PATENT DOCUMENT

Publication Number: US-12013455-B2
Application Number: US-202117200311-A
Country: US
Kind Code: B2

Title: Electronic devices with background-cancelled ultra short range object detection

Abstract:
An electronic device may include a processor and wireless circuitry with transmit and receive antennas. Radar circuitry may use the transmit and receive antennas to perform spatial ranging on external objects farther than a threshold distance (e.g., 1-2 cm) from the transmit antenna. The wireless circuitry may include a voltage standing wave ration (VSWR) sensor coupled to the transmit antenna to detect the presence of objects within the threshold distance from the transmit antenna. This may serve to cover a blind spot for the radar circuitry near to the transmit antenna. The VSWR sensor may gather background VSWR measurements when other wireless performance metric data for the wireless circuitry is within a predetermined range of satisfactory values. The background VSWR measurements may be subtracted from real time VSWR measurements to perform accurate and robust ultra-short range object detection near to the transmit antenna.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a transmit antenna; 
 a receive antenna; 
 a voltage standing wave ratio (VSWR) sensor communicably coupled to the transmit antenna; and 
 one or more processors configured to
 use the transmit antenna and the receive antenna to perform spatial ranging operations on external objects located greater than a threshold distance away from the transmit antenna, and 
 use the VSWR sensor to detect an external object located within the threshold distance from the transmit antenna. 
 
 
     
     
       2. The electronic device of  claim 1 , further comprising radar circuitry communicably coupled to the transmit antenna over a transmit path and communicably coupled to the receive antenna over a receive path, wherein the VSWR sensor is disposed on the transmit path between the radar circuitry and the transmit antenna. 
     
     
       3. The electronic device of  claim 2 , wherein the radar circuitry is configured to:
 transmit radar signals using the transmit antenna; and 
 receive a reflected version of the radar signals using the receive antenna, the one or more processors being configured to perform the spatial ranging operations by processing the radar signals transmitted using the transmit antenna and the reflected version of the radar signals received using the receive antenna. 
 
     
     
       4. The electronic device of  claim 3 , further comprising:
 a wireless communications transceiver communicably coupled to the transmit antenna over the transmit path, wherein the wireless communications transceiver is configured transmit wireless communications data using the transmit antenna. 
 
     
     
       5. The electronic device of  claim 4 , wherein the one or more processors is configured to use the VSWR sensor to detect the external object within the threshold distance from the transmit antenna by:
 measuring VSWR values using radio-frequency transmit signals that include the wireless communications data transmitted by the wireless communications transceiver. 
 
     
     
       6. The electronic device of  claim 4 , further comprising:
 a signal generator separate from the wireless communications transceiver and separate from the radar circuitry, wherein the signal generator is configured to generate radio-frequency test signals and wherein the one or more processors is configured to use the VSWR sensor to detect the external object within the threshold distance from the transmit antenna by measuring VSWR values using the radio-frequency test signals transmitted by the signal generator. 
 
     
     
       7. The electronic device of  claim 3 , wherein the one or more processors is configured to use the VSWR sensor to detect the external object within the threshold distance from the transmit antenna by:
 measuring VSWR values using the radar signals transmitted by the radar circuitry. 
 
     
     
       8. The electronic device of  claim 2 , wherein the one or more processors is configured to use the VSWR sensor to detect the external object by:
 measuring a background VSWR value using the VSWR sensor; 
 measuring a real time VSWR value using the VSWR sensor; and 
 identifying that the external object is present within the threshold distance from the transmit antenna when a difference value between the real time VSWR value and the background VSWR value exceeds a threshold value. 
 
     
     
       9. The electronic device of  claim 8 , wherein the one or more processors is configured to:
 reduce a transmit power level of the transmit antenna in response to identifying that the external object is present within the threshold distance from the transmit antenna. 
 
     
     
       10. The electronic device of  claim 8 , wherein the one or more processors is configured to:
 gather wireless performance metric data; 
 measure the background VSWR value using the VSWR sensor when the gathered wireless performance metric data is within a predetermined range of wireless performance metric values; and 
 measure the real time VSWR value using the VSWR sensor when the gathered wireless performance metric data is outside of the predetermined range of wireless performance metric values. 
 
     
     
       11. The electronic device of  claim 10 , wherein the wireless performance metric data comprises signal-to-noise ratio (SNR) data or receive signal strength indicator (RSSI) data gathered in response to radio-frequency signals received by the receive antenna. 
     
     
       12. The electronic device of  claim 8 , further comprising:
 a temperature sensor configured to measure a temperature value when the VSWR sensor measures the real time VSWR value, wherein the one or more processors is configured to identify a stored background VSWR value as the background VSWR value and wherein the stored background VSWR value corresponds to the temperature value measured by the temperature sensor. 
 
     
     
       13. A method of operating wireless circuitry to perform external object detection, the method comprising:
 transmitting, using a transmit antenna, a radar signal; 
 receiving, using a receive antenna, a reflected version of the radar signal transmitted by the transmit antenna; 
 identifying, using one or more processors, a range from the transmit antenna to an external object farther than a threshold distance from the transmit antenna based on the radar signal transmitted by the transmit antenna and the reflected version of the radar signal received by the receive antenna; 
 generating, using a voltage standing wave ratio (VSWR) sensor, a background VSWR measurement and a real time VSWR measurement for the transmit antenna; and 
 identifying, using the one or more processors, that the external object is closer than the threshold distance from the transmit antenna when a difference between the real time VSWR measurement and the background VSWR measurement exceeds a threshold value. 
 
     
     
       14. The method of  claim 13 , further comprising:
 controlling, using the one or more processors, the VSWR sensor to generate the background VSWR measurement for the transmit antenna when wireless performance metric data associated with the reception of radio-frequency signals by the receive antenna is within a predetermined range of wireless performance metric values; and 
 controlling, using the one or more processors, the VSWR sensor to generate the real time VSWR measurement for the transmit antenna when the gathered wireless performance metric data is outside of the predetermined range of wireless performance metric values. 
 
     
     
       15. The method of  claim 13 , further comprising:
 reducing a maximum transmit power level of the radio-frequency signals transmitted by the transmit antenna when the external object is identified as being closer than the threshold distance. 
 
     
     
       16. The method of  claim 13 , further comprising:
 switching a new transmit antenna into use when the external object is identified as being closer than the threshold distance. 
 
     
     
       17. A method of operating an electronic device having a transmit antenna, a receive antenna, a voltage standing wave ratio (VSWR) sensor communicably coupled to the transmit antenna, and one or more processors, the method comprising:
 performing, using the transmit antenna and the receive antenna, spatial ranging operations on external objects located greater than a threshold distance away from the transmit antenna; and 
 detecting, using the VSWR sensor, an external object located within the threshold distance from the transmit antenna. 
 
     
     
       18. The method of  claim 17 , further comprising:
 transmitting, using radar circuitry communicably coupled to the transmit antenna over a transmit path, radar signals, wherein the radar circuitry is communicably coupled to the receive antenna over a receive path, the VSWR sensor being disposed on the transmit path between the radar circuitry and the transmit antenna. 
 
