Abstract: An object tracking method, in which a radar sensor emits radar signals in successive measurement cycles, said radar signals being reflected by the object and captured by the radar sensor as radar targets, wherein movement information about the object for object tracking is determined on the basis of the radar targets and a search window for the radar targets of the object is defined on the basis of the movement information, wherein the search window is widened if a change in the movement information which exceeds a definable limit value is determined in successive measurement cycles and/or if no radar targets of the tracked object are captured anymore.

Abstract: A system for material detection and identification includes an interface configured to access a material database associating each of a plurality of materials with a resonance frequency and one or more transmission parameters; an RF transmitter configured to, for each material of at least a subset of the plurality of materials in the material database transmit into an environment an RF signal the resonance frequency for the material using the one or more transmission parameters; an RF receiver configured to receive a response signal from the environment; and a processor configured to analyze the response signal for resonance characteristics that indicate a presence of the material and identify the material to a user if the presence of the material is indicated by the resonance characteristics.

Abstract: Low noise amplifiers (LNAs) are disclosed herein. In certain embodiments, an LNA includes an input balun configured to convert a single-ended radio frequency (RF) receive signal to a differential RF receive signal, an amplifier chain configured to amplify the differential RF receive signal to generate a differential amplified RF receive signal, and an output balun configured to convert the differential amplified RF receive signal into a single-ended amplified RF receive signal. The LNA's amplifier chain is operable in multiple gain modes, and includes a first differential amplification stage, a second differential amplification stage, and a third differential amplification stage.

Abstract: An estimation method and system for quasi-real-time monitoring of a moving velocity vector of a typhoon based on a synthetic aperture radar includes: (1) determining, using a threshold method, a position of a typhoon eye wall of a synthetic aperture radar (SAR) sea surface wind field of a typhoon; (2) extracting a final typhoon eye region using a maximum gradient method according to the position of the typhoon eye wall, and estimating an approximate ellipse of the typhoon eye wall and determining a center of the approximate ellipse as a typhoon center; (3) estimating large-scale background wind vector information using the estimated typhoon center and approximate ellipse; and (4) determining a moving velocity vector of the typhoon using the estimated background wind vector information and typhoon center.

Abstract: A view system for a vehicle (1) with a tractor (2) and a trailer (3). The view system has a capture unit (10) with an image sensor (12) for capturing image data of an area of view, around the vehicle, a processing unit (20) for processing the image data, and a reproduction unit (30) for reproducing at least one first image section (410) and one second image section (420) of the area of view (40) captured by the capture unit (10). The processing unit provides different resolutions of image data depending on the position of the tractor with respect to the trailer.

Abstract: A distance measurement method, a distance measurement sensor, and a distance measurement sensing array, for use in improving the signal-to-noise ratio of a distance measurement system and increasing the distance measurement accuracy and a distance measurement distance.

Abstract: This document describes techniques, apparatuses, and systems for multi-channel joint interference mitigation. Radar radiation received by a radar system may include interference from other nearby radar systems. The interference can result in reduced sensitivity of the radar system. The techniques, apparatuses, and systems described herein mitigate the interference by identifying a set of samples of the radar radiation with interference. The interference can be estimated and mitigated by comparing this set (e.g., with interference) to a set of samples without interference and suppressing the interference without suppressing the detected signal. Further, the interference can be analyzed to determine if the interference contains detection information of one or more objects (e.g., other vehicles with radar systems causing interference). In this manner, interference mitigation may be obtained without losing information included in the set of samples including interference.

Abstract: The disclosure relates to an electronic control device and method. According to the disclosure, an electronic control device comprises a sensor unit receiving a reception signal detecting an object and processing the reception signal to obtain object information, a power supply unit supplying power to the sensor unit and processing a signal for a predetermined frequency, and a controller adjusting a frequency processed by the power supply unit in each operation period of the sensor unit.

Abstract: A wireless audio system configured to perform an acoustic ranging operation is disclosed. The audio system comprises an audio transmitter, and audio receiver, and is configured to determine a distance between the audio transmitter and the audio receiver.

