Δθ), where ΔA and Δθ are the amplitude and phase changes, respectively, of the loopback due to the change in calibration. The amplitude change ΔA is measured in digital amplitude levels, not in power or log-scale. For example, if a first measurement is A1and a second measurement is A2, then the amplitude difference is A2/A1and not A2−A1. If instead, log or power scale is used, the amplitude difference may be represented by A2−A1. The phase difference is θ1−θ2. In some examples, the TX compensation can be performed by multiplying the phase shift applied by the TX programmable shifter126and an amplitude difference and/or phase difference.

While an example RF/analog subsystem102is shown inFIGS.1A and1B, RF/analog subsystems according to other architectures having a loopback channel can be used. Other example RF/analog subsystems are disclosed in U.S. patent application Ser. No. 14/870,129, entitled “Measurement of Transceiver Performance Parameters In a Radar System,” and filed on Sep. 30, 2015. U.S. patent application Ser. No. 14/870,129 is hereby incorporated herein by reference in its entirety. Further, while two transmit channels120and four receive channels136are shown inFIGS.1A and1B, an RF/analog subsystem may have other numbers of transmit channels and/or receive channels

While an example radar system100is illustrated inFIGS.1A and1B, one or more of the elements, processes and/or devices illustrated inFIGS.1A and1Bmay be combined, divided, re-arranged, omitted, eliminated and/or implemented in any other way. Further, the example RF synthesizer108, the example timing engine114, the example transmitter118, the example transmit channels120, the example antennas122, the example PPA124, the example programmable shifter126, the example PA128, the receive channels136, the example antennas138, the example LNA140, the example mixer142, the example IFA144, the example ADC146, the example DFE158, the example main processing unit162, the example loopback measurer164, the example loopback channel166, the example combiner168, the example frequency shifter170, the example splitter172, the example tracking system180, the example calibrator182, the example configurer184, the example configuration data store186, the example compensator188and/or, more generally, the example radar system100ofFIGS.1A and1Bmay be implemented by hardware, software, firmware and/or any combination of hardware, software and/or firmware. Thus, for example, any of the example RF synthesizer108, the example timing engine114, the example transmitter118, the example transmit channels120, the example antennas122, the example PPA124, the example programmable shifter126, the example PA128, the receive channels136, the example antennas138, the example LNA140, the example mixer142, the example IFA144, the example ADC146, the example DFE158, the example main processing unit162, the example loopback measurer164, the example loopback channel166, the example combiner168, the example frequency shifter170, the example splitter172, the example tracking system180, the example calibrator182, the example configurer184, the example configuration data store186, the example compensator188and/or, more generally, the example radar system100of FIGS.1A and1B could be implemented by one or more analog or digital circuit(s), logic circuits, programmable processor(s), programmable controller(s), graphics processing unit(s) (GPU(s)), digital signal processor(s) (DSP(s)), application specific integrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)), field programmable gate array(s) (FPGA(s)), and/or field programmable logic device(s) (FPLD(s)). When reading any of the apparatus or system claims of this patent to cover a purely software and/or firmware implementation, at least one of the example RF synthesizer108, the example timing engine114, the example transmitter118, the example transmit channels120, the example antennas122, the example PPA124, the example programmable shifter126, the example PA128, the receive channels136, the example antennas138, the example LNA140, the example mixer142, the example IFA144, the example ADC146, the example DFE158, the example main processing unit162, the example loopback measurer164, the example loopback channel166, the example combiner168, the example frequency shifter170, the example splitter172, the example tracking system180, the example calibrator182, the example configurer184, the example configuration data store186, the example compensator188and/or the example radar system100is/are hereby expressly defined to include a non-transitory computer-readable storage device or storage disk such as a memory, a digital versatile disk (DVD), a compact disc (CD), a compact disc read-only memory (CD-ROM), a Blu-ray disk, etc. including the software and/or firmware. Further still, the example radar system100ofFIGS.1A and1Bmay include one or more elements, processes and/or devices in addition to, or instead of, those illustrated inFIGS.1A and1B, and/or may include more than one of any or all of the illustrated elements, processes and devices. As used herein, the phrase “in communication,” including variations thereof, encompasses direct communication and/or indirect communication through one or more intermediary components, and does not require direct physical (e.g., wired) communication and/or constant communication, but rather additionally includes selective communication at periodic intervals, scheduled intervals, aperiodic intervals, and/or one-time events.