     
     
       19. The method of  claim 18 , further comprising:
 receiving, using the receive antenna, a reflected version of the radar signals; and 
 performing, using the one or more processors, the spatial ranging operations based on the radar signals transmitted using the transmit antenna and the reflected version of the radar signals received using the receive antenna. 
 
     
     
       20. The method of  claim 19 , further comprising:
 transmitting, using a wireless communications transceiver communicably coupled to the transmit antenna over the transmit path, wireless communications data over the transmit antenna.

Description:
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 external objects. 
     It can be challenging to provide wireless circuitry that accurately estimates this distance. For example, the wireless circuitry will often exhibit a blind spot near the device within which the wireless circuitry is unable to accurately detect the presence of external objects. 
     SUMMARY 
     An electronic device may include wireless circuitry controlled by one or more processors. The wireless circuitry may include at least a transmit antenna and a receive antenna. The wireless circuitry may include long range spatial ranging circuitry such as radar circuitry. The long range spatial ranging circuitry may be coupled to the receive antenna over a receive path. The long range spatial ranging circuitry may be coupled to the transmit antenna over a transmit path. The wireless circuitry may include wireless communications circuitry coupled to the transmit antenna over the transmit path. The long range spatial ranging circuitry may use the transmit and receive antennas to perform spatial ranging operations on external objects farther than a threshold distance (e.g., 1-2 cm) from the transmit antenna. The wireless circuitry may include ultra-short range (USR) detector circuitry disposed along the transmit path. The USR detector circuitry may detect the presence of external objects within the threshold distance from the transmit antenna. This may serve to cover an object detection blind spot for the long range spatial ranging circuitry close to the transmit antenna. 
     The USR detector circuitry may include a voltage standing wave ratio (VSWR) sensor. The VSWR sensor may include a directional coupler, switching circuitry, and a phase and amplitude detector, for example. The VSWR sensor may gather VSWR measurements such as complex scattering parameter values (e.g., S 11  values) in response to radio-frequency signals on the transmit path. The VSWR sensor may gather VSWR measurements using radar signals transmitted by the long range spatial ranging circuitry, radio-frequency signals transmitted by the wireless communications circuitry, and/or test signals generated by a dedicated signal generator. The VSWR measurements may include background VSWR measurements and real time VSWR measurements. 
     The one or more processors may generate wireless performance metric data associated with the radio-frequency performance of the wireless circuitry (e.g., signal-to-noise ratio (SNR) values, receive signal strength indicator (RSSI) values, etc.). The background VSWR measurements may be performed when the wireless performance metric data is within a range of satisfactory wireless performance metric values. The real time VSWR measurements may be performed when the wireless performance metric data is outside of the range of satisfactory wireless performance metric values. The one or more processors may generate a difference value between the real time and background VSWR measurements. The one or more processors may determine that the external object is present when the difference value exceeds one or more threshold values. In order to further optimize the robustness of the VSWR measurements, the background and real time measurements may include open switch in-phase quadrature-phase (IQ) signal measurements and optionally matched load IQ signal measurements. 
     An aspect of the disclosure provides an electronic device. The electronic device can include a transmit antenna. The electronic device can include a receive antenna. The electronic device can include a voltage standing wave ratio (VSWR) sensor communicably coupled to the transmit antenna. The electronic device can include one or more processors. The one or more processors may be configured to use the transmit antenna and the receive antenna to perform spatial ranging operations on external objects located greater than a threshold distance away from the transmit antenna. The one or more processors may be configured to use the VSWR sensor to detect an external object located within the threshold distance from the transmit antenna. 
     An aspect of the disclosure provides an electronic device. The electronic device can include an antenna configured to transmit radio-frequency signals. The electronic device can include a radio-frequency transmission line communicably coupled to the antenna. The electronic device can include a voltage standing wave ratio (VSWR) sensor disposed along the radio-frequency transmission line. The electronic device can include one or more processors. The one or more processors may be configured to gather wireless performance metric data associated with reception of radio-frequency signals by the electronic device. The one or more processors may be configured to measure a first VSWR value using the VSWR sensor when the gathered wireless performance metric data exceeds a wireless performance metric threshold value. The one or more processors may be configured to measure a second VSWR value using the VSWR sensor when the gathered wireless performance metric data is less than the wireless performance metric threshold value. The one or more processors may be configured to reduce a maximum transmit power level of the radio-frequency signals transmitted by the antenna when a difference value between the second VSWR value and the first VSWR value exceeds a threshold value. 
     An aspect of the disclosure provides a method of operating wireless circuitry to perform external object detection. The method can include using a transmit antenna to transmit a radar signal. The method can include using a receive antenna to receive a reflected version of the radar signal transmitted by the transmit antenna. The method can include using one or more processors to identify a range from the transmit antenna to an external object farther than a threshold distance from the transmit antenna based on the radar signal transmitted by the transmit antenna and the reflected version of the radar signal received by the receive antenna. The method can include using a voltage standing wave ratio (VSWR) sensor to generate a background VSWR measurement and a real time VSWR measurement for the transmit antenna. The method can include using the one or more processors to identify that the external object is closer than the threshold distance from the antenna when a difference between the real time VSWR measurement and the background VSWR measurement exceeds a threshold value. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a functional block diagram of an illustrative electronic device having a transmit antenna that is used to perform long range object detection and that is used to perform ultra-short range (USR) object detection using a voltage standing wave ratio (VSWR) sensor in accordance with some embodiments. 
         FIG.  2    is a plot of reflection coefficient as a function of frequency that may be produced by an illustrative VSWR sensor in response to the absence and presence of an external object in accordance with some embodiments. 
         FIG.  3    is a circuit diagram of an illustrative VSWR sensor having a directional coupler for performing USR object detection using a transmit antenna in accordance with some embodiments. 
         FIG.  4    is a flow chart of illustrative operations involved in using an illustrative transmit antenna to perform both long range object detection and USR object detection under a time multiplexing scheme in accordance with some embodiments. 
         FIG.  5    is a flow chart of illustrative operations involved in performing background noise cancellation during USR object detection (e.g., using background-cancelled USR index values) in accordance with some embodiments. 
         FIG.  6    is a plot of background-cancelled USR index values as a function of distance between a transmit antenna and an external object in accordance with some embodiments. 
         FIG.  7    is a flow chart of illustrative operations involved in generating background-cancelled USR index values in accordance with some embodiments. 
