PATENT DOCUMENT

Publication Number: US-12047101-B2
Application Number: US-202217716724-A
Country: US
Kind Code: B2

Title: Background noise recorder

Abstract:
An electronic device may include wireless circuitry with a transmit antenna that transmits signals and a receive antenna that receives reflected signals. The wireless circuitry may detect a range between the device and an external object based on the transmitted signals and the reflected signals. When the range exceeds a first threshold, the wireless circuitry may use the transmitted signals and received signals to record background noise. When the range is less than a second threshold value, the wireless circuitry may detect the range based on the reflected signals and the recorded background noise. This may allow the range to be accurately measured within an ultra-short range domain even when the device is placed in different device cases, placed on different surfaces, etc.

Claims:
What is claimed is: 
     
       1. A method of operating an electronic device comprising:
 generating, using wireless circuitry, voltage standing wave ratio (VSWR) values; 
 measuring, using the wireless circuitry, background noise when the VSWR values indicate that a first external object is present near the wireless circuitry; 
 transmitting, using the wireless circuitry, radio-frequency signals and receiving reflected signals from a second external object; 
 performing, using the wireless circuitry, phase measurements from the received reflected signals; and 
 detecting, using the wireless circuitry, a range between the second external object and the electronic device based on the phase measurements and the measured background noise. 
 
     
     
       2. The method of  claim 1 , wherein detecting the range comprises subtracting the measured background noise from the phase measurements. 
     
     
       3. The method of  claim 2 , further comprising:
 performing stabilization on the measured background noise. 
 
     
     
       4. The method of  claim 3 , further comprising discarding the measured background noise when the measured background noise is excessively unstable and subtracting the measured background noise from the phase measurements when the measured background noise is sufficiently stable. 
     
     
       5. The method of  claim 1 , further comprising:
 performing radar operations when the VSWR values indicate that no external objects are present near the wireless circuitry. 
 
     
     
       6. The method of  claim 1 , further comprising:
 decimating and averaging the measured background noise prior to detecting the range based on the phase measurements and the measured background noise. 
 
     
     
       7. The method of  claim 1 , further comprising:
 averaging the measured background noise, wherein detecting the range comprises subtracting the averaged measured background noise from the phase measurements. 
 
     
     
       8. The method of  claim 1 , further comprising:
 decimating the measured background noise, wherein detecting the range comprises subtracting the decimated measured background noise from the phase measurements. 
 
     
     
       9. The method of  claim 1 , further comprising:
 interpolating the measured background noise, wherein detecting the range comprises subtracting the interpolated measured background noise from the phase measurements. 
 
     
     
       10. The method of  claim 1 , wherein the first external object comprises a removable case on the electronic device. 
     
     
       11. The method of  claim 1 , further comprising:
 recording the measured background noise when the VSWR values are indicative of the first external object being an inanimate object present near the wireless circuitry. 
 
     
     
       12. An electronic device comprising:
 one or more antennas configured to transmit radio-frequency signals and to receive reflected signals; and 
 one or more processors configured to
 generate, using the one or more antennas, voltage standing wave ratio (VSWR) values, 
 measure background noise when the VSWR values indicate that a first external object is present near the wireless circuitry, and 
 identify a range between the electronic device and a second external object based on phase measurements from the reflected signals received by the one or more antennas and based on the measured background noise. 
 
 
     
     
       13. The electronic device of  claim 12 , the one or more processors being configured to identify the range by subtracting the measured background noise from the phase measurements. 
     
     
       14. The electronic device of  claim 12 , wherein the radio-frequency signals comprise a chirp signal. 
     
     
       15. The electronic device of  claim 12 , wherein the first external object is a removable case on the electronic device. 
     
     
       16. The electronic device of  claim 15 , wherein the electronic device comprises a cellular telephone. 
     
     
       17. A non-transitory computer-readable storage medium storing one or more programs configured to be executed by at least one processor on an electronic device, the one or more programs including instructions that, when executed by the at least one processor, cause the at least one processor to:
 generate, using wireless circuitry, voltage standing wave ratio (VSWR) values; 
 measure, using the wireless circuitry, background noise when the VSWR values are indicative of a removable case being on the electronic device; 
 transmit, using the wireless circuitry, radio-frequency signals and receiving reflected signals from an external object that is different from the removable case; 
 measure, using the wireless circuitry, a phase of the received reflected signals; and 
 detect a range between the electronic device and the external object based on a difference between the measured phase and the measured background noise. 
 
     
     
       18. The non-transitory computer-readable storage medium of  claim 17 , the one or more programs including instructions that, when executed by the at least one processor, cause the at least one processor to:
 average the measured background noise; and 
 detect the range based on a difference between the measured phase and the averaged measured background noise. 
 
     
     
       19. The non-transitory computer-readable storage medium of  claim 17 , the one or more programs including instructions that, when executed by the at least one processor, cause the at least one processor to:
 decimate the measured background noise; and 
 detect the range based on a difference between the measured phase and the decimated measured background noise. 
 
     
     
       20. The non-transitory computer-readable storage medium of  claim 17 , the one or more programs including instructions that, when executed by the at least one processor, cause the at least one processor to:
 interpolate the measured background noise; and 
 detect the range based on a difference between the measured phase and the interpolated measured background noise.