Abstract: Architectures of millimeter-wave (mm-wave) fully-integrated frequency-division duplex (FDD) transmitting-receiving (T/R) front-end (FE) modules include a duplexer (DUX), power amplifier (PA), and low noise amplifier (LNA) on a single semiconductor substrate to facilitate the development of system on a chip (SoC) for mm-wave 5th Generation (5G) wireless communications applications. The first FE module adopts a passive DUX consisting of Wilkinson power divider and ground-center-tap transformer to achieve high isolation between PA output and LNA inputs. Another FE module combines the advantages of passive DUX and power-efficient cancellation circuits to accomplish high TX-RX isolation and low noise performance at the same time. The DUX can stand alone as a single unit in a system and is used together with external PA and LNA provided in the system, or it can include its own internal PA and LNA to form a DUX FE module.

Abstract: A system for contactless testing of radio frequency apertures is provided. The system comprises a fixture having a fixture mount operable to be received in a fixture receiver of a robotic system, and a vector network analyzer (“VNA”) supported by the fixture. A radiating antenna is supported by the fixture, and is operable to be connected to the VNA via a cable. Upon movement of the fixture via the robotic system, the VNA, the radiating antenna, and the cable maintain a static positional relationship relative to one another.

Abstract: A method of sensing a target in a target detection system having processing circuitry and a multiplexer coupled to the processing circuitry and to a plurality NT of transmit antennas forming a sparse transmit uniform linear array (ULA), the multiplexer being configured to generate multiplexed and phase modulated transmit signals (T1 . . . TNT) based on signals from a local oscillator. The processing circuitry receives signals via a plurality NR of receive antennas forming a dense receive ULA. The method includes transmitting the transmit signals via the transmit antennas as a general radiation pattern corresponding to a block circulant probing signal matrix, and receiving via the receive antennas receive signals resulting from backscattering of the transmit signals transmitted towards K targets. The method further includes processing the received reflection signals to determine the presence, range and/or angular position of a target within a field of view of the transmit antennas.

Abstract: A radar system for tracking UAVs and other low flying objects utilizing wireless networking equipment is provided. The system is implemented as a distributed low altitude radar system where transmitting antennas are coupled with the wireless networking equipment to radiate signals in a skyward direction. A receiving antenna or array receives signals radiated from the transmitting antenna, and in particular, signals or echoes reflected from the object in the skyward detection region. One or more processing components is electronically coupled with the wireless networking equipment and receiving antenna to receive and manipulate signal information to provide recognition of and track low flying objects and their movement within the coverage region. The system may provide detection of objects throughout a plurality of regions by networking regional nodes, and aggregating the information to detect and track UAVs and other low flying objects as they move within the detection regions.

Abstract: A method for radar-based measurement of a filling level of a filling material in a container includes, in successive measurement cycles, generating an evaluation curve, and the relevant current evaluation curve is stored; a first difference curve is formed based on the evaluation curve of the current measurement cycle and a stored evaluation curve of a preceding measurement cycle; and the filling level is determined based on a maximum in the current first difference curve. The filling level is thus established from the difference curve rather than from the evaluation curve, and the filling level can be determined with greater certainty—in particular in the case of filling material having rippled surfaces.

Abstract: A secondary echo and a primary echo subjected to topographic echo processing are compared with each other. When there is a topographic echo in the primary echo or the secondary echo determined as a strong echo, an echo resulting from removal of the topographic echo is defined as a strong-topographic-echo-removed reception signal. Electric power of the topographic echo in the secondary echo or the primary echo determined as a weak echo and the strong-topographic-echo-removed reception signal are defined as weak echo parameters. Electric power of the weak echo estimated from a reception signal in a weak echo region resulting from phase correction of a reception signal resulting from removal of a frequency component of the strong echo from the strong-topographic-echo-removed reception signal representing the weak echo parameter, a spectral width of the weak echo representing the weak echo parameter, and a Doppler velocity of the weak echo are provided as spectral parameters.

Abstract: A temperature insensitive oscillator system. The system includes a substrate having a first surface and an opposing second surface, a CMOS device with one or more CMOS circuits attached to the first surface of the substrate, one or more piezoelectric transducers attached to an outer surface of the CMOS device, a voltage-controlled oscillator generating a RF frequency, which is transmitted as a plurality of short pulses to the one or more piezoelectric transducers, and one or more delays and oscillators using resistor and active components arranged alongside the piezoelectric transducers or on the CMOS device such that the voltage-controlled oscillator has minimal dependence on temperature, and has minimal deviation from a programmed frequency.