         FIG.  8    is a flow chart of illustrative operations involved in generating background-cancelled USR index values that are calibrated using a matched load 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, 5G 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). In one embodiment that is described herein as an example, input-output devices  22  include one or more temperature (T) sensors  45 . Temperature sensors  45  may measure ambient/environmental temperature at one or more locations at or around the exterior of device  10  and/or internal temperature at one or more locations within device  10  (e.g., within housing  12 ). 
     Input-output circuitry  20  may include wireless circuitry  24  to support wireless communications and/or radio-based spatial ranging operations. Wireless 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, analog-to-digital converter (ADC) circuitry, digital-to-analog converter (DAC) circuitry, radio-frequency transmission lines, and/or any other circuitry for transmitting and/or receiving radio-frequency signals using antennas  40 . 
     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. 
     Antennas  40  may include one or more transmit (TX) antennas such as transmit antenna  40 TX and one or more receive (RX) antennas such as receive antenna  40 RX. Antennas  40  may include zero, one, or more than one additional antenna used in the transmission and/or reception of radio-frequency signals. Transmit antenna  40 TX may transmit radio-frequency signals such as radio-frequency signals  42  and/or radio-frequency signals  38 . Receive antenna  40 RX may receive radio-frequency signals such as radio-frequency signals  44  and/or radio-frequency signals  38 . Wireless circuitry  24  may use antennas  40  to transmit and/or receive radio-frequency signals  38  to convey wireless communications data between device  10  and external wireless communications equipment  48  (e.g., one or more other devices such as device  10 , a wireless access point or base station, etc.). 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 include communications circuitry  26  (sometimes referred to herein as wireless communications circuitry  26 ) for transmitting and/or receiving wireless communications data using antennas  40 . Communications circuitry  26  may include baseband circuitry (e.g., one or more baseband processors) and one or more radios (e.g., radio-frequency transceivers, modems, etc.) for conveying radio-frequency signals  38  using one or more antennas  40  (e.g., transmit antenna  40 TX, receive antenna  40 RX, and/or other antennas  40 ). 
     Communications circuitry  26  may transmit and/or receive radio-frequency signals  38  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 communications circuitry  26  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. 
     Communications circuitry  26  may be coupled to antennas  40  using one or more transmit paths and/or one or more receive paths. Communications circuitry  26  uses the transmit paths to transmit radio-frequency signals  38  and uses the receive paths to receive radio-frequency signals  38 . If desired, communications circuitry  26  may be coupled to transmit antenna  40 TX over a transmit path such as transmit path  34 . Communications circuitry  26  may use transmit path  34  to transmit radio-frequency signals  38  using transmit antenna  40 TX. Transmit path  34  (sometimes referred to herein as transmit chain  34 ) may include one or more signal paths (e.g., radio-frequency transmission lines), amplifier circuitry, filter circuitry, switching circuitry, radio-frequency front end circuitry (e.g., components on a radio-frequency front end module), and/or any other desired paths or circuitry for transmitting radio-frequency signals from communications circuitry  26  to transmit antenna  40 TX. 
     In addition to conveying wireless communications data, wireless circuitry  24  may also use antennas  40  to perform spatial ranging operations. Wireless circuitry  24  may include long range spatial ranging circuitry  28  for performing spatial ranging operations. Long range spatial ranging circuitry  28  may include mixer circuitry, amplifier circuitry, transmitter circuitry (e.g., signal generators, synthesizers, etc.), receiver circuitry, filter circuitry, baseband circuitry, ADC circuitry, DAC circuitry, and/or any other desired components used in performing spatial ranging operations using antennas  40 . Long range spatial ranging circuitry  28  may include, for example, radar circuitry (e.g., frequency modulated continuous wave (FMCW) radar circuitry, OFDM radar circuitry, FSCW radar circuitry, a phase coded radar circuitry, other types of radar circuitry). Antennas  40  may include separate antennas for conveying wireless communications data and radio-frequency signals for spatial ranging or may include one or more antennas  40  that are used to both convey wireless communications data and to perform spatial ranging. Using a single antenna  40  to both convey wireless communications data and perform spatial ranging may, for example, serve to minimize the amount of space occupied in device  10  by antennas  40 . 
     In one embodiment that is described herein as an example, wireless circuitry  24  may use transmit antenna  40 TX to both convey wireless communications data for communications circuitry  26  and perform spatial ranging operations for long ranging spatial ranging circuitry  28 . Long range spatial ranging circuitry  28  may therefore be coupled to transmit antenna  40 TX over transmit path  34 . When performing spatial ranging operations, long range spatial ranging circuitry  28  may use transmit antenna  40 TX to transmit radio-frequency signals  42 . Radio-frequency signals  42  may include one or more signal tones, continuous waves of radio-frequency energy, wideband signals, chirp signals, or any other desired transmit signals (e.g., radar signals) for use in spatial ranging operations. Unlike radio-frequency signals  38 , radio-frequency signals  42  may be free from wireless communications data (e.g., cellular communications data packets, WLAN communications data packets, etc.). Radio-frequency signals  42  may sometimes also be referred to herein as spatial ranging signals  42 , long range spatial ranging signals  42 , or radar signals  42 . Long range spatial ranging circuitry  28  may transmit radio-frequency signals  42  at one or more carrier frequencies 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, 20-30 GHz, greater than 40 GHz, etc.). 
     Radio-frequency signals  42  may reflect off of objects external to device  10  such as external object  46 . External object  46  may be, for example, the ground, a building, part of a building, a wall, furniture, a ceiling, a person, a body part, an animal, a vehicle, a landscape or geographic feature, an obstacle, external communications equipment such as external wireless communications equipment  48 , or any other physical object or entity that is external to device  10 . Receive antenna  40 RX may receive reflected radio-frequency signals  44 . Reflected signals  44  may be a reflected version of the transmitted radio-frequency signals  42  that have reflected off of external object  46  and back towards device  10 . 
     Receive antenna  40 RX may be coupled to long range spatial ranging circuitry  28  over receive path  36  (sometimes referred to herein as receive chain  36 ). Long range spatial ranging circuitry  28  may receive reflected signals  44  from receive antenna  40 RX via receive path  36 . Receive path  36  may include one or more signal paths (e.g., radio-frequency transmission lines), amplifier circuitry (e.g., low noise amplifier (LNA) circuitry), filter circuitry, switching circuitry, radio-frequency front end circuitry (e.g., components on a radio-frequency front end module), and/or any other desired paths or circuitry for conveying radio-frequency signals from receive antenna  40 RX to long range spatial ranging circuitry  28 . 