Description:
This application claims the benefit of U.S. provisional patent application No. 63/248,169, filed Sep. 24, 2021, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This disclosure relates generally to electronic devices and, more particularly, to electronic devices with wireless circuitry. 
     BACKGROUND 
     Electronic devices are often provided with wireless capabilities. An electronic device with wireless capabilities has wireless circuitry that includes one or more antennas. The wireless circuitry is sometimes used to perform spatial ranging operations in which radio-frequency signals are used to estimate a distance between the electronic device and an external object. 
     It can be challenging to provide wireless circuitry that accurately estimates this distance, particularly at short ranges. 
     SUMMARY 
     An electronic device may include wireless circuitry controlled by one or more processors. The wireless circuitry may include a transmit antenna and a receive antenna. The transmit antenna may transmit radio-frequency signals. The receive antenna may receive reflected signals corresponding to the transmitted radio-frequency signals. The wireless circuitry may detect a range between the device and an external object based on the transmitted radio-frequency signals and the received reflected signals. 
     When the range exceeds a first threshold value (e.g., in a long-range domain), the wireless circuitry may use the transmitted and received signals to record background noise associated with the absence of the external object near the device. When the range is less than a second threshold value (e.g., within an ultra-short range (USR) domain), the one or more processors may detect the range based on the received reflected signals and the recorded background noise. For example, the one or more processors may identify phase information from the received reflected signals and may subtract the recorded background noise from the phase information. This may allow the range to be accurately measured within the USR domain even when the device is placed in different device cases, placed on different surfaces, etc. 
     An aspect of the disclosure provides a method of operating an electronic device. The method can include with wireless circuitry, transmitting radio-frequency signals and receiving reflected signals to identify a range between an external object and the electronic device. The method can include when the range exceeds a threshold value, controlling the wireless circuitry to record background noise using the transmitted radio-frequency signals. The method can include with the wireless circuitry, performing phase measurements from the received reflected signals. The method can include with the wireless circuitry, detecting the range based on the phase measurements and the recorded background noise. 
     An aspect of the disclosure provides a method of operating an electronic device. The method can include with wireless circuitry, performing frequency-modulated continuous-wave (FMCW) radar operations to identify a range between an external object and the electronic device by transmitting radio-frequency signals and receiving reflected signals. The method can include when the range exceeds a first threshold value, recording background noise at the wireless circuitry using the transmitted radio-frequency signals. The method can include when the range is less than a second threshold value that is lower than the first threshold value, performing phase measurements from the received reflected signals and detecting the range based on the phase measurements and the recorded background noise. 
     An aspect of the disclosure provides an electronic device. The electronic device can include one or more antennas configured to transmit radio-frequency signals and configured to receive reflected signals. The electronic device can include one or more processors. The one or more processors can be configured to identify a range between the electronic device and an external object based on the reflected signals received by the one or more antennas. The one or more processors can be configured to, when the range exceeds a first threshold value, record background noise using the radio-frequency signals transmitted by the one or more antennas and corresponding signals received by the one or more antennas. The one or more processors can be configured to, when the range is less than a second threshold value that is lower than the first threshold value, detect the range based on phase measurements from the reflected signals received by the one or more antennas and based on the recorded background noise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a functional block diagram of an illustrative electronic device having radar circuitry in accordance with some embodiments. 
         FIG.  2    is a circuit diagram of illustrative radar circuitry with reconfigurable filters for performing long range and ultra-short range (USR) detection in accordance with some embodiments. 
         FIGS.  3  and  4    are diagrams of illustrative transmit signals that may be used by radar circuitry to perform long range and USR detection in accordance with some embodiments. 
         FIG.  5    is a flow chart of illustrative operations involved in using an electronic device to perform both long range and USR detection in accordance with some embodiments. 
         FIG.  6    is a plot of group delay as a function of range that shows how using radar circuitry to measure group delay may allow the radar circuitry to detect distance in accordance with some embodiments. 
         FIG.  7    is a diagram showing how an illustrative high pass filter may be used to maximize signal-to-noise ratio for long range detection in accordance with some embodiments. 
         FIG.  8    is a flow chart of illustrative operations involved in performing background recording and cancellation in accordance with some embodiments. 
         FIG.  9    is a flow chart of illustrative operations involved in performing background recording and cancellation for short range and USR detection in accordance with some embodiments. 
         FIG.  10    is a flow chart of illustrative operations involved in performing background recording and cancellation for a hybrid radar that performs long range and USR detection in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic device  10  of  FIG.  1    may be a computing device such as a laptop computer, a desktop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a wireless internet-connected voice-controlled speaker, a home entertainment device, a remote control device, a gaming controller, a peripheral user input device, a wireless base station or access point, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     As shown in the functional block diagram of  FIG.  1   , device  10  may include components located on or within an electronic device housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, metal alloys, etc.), other suitable materials, or a combination of these materials. In some situations, parts or all of housing  12  may be formed from dielectric or other low-conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may include control circuitry  14 . Control circuitry  14  may include storage such as storage circuitry  16 . Storage circuitry  16  may include hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Storage circuitry  16  may include storage that is integrated within device  10  and/or removable storage media. 