Abstract: An object is to enable measurement of position and velocity of a measurement object. A velocity measurement device includes a transmitting means, a receiving means, and a signal processing means. The transmitting means transmits a transmission signal by a transmitting antenna toward a measurement object. The receiving means receives a reflected wave from the measurement object with multiple receiving antennas and generates a reception signal for each of the receiving antennas. The signal processing means obtains a phase plane of the reflected wave with respect to an antenna plane of the multiple receiving antennas from a phase difference between the reception signals to specify an arrival direction of the reflected wave, obtains a distance to the measurement object from a propagation delay time of the reflected wave, and calculates a phase fluctuation of the reflected wave to calculate a velocity of the measurement object from the phase fluctuation.

Abstract: Disclosed is a method and apparatus for generating a radar signal, in which performance of radar detection is ensured while increasing a spectrum efficiency in a radar network. The method comprises generating a set of frequency-modulation waveforms, generating an orthogonal code set, generating a set of coded frequency-modulation waveforms through element operation between the set of frequency-modulation waveforms and the orthogonal code set, calculating an objective function for the set of frequency-modulation waveforms with regard to a different set of coded frequency-modulation waveforms and previous sets of coded frequency-modulation waveforms, and selecting a current polyphase code set as an optimized polyphase code set when a result of current calculation is better or smaller than a result of previous iteration, and performing phase perturbation by replacing an element randomly selected in the current polyphase code set selected as the optimized polyphase code set with another admissible-phase element.

Abstract: Radio frequency motion sensors may be configured for operation in a common vicinity so as to reduce interference. In some versions, interference may be reduced by timing and/or frequency synchronization. In some versions, a master radio frequency motion sensor may transmit a first radio frequency (RF) signal. A slave radio frequency motion sensor may determine a second radio frequency signal which minimizes interference with the first RF frequency. In some versions, interference may be reduced with additional transmission adjustments such as pulse width reduction or frequency and/or timing dithering differences. In some versions, apparatus may be configured with multiple sensors in a configuration to emit the radio frequency signals in different directions to mitigate interference between emitted pulses from the radio frequency motion sensors.

Abstract: To provide a radar device capable of improving azimuth estimation accuracy by compensating the Doppler phase shift of a moving target in a TDMA FMCW MIMO radar device. Provided is a radar device that allows transmitting antennas to perform transmission by performing sequential switching such that antenna element numbers are anterior-posterior symmetrical centering on a reference time and synthesizes a beat signal at the reference time from a first beat signal received by a receiving antenna before the reference time and a second beat signal received after the reference time.

Abstract: A phased-array Doppler radar includes a two-way splitter, a transmit antenna, a receive antenna array, an ILO, a demodulation unit and a digital signal processing unit. A reference signal is split by the two-way splitter to the transmit antenna for transmission to targets and the ILO for injection locking. Signals reflected by the targets are received by the receive antenna array as received signals. An injection-locked signal generated by the ILO and the received signals received by the receive antenna array are delivered to the demodulation unit. The received signals are demodulated into baseband I/Q signals by the demodulation unit that uses the injection-locked signal as a local oscillator signal. The baseband I/Q signals are processed by the digital signal processing unit to obtain a digital beamforming pattern.

Abstract: A probe is described. The probe includes a probe antenna, a transmitter, a receiver and circuitry including hardware. The probe antenna is constructed of a dielectric material connected to a waveguide, the probe antenna has a far field region. The transmitter is coupled to the probe antenna. The receiver is coupled to the probe antenna. The hardware is configured to communicate with the transmitter to enable the transmitter to direct a pulse of electromagnetic energy to the probe antenna and to receive a reflection signal from the receiver, the hardware is configured to determine a material property of a material within the far-field region of the probe antenna by analyzing the reflection signal.

Abstract: Disclosed active reflector apparatus and methods that inhibit self-induced oscillation. One illustrative apparatus embodiment includes an amplifier and an adjustable phase shifter. The amplifier amplifies a receive signal to generate a transmit signal, the transmit signal causing interference with the receive signal. The adjustable phase shifter modifies the phase of the transmit signal relative to that of the receive signal to inhibit oscillation. A controller may periodically test a range of settings for the adjustable phase shifter to identify undesirable phase shifts prone to self-induced oscillation, and may maintain the phase shift setting at a value that inhibits oscillation.