     Control circuitry  14  may process the transmitted radio-frequency signals  42  and the received reflected signals  44  to detect or estimate the range R between device  10  and external object  46 . 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  46 , a velocity of external object  46 , and/or an angle of arrival of reflected signals  44 . If desired, a loopback path such as loopback path  50  may be coupled between transmit path  34  and receive path  36 . Loopback path  50  may be used to convey transmit signals on transmit path  34  to receiver circuitry in long range spatial ranging circuitry  28 . As an example, in embodiments where long range spatial ranging circuitry  28  performs spatial ranging using an FMCW scheme, loopback path  50  may be a de-chirp path that conveys chirp signals on transmit path  34  to a de-chirp mixer in long range spatial ranging circuitry  28 . In these embodiments, doppler shifts in continuous wave transmit signals may be detected and processed to identify the velocity of external object  46 , and the time dependent frequency difference between radio-frequency signals  42  and reflected signals  44  may be detected and processed to identify range R and/or the position of external object  46 . Use of continuous wave signals for estimating range R may allow control circuitry  14  to reliably distinguish between external object  46  and other background or slower-moving objects, for example. This example is merely illustrative and, in general, long range spatial ranging circuitry  28  may implement any desired radar or long range spatial ranging scheme. 
     The radio-frequency transmission lines in transmit path  34  and receive path  36  may include coaxial cables, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Transmission lines in device may be integrated into rigid and/or flexible printed circuit boards if desired. One or more radio-frequency lines may be shared between transmit path  34  and receive path  36  if desired. The components of wireless circuitry  24  may be formed on one or more common substrates or modules (e.g., rigid printed circuit boards, flexible printed circuit boards, integrated circuits, chips, packages, systems-on-chip, etc.). 
     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 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, some or all of the baseband circuitry in wireless circuitry  24  may form a part of control circuitry  14 . In addition, wireless circuitry  24  may include any desired number of antennas  40 . Antennas  40  may include more than one transmit antenna  40 TX, more than one receive antenna  40 RX, and zero, one, or more than one other antenna  40 . Each antenna  40  may be coupled to communications circuitry  26  and/or long range spatial ranging circuitry  28  over dedicated transmit and/or receive paths or over one or more transmit and/or receive paths that are shared between antennas. 
     Long range spatial ranging circuitry  28  need not be coupled to all of the antennas  40  in wireless circuitry  24 . Similarly, communications circuitry  26  need not be coupled to all of the antennas  40  in wireless circuitry  24  (e.g., some antennas  40  may be used to only perform spatial ranging operations without conveying wireless communications data or to only convey wireless communications data without performing spatial ranging). Antennas  40  that are only used to receive signals may be coupled to communications circuitry  26  and/or long range spatial ranging circuitry  28  using one or more receive paths (e.g., receive path  36 ). Antennas  40  that are only used to transmit signals may be coupled to communications circuitry  26  and/or long range spatial ranging circuitry  28  using one or more transmit paths (e.g., transmit path  34 ). One or more antennas  40  may be used to both transmit and receive signals. In these scenarios, the antenna may be coupled to communications circuitry  26  and/or long range spatial ranging circuitry  28  using both a transmit path and a receive path and, if desired, one or more components or signal paths (e.g., radio-frequency transmission lines) may be shared between both the transmit path and the receive path. While described herein as a transmit antenna for the sake of simplicity, transmit antenna  40 TX may also be used in the reception of radio-frequency signals for communications circuitry  26  if desired (e.g., an additional receive path (not shown) may couple transmit antenna  40 TX to communications circuitry  26 ). Similarly, receive antenna  40 RX may also be used in the transmission of radio-frequency signals if desired. While receive antenna  40 RX is only illustrated as providing reflected signals  44  to long range spatial ranging circuitry  28 , receive antenna  40 RX may also provide received radio-frequency signals  38  to communications circuitry  26  (e.g., receive path  36  may also couple receive antenna  40 RX to communications circuitry  26 ). 
     Long range spatial ranging circuitry  28  may be used to accurately identify range R when external object  46  is at relatively far distances from device  10 . However, in practice, long range spatial ranging circuitry  28  exhibits a blind spot to nearby external objects at distances less than threshold range R TH  (e.g., around 1-2 cm) from device  10 . When external object  46  is located within this blind spot (e.g., within threshold range R TH  from transmit antenna  40 TX), long range spatial ranging circuitry  28  may be unable to identify the presence, location, and/or velocity of external object  46  with a satisfactory level of accuracy. External objects  46  within threshold range R TH  of transmit antenna  40 TX may be exposed to relatively high amounts of radio-frequency energy (e.g., from the radio-frequency signals  38  and/or  42  that are transmitted by transmit antenna  40 TX). In scenarios where external object  46  is a body part or person, if care is not taken, this transmitted radio-frequency energy may cause wireless circuitry  24  to exceed regulatory limits or other limits on specific absorption rate (SAR) (e.g., when the transmitted signals are at frequencies below 6 GHz) and/or maximum permissible exposure (MPE) (e.g., when the transmitted signals are at frequencies above 6 GHz). In order to detect the presence of external object  46  within threshold range R TH  from transmit antenna  40 TX, wireless circuitry  24  may include an ultra-short range (USR) object detector such as USR detector  30 . USR detector  30  may serve to detect external object  46  at ultra-short ranges (e.g., at ranges within threshold range R TH  from transmit antenna  40 TX). In other words, USR detector  30  may perform external object detection within the blind spot of long range spatial ranging circuitry  28 . 
     USR detector  30  may include a voltage standing wave ratio (VSWR) sensor such as VSWR sensor  32 . VSWR sensor  32  may be interposed on transmit path  34 . VSWR sensor  32  may gather VSWR values using transmit antenna  40 TX. The VSWR values may include complex scattering parameter values (S-parameter values) such as reflection coefficient values (e.g., S 11  values). The magnitude of the S 11  values (e.g., |S 11 | values) may be indicative of the amount of transmitted radio-frequency energy that is reflected in a reverse direction along transmit path  34  (e.g., in response to the presence of external object  46  at or adjacent to transmit antenna  40 TX). The VSWR values gathered by VSWR sensor  32  may be insensitive to situations where external object  46  is located at distances greater than threshold range R TH  from transmit antenna  40 TX. However, the VSWR values gathered by VSWR sensor  32  may allow control circuitry  14  to identify when external object  46  is located within threshold range R TH  from transmit antenna  40 TX (e.g., within the blind spot of long range spatial ranging circuitry  28 ). 
     In this way, USR detector  30  and long range spatial ranging circuitry  28  may identify the presence of external object  46  and optionally the range R to external object  46 , regardless of whether external object  46  has moved to a position that is relatively close or relatively far from device  10  over time. In addition, USR detector  30  may identify the presence of external object  46  within the blind spot of long range spatial ranging circuitry  28  so that suitable action can be taken to ensure that wireless circuitry  24  continues to satisfy any applicable SAR and/or MPE regulations. By using the same transmit antenna  40 TX to both transmit radio-frequency signals  38 / 42  and measure VSWR, the VSWR measurements will be very closely correlated with the amount of radio-frequency energy absorbed by external object  46  from the transmitted radio-frequency signals  38 / 42 , thereby providing high confidence in the use of USR detector  30  for meeting any applicable SAR and/or MPE regulations (e.g., greater confidence than in scenarios where proximity sensors that are separate from the transmit antenna or transmit chain are used to identify the presence of external objects within threshold range R TH  of device  10 ). 
       FIG.  2    is a plot showing how VSWR measurements made by VSWR sensor  32  may change due to the presence of external object  46  adjacent to transmit antenna  40 TX. Curve  60  plots the magnitude of reflection S-parameter S 11  (i.e., |S 11 |) as a function of frequency in the absence of external object  46  within threshold range R TH . As shown by curve  60 , in the absence of external object  46 , |S 11 | may have a relatively high value across a frequency band of interest B (e.g., the frequency band used to convey radio-frequency signals  38  or  42  of  FIG.  1   ). 
