PATENT DOCUMENT

Publication Number: US-12111393-B2
Application Number: US-202217893034-A
Country: US
Kind Code: B2

Title: Electronic devices with multi-antenna sensing

Abstract:
An electronic device may include wireless circuitry that detects the location of external objects. A signal generator may concurrently transmit different radio-frequency ranging signals over two or more transmit antennas. The ranging signals may include waveforms with time-varying frequencies, where each waveform includes frequencies that are non-overlapping with the frequencies of each of the other waveforms at any given time. Antennas may receive reflected versions of the ranging signals and a processor may process the reflected versions of the ranging signals to identify the location of the external objects. This may prevent interference between the ranging signals and may significantly reduce the latency of location detection relative to examples where the ranging signals are transmitted by different transmit antennas in series.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a signal generator configured to generate a first radio-frequency signal having a first waveform and a second radio-frequency having a second waveform, the first waveform and the second waveform having non-overlapping frequencies as a function of time; 
 a first antenna configured to transmit the first radio-frequency signal; 
 a second antenna configured to transmit the second radio-frequency signal concurrent with transmission of the first radio-frequency signal by the first antenna; 
 a set of one or more antennas configured to receive a reflected version of the first radio-frequency signal and a reflected version of the second radio-frequency signal, wherein the set of one or more antennas is different from the first antenna and the second antenna; and 
 one or more processors configured to identify a location of one or more external objects based on the reflected version of the first radio-frequency signal and the reflected version of the second radio-frequency signal received by the set of one or more antennas. 
 
     
     
       2. The electronic device of  claim 1 , wherein the first waveform comprises a first linear frequency ramp and the second waveform comprises a second linear frequency ramp. 
     
     
       3. The electronic device of  claim 2 , wherein the first linear frequency ramp increases from a first frequency at a first time to a second frequency at a second time and wherein the second linear frequency ramp decreases from the second frequency at the first time to the first frequency at the second time. 
     
     
       4. The electronic device of  claim 2 , wherein the first linear frequency ramp increases from a first frequency at a first time to a second frequency greater than the first frequency at a second time subsequent to the first time and increases from a third frequency less than the first frequency at the second time to the first frequency at a third time subsequent to the second time and wherein the second linear frequency ramp decreases from the first frequency at the first time to the third frequency at the second time and decreases from the second frequency at the second time to the first frequency at the third time. 
     
     
       5. The electronic device of  claim 4 , wherein the signal generator is configured to generate a third radio-frequency signal having a third linear frequency ramp that increases from the third frequency at the first time to the second frequency at the third time and a fourth radio-frequency signal having a fourth linear frequency ramp that decreases from the second frequency at the first time to the third frequency at the third time, the electronic device further comprising:
 a third antenna configured to transmit the third radio-frequency signal concurrent with transmission of the first radio-frequency signal by the first antenna and transmission of the second radio-frequency signal by the second antenna; and 
 a fourth antenna configured to transmit the fourth radio-frequency signal concurrent with transmission of the first radio-frequency signal by the first antenna, transmission of the second radio-frequency signal by the second antenna, and transmission of the third radio-frequency signal by the third antenna, wherein
 the set of one or more antennas is configured to receive a reflected version of the third radio-frequency signal and a reflected version of the fourth radio-frequency signal, and 
 the one or more processors is configured to identify the location of the one or more external objects based on the reflected version of the third radio-frequency signal and the reflected version of the fourth radio-frequency signal received by the set of one or more antennas. 
 
 
     
     
       6. The electronic device of  claim 1 , wherein the signal generator is configured to generate a third radio-frequency signal having a third waveform and a fourth radio-frequency signal having a fourth waveform, the first waveform, the second waveform, the third waveform, and the fourth waveform having non-overlapping frequencies as a function of time;
 a third antenna configured to transmit the third radio-frequency signal concurrent with transmission of the second radio-frequency signal by the second antenna and transmission of the first radio-frequency signal by the first antenna; and 
 a fourth antenna configured to transmit the fourth radio-frequency signal concurrent with transmission of the first radio-frequency signal by the first antenna, transmission of the second radio-frequency signal by the second antenna, and transmission of the third radio-frequency signal by the third antenna, wherein:
 the set of one or more antennas is configured to receive a reflected version of the third radio-frequency signal and a reflected version of the fourth radio-frequency signal, and 
 the one or more processors is configured to identify the location of the one or more external objects based on the reflected version of the third radio-frequency signal and the reflected version of the fourth radio-frequency signal received by the set of one or more antennas. 
 
 
     
     
       7. The electronic device of  claim 6 , further comprising:
 a first antenna panel that includes the first antenna; 
 a second antenna panel that includes the second antenna; 
 a third antenna panel that includes the third antenna; and 
 a fourth antenna panel that includes the fourth antenna. 
 
     
     
       8. The electronic device of  claim 7 , wherein the set of one or more antennas includes at least one antenna on the first antenna panel, at least one antenna on the second antenna panel, at least one antenna on the third antenna panel, and at least one antenna on the fourth antenna panel. 
     
     
       9. The electronic device of  claim 1 , wherein the first waveform comprises a first step function in frequency as a function of time and the second waveform comprises a second step function in frequency as a function of time. 
     
     
       10. The electronic device of  claim 9 , wherein the first step function increases from a first frequency at a first time to a second frequency at a second time and wherein the second step function decreases from the second frequency at the first time to the first frequency at the second time. 
     