     Control circuitry  14  may include processing circuitry such as processing circuitry  18 . Processing circuitry  18  may be used to control the operation of device  10 . Processing circuitry  18  may include on one or more microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), etc. Control circuitry  14  may be configured to perform operations in device  10  using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device  10  may be stored on storage circuitry  16  (e.g., storage circuitry  16  may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry  16  may be executed by processing circuitry  18 . 
     Control circuitry  14  may be used to run software on device  10  such as satellite navigation applications, internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  14  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  14  include internet protocols, wireless local area network (WLAN) protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network (WPAN) protocols, IEEE 802.11ad protocols (e.g., ultra-wideband protocols), cellular telephone protocols (e.g., 3G protocols, 4G (LTE) protocols, 3GPP 5G protocols, 6G protocols, etc.), antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), antenna-based spatial ranging protocols (e.g., radio detection and ranging (RADAR) protocols or other desired range detection protocols for signals conveyed at millimeter and centimeter wave frequencies), or any other desired communications protocols. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol. 
     Device  10  may include input-output circuitry  20 . Input-output circuitry  20  may include input-output devices  22 . Input-output devices  22  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  22  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  22  may include touch sensors, displays (e.g., touch-sensitive and/or force-sensitive displays), light-emitting components such as displays without touch sensor capabilities, buttons (mechanical, capacitive, optical, etc.), scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, audio jacks and other audio port components, digital data port devices, motion sensors (accelerometers, gyroscopes, and/or compasses that detect motion), capacitance sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to a display to detect pressure applied to the display), etc. In some configurations, keyboards, headphones, displays, pointing devices such as trackpads, mice, and joysticks, and other input-output devices may be coupled to device  10  using wired or wireless connections (e.g., some of input-output devices  22  may be peripherals that are coupled to a main processing unit or other portion of device  10  via a wired or wireless link). 
     Input-output circuitry  20  may include wireless circuitry  24  to support wireless communications. Wireless circuitry  24  (sometimes referred to herein as wireless communications circuitry  24 ) may include two or more antennas  40 . Wireless circuitry  24  may also include baseband processor circuitry, transceiver circuitry, amplifier circuitry, filter circuitry, switching circuitry, radio-frequency transmission lines, and/or any other circuitry for transmitting and/or receiving radio-frequency signals using antennas  40 . 
     Wireless circuitry  24  may transmit and/or receive radio-frequency signals within a corresponding frequency band at radio frequencies (sometimes referred to herein as a communications band or simply as a “band”). The frequency bands handled by radios  28  may include wireless local area network (WLAN) frequency bands (e.g., Wi-Fi® (IEEE 802.11) or other WLAN communications bands) such as a 2.4 GHz WLAN band (e.g., from 2400 to 2480 MHz), a 5 GHz WLAN band (e.g., from 5180 to 5825 MHz), a Wi-Fi® 6E band (e.g., from 5925-7125 MHz), and/or other Wi-Fi® bands (e.g., from 1875-5160 MHz), wireless personal area network (WPAN) frequency bands such as the 2.4 GHz Bluetooth® band or other WPAN communications bands, cellular telephone frequency bands (e.g., bands from about 600 MHz to about 5 GHz, 3G bands, 4G LTE bands, 5G New Radio Frequency Range 1 (FR1) bands below 10 GHz, 5G New Radio Frequency Range 2 (FR2) bands between 20 and 60 GHz, etc.), other centimeter or millimeter wave frequency bands between 10-300 GHz, near-field communications frequency bands (e.g., at 13.56 MHz), satellite navigation frequency bands (e.g., a GPS band from 1565 to 1610 MHz, a Global Navigation Satellite System (GLONASS) band, a BeiDou Navigation Satellite System (BDS) band, etc.), ultra-wideband (UWB) frequency bands that operate under the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols, communications bands under the family of 3GPP wireless communications standards, communications bands under the IEEE 802.XX family of standards, and/or any other desired frequency bands of interest. 
     Antennas  40  may be formed using any desired antenna structures. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antennas, dipoles, hybrids of these designs, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and/or other antenna tuning components may be adjusted to adjust the frequency response and wireless performance of antennas  40  over time. 
     The radio-frequency signals handled by antennas  40  may be used to convey wireless communications data between device  10  and external wireless communications equipment (e.g., one or more other devices such as device  10 ). Wireless communications data may be conveyed by wireless circuitry  24  bidirectionally or unidirectionally. The wireless communications data may, for example, include data that has been encoded into corresponding data packets such as wireless data associated with a telephone call, streaming media content, internet browsing, wireless data associated with software applications running on device  10 , email messages, etc. 
     Wireless circuitry  24  may additionally or alternatively perform spatial ranging operations using antennas  40 . In scenarios where wireless circuitry  24  both conveys wireless communications data and performs spatial ranging operations, one or more of the same antennas  40  may be used to both convey wireless communications data and perform spatial ranging operations. In another implementation, wireless circuitry  24  may include a set of antennas  40  that only conveys wireless communications data and a set of antennas  40  that is only used to perform spatial ranging operations. 