A flowchart representative of example hardware logic, machine-readable instructions, hardware implemented state machines, and/or any combination thereof for implementing the radar system100ofFIGS.1A and1Bis shown inFIG.2. The machine-readable instructions may be an executable program or portion of an executable program for execution by a computer processor such as the processor502shown in the example processor platform500discussed below in connection withFIG.5. The program may be embodied in software stored on a non-transitory computer-readable storage medium such as a CD, a CD-ROM, a floppy disk, a hard drive, a DVD, a Blu-ray disk, or a memory associated with the processor502, but the entire program and/or parts thereof could alternatively be executed by a device other than the processor502and/or embodied in firmware or dedicated hardware. Further, although the example program is described with reference to the flowchart illustrated inFIG.2, many other methods of implementing the example radar system100may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. Additionally, and/or alternatively, any or all of the blocks may be implemented by one or more hardware circuits (e.g., discrete and/or integrated analog and/or digital circuitry, an FPGA, an ASIC, a PLD, an FPLD, a comparator, an operational-amplifier (op-amp), a logic circuit, etc.) structured to perform the corresponding operation without executing software or firmware.

The program ofFIG.2begins at block202, where the configurer184configures the RF/analog subsystem102with the TX_OLD and the RX_OLD calibration configurations (block202). The example loopback measurer164measures a first loopback, which includes a phase PHASE1and an amplitude AMP1(block204). InFIGS.1A and1Bthe loopback path includes the transmit channel120, the loopback channel166, and the receive channel136. InFIGS.1A and1B, the transmit channel120is configured to obtain the RF transmit signal110to be transmitted through the loopback channel166, into the receive channel136, and to be measured by the loopback measurer164. The configurer184configures the RF/analog subsystem102with the TX_OLD and the RX_NEW calibration configurations (block206). The loopback measurer164measures a second loopback, which includes a phase PHASE2and an amplitude AMP2(block208). The compensator188computes a first phase difference Δθ_1=θ2−θ1, and a first amplitude difference ΔA_1=A2/A1(block210). The configurer184configures the RF/analog subsystem102with the TX_NEW and the RX_OLD calibration configurations (block212). The loopback measurer164measures a third loopback, which includes a phase θ3and an amplitude A3(block214). The compensator188computes a second phase difference Δθ_2=θ3−θ1, and a second amplitude difference ΔA_2=A3/A1(block216). The compensator188compensates for the first phase difference Δθ_1, the first amplitude difference ΔA_1, the second phase difference Δθ_2, and the second amplitude difference ΔA_2 by adjusting the parameters, settings, variables, etc. of the programmable shifters126, the DFE158, and/or the tracking system180(block218).

While TX and RX amplitude and phase differences can be identified and compensated in the illustrated example ofFIG.1, the radar system100may not be able to identify amplitude and/or phase differences on a common mode path.

FIG.3is a block diagram of another radar system300constructed in accordance with aspects of this disclosure that can identify amplitude and/or phase differences on a common mode path using antenna coupling between antennae of different radar systems. The example radar system300ofFIG.2includes two separate radar systems302and304, such as two of the radar system100ofFIGS.1A and1B. In the illustrated example ofFIG.3, a loopback channel306includes the transmit channel120of the radar system302, a loopback transmission path308between the antenna122of the radar system302and the antenna138of the radar system304, and the receive channel136of the radar system304. The loopback transmission path308includes, for example, electro-magnetic coupling, reflections of radar signals by surfaces of a mechanical housing, etc. In the illustrated example, a common local oscillator (e.g., the RF synthesizer108) is used by the transmit channel120of the radar system302and by the receive channel136of the radar system304. Use of the common local oscillator enables the loopback measurer164to measure a loopback between the radar system302and the radar system304. Using loopback measurements by the loopback measurer164enables the compensator188to compensate changes in the transmit channel120and/or a common mode path. To compensate for the changes, the compensator188adjusts the parameters, settings, variables, etc. of the programmable shifters126, the DFE158, and/or the tracking system180.