     
       11. The electronic device of  claim 9 , wherein the first step function increases from a first frequency at a first time to a second frequency greater than the first frequency at a second time subsequent to the first time and increases from a third frequency less than the first frequency at the second time to the first frequency at a third time subsequent to the second time and wherein the second step function decreases from the first frequency at the first time to the third frequency at the second time and decreases from the second frequency at the second time to the first frequency at the third time. 
     
     
       12. The electronic device of  claim 11 , wherein the signal generator is configured to generate a third radio-frequency signal having a third step function that increases from the third frequency at the first time to the second frequency at the third time and a fourth radio-frequency having a fourth step function that decreases from the second frequency at the first time to the third frequency at the third time, the electronic device further comprising:
 a third antenna configured to transmit the third radio-frequency signal concurrent with transmission of the first radio-frequency signal by the first antenna and transmission of the second radio-frequency signal by the second antenna; and 
 a fourth antenna configured to transmit the fourth radio-frequency signal concurrent with transmission of the first radio-frequency signal by the first antenna, transmission of the second radio-frequency signal by the second antenna, and transmission of the third radio-frequency signal by the third antenna, wherein
 the set of one or more antennas is configured to receive a reflected version of the third radio-frequency signal and a reflected version of the fourth radio-frequency signal, and 
 the one or more processors is configured to identify the location of the one or more external objects based on the reflected version of the third radio-frequency signal and the reflected version of the fourth radio-frequency signal received by the set of one or more antennas. 
 
 
     
     
       13. A method of operating an electronic device to perform radio-frequency spatial ranging, the method comprising:
 with a first antenna, transmitting a first radio-frequency signal that includes a first linear frequency ramp increasing in frequency from a first time to a second time; 
 with a second antenna, concurrent with transmission of the first radio-frequency signal by the first antenna, transmitting a second radio-frequency signal that includes a second linear frequency ramp decreasing in frequency from the first time to the second time; 
 with a set of one or more antennas, receiving a reflected version of the first radio-frequency signal and a reflected version of the second radio-frequency signal; and 
 with one or more processors, identifying a location of one or more external objects based on the reflected version of the first radio-frequency signal and the reflected version of the second radio-frequency signal received by the set of one or more antennas. 
 
     
     
       14. The method of  claim 13 , further comprising:
 with a third antenna, concurrent with transmission of the first radio-frequency signal by the first antenna and transmission of the second radio-frequency signal by the second antenna, transmitting a third radio-frequency signal that includes a third linear frequency ramp increasing in frequency from the first time to the second time; and 
 with a fourth antenna, concurrent with transmission of the first radio-frequency signal by the first antenna, transmission of the second radio-frequency signal by the second antenna, and transmission of the third radio-frequency signal by the third antenna, transmitting a fourth radio-frequency signal that includes a fourth linear frequency ramp decreasing in frequency from the first time to the second time. 
 
     
     
       15. The method of  claim 14 , wherein the first linear frequency ramp increases from a first frequency at the first time to a second frequency at a third time subsequent to the second time, the second linear frequency ramp decreases from the second frequency at the first time to the first frequency at the third time, the third linear frequency ramp increases from a third frequency that is greater than the first frequency and less than the second frequency at the first time to the second frequency at the second time and increases from the first frequency at the second time to the third frequency at the third time, and the fourth linear frequency ramp decreases from the third frequency at the first time to the first frequency at the second time and decreases from the second frequency at the second time to the third frequency at the third time. 
     
     
       16. The method of  claim 13 , wherein the first linear frequency ramp increases from a first frequency at the first time to a second frequency at the second time and the second linear frequency ramp decreases from the second frequency at the first time to the first frequency at the second time. 
     
     
       17. The method of  claim 13 , wherein the first linear frequency ramp increases from a first frequency at the first time to a second frequency at the second time and the second linear frequency ramp decreases from the first frequency at the first time to a third frequency that is less than the first frequency at the second time. 
     
     
       18. The method of  claim 17 , further comprising:
 with a third antenna, concurrent with transmission of the first radio-frequency signal by the first antenna and transmission of the second radio-frequency signal by the second antenna, transmitting a third radio-frequency signal that includes a third linear frequency ramp that increases from the third frequency at the first time to the first frequency at the second time; and 
 with a fourth antenna, concurrent with transmission of the first radio-frequency signal by the first antenna, transmission of the second radio-frequency signal by the second antenna, and transmission of the third radio-frequency signal by the third antenna, transmitting a fourth radio-frequency signal that includes a fourth linear frequency ramp that decreases from the second frequency at the first time to the first frequency at the second time. 
 
     
     
       19. An electronic device comprising:
 a first antenna; 
 a second antenna; 
 a set of antennas; 
 a signal generator configured to transmit, over the first antenna, a first radio-frequency signal that includes a first step function that increases in frequency from a first time to a second time and configured to concurrently transmit, over the second antenna, a second radio-frequency signal that includes a second step function that decreases in frequency from the first time to the second time, the set of antennas being configured to receive a reflected version of the first radio-frequency signal and a reflected version of the second radio-frequency signal; and 
 one or more processors configured to identify a location of one or more external objects based on the reflected version of the first radio-frequency signal and the reflected version of the second radio-frequency signal received by the set of antennas. 
 