     When performing spatial ranging operations (sometimes referred to herein as range detection operations, ranging operations, or radar operations), antennas  40  may transmit radio-frequency signals  36 . Wireless circuitry  24  may transmit radio-frequency signals  36  in a corresponding radio frequency band such (e.g., a frequency band that includes frequencies greater than around 10 GHz, greater than around 20 GHz, less than 10 GHz, etc.). Radio-frequency signals  36  may reflect off of objects external to device  10  such as external object  34 . External object  34  may be, for example, the ground, a building, a wall, furniture, a ceiling, a person, a body part, an accessory device, a game controller, an animal, a vehicle, a landscape or geographic feature, an obstacle, or any other object or entity that is external to device  10 . Antennas  40  may receive reflected radio-frequency signals  38 . Reflected signals  38  may be a reflected version of the transmitted radio-frequency signals  36  that have reflected off of external object  34  and back towards device  10 . 
     Control circuitry  14  may process the transmitted radio-frequency signals  36  and the received reflected signals  38  to detect or estimate the range R between device  10  and external object  34 . If desired, control circuitry  14  may also process the transmitted and received signals to identify a two or three-dimensional spatial location (position) of external object  34 , a velocity of external object  34 , and/or an angle of arrival of reflected signals  38 . In one implementation that is described herein as an example, wireless circuitry  24  performs spatial ranging operations using a frequency-modulated continuous-wave (FMCW) radar scheme. This is merely illustrative and, in general, other radar schemes or spatial ranging schemes may be used (e.g., an OFDM radar scheme, an FSCW radar scheme, a phase coded radar scheme, etc.). 
     To support spatial ranging operations, wireless circuitry  24  may include spatial ranging circuitry such as radar circuitry  26 . In one embodiment that is sometimes described herein as an example, radar circuitry  26  includes FMCW radar circuitry that performs spatial ranging using an FMCW radar scheme. Radar circuitry  26  may therefore sometimes be referred to herein as FMCW radar circuitry  26 . Radar circuitry  26  may use one or more antennas  40  to transmit radio-frequency signals  36  (e.g., as a continuous wave of radio-frequency energy under an FMCW radar scheme). One or more antennas  40  may also receive reflected signals  38  (e.g., as a continuous wave of radio-frequency energy under the FMCW radar scheme). Radar circuitry  26  may process radio-frequency signals  36  and reflected signals  38  to identify/estimate range R, the position of external object  34 , the velocity of external object  34 , and/or the angle-of-arrival of reflected signals  38 . In embodiments where radar circuitry  26  uses an FMCW radar scheme, doppler shifts in the continuous wave signals may be detected and processed to identify the velocity of external object  34  and the time dependent frequency difference between radio-frequency signals  36  and reflected signals  38  may be detected and processed to identify range R and/or the position of external object  34 . Use of continuous wave signals for estimating range R may allow control circuitry  10  to reliably distinguish between external object  34  and other background or slower-moving objects, for example. 
     As shown in  FIG.  1   , radar circuitry  26  may include transmit (TX) signal generator circuitry such as transmit signal generator  28 . Transmit signal generator  28  may generate transmit signals for transmission over antenna(s)  40 . In some implementations that are described herein as an example, transmit signal generator  28  includes a chirp generator that generates chirp signals for transmission over antenna(s)  40  (e.g., in embodiments where radar circuitry  26  uses an FMCW radar scheme). Transmit signal generator  28  may therefore sometimes be referred to herein as chirp generator  28 . Transmit signal generator  28  may, for example, produce chirp signals that are transmitted as a continuous wave of radio-frequency signals  36 . The chirp signals may be formed by periodically ramping up the frequency of the transmitted signals in a linear manner over time, for example. Radar circuitry  26  may also include digital-to-analog converter (DAC) circuitry such as DAC  32 . DAC  32  may convert the transmit signals (e.g., the chirp signals) from the digital domain to the analog domain prior to transmission by antennas  40  (e.g., in radio-frequency signals  36 ). Radar circuitry  26  may also include analog-to-digital converter (ADC) circuitry such as ADC  42 . ADC  42  may convert signals from the analog domain to the digital domain for subsequent processing by control circuitry  14 . If desired, radar circuitry  26  may include distortion circuitry  30 . Distortion circuitry  30  may include predistortion circuitry that predistorts the transmit signals prior to transmission by antennas  40  and/or may include post-distortion circuitry that distorts received signals. 
     The example of  FIG.  1    is merely illustrative. While control circuitry  14  is shown separately from wireless circuitry  24  in the example of  FIG.  1    for the sake of clarity, wireless circuitry  24  may include processing circuitry (e.g., one or more processors) that forms a part of processing circuitry  18  and/or storage circuitry that forms a part of storage circuitry  16  of control circuitry  14  (e.g., portions of control circuitry  14  may be implemented on wireless circuitry  24 ). As an example, control circuitry  14  may include baseband circuitry (e.g., one or more baseband processors), digital control circuitry, analog control circuitry, and/or other control circuitry that forms part of radar circuitry  26 . The baseband circuitry may, for example, access a communication protocol stack on control circuitry  14  (e.g., storage circuitry  20 ) to: perform user plane functions at a PHY layer, MAC layer, RLC layer, PDCP layer, SDAP layer, and/or PDU layer, and/or to perform control plane functions at the PHY layer, MAC layer, RLC layer, PDCP layer, RRC, layer, and/or non-access stratum layer. If desired, the PHY layer operations may additionally or alternatively be performed by radio-frequency (RF) interface circuitry in wireless circuitry  24 . 