While an example manner of implementing the radar system300is shown inFIG.3, one or more of the elements, processes and/or devices illustrated inFIG.3may be combined, divided, re-arranged, omitted, eliminated and/or implemented in any other way. Further, the example RF synthesizer108, the example radar systems302and304, the example transmit channel120, the example receive channel136, the example mixer142, the example DFE158, the example loopback measurer164, the example configurer184, the example compensator188and/or, more generally, the example radar system300ofFIG.3may be implemented by hardware, software, firmware and/or any combination of hardware, software and/or firmware. Thus, for example, any of the example RF synthesizer108, the example radar systems302and304, the example transmit channel120, the example receive channel136, the example mixer142, the example DFE158, the example loopback measurer164, the example configurer184, the example compensator188and/or, more generally, the example radar system300could be implemented by one or more analog or digital circuit(s), logic circuits, programmable processor(s), programmable controller(s), GPU(s), DSP(s), ASIC(s), PLD(s), FPGA(s), and/or FPLD(s). When reading any of the apparatus or system claims of this patent to cover a purely software and/or firmware implementation, at least one of the example RF synthesizer108, the example radar systems302and304, the example transmit channel120, the example receive channel136, the example mixer142, the example DFE158, the example loopback measurer164, the example configurer184, the example compensator188, and/or the example radar system300is/are hereby expressly defined to include a non-transitory computer-readable storage device or storage disk such as a memory, a DVD, a CD, a CD-ROM, a Blu-ray disk, etc. including the software and/or firmware. Further still, the example radar system300ofFIG.3may include one or more elements, processes and/or devices in addition to, or instead of, those illustrated inFIG.4, and/or may include more than one of any or all of the illustrated elements, processes and devices.

A flowchart representative of example hardware logic, machine-readable instructions, hardware implemented state machines, and/or any combination thereof for implementing the radar system300ofFIG.3is shown inFIG.4. The machine-readable instructions may be an executable program or portion of an executable program for execution by a computer processor such as the processor502shown in the example processor platform500discussed below in connection withFIG.5. The program may be embodied in software stored on a non-transitory computer-readable storage medium such as a CD, a CD-ROM, a floppy disk, a hard drive, a DVD, a Blu-ray disk, or a memory associated with the processor502, but the entire program and/or parts thereof could alternatively be executed by a device other than the processor502and/or embodied in firmware or dedicated hardware. Further, although the example program is described with reference to the flowchart illustrated inFIG.4, many other methods of implementing the example radar system300may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. Additionally, and/or alternatively, any or all of the blocks may be implemented by one or more hardware circuits (e.g., discrete and/or integrated analog and/or digital circuitry, an FPGA, an ASIC, a PLD, an FPLD, a comparator, an op-amp, a logic circuit, etc.) structured to perform the corresponding operation without executing software or firmware.

The program ofFIG.4begins at block402, where the configurer184configures the radar system302with the TX_OLD calibration configuration, and configures the radar system304with the RX_OLD calibration configuration (block402). The loopback measurer164measures a first loopback, which includes a phase θ1and an amplitude A1(block404). InFIG.3the loopback path includes the transmit channel120of the radar system302, the loopback transmission path308between the antenna122of the radar system302and the antenna138of the radar system304, and the receive channel136of the radar system304. The configurer184configures the radar system302with the TX_NEW calibration configuration, and configures the radar system304with the RX_OLD calibration configuration (block406). The loopback measurer164measures a second loopback, which includes a phase θ2and an amplitude AMP2(block408). The compensator188computes a phase difference Δθ=θ2−θ1, and an amplitude difference ΔA=A2−A1(block410). The compensator188compensates for the phase difference Δθ, and the amplitude difference ΔA by adjusting the parameters, settings, variables, etc. of the DFE158(block412).

In examples disclosed herein, phase correction for TX involves compensating the shift in phase at TX path (say θnew−θold) by adding this to the existing phase shifter correction (θexist). Therefore, the new correction to be configured is θexist+θnew−θold. Phase correction at RX involves compensating the shift in phase at RX path in a manner similar to the TX case. However, in some examples, such RX path correction is applied digitally at the DFE158(e.g., after ADC samples are recorded). A gain correction ΔAnew=Aold/Anewis also applied. In some examples, such gain correction is processed digitally (e.g., at the DFE158). The transformed ADC data is then computed as ADC_data*ΔAexist*ΔAnew*exp(j(θexist+θnew−θold)). The amplitude shift is corrected at the TX power backoff in dB by adding (or subtracting) the delta change in power during a settings update.