     
     
       20. The electronic device of  claim 19 , wherein the first step function increases from a first frequency at the first time to a second frequency at the second time, the second step function decreases from the first frequency at the first time to a third frequency lower than the first frequency at the second time, and the electronic device further comprises:
 a third antenna; and 
 a fourth antenna, the signal generator being configured to
 transmit, over the third antenna, a third radio-frequency signal that includes a third step function that increases from the third frequency at the first time to the first frequency at the second time, and 
 transmit, over the fourth antenna, a fourth radio-frequency signal that includes a fourth step function that decreases from the second frequency at the first time to the first frequency at the second time.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 63/246,636, filed Sep. 21, 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 in scenarios where multiple external objects are present and/or moving within the field of view of the wireless circuitry. 
     SUMMARY 
     An electronic device may include wireless circuitry. The wireless circuitry may include spatial ranging circuitry and antennas. The spatial ranging circuitry may detect the location of multiple external objects using radio-frequency signals. The spatial ranging circuitry may include a signal generator that concurrently transmits different radio-frequency ranging signals over respective transmit antennas in a set of two or more transmit antennas. The ranging signals may include waveforms with time-varying frequencies, where each waveform includes frequencies that are non-overlapping with the frequencies of each of the other waveforms at any given time. As examples, the ranging signals may include frequency ramps or frequency step functions. 
     A set of one or more antennas may receive reflected versions of the radio-frequency ranging signals transmitted by the set of transmit antennas. One or more processors may process the reflected versions of the radio-frequency ranging signals received by the set of antennas to identify the location of one or more external objects. Transmitting the ranging signals using waveforms that are non-overlapping in frequency may prevent interference between the ranging signals and may allow the one or more processors to distinguish each of the ranging signals transmitted and received by each pair of antennas. Concurrently transmitting the ranging signals may significantly reduce the latency of location detection relative to examples where the ranging signals are transmitted by different transmit antennas in series. 
     An aspect of the disclosure provides an electronic device. The electronic device can include a signal generator configured to generate a first radio-frequency signal having a first waveform and a second radio-frequency signal having a second waveform, the first waveform and the second waveform having non-overlapping frequencies as a function of time. The electronic device can include a first antenna configured to transmit the first radio-frequency signal. The electronic device can include a second antenna configured to transmit the second radio-frequency signal concurrent with transmission of the first radio-frequency signal by the first antenna. The electronic device can include a set of one or more antennas configured to receive a reflected version of the first radio-frequency signal and a reflected version of the second radio-frequency signal. The electronic device can include one or more processors configured to identify a location of one or more external objects based on the reflected version of the first radio-frequency signal and the reflected version of the second radio-frequency signal received by the set of one or more antennas. 
     An aspect of the disclosure provides a method of operating an electronic device to perform radio-frequency spatial ranging. The method can include with a first antenna, transmitting a first radio-frequency signal that includes a first linear frequency ramp increasing in frequency from a first time to a second time. The method can include with a second antenna, concurrent with transmission of the first radio-frequency signal by the first antenna, transmitting a second radio-frequency signal that includes a second linear frequency ramp decreasing in frequency from the first time to the second time. The method can include with a set of one or more antennas, receiving a reflected version of the first radio-frequency signal and a reflected version of the second radio-frequency signal. The method can include with one or more processors, identifying a location of one or more external objects based on the reflected version of the first radio-frequency signal and the reflected version of the second radio-frequency signal received by the set of one or more antennas. 
     An aspect of the disclosure provides an electronic device. The electronic device can include a first antenna. The electronic device can include a second antenna. The electronic device can include a set of antennas. The electronic device can include a signal generator configured to transmit, over the first antenna, a first radio-frequency signal that includes a first step function that increases in frequency from a first time to a second time and configured to concurrently transmit, over the second antenna, a second radio-frequency signal that includes a second step function that decreases in frequency from the first time to the second time, the set of antennas being configured to receive a reflected version of the first radio-frequency signal and a reflected version of the second radio-frequency signal. The electronic device can include one or more processors configured to identify a location of one or more external objects based on the reflected version of the first radio-frequency signal and the reflected version of the second radio-frequency signal received by the set of antennas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a functional block diagram of an illustrative electronic device having spatial ranging circuitry in accordance with some embodiments. 
         FIG.  2    is a diagram of an illustrative electronic device having multiple antennas across one or more antenna panels that may be used to perform spatial ranging operations in accordance with some embodiments. 
         FIG.  3    is a flow chart of illustrative operations involved in using multiple antennas to transmit and receive spatial ranging signals while mitigating interference between the antennas in accordance with some embodiments. 