     If desired, radar circuitry  26  may be used to measure the proximity of a human body to antennas  40 . Measurement of this proximity (e.g., range R) may allow the device to adjust the transmit power level of antennas  40  (e.g., based on range R) to ensure that wireless circuitry  24  complies with regulatory requirements on radio-frequency exposure (RFE). For example, the transmit power level and/or transmit duration of the wireless circuitry can be reduced and/or different antennas can be switched into use when range R is small to ensure compliance with these requirements. When no external object  34  is located close to antennas  40  (e.g., when range R is high), wireless circuitry  24  may transmit radio-frequency signals at a maximum transmit power level, thereby maximizing throughput. In general, radar circuitry  26  needs to be very accurate to perform such detection of a human body (sometimes referred to herein as body proximity sensing (BPS)). However, a relatively high dynamic range is needed to resolve a wide number of ranges R (e.g., limits in dynamic range can limit the overall detection range of radar circuitry  26 ). If care is not taken, it can be difficult to configure radar circuitry  26  to detect range R over both relatively long distances (e.g., ranges greater than around 10 cm, generally referred to herein as “long range”) and relatively short distances (e.g., ranges less than around 10 cm, generally referred to herein as “ultra-short range (USR)”) with sufficient dynamic range. 
     To allow radar circuitry  26  to perform spatial ranging operations within both the long range domain (sometimes referred to herein as the far field domain) and within the USR domain, radar circuitry  26  may include reconfigurable high pass filters.  FIG.  2    is a circuit diagram of radar circuitry  26  having reconfigurable high pass filters. 
     As shown in  FIG.  2   , radar circuitry  26  may include a transmit chain  52  (sometimes referred to herein as transmitter chain  52 , transmit line-up  52 , or transmit path  52 ) and a receive chain  54  (sometimes referred to herein as receiver chain  54 , receive line-up  54 , or receive path  52 ). Transmit (TX) chain  52  may include a digital-to-analog converter (DAC) such as DAC  62 . DAC  62  may include an in-phase (I) DAC  62 I that operates on in-phase (I) signals and a quadrature-phase (Q) DAC  62 Q that operates on quadrature-phase (Q) signals (e.g., of an I/Q signal pair). Transmit chain  52  may include mixers  68  (e.g., an in-phase mixer  68 I and a quadrature phase mixer  68 Q) having first inputs coupled to the outputs of DACs  62 I and  62 Q and having second inputs coupled to clocking circuitry such as local oscillator (LO)  66 . Mixers  68  may have outputs coupled to the input of power amplifier (PA)  70  in transmit chain  52 . The output of PA  70  may be coupled to a first antenna  40  ( FIG.  1   ). 
     Receive (RX) chain  54  may include a low noise amplifier (LNA)  72  and mixers  74  (e.g., an in-phase mixer  74 I and a quadrature-phase mixer  74 Q) having first inputs coupled to the output of LNA  72  and having second inputs coupled to LO  66 . The input of LNA  72  may be coupled to a second antenna  40  ( FIG.  1   ). Receive chain  54  may include high pass filters  76  having inputs coupled to mixers  74  and having outputs coupled to analog-to-digital converter (ADC)  64  (e.g., an in-phase (I) ADC  64 I and a quadrature-phase (Q) ADC  34 Q). For example, a first high pass filter  76 I may be interposed between the output of mixer  74 I and the input of ADC  64 I and a second high pass filter  76 Q may be interposed between the output of mixer  74 Q and the input of ADC  64 Q. The outputs of ADC  64 I and  64 Q and the inputs of DACs  62 I and  62 Q may be coupled to digital signal processor (DSP)  50 . DSP  50  may include a digital background (BG) canceller  56 , FMCW or other long range radar circuitry such as FMCW circuitry  58 , and phase detector  60 . 
     High pass filters  76 I and  76 Q may be reconfigurable (bypassable). For example, a bypass path  78 I may couple the input of high pass filter (HPF)  76 I to the output of HPF  76 I. Similarly, a bypass path  78 Q may couple the input of HPF  76 Q to the output of HPF  76 Q. Switches such as switches (SW)  80  may be disposed on bypass paths  78 I and  78 Q. If desired, an optional all pass filter (APF)  82  may be disposed on bypass paths  78 I and  78 Q (e.g., between switch  80  and ADC  64 ). Switches  80  may have a first state (e.g., where switches  80  are closed or turned on) in which HPFs  76  are bypassed and may have a second state (e.g., where switches  80  are open or turned off) in which HPFs  76  are switched into use and bypass paths  78  form open circuits. 
     If desired, a feedback path  84  may couple transmit chain  52  to receive chain  54 . A de-chirp path may additionally or alternatively couple transmit chain  52  to a de-chirp mixer in receive chain  54 . As shown in  FIG.  2   , feedback path  84  may include an optional multi-tab analog interference canceller  86  having an output coupled to an adder such as adder  87  in receive chain  54 . Adder  87  and/or feedback path  84  may be omitted if desired. The example of  FIG.  2    is merely illustrative. In general, other circuit architectures may be used to form radar circuitry  26 . Additional filters, amplifiers, switches, delay stages, splitters, and/or other circuit components may be formed at other locations in radar circuitry  26 . 
     When performing spatial ranging (radar) operations, transmit signal generator  28  ( FIG.  1   ) may generate transmit signals (e.g., digital chirp signals) for subsequent transmission by the antenna coupled to transmit chain  52  (e.g., using a continuous wave of radio-frequency energy). FMCW circuitry  58  may, for example, control the transmit signal generator to generate desired transmit signal waveforms. If desired, digital BG canceler  56  may perform background cancellation (pre-compensation) on the generated transmit signals. DAC  62  may convert the transmit signals to the digital domain. Mixers  68  may upconvert the transmit signals to radio frequencies or intermediate frequencies for later upconversion to radio-frequencies (e.g., using a local oscillator (LO) signal from LO  66 ). These frequencies may be 5G NR FR1 or FR2 frequencies, for example. PA  70  may amplify the transmit signals for transmission by the corresponding antenna  40  coupled to transmit chain  52  (e.g., as radio-frequency signals  36  of  FIG.  1   ). 
     The antenna  40  coupled to receive chain  54  may receive reflected signals  38  (e.g., a reflected version of the transmit signals transmitted over transmit chain  52 ). LNA  72  may amplify the received reflected signals  38 . Mixers  74  may downconvert the reflected signals to baseband. During long range detection, switches  80  may be open (e.g., bypass paths  78  may form open circuits) and HPFs  76  may filter the received reflected signals to output filtered signals. ADC  64  may convert the filtered signals to the digital domain for subsequent processing by DSP  50 . FMCW circuitry  58  may process the transmit signals provided to transmit chain  52  and the reflected signals received over receive chain  54  to identify range R to external object  34 . For example, FMCW circuitry  58  may detect (e.g., identify) time delays between the transmitted and received signals, may generate time of flight (TOF) information for the signals, and may identify (e.g., generate, compute, calculate, etc.) range R from the TOF information. HPFs  76  may serve to filter out leakage/interference signal (e.g., from coupling or a dielectric cover layer on device  10  through which the radio-frequency signals and reflected signals pass) from the received reflected signals, thereby maximizing the signal-to-noise ratio SNR and dynamic range of the received signals to allow for accurate long range measurements of range R. 