As mentioned above, the example processes ofFIGS.2and4may be implemented using executable instructions (e.g., computer and/or machine-readable instructions) stored on a non-transitory computer and/or machine-readable medium such as a hard disk drive, a flash memory, a read-only memory, a CD, a CD-ROM, a DVD, a cache, a random-access memory and/or any other storage device or storage disk in which information is stored for any duration (e.g., for extended time periods, permanently, for brief instances, for temporarily buffering, and/or for caching of the information). As used herein, the term non-transitory computer-readable medium is expressly defined to include any type of computer-readable storage device and/or storage disk and to exclude propagating signals and to exclude transmission media.

As used herein, when the phrase “at least” is used as the transition term in, for example, a preamble of a claim, it is open-ended in the same manner as the term “comprising” and “including” are open ended. The term “and/or” when used, for example, in a form such as A, B, and/or C refers to any combination or subset of A, B, C such as (1) A alone, (2) B alone, (3) C alone, (4) A with B, (5) A with C, (6) B with C, and (7) A with B and with C. As used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. Similarly, as used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. As used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, and (3) at least one A and at least one B. Similarly, as used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, and (3) at least one A and at least one B.

FIG.5is a block diagram of an example processor platform500structured to execute the instructions ofFIGS.2and3to implement the radar system100ofFIGS.1A and1B, and the radar systems300,302and304ofFIG.3. The processor platform500can be, for example, an automobile, a server, a personal computer, a workstation, a mobile device (e.g., a cell phone, a smart phone, a tablet such as an IPAD™), a headset or other wearable device, or any other type of computing device implementing radar.

The processor platform500of the illustrated example includes a processor502. The processor502of the illustrated example is hardware. For example, the processor502can be implemented by one or more integrated circuits, logic circuits, microprocessors, GPUs, DSPs, or controllers from any desired family or manufacturer. The hardware processor may be a semiconductor based (e.g., silicon based) device. In this example, the processor implements the example RF synthesizer108, the example timing engine114, the example transmitter118, the example transmit channels120, the example antennas122, the example PPA124, the example programmable shifter126, the example PA128, the receive channels136, the example antennas138, the example LNA140, the example mixer142, the example IFA144, the example ADC146, the example DFE158, the example main processing unit162, the example loopback measurer164, the example loopback channel166, the example combiner168, the example frequency shifter170, the example splitter172, the example tracking system180, the example calibrator182, the example configurer184, the example configuration data store186, and the example compensator188.

The processor502of the illustrated example includes a local memory504(e.g., a cache). The processor502of the illustrated example is in communication with a main memory including a volatile memory506and a non-volatile memory508via a bus510. The volatile memory506may be implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS® Dynamic Random Access Memory (RDRAM®) and/or any other type of random access memory device. The non-volatile memory508may be implemented by flash memory and/or any other desired type of memory device. Access to the main memory506,508is controlled by a memory controller.

The processor platform500of the illustrated example also includes an interface circuit512. The interface circuit512may be implemented by any type of interface standard, such as an Ethernet interface, a universal serial bus (USB), a Bluetooth® interface, a near field communication (NFC) interface, and/or a peripheral component interface (PCI) express interface.

In the illustrated example, one or more input devices514are connected to the interface circuit512. The input device(s)514permit(s) a user to enter data and/or commands into the processor502. The input device(s) can be implemented by, for example, an audio sensor, a microphone, a camera (still or video), a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, isopoint and/or a voice recognition system.

One or more output devices516are also connected to the interface circuit512of the illustrated example. The output devices516can be implemented, for example, by display devices (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display (LCD), a cathode ray tube display (CRT), an in-place switching (IPS) display, a touchscreen, etc.), a tactile output device, a printer and/or speaker. The interface circuit512of the illustrated example, thus, typically includes a graphics driver card, a graphics driver chip and/or a graphics driver processor.

The interface circuit512of the illustrated example also includes a communication device such as a transmitter, a receiver, a transceiver, a modem, a residential gateway, a wireless access point, and/or a network interface to facilitate exchange of data with external machines (e.g., computing devices of any kind) via a network518. The communication can be via, for example, an Ethernet connection, a digital subscriber line (DSL) connection, a telephone line connection, a coaxial cable system, a satellite system, a line-of-site wireless system, a cellular telephone system, etc.

The processor platform500of the illustrated example also includes one or more mass storage devices520for storing software and/or data. Examples of such mass storage devices520include floppy disk drives, hard drive disks, CD drives, Blu-ray disk drives, redundant array of independent disks (RAID) systems, and DVD drives.