         FIG.  4    is a plot showing one example of how distances gathered using different pairs of transmit and receive antennas may be processed to identify the location of an external object in accordance with some embodiments. 
         FIG.  5    is a plot of illustrative spatial ranging signals (in frequency as a function of time) that include linear frequency ramps for concurrent transmission by different antennas without generating interference between the antennas in accordance with some embodiments. 
         FIG.  6    is a plot of illustrative spatial ranging signals (in frequency as a function of time) that include frequency staircases for concurrent transmission by different antennas without generating interference between the antennas 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 Fifth Generation (5G) New Radio (NR) 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., radar protocols), 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 wireless circuitry  24  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 communications bands such as a cellular low band (LB) (e.g., 600 to 960 MHz), a cellular low-midband (LMB) (e.g., 1400 to 1550 MHz), a cellular midband (MB) (e.g., from 1700 to 2200 MHz), a cellular high band (HB) (e.g., from 2300 to 2700 MHZ), a cellular ultra-high band (UHB) (e.g., from 3300 to 5000 MHz, or other cellular communications bands between about 600 MHz and about 5000 MHz), 3G bands, 4G LTE bands, 3GPP 5G New Radio Frequency Range 1 (FR1) bands below 10 GHz, 3GPP 5G New Radio (NR) Frequency Range 2 (FR2) bands between 20 and 60 GHz, 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 such as the Global Positioning System (GPS) L1 band (e.g., at 1575 MHz), L2 band (e.g., at 1228 MHz), L3 band (e.g., at 1381 MHZ), LA band (e.g., at 1380 MHz), and/or L5 band (e.g., at 1176 MHz), a Global Navigation Satellite System (GLONASS) band, a BeiDou Navigation Satellite System (BDS) band, ultra-wideband (UWB) frequency bands that operate under the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols (e.g., a first UWB communications band at 6.5 GHz and/or a second UWB communications band at 8.0 GHz), communications bands under the family of 3GPP wireless communications standards, communications bands under the IEEE 802.XX family of standards, satellite communications bands such as an L-band, S-band (e.g., from 2-4 GHz), C-band (e.g., from 4-8 GHZ), X-band, Ku-band (e.g., from 12-18 GHz), Ka-band (e.g., from 26-40 GHz), etc., industrial, scientific, and medical (ISM) bands such as an ISM band between around 900 MHz and 950 MHz or other ISM bands below or above 1 GHz, one or more unlicensed bands, one or more bands reserved for emergency and/or public services, 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. 
     The term “convey radio-frequency signals” as used herein means the transmission and/or reception of the radio-frequency signals (e.g., for performing unidirectional and/or bidirectional wireless communications with external wireless communications equipment). Antenna(s)  40  may transmit the radio-frequency signals by radiating the radio-frequency signals into free space (or to free space through intervening device structures such as a dielectric cover layer). Antenna(s)  40  may additionally or alternatively receive the radio-frequency signals from free space (e.g., through intervening devices structures such as a dielectric cover layer). The transmission and reception of radio-frequency signals by antennas  40  each involve the excitation or resonance of antenna currents on an antenna resonating element in the antenna by the radio-frequency signals within the frequency band(s) of operation of the antenna. 
     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, antennas  40  may transmit radio-frequency signals  36 . Wireless circuitry  24  may transmit radio-frequency signals  36  in a corresponding radio frequency band (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 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 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 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 . 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 ). 
     Radar circuitry  26  may perform spatial ranging operations using radio-frequency signals  36  and reflected signals  38  to detect the presence, position, orientation, and/or velocity of external object  34  at any given time and/or to track the presence, position, orientation, and/or velocity of external object  34  over time. The spatial ranging operations may sometimes be referred to herein as radio-frequency sensing operations. The spatial ranging operations may be used to identify user inputs or gestures performed by a user of device  10  or another person, to perform healthcare functions, to perform search and rescue operations, to perform security operations, to perform automotive operations, etc. The spatial ranging operations may allow wireless circuitry  24  to detect and track one or more persons (e.g., a user) without requiring the persons to also be holding an active device such as device  10 . 
     Performing spatial ranging operations using radio-frequency signals allows wireless circuitry  24  to distinguish between animate external objects  34  such as persons from inanimate external objects such as walls, floors, furniture, etc. (e.g., because the radio-frequency spatial ranging may allow wireless circuitry  24  to rapidly detect and track movement of external object  34 ). For example, radar circuitry  26  may gather multiple measurements over time and may process differences between the measurements to identify movement of external object  34  (e.g., movement indicative of external object  34  being a human). However, in practice, sensing humans using radio-frequency signals can be very difficult because different humans move at different speeds in different contexts. In addition, making multiple measurements over time to identify humans can be very time consuming and can result in excessive latency in identifying location. Further, there are many scenarios in which there are multiple moving external objects  34  (e.g., people) within the field of view of antennas  40 . If care is not taken, merely processing changes in distance gathered using radio-frequency signals  36  can be insufficient to properly detect and track multiple different external objects  34  (e.g., persons) in the vicinity of device  10 . 
     To allow radar circuitry  26  to localize, detect, and/or track multiple animate external objects  34  (e.g., multiple moving persons) in the vicinity of device  10 , radar circuitry  26  may use more than one antenna  40  to transmit radio-frequency signals  36  and may use more than one antenna  40  to receive reflected signals  38 .  FIG.  2    is a diagram showing how device  10  may include multiple antennas for transmitting radio-frequency signals  36  and for receiving reflected signals  38 . 