Abstract: Methods for determining calibration parameters to correct for frequency responses of one or more dielectric waveguides coupling a control unit to a first antenna node or to a series of antenna nodes that includes the first antenna node. An example method comprises transmitting, via a first dielectric waveguide coupling the control unit to the first antenna node, a radiofrequency (RF) test signal having a signal bandwidth covering a bandwidth of interest. The method further comprises receiving, via a second dielectric waveguide coupling the control unit to the first antenna node, a looped-back version of the transmitted RF test signal, and estimating a first one-way frequency response corresponding to the first (or second) dielectric waveguide, based on the RF test signal and the received loop-back version of the transmitted RF test signal.

Abstract: An apparatus for ascertaining a distance to an object has a light source unit for emitting an optical signal with a time-varying frequency, an evaluation device for ascertaining a distance to the object based on (a) a measurement signal that arose from the signal and was reflected at the object and (b) a reference signal that was not reflected at the object. The apparatus has also a dispersive element disposed in the signal path of the optical signal and an optical position sensor disposed downstream of this dispersive element in the signal path.

Abstract: A method for operating a radar sensor system including multiple radar sensors operating independently of one another in a motor vehicle, wherein the radar sensors are synchronized with one another with respect to their transmission times and transmission frequencies in such a way that two radar signals whose frequency separation is smaller than a certain minimum frequency separation are at no point in time transmitted simultaneously.

Abstract: The apparatus (e.g., a first radar device) may be configured to receive a second radar waveform from a second radar device; determine a transmission timing difference between a transmission time of a first radar waveform and a transmission time of the second radar waveform, where the first radar waveform may be transmitted by the first radar device; and generate a radar point cloud associated with one or more targets based on the received second radar waveform and the determined transmission timing difference. A second radar device may be configured to transmit a second radar waveform; receive, from one or more targets, one or more reflections of the second radar waveform; and transmit, to a first radar device, cooperative radar sensing information regarding the received one or more reflections.

Abstract: A MIMO radar system.

Abstract: Disclosed are an apparatus and a method for controlling a radar. More specifically, disclosed is a method of setting detection modes of a radar mounted to a vehicle and controlling radar transmission signals according to the detection modes. An embodiment provides an apparatus for controlling a radar including: a target detector configured to detect targets around a vehicle and classify the detected targets; a transmission pattern setter configured to set a transmission pattern of transmission signals, based on at least one piece of detection distance information of the detected targets, detection location information, detection height information, and information on a number of detected targets; and a transmission signal controller configured to select at least one array antenna from a plurality of array antennas according to the transmission pattern and radiate the transmission signals through the selected array antenna, a method thereof, and a system.

Abstract: A radar method is described. According to one exemplary embodiment, the method includes generating a first RF oscillator signal in a first chip and supplying the first RF oscillator signal to a transmission (TX) channel of the first chip and transmitting the first RF oscillator signal from the TX channel of the first chip to the second chip via a transmission line.

Abstract: An apparatus including a transmitter including a pulsed Radio Frequency (RF) source coupled to an antenna. A receiver includes an amplifier coupled to the antenna. A controller is configured to adjust one or more durations of a ranging cycle of the apparatus, wherein the ranging cycle includes a first duration of a gated mode and a second duration of a non-gated mode. The gated mode blinds the amplifier during a transmission of the transmitter. The non-gated mode reduces a gain of the amplifier during the transmission.

Abstract: Systems, methods, and apparatus for radar waveforms using orthogonal sequence sets are disclosed. In one or more examples, a vehicle for autonomous driving comprises a radar sensor. In some examples, the radar sensor comprises a waveform transmission module adapted to generate a phase-coded waveform based on a set of concatenated orthogonal sequences. Also, in some examples, the radar sensor comprises a receiver adapted to estimate a range and Doppler from a received echo from the phase-coded waveform. In one or more examples, the orthogonal sequences are Zadoff-Chu (ZC) sequences.

Abstract: Lidar and method for generating repeatable PPM waveforms to determine a range to a target include: a processor for a) creating a modulation pool, based on a maximum nominal PRF and a specified final PPM code length of N; b) obtaining a seed code; c) eliminating bad modulation levels from the modulation pool to generate a good modulation pool, d) selecting a modulation level from the good modulation pool; e) concatenating the selected modulation level to the seed code to generate an i-element modulation sequence; f) repeating steps c to e N times to generate an N-element modulation sequence; g) selecting a PRF less than the maximum nominal PRF; and h) generating a repeatable PPM waveform by applying the N-element modulation sequence to the selected PRF.