Coded instructions522including the coded instructions ofFIGS.2and4may be stored in the mass storage device520, in the volatile memory506, in the non-volatile memory508, and/or on a removable non-transitory computer-readable storage medium such as a CD-ROM or a DVD.

From the foregoing, it will be appreciated that example methods, apparatus and articles of manufacture have been disclosed that compensate for RF/analog TX and RX changes resulting from calibration configuration changes. From the foregoing, it will be appreciated that methods, apparatus and articles of manufacture have been disclosed which enhance the operations of a computer by allowing object tracking and/or customer algorithms to be performed without interruption resulting from calibration changes. The disclosed methods, apparatus and articles of manufacture improve the efficiency of using a computing device by maintaining phase coherence across calibration intervals using internal loopbacks and/or loopbacks across cascaded radar devices. Moreover, performance of location and/or velocity tracking systems is improved as a result of the improved phase coherency across tracked frames. Furthermore, example methods, apparatus, and/or articles of manufacture disclosed herein identify and overcome inaccuracies and inability in the prior art to perform object tracking. The disclosed methods, apparatus and articles of manufacture are accordingly directed to one or more improvement(s) in the functioning of a computer.

Example methods, apparatus, and articles of manufacture to compensate radar system calibration changes are disclosed herein. Further examples and combinations thereof include at least the following.

Example 1 comprises a radar system, comprising a radio-frequency (RF) subsystem having a transmit channel, a receive channel, and a loopback path comprising at least a portion of the transmit channel and at least a portion of the receive channel, a loopback measurer to measure a first loopback response of the RF subsystem for a first calibration configuration of the RF subsystem, and to measure a second loopback response of the RF subsystem for a second calibration configuration of the RF subsystem, and a compensator to adjust at least one of a transmit programmable shifter or a digital front end based on a difference between the first loopback response and the second loopback response to compensate for a loopback response change when the RF subsystem is changed from the first calibration configuration to the second calibration configuration.

Example 2 comprises the radar system of example 1, wherein the radar system is a system-on-a-chip device.

Example 3 comprises the radar system of example 2, wherein the first calibration configuration of the RF subsystem comprises a current calibration configuration of the transmit channel, and a current calibration configuration of the receive channel, the second calibration configuration is the current calibration configuration of the transmit channel, and a new calibration configuration of the receive channel, and the difference between the first loopback response and the second loopback response represents a change in the receive channel.

Example 4 comprises the radar system of example 2, wherein the first calibration configuration of the RF subsystem comprises a current calibration configuration of the transmit channel, and a current calibration configuration of the receive channel, the second calibration configuration is a new calibration configuration of the transmit channel, and the current calibration configuration of the receive channel, and the difference between the first loopback response and the second loopback response represents a change in the transmit channel.

Example 5 comprises the radar system of example 1, wherein the radar system comprises a first radar system-on-a-chip device that includes the transmit channel and a second radar system-on-a-chip device that includes the receive channel.

Example 6 comprises the radar system of example 5, wherein the first calibration configuration of the RF subsystem is a current calibration configuration of the transmit channel of the first radar system-on-a-chip device, and a current calibration configuration of the receive channel of the second radar system-on-a-chip device, the second calibration configuration of the RF subsystem is a new calibration configuration of the transmit channel of the first radar system-on-a-chip device, and the current calibration configuration of the receive channel of the second radar system-on-a-chip device, and the difference between the first loopback response and the second loopback response represents a change in at least one of the transmit channel of the first radar system-on-a-chip device, or a common mode path.

Example 7 comprises the radar system of example 6, wherein the compensator is to adjust the digital front end based on the difference between the first loopback response and the second loopback response.

Example 8 comprises the radar system of example 1, wherein the compensator adjusts the at least one of the transmit programmable shifter or the digital front end corresponding to multiplying a signal and the loopback response change.

Example 9 comprises the radar system of example 1, wherein the receive channel comprises a low-noise amplifier, a mixer, an intermediate frequency amplifier, and an analog-to-digital converter.

Example 10 comprises the radar system of example 1, wherein the transmit channel comprises an RF synthesizer, a programmable shifter, and a power amplifier.

Example 11 comprises the radar system of example 1, wherein the loopback path comprises a combiner, a frequency shifter, and a splitter.