     As shown in  FIG.  2   , device  10  may include one or more antenna panels  42  (e.g., a first antenna panel  42 - 1 , a second antenna panel  42 - 2 , a Kth antenna panel  42 -K, etc.). Each antenna panel  42  may include one or more respective antennas  40 . Each antenna panel  42  may, if desired, include a common substrate (module) to which each of the antennas  40  in that antenna panel  42  are mounted and/or a radio-frequency integrated circuit (chip) that includes control circuitry (e.g., phase and magnitude controllers, amplifiers, switches, filters, matching circuitry, transmission lines, etc.) for the antennas  40  in that antenna panel  42 . Antenna panels  42  may sometimes also be referred to herein as antenna modules  42 . Each antenna panel  42  may be disposed at a respective location on or in device  10 . Disposing antenna panels  42  at different ends, edges, or corners of device  10  may help to maximize the accuracy and precision with which the antenna panels perform spatial ranging operations, for example. If desired, each of the antennas  40  on any given antenna panel  42  may form a phased antenna array that forms a signal beam oriented in a selected beam pointing angle (e.g., based on the phases provided to each antenna in the array) and/or different antennas  40  on different antenna panels  42  may form part of the same phased antenna array (sometimes referred to as a phased array antenna). 
     To detect multiple external objects  34  (or multiple portions of the same external object such as different body parts of a user) in the vicinity of device  10 , radar circuitry  26  ( FIG.  1   ) may use more than one antenna  40  (e.g., antennas  40  located at different spatial locations across device  10 ) to transmit radio-frequency signals  36  (sometimes referred to herein as transmit (TX) antennas) and may use more than one antenna  40  (e.g., antennas  40  located at different spatial locations across device  10 ) to receive reflected signals  38  (sometimes referred to herein as receive (RX) antennas). For example, multiple TX antennas  40  may transmit chirp signals in radio-frequency signals  36 . However, radar circuitry  26  may be unable to resolve multiple external objects  34  when multiple TX antennas  40  transmit chirp signals at the same time, because the chirp signals would interfere with each other and control circuitry  14  would therefore be unable to distinguish between the chirp signals transmitted by each of the TX antennas. 
     To help mitigate these issues, the multiple TX antennas  40  may take turns transmitting chirp signals in series (sequence). For example, a first TX antenna  40  may transmit a first chirp signal and a first RX antenna  40  may receive a reflected version of the first chirp signal, a second TX antenna  40  may then transmit a second chirp signal and a second RX antenna  40  may receive a reflected version of the second chirp signal, etc. Sequential transmission in this way may prevent interference between the TX antennas to help control circuitry  14  to locate multiple external objects  34  but consumes an excessive amount of time and introduces excessive latency in identifying the locations of the external objects. Software applications running on device  10  that use the identified locations for other purposes will therefore experience excessive latency in performing other processing operations based on the identified locations. 
     To allow radar circuitry  26  to detect multiple external objects  34  (or multiple portions of the same external object such as different body parts of a user) while minimizing latency, radar circuitry  26  may generate ranging signals for concurrent transmission by multiple antennas  40  without interference between the ranging signals.  FIG.  3    is a flow chart of illustrative operations involved in using radar circuitry  26  to perform spatial ranging operations using multiple concurrently active TX antennas without producing interference between the antennas. 
     At operation  50 , radar circuitry  26  may use a set of TX antennas  40  to transmit spatial ranging signals (sometimes referred to herein as ranging signals). The set of TX antennas  40  may include two or more TX antennas  40 . TX signal generator  28  may generate a respective ranging signal for each of the TX antennas in the set of TX antennas. Each of the TX antennas in the set of TX antennas may be on the same antenna panel  42  ( FIG.  2   ) or different TX antennas in the set of TX antennas may be located on two or more antenna panels  42  (e.g., each of the TX antennas in the set of TX antennas may be located (disposed) on a respective antenna panel  42 ). If desired, one or more of the antenna panels  42  may be muted from transmitting ranging signals (e.g., antenna panels with insufficient signal-to-noise ratio (SNR)). TX signal generator  28  may generate the ranging signals using different waveforms for each TX antenna in the set of TX antennas, where the waveforms do not interfere with each other despite concurrent transmission over the set of TX antennas. For example, the waveforms may be such that no two TX antennas in the set of TX antennas transmit ranging signals at the same frequency at any given time. While the spatial ranging signals are sometimes referred to as not having the same frequency at any given time, “at any given time” as used herein allows for an instant in time (e.g., an instantaneous time, an extremely short overlapping time period on the order of a few sequential bits, or any sufficiently instantaneous time that is too short for measurable interference to be reasonably observed) in which the ranging signals transmitted by two of the antennas in the set of TX antennas are at the same frequency. 