     When performing USR measurements, the high dynamic range required for long range detection is not needed. As such, HPFs  76  may be bypassed or switched out of use while performing USR measurements. For example, switches  80  may be closed, allowing the received reflected signals to pass from mixers  74  directly to ADC  64  without being filtered. If desired, APFs  82  may filter these signals to correct for imperfections in the channel response, for example. Phase detector  60  may process the received reflected signals to identify (e.g., generate, detect, estimate, measure, etc.) the phase and/or phase delay of the signals (e.g., group phase delay), in a process sometimes referred to herein as performing phase measurements. Control circuitry  14  ( FIG.  1   ) may determine (e.g., identify, generate, calculate, etc.) range R based on the identified phase delay (based on the phase measurements). If desired, digital BG canceller  56  may perform BG noise cancellation on the transmitted and/or received signals used to perform USR detection. HPFs  76  may be replaced with DC notch filters if desired. 
       FIG.  3    is a diagram (in frequency as a function of time) of illustrative transmit signals that may be transmitted over transmit chain  52  for performing long range and USR detection. Curve  100  plots a digital FMCW or continuous FMCW signal (e.g., a frequency ramp or chirp signal) that may be transmitted for performing long range detection (e.g., while HPFs  76  are switched into use in the receive chain). Curve  102  plots discrete frequencies (e.g., a step function in frequency versus time) that may be used in the transmit signal for performing USR detection. If desired, LO  66  may generate coarse steps LO_ 1  through LO_N used in generating the transmit signal whereas the finer steps or continuous steps are provided from DAC  62  of  FIG.  2   . The example of  FIG.  3    is merely illustrative and, in general, curves  100  and  102  may have other shapes. 
       FIG.  4    is a plot of the transmit signals associated with curve  102  of  FIG.  3    that may be used in performing USR detection, but in units of power as a function of frequency. As shown in  FIG.  4   , the transmit signal involves a series of peaks (lines)  104  each separated by frequency gap Δf. Control circuitry  14  may process the transmit signal associated with peaks  104  as well as the reflected version of the transmit signal (e.g., as received while HPFs  76  are bypassed) to identify range R to the external object (e.g., using equation 106). As shown by equation 106, distance d (range R) may be computed as a function of the measured phase delay detected by phase detector  60  from the received reflected version of transmit signal  104  (e.g., where Ω d  is a factor that accounts for the phase delay, co is the speed of light, and τ is a complex phase delay factor). Control circuitry  14  may identify range R (distance d) using equation 106 or by comparing the measured phase delay to a look up table of predetermined phase delays stored on device  10  (e.g., where each stored phase delay corresponds to a stored distance d that is retrieved by comparing the measured phase delay to the predetermined phase delays in the look up table). 
       FIG.  5    is a flow chart of illustrative operations involved in performing ranging using radar circuitry  26 . At operation  110 , radar circuitry  26  may begin recording (gathering) background noise measurements. For example, radar circuitry  26  may perform USR detection when no objects are present near device  10  to measure background noise associated with the housing for device  10 , a removable case on device  10 , etc. This background noise may later be subtracted off of subsequent USR detections to generate accurate ranges R for objects within 10 cm. 
     At operation  112 , radar circuitry  26  may perform long range detection (e.g., using the transmit signal associated with curve  100  of  FIG.  3   , such as using an FMCW scheme and transmit signal). HPFs  76  may be switched into use and may filter the received reflected signals to maximize dynamic range. Control circuitry  14  may identify range R based on the transmitted and reflected signals (e.g., by identifying TOF information from time delays between the transmitted and reflected signals). 
     At operation  114 , radar circuitry  26  may perform USR detection (e.g., using the transmit signal associated with curve  102  of  FIG.  3   ). HPFs  76  may be switched out of use (bypassed). Phase detector  60  may measure the phase delay of the received reflected signals (e.g., may perform phase measurements). Control circuitry  14  may process the phase delay to identify range R based on the phase delay (e.g., either as input to a function or by comparison to stored information such as look up table information mapping predetermined/calibrated ranges to phase delays). Control circuitry  14  may also perform background noise cancellation using the gathered BG measurements to ensure that the identified range R is accurate (at operation  116 ). The background noise cancellation may occur in the digital domain, for example (e.g., at DSP  50  of  FIG.  2   ). Processing may then loop back to path  112  via path  118  (e.g., radar circuitry  26  may perform long range detection and USR detection in a time-interleaved/duplexed manner). 
     If desired, analog interference cancellation may also be performed using multi-tab AIC  86  of  FIG.  2   . For example, AIC  86  may be used to perform coefficient adaption from background measurements and analog multi-tab cancellation may be performed. However, analog interference cancellation may undesirably increase RF hardware complexity, reduce tunability, and degrade SNR. Performing digital BG cancellation using digital BG canceller  56  of  FIG.  2    may allow DSP  50  to perform coefficient adaptation from background measurements, where the background measurements are subtracted in the complex domain from the transmitted and/or received signals (e.g., at operation  116  of  FIG.  5   ). Digital BG cancellation may involve greater hardware flexibility than analog cancellation. 
       FIG.  6    is a plot showing how measured group delay may vary as a function of distance (range R) to external object  34 . As shown by curve  120 , group delay generally increases as range (distance) R increases. Bypassing HPFs  76  and performing digital BG cancellation may allow device  10  to perform USR detection based on the measured group delay with finer resolution than would otherwise be possible (e.g., within 4 cm or less). 