     Curve  62  plots |S 11 | as a function of frequency when external object  46  is within threshold range R TH  from transmit antenna  40 TX. As shown by curve  62 , |S 11 | may have a relatively low value across frequency band B due to the presence of external object  46 . In general, once external object  46  is within threshold range R TH , |S 11 | will continue to decrease, as shown by arrow  64  as the object approaches transmit antenna  40 TX. Control circuitry  14  may gather VSWR values using VSWR sensor  32  (e.g., |S 11 | values such as those shown by curves  60  and  62 ) and may process the gathered VSWR values to identify when external object  46  is within threshold range R TH  (e.g., by comparing the gathered Bill values to one or more threshold levels). Beyond threshold range R TH , |S 11 | will exhibit no change or a negligible change in response to changes in distance between transmit antenna  40 TX and external object  46 . At these relatively far distances, long range spatial ranging circuitry  28  ( FIG.  1   ) may be used to detect the presence, position (e.g., range R), and/or velocity of external object  46 . 
       FIG.  3    is a circuit diagram showing how VSWR sensor  32  maybe disposed on transmit path  34 . As shown in  FIG.  3   , transmit path  34  may include a power amplifier (PA) such as PA  96 . The input of PA  96  may be coupled to long range spatial ranging circuitry  28  and/or communications circuitry  26  of  FIG.  1   . The output of PA  96  may be coupled to transmit antenna  40 TX via a switch such as antenna switch  94 . The output of PA  96  may also be coupled to matched load  88  via a switch such as matched load switch  90 . Matched load  88  may be coupled in series between matched load switch  90  and ground  82 . 
     In the example of  FIG.  3   , VSWR sensor  32  is a directional switch coupler. This is merely illustrative and, in general, VSWR sensor  32  may be implemented using any desired VSWR sensor architecture. As shown in  FIG.  3   , VSWR sensor  32  may include directional coupler  72  interposed on transmit path  34  between PA  96  and transmit antenna  40 TX (e.g., along a radio-frequency transmission line in transmit path  34  coupled between the output of PA  96  and transmit antenna  40 TX). Directional coupler  72  may have a first port (P 1 ) coupled to the output of PA  96  and a second port (P 2 ) communicably coupled to transmit antenna  40 TX. Directional coupler  72  may have a third port (P 3 ) coupled to a first termination that includes resistor  84  coupled in series between termination switch  78  and ground  82 . Directional coupler  72  may also have a fourth port (P 4 ) coupled to a second termination that includes resistor  86  coupled in series between termination switch  80  and ground  82 . VSWR sensor  32  may have a forward (FW) switch  74  coupled between port P 3  and phase and amplitude (magnitude) detector  70 . VSWR sensor  32  may also have a reverse (RW) switch  76  coupled between port P 4  and phase and amplitude detector  70 . Phase and amplitude detector  70  may have a control path  98  coupled to other components in USR detector  30  or control circuitry  14  ( FIG.  1   ). 
     When gathering VSWR measurements (e.g., S-parameter values such as S 11  values), PA  96  may output a transmit signal sigtx (e.g., while antenna switch  94  is closed). Transmit signal sigtx may be a radar transmit signal transmitted by long range spatial ranging circuitry  28  (e.g., radio-frequency signals  42  of  FIG.  1   ), a wireless communications data transmit signal transmitted by communications circuitry  26  (e.g., radio-frequency signals  38  of  FIG.  1   ), or a dedicated test signal for use in VSWR measurement (e.g., one or more tones transmitted by a signal generator, local oscillator, and/or other signal generation circuitry in USR detector  30  of  FIG.  1   ). 
     In gathering VSWR measurements, VSWR sensor  32  may perform forward path measurements and reverse path measurements using transmit signal sigtx. When performing forward path measurements, FW switch  74  is closed, RW switch  76  is open, switch  80  is closed, and switch  78  is open so that transmit signal sigtx is coupled off from transmit path  34  by directional coupler  72  and routed to phase and amplitude director  70  through FW switch  74 . Phase and amplitude detector  70  may measure and store the amplitude (magnitude) and/or phase of transmit signal sigtx for further processing (e.g., as a forward signal phase and magnitude measurement). 
     At least some of transmit signal sigtx will reflect off of transmit antenna  40 TX (e.g., due to impedance discontinuities between transmit path  34  and transmit antenna  40 TX subject to impedance loading from any external objects at or adjacent to transmit antenna  40 TX) and back towards PA  96  as reflected transmit signal sigtx′. When performing reverse path measurements, FW switch  74  is open, RW switch  76  is closed, switch  80  is open, and switch  78  is closed so that reflected transmit signal sigtx′ is coupled off of transmit path  34  by directional coupler  72  and routed to phase and amplitude director  70  through RW switch  76 . Phase and amplitude detector  70  may measure and store the amplitude (magnitude) and/or phase of reflected transmit signal sigtx′ for further processing (e.g., as a reverse signal phase and magnitude measurement). Control circuitry  14  may process the stored forward and reverse phase and magnitude measurements to identify complex scattering parameter values such as S 11  values. The S 11  values are characterized by a scalar magnitude |S 11 | and a corresponding phase. In this way, VSWR sensor  32  may measure VSWR values (e.g., S 11  values) that can be used to determine when external object  46  is located at a range R that is less than or equal to threshold range R TH . Long range spatial ranging circuitry  28  ( FIG.  1   ) may also use transmit antenna  40 TX to identify range R when external object  46  is located at a range R that is beyond threshold range R TH  from transmit antenna  40 TX. 
       FIG.  4    is a flow chart of illustrative operations that may be involved in using long range spatial ranging circuitry  28  ( FIG.  1   ) to perform long range (far-field) spatial ranging operations and using VSWR sensor  32  to perform USR detection operations under a time multiplexing scheme. The time multiplexing scheme involves periodically switching between using transmit antenna  40 TX to perform long range or USR detection over time to ensure that external object  46  can be detected even if external object  46  moves within or beyond threshold range R TH  over time. 
     At operation  100 , wireless circuitry  24  may perform USR object detection using VSWR sensor  32  for a first time period. The USR object detection may involve measuring S 11  values in response to transmit signals sigtx transmitted over transmit path  34 . Control circuitry  14  may compare the magnitude of the S 11  values (e.g., |S 11 | values) to one or more threshold values associated with the presence of external objects within threshold range R TH  of transmit antenna  40 TX. If an object is detected within threshold range R TH  (e.g., if the |S 11 | values fall below the threshold value), processing may proceed to operation  104  via path  102 . 
     At operation  104 , control circuitry  14  may take suitable action based on the detected (identified) presence of external object  46  within threshold range R TH . For example, control circuitry  14  may reduce the transmit power level of subsequent transmit signals sigtx, may reduce the maximum permissible transmit power level of subsequent transmit signals sigtx, may switch a different antenna into use for the transmission of transmit signals sigtx, etc. This may help to ensure that wireless circuitry  24  continues to meet any applicable SAR/MPE regulations in the presence of external object  46  within threshold range R TH . Processing may loop back to operation  100  via path  106  to continue to monitor for the presence of external object  46  within threshold range R TH . 