     At operation  52 , while the set of TX antennas is transmitting the ranging signals, a set of RX antennas  40  may receive reflected versions of the transmitted ranging signals that have reflected off one or more external objects  34  (e.g., as reflected signals  38  of  FIG.  1   ). The set of RX antennas may include one or more RX antennas. The set of RX antennas may, if desired, include all the antennas  40  that are not being used as TX antennas. If desired, some of the antennas  40  (e.g., one or more antenna panels  42 ) may be disabled from receiving ranging signals during spatial ranging operations (e.g., antennas or antenna panels having insufficient received signal SNR). In these examples, the set of RX antennas may include all the antennas  40  that are not disabled and that are not TX antennas. In general, a greater number of RX antennas may increase the accuracy and precision with which control circuitry  14  is able to resolve the position of external object(s)  34 . Each of the RX antennas in the set of RX antennas may be on the same antenna panel  42  ( FIG.  2   ) or different RX antennas in the set of RX antennas may be located on two or more antenna panels  42  (e.g., each RX antenna may be located on a respective antenna panel  42 ). In some implementations, the set of RX antennas may include only a single antenna  40  on each antenna panel  42 . Each RX antenna in the set of RX antennas may receive a reflected version of each of the ranging signals transmitted by each of the TX antennas. 
     At operation  54 , control circuitry  14  ( FIG.  1   ) may process the ranging signals transmitted by the set of TX antennas  40  and the reflected signals received by the set of RX antennas  40  to detect and/or track the presence, location, orientation, and/or velocity of one or more external objects  34  at one time or over time. Since each respective ranging signal is transmitted by a corresponding TX antenna  40  at a different frequency at all times, the ranging signals will not interfere with each other. For example, control circuitry  14  may process the signal received at each RX antenna in the set of RX antennas and may filter the received signal by frequency. Given the known frequency of the transmitted ranging signals, control circuitry  14  may identify (e.g., distinguish, determine, etc.) which of the transmitted ranging signals is present in the received signal at any given time to distinguish between each of the transmitted ranging signals in the received signal (and the corresponding TX antenna) despite the fact that the set of TX antennas concurrently transmitted all the ranging signals at the same time. Since control circuitry  14  can distinguish between each ranging signal in the received signal for each antenna, control circuitry  14  is subsequently able to detect the time of flight (TOF) for each ranging signal between each pair of TX antennas and RX antennas, which is then used to determine (e.g., compute, calculate, identify, estimate, etc.) the distance between each external object  34  and each TX antenna and the distance between each external object  34  and each RX antenna. Control circuitry  14  may process these distances to resolve the true location, orientation, and/or velocity of each external object  34  relative to device  10 . Control circuitry  14  may perform any desired subsequent processing operations based on the identified location, orientation, and/or velocity of each external object  34 . 
       FIG.  4    is a diagram showing one example of how control circuitry  14  may process transmitted and received ranging signals from different pairs of TX and RX antennas to identify the location of a single external object  34  (e.g., while processing operation  54  of  FIG.  3   ). The X-axis of  FIG.  4    plots a first spatial coordinate and the Y-axis of  FIG.  4    plots a second spatial coordinate (e.g., along orthogonal Cartesian axes). Point  68  represents the spatial location of a first TX antenna in device  10 . Point  67  represents the spatial location of a first RX antenna in device  10 . 
     Control circuitry  14  may use the known waveform of the ranging signal transmitted by the TX antenna at location  68  (e.g., as transmitted while processing operation  50  of  FIG.  3   ) to identify the reflected version of that ranging signal in the signal received by the RX antenna at location  67  (e.g., as received while processing operation  52  of  FIG.  3   ), because each of the ranging signals transmitted by the set of TX antennas has a different respective frequency at each moment in time. Control circuitry  14  may then process the ranging signal transmitted by the TX antenna at location  68  and the reflected version of the ranging signal transmitted by the TX antenna at location  68  as received by the RX antenna at location  67  to identify (e.g., determine, generate, compute, calculate, estimate, etc.) that the external object  34  that reflected the ranging signal is located at a distance D 1  from the TX antenna at location  68  and is located at a distance D 2  from the RX antenna at location  67 . In other words, control circuitry  14  may identify an ellipse  60  of points at which external object  34  may be located (e.g., where each point on ellipse  60  is located distance D 1  from point  68  and distance D 2  from point  67 ). The example of  FIG.  4    is not to scale. 
     Control circuitry  14  may repeat this process for the ranging signal transmitted by a second pair of TX and RX antennas (e.g., the TX antenna located at point  68  and a second RX antenna located at a point other than point  67 , a second TX antenna located at a point other than point  68  and the RX antenna located at point  67 , or a TX antenna located at a point other than point  68  and an RX antenna located at a point other than point  67 ) to generate an additional ellipse such as ellipse  62  of points at which external object  34  may be located (e.g., external object  34  may be located at any of the intersections of ellipses  60  and  62 ). To resolve any ambiguity in the position of external object  34 , control circuitry  14  may repeat this process for the ranging signal transmitted by a third pair of TX and RX antennas to generate an additional ellipse such as ellipse  64  of points at which external object  34  may be located. Control circuitry  14  may then identify the location of external object  34  as the point at which ellipses  62 ,  64 , and  60  intersect. In the example of  FIG.  4   , external object  34  is located at point  66 . This process may be repeated for every combination of TX antennas in the set of TX antennas and RX antennas in the set of RX antennas to resolve the location of each external object  34 , for example. If desired, control circuitry  14  may identify these ellipses after taking an inverse Fast Fourier Transform (iFFT) of the received signal and subtracting a reference snapshot (e.g., as taken by the IFFT at a previous time used as a reference). If desired, users (e.g., external objects  34 ) may be located based on SNR where the ellipses overlap and, when SNR is below a threshold, the detection/localization may terminate. 