       FIG.  7    is a plot showing how HPFs  76  may be used to maximize dynamic range for long range detection (in power spectral density (PSD) as a function of frequency). Curve  132  of  FIG.  7    plots the PSD at the antennas generated by signal leakage or coupling as the transmit signals and reflected signals pass through the cover layer(s) of device  10  from free space to antennas  40 . Curve  132  may peak at a frequency such as frequency F0. Curve  134  plots the expected PSD produced at the antennas by reflection of the transmit signals off external object  34  located within the USR domain (e.g., within 10 cm). Curve  134  may peak at a frequency such as frequency F1. Curve  136  plots the expected PSD produced by reflection of the transmit signals off external object  34  located within the long range domain (e.g., beyond 10 cm). Curve  136  may peak at a frequency such as frequency F3. 
     Curve  130  plots the filter response of HPFs  76 . As shown by curve  130 , HPFs  76  may have a roll off (edge) frequency F2, a pass band at frequencies greater than F2, and a stop band (e.g., notch) at frequencies less than F2. Frequency F2 may be selected to be greater than frequency F1 and less than frequency F3. In this way, HPFs  76  may filter out the PSD associated with leakage or coupling (curve  132 ) from the reflected signals received and measured by radar circuitry  26 . This may serve to maximize dynamic range for detecting range R to external object  34  in the long range domain. Since curve  134  is below frequency F2, HPFs  76  need to be disabled (bypassed) to allow radar circuitry  26  to receive the PSD produced by reflection off external object  34  (curve  134 ), which is then used to identify the range to the external object (e.g., within 10 cm). 
     As described above, USR detection may involve the cancellation (subtraction) of background noise (e.g., at operation  116  of  FIG.  5   ). Background noise cancellation may allow for USR detection with fine range resolution.  FIG.  8    is a flow chart of illustrative operations involved in gathering background measurements (e.g., as begun at operation  110  of  FIG.  5   ) and in applying the gathered background measurements to USR detection operations (e.g., via background subtraction). 
     At operation  150 , radar circuitry  26  may perform radar operations (e.g., long range detection or USR detection at operations  112 / 114  of  FIG.  5   ). Radar circuitry  26  may identify range R by performing radar operations, for example. Radar circuitry  26  may perform background recording operations/algorithm  152  (e.g., gathering and storing of background noise measurements for use in later background cancellation while performing USR operations) periodically, upon boot up, in the factory, upon software update, and/or in response to any desired trigger condition. 
     At operation  154 , control circuitry  14  may determine whether range R exceeds a long threshold value (e.g., 2 m, 10 cm, 1 m, other values greater than or equal to 1 m or 0.5 m, etc.). If range R is less than this threshold value, there is an external object  34  located relatively close to device  10  and any subsequent measurements will not be indicative of the true background noise of the radar circuitry. As such, if range R does not exceed the long threshold value, processing may loop back to operation  150  via path  164 . Range R may be determined using range circuitry  26  and/or other sensors on device  10  if desired. 
     If range R is greater than the long threshold value, there are no external objects  34  located relatively close to device  10  and processing may proceed to operation  156 . At operation  156 , radar circuitry  26  may perform other object detection (e.g., inanimate object detection) if desired. This may involve performing object detection using other proximity sensors such as a voltage standing wave ratio (VSWR) sensor coupled to one or more antennas  40 . 
     At operation  158 , control circuitry  14  may determine whether an object was detected at operation  156 . This may involve, for example, comparing VSWR values to stored VSWR values associated with known inanimate objects or may involve tracking changes in measured VSWR values over time (e.g., where the amount of change in the VSWR values over time is less than a threshold amount over a predetermined time period). If no inanimate object is detected, processing may loop back to path  150  via path  164 . If an inanimate object is detected, this may be indicative of a device case or other inanimate object being present on device  10 . It would therefore be desirable to be able to characterize the background noise effects (e.g., which produces the PSD associated with curve  132  of  FIG.  7   ) that such an inanimate object has on radar circuitry  26  (e.g., for later subtraction of the effects of the inanimate object on measurements of range R due to signal reflections, attenuation, diffraction, etc. as the signals pass through the inanimate object). In other words, if an inanimate object is detected, processing may proceed to operation  160 . 
     At operation  160 , radar circuitry  16  may enter a USR background recording mode in which radar circuitry  16  gathers (measures) and stores background noise using the transmitted and received signals. For example, control circuitry  14  may switch HPFs  76  ( FIG.  2   ) out of use and may switch APF  82  on bypass paths  78  into use. TX signal generator  28  may transmit N tones over transmit chain  52 . The N tones may be defined from channel conditions such as resonance removal conditions (e.g., to measure channel performance). Control circuitry  14  may then memorize/record (e.g., measure and store) the amplitude and/or phase of each of the N tones as received over receive chain  54  (e.g., using measurement of offset phases, least mean squares (LMS), least squares (SQ), etc. using a multi tab filter). 
     At operation  162 , control circuitry  14  may run a background (BG) stabilizer on the recorded amplitudes and/or phases. The BG stabilizer may include decimation, averaging, and/or interpolation of the gathered amplitudes and/or phases (e.g., stabilization operations that minimize noise or otherwise enhance the time-stability of the data). 
     At operation  166 , control circuitry  14  may determine whether the phase and/or magnitude values are sufficiently stable after running the BG stabilizer. If the values are not sufficiently stable (e.g., exhibit excessive change over a period of time, exhibit a stability value less than a threshold stability value, etc.), the values may be insufficient for use in background cancellation and can be discarded (e.g., processing may loop back to operation  150  via path  164 ). If the values are sufficiently stable (e.g., exhibit relatively little change over a period of time, exhibit a stability value greater than a threshold stability value, etc.), the values may be satisfactory for use in background cancellation and processing may proceed to operation  170  via path  168 . 