     If no object is detected within threshold range R TH  (e.g., if one or more of the |S 11 | values exceed the threshold value), processing may proceed to operation  110  via path  108 . At operation  110 , long range spatial ranging circuitry  28  may perform ranging operations using transmit antenna  40 TX to detect the presence, position, and/or velocity of external object  46  beyond threshold range R TH  from transmit antenna  40 TX. Long range spatial ranging circuitry  28  may perform these operations for a second time period. This may, for example, involve the transmission of radio-frequency signals  42  using transmit antenna  40 TX and the reception of reflected signals  44  using receive antenna  40 RX ( FIG.  1   ). 
     At operation  112 , control circuitry  14  may store the position of external object  46  (e.g., range R) and/or the velocity of object  46  for subsequent processing. For example, one or more software applications running on device  10  may use the identified position/velocity to perform software tasks. If desired, control circuitry  14  may increase the transmit power level or the maximum permissible transmit power level of subsequent transmit signals sigtx. Processing may subsequently loop back to operation  100  via path  114 , and wireless circuitry  24  may continue to alternate between USR detection and long range spatial ranging to identify the presence, position, and/or velocity of external object  46  over time, even if the external object moves within or beyond threshold range R TH . 
     In order to maximize the reliability and accuracy of the USR operations performed using VSWR sensor  32 , VSWR sensor  32  may perform USR object detection using a background cancellation scheme.  FIG.  5    is a flow chart of illustrative operations involved in using wireless circuitry  24  to perform long range spatial ranging operations and USR object detection using a background cancellation scheme. 
     In order to perform background cancellation, VSWR sensor  32  needs to characterize the background VSWR at transmit antenna  40 TX in the absence of an external object within threshold range R TH . At operation  120 , wireless circuitry  24  may gather wireless performance metric data associated with the radio-frequency performance of transmit antenna  40 TX and/or receive antenna  40 RX. The wireless performance metric data may include signal-to-noise ratio (SNR) data, receive signal strength indicator (RSSI) data, or any other desired performance metric data gathered during the transmission of radio-frequency signals  38 , the transmission of radio-frequency signals  42 , the reception of radio-frequency signals  38 , and/or the reception of reflected signals  44  of  FIG.  1   , for example. Control circuitry  14  may compare the gathered wireless performance metric data with a predetermined range of wireless performance metric values associated with satisfactory radio-frequency performance and/or the operation of wireless circuitry  24  in the absence of external objects within threshold range R TH  (e.g., a predetermined range of satisfactory RSSI values, SNR values, etc.). The predetermined range of wireless performance metric values may be characterized by an upper threshold limit or value and/or a lower threshold limit or value. 
     The wireless performance metric data may serve as a coarse indicator for whether external object  46  is within threshold range R TH . For example, if external object  46  is within range R TH , external object  46  may partially block or cover one or more antennas  40  (thereby preventing the antenna from properly receiving radio-frequency signals), may undesirably load or detune one or more antennas  40  in device  10 , etc. When the gathered wireless performance metric data falls outside of the predetermined range, this may be indicative of the potential presence of external object  46  within threshold range R TH . However, when the gathered wireless performance metric data falls within the predetermined range, this may indicate that it is very unlikely that there is an external object present within threshold range R TH  (e.g., because wireless circuitry  24  is performing nominally as expected in the absence of an external object within threshold range R TH ). If the gathered wireless performance metric data falls within the predetermined range (thereby indicating that there is no external object within threshold range R TH ), VSWR sensor  32  may be able to gather background VSWR measurements for performing background cancellation. Processing may thereby proceed to operation  124  via path  122 . 
     At operation  124 , VSWR sensor  32  may gather a background VSWR value (measurement) VSWR_BG using transmit signals sigtx provided to transmit antenna  40 TX ( FIG.  3   ). Background VSWR value VSWR_BG may include, for example, a background S 11  value. Temperature sensor  45  ( FIG.  1   ) may also gather a temperature measurement Tn corresponding to the temperature at, around, and/or within device  10  when background VSWR measurement VSWR_BG was gathered. In general, VSWR measurements can be sensitive to temperature. For example, different VSWR measurements may be obtained under the same antenna loading conditions at different temperatures. By gathering temperature measurement Tn, control circuitry  14  may identify that the background VSWR value VSWR_BG corresponds to a particular temperature (e.g., to ensure that accurate VSWR measurements are made for performing USR detection even as temperature changes over time). 
     At operation  126 , control circuitry  14  may store background VSWR value VSWR_BG and the corresponding temperature Tn (VSWR_BG(Tn)) in a VSWR data table for later processing (e.g., control circuitry  14  may associate the background VSWR_BG value with the corresponding temperature Tn in the VSWR data table so the control circuitry remains aware of the temperature at which the background VSWR value was gathered). Control circuitry  14  may store the VSWR data table in memory (e.g., storage circuitry  16  of  FIG.  1   ) and/or using any desired data structure(s). 
     At optional operation  128 , control circuitry  14  may update the stored VSWR data table. For example, control circuitry  14  may remove outlier background VSWR values VSWR_BG in the VSWR data table (e.g., VSWR_BG values that differ from the other VSWR_BG values in the VSWR data table by an excessive amount). This may help to ensure that the background VSWR values in the VSWR data table remain an accurate representation of the background VSWR measurement for VSWR sensor  32  over time. If desired, control circuitry  14  may average two or more of the background VSWR values VSWR_BG stored in the VSWR data table (e.g., so that the average background VSWR values are used instead of individual background VSWR measurements during subsequent processing). Any other desired data filtering operations may be performed on the VSWR data table. 
     If desired, control circuitry  14  may perform a case detection algorithm to detect whether a removable device case is present on device  10  (e.g., by comparing the gathered background VSWR values in the VSWR data table to expected background VSWR values for device  10  in the absence of a removable device case as determined during factory calibration or at other times). Control circuitry  14  may update the VSWR data table so that each stored background VSWR value VSWR_BG is associated with a case state identifier that identifies whether a removable device case was present on device  10  and/or what type of removable device case was present when that background VSWR value was gathered. Associating a case state identifier with the stored background VSWR values may allow control circuitry  14  to ensure that accurate VSWR measurements are made for performing USR detection even if the device has a removable case that may load the impedance of transmit antenna  40 TX and even if a user removes, adds, or changes the device case over time. 
     Processing may subsequently loop back to operation  120  via path  130 . Wireless circuitry  24  may perform only one iteration of operations  124 - 128  or may continue to gather background VSWR values VSWR_BG (e.g., adding to and/or updating the VSWR data table) periodically (e.g., according to a fixed schedule), for a predetermined number of iterations, in response to an application call or user input to device  10  (e.g., instructing wireless circuitry  24  to update or refresh its background VSWR measurements), and/or in response to any desired trigger condition. Long range spatial ranging circuitry  28  may concurrently perform long range spatial ranging operations using transmit antenna  40 TX and/or communications circuitry  26  may concurrently perform wireless communications using transmit antenna  40 TX during operations  120 - 128  if desired. When the wireless performance metric data gathered at operation  120  falls outside of the predetermined range, this may be indicative of the presence of a potential external object within threshold range R TH  and processing may proceed to operation  134  via path  132 . 