     Performing spatial ranging operations in this way may significantly reduce the latency with which control circuitry  14  detects the location of external object(s)  34  relative to scenarios where ranging signals are sequentially transmitted by different TX antennas (e.g., without requiring additional hardware). In the example of  FIG.  4   , only three measurements are used to detect the location of external object  34 . This is merely illustrative and, in general, any desired number of measurements may be used (e.g., 20-40 or more sequential transmissions of the ranging signals by each of the TX antennas in the set of TX antennas in parallel). This may also reduce the snapshot window time with which external objects  34  are located, thereby giving the environment less time to change during measurement. This may help to minimize the presence of ghost images of external objects  34  in the location data (e.g., measurements of the location of external object  34 ) gathered using radar circuitry  26  and may eliminate coherence time expiry issues. 
     In general, the ranging signals transmitted by the set of TX antennas may include any desired ranging signals that do not have the same frequency at any given time (e.g., while allowing for an instantaneous time or an extremely short overlapping time period that does not produce measurable or substantial interference). As one example, each of the ranging signals may include a respective linear frequency ramp.  FIG.  5    is a plot of frequency as a function of time that shows four illustrative ranging signals with linear frequency ramps that may be concurrently transmitted by a set of four TX antennas  40  (e.g., while processing operation  50  of  FIG.  3   ). 
     As shown in  FIG.  5   , curve  70  plots a first ranging signal transmitted by a first TX antenna in the set of TX antennas. Curve  72  plots a second ranging signal transmitted by a second TX antenna in the set of TX antennas. Curve  74  plots a third ranging signal transmitted by a third TX antenna in the set of TX antennas. Curve  76  plots a fourth ranging signal transmitted by a fourth TX antenna in the set of TX antennas. 
     As shown by curve  70 , the first ranging signal may include a positive-slope linear frequency ramp (e.g., chirp) that increases from a minimum frequency FMIN at time T0 to a maximum frequency FMAX at time TA. Mathematically, the first ranging signal may be represented by the function f 1 (t)=FMIN+a*t for T0&lt;t&lt;TA, where a is the slope of the line given by a=(FMAX−FMIN)/(TA−T0). As shown by curve  72 , the second ranging signal may include a negative-slope linear frequency ramp that decreases from maximum frequency FMAX at time T0 to minimum frequency FMIN at time TA. Mathematically, the second ranging signal may be represented by the function f 2 (t)=FMIN−a*t for T0≤t≤TA. As shown by curves  70  and  72 , the first and second ranging signals are each at a different respective frequency for all times between time T0 and time TA (e.g., except for the instantaneous time at (TA−T0)/2 at which the ranging signals instantaneously exhibit the same frequency), thereby allowing for concurrent transmission of both ranging signals without interference. The first and second ranging signals are still referred to herein as having different frequencies at all times between times T0 and TA (e.g., as having non-overlapping frequencies as a function of time) despite the instantaneous overlap at time (TA−T0)/2 (e.g., this instantaneous time may be insufficient to result in measurable and/or substantial interference between the ranging signals). Nevertheless, if desired, the first and/or second ranging signal may be instantaneously muted at time (TA−T0)/2. 
     As shown by curve  74 , the third ranging signal may include a positive-slope linear frequency ramp that increases from frequency FMID (e.g., a midpoint or average frequency equal to (FMAX−FMIN)/2) at time T0 to frequency FMAX at time (TA−T0)/2 and that increases from frequency FMIN at time (TA−T0)/2 to frequency FMID at time TA. Mathematically, the third ranging signal may be represented by the function f 3 (t)=(FMIN+FMAX)/2+a*t for T0≤t≤(TA−T0)/2 and FMIN+a*(t−(TA−T0)/2) for (TA−T0)/2&lt;t≤T. As shown by curves  70 ,  72 , and  74 , the first, second, and third ranging signals are each at a different respective frequency for all times between time T0 and time TA. 
     As shown by curve  76 , the fourth ranging signal may include a negative-slope linear frequency ramp that decreases from frequency FMID at time T0 to frequency FMIN at time (TA T0)/2 and that decreases from frequency FMAX at time (TA−T0)/2 to frequency FMID at time TA. Mathematically, the fourth ranging signal may be represented by the function f 4 (t)=(FMIN+FMAX)/2−a*t for T0≤t≤(TA−T0)/2 and FMAX−a*(t−(TA−T0)/2) for (TA−T0)/2&lt;t≤T. As shown by curves  70 ,  72 ,  74 , and  76 , the first, second, third, and fourth ranging signals are each at a different respective frequency for all times between time T0 and time TA. The third and fourth ranging signals are still referred to herein as having different frequencies at all times between times T0 and TA (e.g., as having non-overlapping frequencies as a function of time) despite the instantaneous overlap at times T0, (TA−T0)/2, and TA (e.g., these instantaneous times may be insufficient to result in measurable and/or substantial interference between the ranging signals). Nevertheless, if desired, the third and/or fourth ranging signal may be instantaneously muted at times T0, (TA−T0)/2, and/or TA. 
     The four ranging signals shown in  FIG.  5    may allow the set of TX antennas to include four TX antennas that each transmit a respective one of the four ranging signals without producing interference between the ranging signals. If desired, the set of TX antennas may include three TX antennas that each transmit a respective one of the four ranging signals of  FIG.  5    or may include two TX antennas that each transmit a respective one of the four ranging signals of  FIG.  5   . 
     The linear frequency ramping scheme of  FIG.  5    may be generalized to include 2N ranging signals for transmission over 2N TX antennas (e.g., when the set of TX antennas includes 2N TX antennas). For example, when the set of TX antennas includes 2N TX antennas and there is an available bandwidth of FMAX−FMIN, N of the TX antennas may begin at an initial frequency FMIN+(FMAX−FMIN)/(N×i), where i=0, . . . , N−1, and may linearly ramp up in frequency (e.g., at slope a). Meanwhile, the other N TX antennas in the set of 2N TX antennas may begin at an initial frequency FMIN−(FMAX−FMIN)/(N×i) where i=0, . . . , N−1, and may linearly ramp down in frequency (e.g., at slope −a). When an extreme of the bandwidth is reached, each TX antenna may cycle back and continue from the other extreme. 