     At operation  170 , control circuitry  14  (radar circuitry  26 ) may perform BG subtraction operations that configure radar circuitry  26  (e.g., digital BG canceller  56 ) to mitigate/cancel/subtract out the measured/recorded background noise during subsequent radar operations. Processing may proceed to operation  150  and radar operations may be performed while subtracting out the background noise as configured during operation  170 . For example, digital BG canceller  56  may perform complex subtraction, multi-tab LMS, and/or LS on subsequently transmitted and/or received signals used in performing USR detection (e.g., at operation  114  of  FIG.  5   ). 
       FIG.  9    is a flow chart showing how these operations may be adapted to implementations in which radar circuitry  26  is operable to perform short range detection and then USR detection. At operation  180 , radar circuitry  26  may perform short range (SR) detection using transmitted and reflected signals. SR detection may be at longer ranges than USR but shorter ranges than far field detection. Radar circuitry  26  may then perform background recording operations/algorithm  152 . 
     At operation  166 , control circuitry  14  may determine whether the phase and/or magnitude values are sufficiently stable after running the BG stabilizer in background recording operations/algorithm  152 . If the values are not sufficiently stable, processing may loop back to operation  180  via path  164 . If the values are sufficiently stable, processing may proceed to operation  170  via path  168 . 
     At operation  170 , radar circuitry  26  may perform USR detection using transmitted and reflected signals (e.g., transmit signals as shown by curve  102  of  FIG.  3   ). Radar circuitry  26  may perform USR detection while subtracting/cancelling out background noise as recorded while performing background recording operations/algorithm  152  after operation  180 . Radar circuitry  26  may then repeat the background recording operations/algorithm as background recording operations/algorithm  152 ′. Background recording operations/algorithm  152 ′ may loop back to operation  170 . 
       FIG.  10    is a flow chart showing how these operations may be adapted to implementations in which radar circuitry  26  is operable to perform long range detection and then USR detection. At operation  200 , radar circuitry  26  may perform long range detection using transmitted and reflected signals (e.g., using FMCW signals such as the signals associated with curve  100  of  FIG.  3   ). Radar circuitry  26  may gather measurements of range R during operation  200 . 
     If/when range R exceeds the long threshold value (e.g., 2 m) during the long range radar operations, radar circuitry  26  may proceed with performing background recording operations/algorithm  152 . Background recording operations/algorithm  152  may produce and store background noise values for use during later USR operations, and processing may loop back to operation  200  via path  202 . 
     During the long range radar operations, control circuitry  14  may determine whether range R falls below a short threshold value (e.g., 10 cm) (at operation  204 ). If range R does not fall below the short threshold value, processing may loop back to operation  200  via path  206 . If range R falls below the short threshold value, processing may proceed to operation  206 . 
     At operation  206 , radar circuitry  26  may perform a stable statistic determination (e.g., operation  166  of  FIG.  8   ) on the background measurements gathered during background recording operations/algorithm  152 . If the background measurements are sufficiently stable, radar circuitry  26  may perform USR detection (e.g., by transmitting and receiving signals such as the signals associated with curve  102  of  FIG.  3   ) while performing background cancellation using the background measurements gathered during background recording operations/algorithm  152  (e.g., via complex subtraction of the background measurements from the phase measurements gathered in the USR detection). If the background measurements are not sufficiently stable, radar circuitry  26  may perform SR detection (e.g., operation  180  of  FIG.  9   ). 
     At operation  208 , control circuitry  14  may determine if range R has fallen below the short threshold (e.g., 10 cm). If range R as detected during SR detection falls below 10 cm, processing may loop back to operation  206  via path  210 . If range R is not below 10 cm, processing may loop back to operation  200  via path  206 . HPF filters  76  ( FIG.  2   ) may be switched into use on receive chain  54  at operation  200 . Performing background noise subtraction may allow radar circuitry  26  to detect ranges R that are less than 10 cm, for example. 
     Device  10  may gather and/or use personally identifiable information. It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     The methods and operations described above may be performed by the components of device  10  using software, firmware, and/or hardware (e.g., dedicated circuitry or hardware). Software code for performing these operations may be stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media) stored on one or more of the components of device  10  (e.g., storage circuitry  16  of  FIG.  1   ). The software code may sometimes be referred to as software, data, instructions, program instructions, or code. The non-transitory computer readable storage media may include drives, non-volatile memory such as non-volatile random-access memory (NVRAM), removable flash drives or other removable media, other types of random-access memory, etc. Software stored on the non-transitory computer readable storage media may be executed by processing circuitry on one or more of the components of device  10  (e.g., processing circuitry  18  of  FIG.  1   , etc.). The processing circuitry may include microprocessors, central processing units (CPUs), application-specific integrated circuits with processing circuitry, or other processing circuitry. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20220408
Publication Date: 20240723
Grant Date: 20240723
Priority Date: 20210924
Inventors: HUR, JOONHOI
Schrattenecker, Jochen
XIAO, BIN
HANKE, ANDRE
PRETL, HARALD
VAZNY, RASTISLAV
SOGL, BERNHARD
MENKHOFF, ANDREAS
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B15/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/123", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/038", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/4021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01S13/343", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01S7/006", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/354", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/1027", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S7/358", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B15/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/123", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/1027", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 83355251