     At operation  134 , VSWR sensor  32  may gather a real time (RT) VSWR value (measurement) VSWR_RT using transmit signals sigtx provided to transmit antenna  40 TX ( FIG.  3   ). Real time VSWR measurement VSWR_RT may include, for example, a real time S 11  value. Temperature sensor  45  ( FIG.  1   ) may also gather a real time temperature measurement Tn′ corresponding to the temperature at, around, and/or within device  10  when background VSWR measurement VSWR_RT was gathered. 
     At operation  136 , control circuitry  14  may generate (calculate, compute, determine, identify, define, etc.) a USR index value USR_INDEX (sometimes referred to herein as background-cancelled reflection coefficient index value USR_INDEX) by subtracting a gathered background VSWR value VSWR_BG from real time VSWR value VSWR_RT. USR index value USR_INDEX may sometimes also be referred to herein as difference value USR_INDEX. If desired, the gathered background VSWR value VSWR_BG may be a background VSWR value VSWR_BG gathered while temperature sensor  45  measured temperature Tn′ during an iteration of operation  124 . Control circuitry  14  may, for example, identify a background VSWR value VSWR_BG from the stored VSWR data table that is associated with measured temperature Tn=Tn′ in the VSWR data table. If there are no background VSWR values VSWR_BG in the data table that are associated with measured temperature Tn′, the control circuitry may use the background VSWR value measured at the temperature Tn closest to measured temperature Tn′, may interpolate multiple background VSWR values to estimate a background VSWR value VSWR_BG at measured temperature Tn′ for subtraction from real time VSWR value VSWR_RT, etc. In embodiments where the case detection algorithm is performed, control circuitry  14  may subtract a background VSWR_BG value corresponding to the current case state of device  10  (and temperature Tn′) from real time VSWR value VSWR_RT (e.g., based on case state identifiers in the VSWR data table). 
     At operation  138 , control circuitry  14  may compare USR index value USR_INDEX to one or more predetermined USR index threshold values TH. USR index threshold value TH may correspond to a VSWR measurement (e.g., an |S 11 | value) associated with the presence of external objects at threshold range R TH  from transmit antenna  40 TX. If a single USR index threshold value TH is used, the comparison may allow control circuitry  14  to identify the presence of external object  46  within threshold range R TH . If multiple index threshold values TH are used, the comparison(s) may also allow control circuitry  14  estimate the range R to external object  46  within threshold range R TH . If USR index value USR_INDEX exceeds USR index threshold value TH, this may be indicative of the presence of external object  46  within threshold range R TH  and processing may proceed to operation  142  via path  140 . 
     At operation  142 , control circuitry  14  may identify that external object  46  is within threshold range R TH  of device  10  (transmit antenna  40 TX). If multiple index threshold values TH are used, control circuitry  14  may further estimate the range R to external object  46  within threshold range R TH  (e.g., where each index threshold value TH corresponds to a different range within threshold range R TH ). 
     At operation  144 , control circuitry  14  may take further action based on the identified (detected) presence of external object  46  within threshold range R TH . For example, control circuitry  14  may use the identified presence of external object  46  as an input to one or more software applications running on device  10  (e.g., software applications that perform operations based on whether or not an external object  46  is present within threshold range R TH ). Control circuitry  14  may control wireless circuitry  24  to reduce the transmit power level or the maximum transmit power level used to transmit subsequent radio-frequency signals using transmit antenna  40 TX (e.g., radio-frequency signals  38  or  42  of  FIG.  1   ). If desired, control circuitry  14  may control wireless circuitry  24  to switch transmit antenna  40 TX out of use in favor of a different antenna in device  10 . Reducing transmit power level, limiting maximum transmit power level, or switching transmit antenna  40 TX out of use may prevent transmit antenna  40 TX from transmitting an excessive amount of radio-frequency energy into the nearby external object  46 , thereby allowing device  10  to continue to satisfy any applicable SAR/MPE regulations. Processing may subsequently loop back to operation  120  via path  130  and wireless circuitry  24  may continue to monitor the presence of external object  46  near transmit antenna  40 TX (e.g., until external object  46  moves beyond threshold range R TH , at which point long range spatial ranging circuitry  28  will be able to resume detection of external object  46 ). 
     When USR index value USR_INDEX is less than or equal to threshold value TH during the comparison in operation  138 , this may be indicative of the absence of external object  46  within threshold range R TH  and processing may proceed to operation  148  via path  146 . At operation  148 , control circuitry  14  may identify that no object is present within threshold range R TH . Long range spatial ranging circuitry  28  may then use transmit antenna  40 TX to detect/track the position of external object  46  beyond threshold range R TH . If desired, control circuitry  14  may increase the transmit power level or the maximum transmit power level of transmit antenna  40 TX. Any other desired processing operations may be performed in response to the absence of external object  46  within threshold range R TH . Processing may subsequently loop back to operation  120  via path  130 . 
       FIG.  6    is a plot of USR index value USR_INDEX (in units of V) as a function of the range R between external object  46  and transmit antenna  40 TX. USR index values USR_INDEX are background-cancelled values because USR index values USR_INDEX are generated using a subtraction of background VSWR measurements from real time VSWR measurements made using VSWR sensor  32 . As shown by curve  150  of  FIG.  6   , at relatively far ranges R, USR index value USR_INDEX is unperturbed by changes in range R. However, USR index value USR_INDEX will increase as external object  46  approaches threshold range R TH  (e.g., within 1-2 cm of transmit antenna  40 TX). Index threshold value TH may correspond to the USR index value USR_INDEX when external object  46  is located at threshold range R TH  from transmit antenna  40 TX. Control circuitry  14  may therefore determine that external object  46  is within threshold range R TH  of transmit antenna  40 TX when USR index value USR_INDEX exceeds index threshold value TH (e.g., during operation  138  of  FIG.  5   ). The example of  FIG.  6    is merely illustrative and, in general, curve  150  may have other shapes. Multiple index threshold values TH may be used (e.g., to provide an estimate of range R within threshold range R TH ). 
     If desired, additional calibration operations may be performed while gathering VSWR measurements to increase the robustness of the USR detection.  FIG.  7    is a flow chart of illustrative operations that may be performed by control circuitry  14  when gathering VSWR measurements using these additional calibration operations. Operations  160 - 166  of  FIG.  7    may be performed during operation  124  of  FIG.  5   , operations  168 - 172  of  FIG.  7    may be performed during operation  134  of  FIG.  5   , and operation  174  may be performed during operation  136  of  FIG.  5   , for example. 
     At operation  160 , PA  96  ( FIG.  3   ) may begin transmitting transmit signal sigtx. Transmit signal sigtx may be a dedicated test signal (e.g., a single tone, multiple tones, or other transmit signals produced by a signal generator separate from communications circuitry  26  and long range spatial ranging circuitry  28  of  FIG.  1   ), may be a communication transmit signal generated by communications circuitry  26  (e.g., radio-frequency signals  38 ), or may be a transmit signal generated by long range spatial ranging circuitry  28  (e.g., radio-frequency signals  42 ). 
     At operation  162 , control circuitry  14  may use VSWR sensor  32  (e.g., phase and amplitude detector  70  or other signal measurement circuitry) to measure a reverse background in-phase quadrature-phase (IQ) signal S BG_RW . During this measurement, antenna switch  94  of  FIG.  3    is closed, FW switch  74  is open, RW switch  76  is closed, switch  80  is open, and switch  78  is closed. 