Abstract: A method for checking the plausibility of an initially known transverse movement of an object. The method includes: emission of a radar signal having constant signal frequency, and reception by a radar device of reflections of the radar signal having constant signal frequency; and checking the plausibility of the transverse movement of the object by analyzing frequency ranges corresponding to the transverse movement in a spectrum of the reflected radar signal having constant signal frequency.

Abstract: A method is described below which can be used in a radar system. According to one example implementation, the method comprises providing a digital baseband signal using a radar receiver. The baseband signal comprises a plurality of segments, wherein each segment is assigned to a chirp of an emitted chirp sequence and each segment comprises a specific number of samples.

Abstract: Low noise amplifiers (LNAs) with low noise figure are provided. In certain embodiments, an LNA includes a single-ended LNA stage including an input for receiving a single-ended input signal from an antenna and an output for providing a single-ended amplified signal, a balun for converting the single-ended amplified signal to a differential signal, and a variable gain differential amplification stage for amplifying the differential signal from the balun. Implementing the LNA in this manner provides low noise figure, high gain, flexibility in controlling gain, and less sensitivity to ground/supply impedance.

Abstract: Radio frequency motion sensors may be configured for operation in a common vicinity so as to reduce interference. In some versions, interference may be reduced by timing and/or frequency synchronization. In some versions, a master radio frequency motion sensor may transmit a first radio frequency (RF) signal. A slave radio frequency motion sensor may determine a second radio frequency signal which minimizes interference with the first RF frequency. In some versions, interference may be reduced with additional transmission adjustments such as pulse width reduction or frequency and/or timing dithering differences. In some versions, apparatus may be configured with multiple sensors in a configuration to emit the radio frequency signals in different directions to mitigate interference between emitted pulses from the radio frequency motion sensors.

Abstract: A radar system includes a transmitter including a power amplifier (PA) for amplifying a local oscillator (LO) signal, to generate an amplified signal. The radar system also includes a receiver including an IQ generator for generating an I signal based on the LO signal and for generating a Q signal based on the LO signal and a low noise amplifier (LNA) for amplifying a looped back signal, to generate a receiver signal. The receiver also includes a first mixer for mixing the receiver signal and the I signal, to generate a baseband I signal and a second mixer for mixing the receiver signal and the Q signal, to generate a baseband Q signal. Additionally, the radar system includes a waveguide loopback for guiding the amplified signal from the transmitter to the receiver as the looped back signal.

Abstract: In one embodiment, a LIDAR device of an autonomous driving vehicle (ADV) includes a light emitter to emit a light beam towards a target, wherein at least a portion of the light beam is reflected from the target. The LIDAR device further includes an optical sensing unit including a first photodetector and a second photodetector. The first photodetector is a different type of photodetector from the second photodetector, where the optical sensing unit is to receive the portion of the light beam reflected from the target. When the optical sensing unit receives the portion of the light beam, the first photodetector generates a first optical sensor output signal and the second photodetector generates a second optical sensor output signal. The LIDAR device further includes a first circuitry portion to generate an intensity signal indicative of an intensity of the received portion of the light beam responsive to the first optical sensor output signal.

Abstract: The invention relates to a filter unit for filtering multiple pulse signals comprising a number of filter circuits, which are connected in parallel. Each filter circuit comprises an input and an output, wherein the input is configured to receive an amplitude of an input signal and the output is configured to activate an output signal. Each filter circuit has an allocated filter level and further comprises a pulse level detection circuit configured to detect a change of state of a pulse level of the input signal. The change of state comprises a transition from a first pulse level to a second pulse level and if the pulse level corresponds to the allocated filter level of the filter circuit the output of said filter circuit is activated.

Abstract: Systems, apparatus, articles of manufacture, and methods to reduce a scan for identifying physical objects are disclosed. An example system includes a light source to broadcast a light signal, a window adjuster to set a scan parameter for the light signal, and a transceiver to receive communication indicative of a physical position of a mobile unit. In the example system, the window adjuster is to adjust the scan parameter based on the physical position.