     The example of  FIG.  5    in which the ranging signals include linear frequency ramps is merely illustrative. If desired, the ranging signals may include frequency staircases that increase or decrease frequency at each TX antenna within the available bandwidth.  FIG.  6    is a plot of frequency as a function of time that shows four illustrative ranging signals with frequency staircases (step-functions) that may be concurrently transmitted by a set of four TX antennas  40  (e.g., while processing operation  50  of  FIG.  3   ). 
     As shown in  FIG.  6   , curve  80  plots a first ranging signal transmitted by a first TX antenna in the set of TX antennas. Curve  82  plots a second ranging signal transmitted by a second TX antenna in the set of TX antennas. Curve  84  plots a third ranging signal transmitted by a third TX antenna in the set of TX antennas. Curve  86  plots a fourth ranging signal transmitted by a fourth TX antenna in the set of TX antennas. 
     As shown by curve  80 , the first ranging signal may include a frequency staircase (e.g., step-function) that increases from minimum frequency FMIN at time T0 to maximum frequency FMAX at time TA. The frequency staircase may include N steps (e.g., constant frequency periods) that are separated by frequency gap Δf=(FMAX−FMIN)/N. Each constant frequency period may last for duration (TA−T0)/N. Mathematically, the first ranging signal may be represented by the (step) function f 1 [n]=FMIN+n*Δf, where 0≤n≤N and n=floor(N*t/(TA−T)). 
     As shown by curve  82 , the second ranging signal may include a frequency staircase (e.g., step-function) that decreases from maximum frequency FMAX at time T0 to minimum frequency FMIN at time TA. The frequency staircase may include N steps (e.g., constant frequency periods) that are separated by frequency gap Δf. Each constant frequency period may last for duration (TA−T0)/N. Mathematically, the second ranging signal may be represented by the (step) function f 2 [n]=FMAX−n*Δf, where 0≤n≤N and n=floor(N*t/(TA−T)). As shown by curves  80  and  82 , the first and second ranging signals are each at a different respective frequency for all times between time T0 and time TA, thereby allowing for concurrent transmission of both ranging signals without interference. If desired, the first and/or second ranging signal may be muted at any periods where the signals would otherwise overlap. 
     As shown by curve  84 , the third ranging signal may include a frequency staircase (e.g., step-function) that increases from frequency FMID at time T0 to maximum frequency FMAX at time (TA−T0)/2 and that increases from frequency FMIN at time (TA−T0)/2 to frequency FMID at time TA. Mathematically, the third ranging signal may be represented by the (step) function f 3 [n]=(FMIN+FMAX)/2+n*Δf when 0≤n&lt;N/2 and FMIN+(n−N/2)*Δf when N/2≤n≤N. As shown by curves  80 ,  82 , and  84 , the first, second, and third ranging signals are each at a different respective frequency for all times between time T0 and time TA. 
     As shown by curve  86 , the fourth ranging signal may include a frequency staircase (e.g., step-function) that decreases from frequency FMID at time T0 to minimum frequency FMIN at time (TA−T0)/2 and that decreases from frequency FMAX at time (TA−T0)/2 to frequency FMID at time TA. Mathematically, the fourth ranging signal may be represented by the (step) function f 4 [n]=(FMIN+FMAX)/2−n*Δf when 0≤n&lt;N/2 and FMAX−(n−N/2)*Δf when N/2≤n≤N. As shown by curves  80 ,  82 ,  84 , and  86 , the first, second, third, and fourth ranging signals are each at a different respective frequency for all times between time T0 and time TA. 
     The four ranging signals shown in  FIG.  6    may allow the set of TX antennas to include four TX antennas that each transmit a respective one of the four ranging signals without producing interference between the ranging signals. If desired, the set of TX antennas may include three TX antennas that each transmit a respective one of the four ranging signals of  FIG.  6    or may include two TX antennas that each transmit a respective one of the four ranging signals of  FIG.  6   . 
     The frequency staircase scheme of  FIG.  6    may be generalized to include 2N ranging signals for transmission over 2N TX antennas (e.g., when the set of TX antennas includes 2N TX antennas). For example, when the set of TX antennas includes 2N TX antennas and there is an available bandwidth of FMAX−FMIN, N of the TX antennas may begin at an initial frequency FMIN+(FMAX−FMIN)/(N×i), where i=0, . . . , N−1, and may go to the next higher-frequency sub-carrier to increase frequency. Meanwhile, the other N TX antennas in the set of 2N TX antennas may begin at an initial frequency FMIN−(FMAX−FMIN)/(N×i) where i=0, . . . , N−1, and may go to the next lower-frequency sub-carrier to decrease frequency. When an extreme of the bandwidth is reached, each TX antenna may cycle back and continue from the other extreme. 
     The example of  FIGS.  5  and  6    are merely illustrative. In general, the ranging signals may have any desired waveforms that have non-overlapping frequencies from time T0 to TA (e.g., where the waveforms are still referred to as non-overlapping when two of the waveforms instantaneously overlap at some point between time T0 and time TA or when the overlap would have no measurable or substantial effect on the interference between the ranging signals). In other words, curves  70 - 76  of  FIG.  5    and curves  80 - 86  of  FIG.  6    may have other shapes. 
     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 in connection with  FIGS.  1 - 6    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: 20220822
Publication Date: 20241008
Grant Date: 20241008
Priority Date: 20210921
Inventors: BEHNAMFAR, FIROUZ
MUCKE, Christian W
NAGUIB, AYMAN F
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W64/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0055", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01S13/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S5/0246", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S5/02521", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/878", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/343", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/0235", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/89", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S7/0232", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/0055", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W64/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S5/02521", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S5/0246", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S13/89", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 83228553