     At operation  164 , control circuitry  14  may use VSWR sensor  32  to measure a forward background IQ signal S BG_FW . During this measurement, antenna switch  94  is closed, FW switch  74  is closed, RW switch  76  is open, switch  80  is closed, and switch  78  is open. 
     At operation  166 , control circuitry  14  may perform an additional calibration step by using VSWR sensor  32  to measure a forward open switch background IQ signal S BG_OPEN . During this measurement, both FW switch  74  and RW switch  76  are open. 
     At operation  168 , control circuitry  14  may use VSWR sensor  32  to measure a reverse real time in-phase quadrature-phase (IQ) signal S RT_RW . During this measurement, antenna switch  94  is closed, FW switch  74  is open, RW switch  76  is closed, switch  80  is open, and switch  78  is closed. 
     At operation  170 , control circuitry  14  may use VSWR sensor  32  to measure a forward real time in-phase quadrature-phase (IQ) signal S RT_FW . During this measurement, antenna switch  94  is closed, FW switch  74  is closed, RW switch  76  is open, switch  80  is closed, and switch  78  is open. 
     At operation  172 , control circuitry  14  may perform an additional calibration step by using VSWR sensor  32  to measure a forward open switch real time IQ signal S RT_OPEN . During this measurement, both FW switch  74  and RW switch  76  are open. 
     At operation  174 , control circuitry  14  may generate USR index value USR_INDEX according to the equation USR_INDEX=[(S RT_RW −S RT_OPEN )/(S RT_FW −S RT_OPEN )]−[(S BG_RW −S BG_OPEN )/(S BG_FW −S BG_OPEN )] (e.g., when performing the subtraction in operation  136  of FIG.  5 ). IQ signals S RT_FW , S BG_FW , S RT_RW , S BG_FW , S RT_OPEN , and S BG_OPEN  may be complex values whereas USR index value USR_INDEX is a real-valued scalar. Calculating USR_INDEX in this way may provide a relatively robust USR object detection for device  10 . The example of  FIG.  7    is merely illustrative. If desired, wireless circuitry  24  may further calibrate USR index value USR_INDEX using matched load  88  of  FIG.  3   . 
       FIG.  8    is a flow chart of illustrative operations that may be performed by control circuitry  14  when gathering VSWR measurements that are calibrated using matched load  88 . Operations  180 - 188  of  FIG.  8    may be performed during operation  124  of  FIG.  5   , operations  190 - 196  of  FIG.  8    may be performed during operation  134  of  FIG.  5   , and operation  198  may be performed during operation  136  of  FIG.  5   , for example. 
     At operation  182 , control circuitry  14  may use VSWR sensor  32  to measure reverse background IQ signal S BG_RW . During this measurement, antenna switch  94  of  FIG.  3    is closed, matched load switch  90  is open, FW switch  74  is open, RW switch  76  is closed, switch  80  is open, and switch  78  is closed. 
     At operation  184 , control circuitry  14  may use VSWR sensor  32  to measure forward background IQ signal S BG_FW . During this measurement, antenna switch  94  is closed, matched load switch  90  is open, FW switch  74  is closed, RW switch  76  is open, switch  80  is closed, and switch  78  is open. 
     At operation  186 , control circuitry  14  may use VSWR sensor  32  to measure a forward open switch background IQ signal S BG_OPEN . During this measurement, both FW switch  74  and RW switch  76  are open. 
     At operation  188 , control circuitry  14  may perform an additional calibration step by using VSWR sensor  32  to measure a reverse background matched load IQ signal S BG_MATCH . During this measurement, antenna switch  94  is open, matched load switch  90  is closed, FW switch  74  is open, RW switch  76  is closed, switch  80  is open, and switch  78  is closed. 
     At operation  190 , control circuitry  14  may use VSWR sensor  32  to measure reverse real time IQ signal S RT_RW . During this measurement, antenna switch  94  is closed, matched load switch  90  is open, FW switch  74  is open, RW switch  76  is closed, switch  80  is open, and switch  78  is closed. 
     At operation  192 , control circuitry  14  may use VSWR sensor  32  to measure forward real time IQ signal S RT_FW . During this measurement, antenna switch  94  is closed, matched load switch  90  is open, FW switch  74  is closed, RW switch  76  is open, switch  80  is closed, and switch  78  is open. 
     At operation  194 , control circuitry  14  may use VSWR sensor  32  to measure a forward open switch real time IQ signal S RT_OPEN . During this measurement, both FW switch  74  and RW switch  76  are open. 
     At operation  196 , control circuitry  14  may perform an additional calibration step by using VSWR sensor  32  to measure a reverse real time matched load IQ signal S BG_MATCH . During this measurement, antenna switch  94  is open, matched load switch  90  is closed, FW switch  74  is open, RW switch  76  is closed, switch  80  is open, and switch  78  is closed. 
     At operation  198 , control circuitry  14  may generate USR index value USR_INDEX according to the equation USR_INDEX=[(S RT_RW −S RT_MATCH )/(S RT_FW −S RT_OPEN )]−[(S BG_RW −S BG_MATCH )/(S BG_FW −S BG_OPEN )]. Calculating USR_INDEX in this way may provide a relatively robust USR object detection for device  10 . The examples of  FIGS.  7  and  8    are merely illustrative. While the calibration operations are described in  FIGS.  7  and  8    in the context of USR detection, these calibration operations may be used to calibrate any directional coupler-based VSWR sensor for use in performing any desired VSWR measurements. 
     Switches  78 ,  80 ,  74 ,  76 ,  90 , and  94  of  FIG.  3    may be implemented using any desired switching architecture. When referred to herein as “open,” each switch  78 ,  80 ,  74 ,  76 ,  90 , and  94  may form a very high impedance or very low transconductance g m  through the switch (e.g., an impedance that exceeds a threshold impedance value or a transconductance that is less than a threshold transconductance value). When referred to herein as “closed,” each switch  78 ,  80 ,  74 ,  76 ,  90 , and  94  may form a very low impedance or very high transconductance g m  through the switch (e.g., an impedance that exceeds a threshold impedance value or a transconductance that is less than a threshold transconductance value). As an example, switches such as switches  78 ,  80 ,  74 ,  76 ,  90 , and  94  may each be formed using transistors having source, drain, and gate terminals. Each switch may be closed or “turned on” by asserting a gate voltage provided to the gate terminal to provide an electrical connection between its source and drain terminals. Similarly, each switch may be opened or “turned off” by deasserting the gate voltage to provide electrical isolation between its source and drain terminals. 
     The methods and operations described above in connection with  FIGS.  1 - 8    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 components of  FIGS.  1  and  3    may be implemented using hardware (e.g., circuit components, digital logic gates, etc.) and/or using software where applicable. 
     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: 20210312
Publication Date: 20240618
Grant Date: 20240618
Priority Date: 20210312
Inventors: HUR, JOONHOI
SOGL, BERNHARD
Schrattenecker, Jochen
MENKHOFF, ANDREAS
XIAO, BIN
CALDERIN, LUCAS
HANKE, ANDRE
PRETL, HARALD
VAZNY, RASTISLAV
Assignee: APPLE INC
CPC Classifications: [{"code": "G01R27/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/86", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S11/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/41", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B17/309", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/006", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/87", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/006", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/343", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01R27/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/354", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/2927", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/41", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S13/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S7/35", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S13/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S13/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R27/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/03", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/86", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 83005314