Example 12 comprises a method, comprising measuring a first loopback response of a radio-frequency (RF) subsystem for a first calibration configuration of the RF subsystem, measuring a second loopback response of the RF subsystem for a second calibration configuration of the RF subsystem, and adjusting at least one of a transmit programmable shifter or a digital front end based on a difference between the first loopback response and the second loopback response to compensate for a loopback response change when the RF subsystem is changed from the first calibration configuration to the second calibration configuration.

Example 13 comprises the method of example 12, wherein the first calibration configuration of the RF subsystem comprises a current calibration configuration of a transmit channel, and a current calibration configuration of a receive channel, the second calibration configuration is the current calibration configuration of the transmit channel, and a new calibration configuration of the receive channel, and the difference between the first loopback response and the second loopback response represents a change in the receive channel.

Example 14 comprises the method of example 12, wherein the first calibration configuration of the RF subsystem comprises a current calibration configuration of a transmit channel, and a current calibration configuration of a receive channel, the second calibration configuration is a new calibration configuration of the transmit channel, and the current calibration configuration of the receive channel, and the difference between the first loopback response and the second loopback response represents a change in the transmit channel.

Example 15 comprises the method of example 12, wherein the first calibration configuration of the RF subsystem is a current calibration configuration of a transmit channel of a first system-on-a-chip device, and a current calibration configuration of a receive channel of a second system-on-a-chip device, the second calibration configuration of the RF subsystem is a new calibration configuration of the transmit channel of the first system-on-a-chip device, and the current calibration configuration of the receive channel of the second system-on-a-chip device, and the difference between the first loopback response and the second loopback response represents a change in the transmit channel and a common mode path.

Example 16 comprises the method of example 12, wherein the first calibration configuration of the RF subsystem is a current calibration configuration of a transmit channel of a first system-on-a-chip device, and a current calibration configuration of a receive channel of a second system-on-a-chip device, the second calibration configuration of the RF subsystem is the current calibration configuration of the transmit channel of the first system-on-a-chip device, and a new calibration configuration of the receive channel of the second system-on-a-chip device, and the difference between the first loopback response and the second loopback response represents a change in the receive channel.

Example 17 comprises the method of example 12, wherein adjusting the at least one of a transmit programmable shifter or a digital front end based on a difference between the first loopback response and the second loopback response comprises multiplying at least one of a transmit signal or a receive signal, and the loopback response change.

Example 18 comprises a non-transitory computer-readable storage medium comprising instructions that, when executed, cause a machine to at least measure a first loopback response of a radio-frequency (RF) subsystem for a first calibration configuration of the RF subsystem, measure a second loopback response of the RF subsystem for a second calibration configuration of the RF subsystem, and adjust at least one of a transmit programmable shifter or a digital front end based on a difference between the first loopback response and the second loopback response to compensate for a loopback response change when the RF subsystem is changed from the first calibration configuration to the second calibration configuration.

Example 19 comprises the non-transitory computer-readable storage medium of example 18, wherein the first calibration configuration of the RF subsystem comprises a current calibration configuration of a transmit channel, and a current calibration configuration of a receive channel, the second calibration configuration is the current calibration configuration of the transmit channel, and a new calibration configuration of the receive channel, and the difference between the first loopback response and the second loopback response represents a change in the receive channel.

Example 20 comprises the non-transitory computer-readable storage medium of example 18, wherein the first calibration configuration of the RF subsystem comprises a current calibration configuration of a transmit channel, and a current calibration configuration of a receive channel, the second calibration configuration is a new calibration configuration of the transmit channel, and the current calibration configuration of the receive channel, and the difference between the first loopback response and the second loopback response represents a change in the transmit channel.

Example 21 comprises the non-transitory computer-readable storage medium of example 18, wherein the first calibration configuration of the RF subsystem is a current calibration configuration of a transmit channel of a first system-on-a-chip device, and a current calibration configuration of a receive channel of a second system-on-a-chip device, the second calibration configuration of the RF subsystem is a new calibration configuration of the transmit channel of the first system-on-a-chip device, and the current calibration configuration of the receive channel of the second system-on-a-chip device, and the difference between the first loopback response and the second loopback response represents a change in at least one of the transmit channel, or a common mode path. It is noted that this patent claims priority to Indian Provisional Patent Application Serial No. 201841040934, which was filed on Oct. 26, 2018, and is hereby incorporated by reference in its entirety.

Any references, comprising publications, patent applications, and patents cited herein are hereby incorporated in their entirety by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.