Abstract: In some examples, a radar system includes first direct digital synthesizer (DDS) circuitry and first phase-locked loop (PLL) circuitry configured to generate a first sinusoidal signal based on a first DDS signal generated by the first DDS circuitry. In some examples, the radar system further includes transmitter circuitry configured to generate a radar signal based on the first sinusoidal signal. In some examples, the radar system also includes one or more antennas configured to transmit the radar signal and receive a return signal based on the radar signal. In some examples, the radar system includes second DDS circuitry, second PLL circuitry configured to generate a second sinusoidal signal based on a second DDS signal generated by the second DDS circuitry, and receiver circuitry configured to process the return signal based on the second sinusoidal signal.

Abstract: A radar sensing system for a vehicle includes a transmitter configured for installation and use on a vehicle and able to transmit radio signals. The radar sensing system also includes a receiver and a processor. The receiver is configured for installation and use on the vehicle and is able to receive radio signals that include transmitted radio signals reflected from objects in the environment. The processor samples the received radio signals to produce a sampled stream. The processor processes the sampled stream such that the sampled stream is correlated with various delayed versions of a baseband signal. The correlations are used to determine an improved range, velocity, and angle of targets in the environment.

Abstract: A controller for a FMCW radar system configured to: provide for emission by the FMCW radar system of a plurality of consecutive frequency modulated detection signals for detection and ranging, each of the frequency modulated detection signals varying between an initial frequency and a final frequency over a period of time extending from a start time to an end time; wherein at least one of said consecutive frequency modulated detection signals is provided with an offset to one or more of; the start time of the detection signal relative to a predetermined start time schedule; the end time of the detection signal relative to a predetermined end time schedule; the initial frequency of the detection signal relative to a predetermined initial frequency schedule; and the final frequency of the detection signal relative to a predetermined final frequency schedule; the offset based on a random value.

Abstract: Provided is a distance measuring device and a method of measuring a distance. The distance measuring device detects light reflected by an object, generates an electrical signal based on the detected light, detects whether the electrical signal is saturated or not by comparing the electrical signal with a reference value, controls a magnitude of the electrical signal based on whether the signal is saturated, and calculates a distance to the object using the electrical signal.

Abstract: Space-time-frequency multiplexing (STFM) schemes for radio frequency (RF) scanning are disclosed in which complementary pairs of sequences (or “Golay pairs”) are transmitted at different times using multiple frequencies. The transmission and reception of the sequences can occur over multiple transmit (Tx) and/or receive (Rx) radio sectors to scan an entire area for range, azimuth, elevation, and (optionally) velocity of objects therein.

Abstract: A method for processing echo pulses of an active 3D sensor to provide distance measurements of surroundings in front of the active 3D sensor includes defining a near range distance from the active 3D sensor and defining a last echo distance from the active 3D sensor greater than said defined near range distance. The method includes receiving a sequence of echo pulses of a signal emitted by the active 3D sensor and subjecting the sequence of echo pulses to a pre-defined trigger condition such that only those echo pulses are taken into consideration which fulfill the predefined trigger condition. The method also includes determining, from the echo pulses which fulfill the predefined trigger condition and that are received from distances greater than a defined near range distance, a first echo pulse and an adaptive echo pulse, and providing distance measurements of the surroundings in front of the 3D sensor using the determined first echo pulse and the determined adaptive echo pulse.

Abstract: A pulse running time filling level sensor includes a sampling device for sampling an IF signal at discrete instants and for converting the sampling values into digital sampling values, and a digital signal processing device for subsequent processing of the digital sampling values by calculating at least one new value characterizing the IF curve from respectively exactly two digital sampling values.

Abstract: One embodiment of the invention includes moving target indication (MTI) system. The system includes an MTI data processor configured to receive time-sampled location indicators associated with an approximate location of a moving target in a geographic scene of interest and to generate a moving target indicator associated with the moving target based on the time-sampled location indicators. The system also includes an image integrator configured to receive the moving target indicator associated with the moving target, to receive geography data associated with the geographic scene of interest, and to integrate the moving target indicator into the geography data as a three-dimensional moving target indicator at an approximate geographic location of the moving target.

Abstract: Embodiments for securely determining a separation distance between wireless communication devices is provided. These embodiments include receiving a measurement request and a first random identifier from a first wireless communication device at a second wireless communication device. The embodiments also includes deriving a transient key using the first random identifier, a second random identifier (generated by the second device), and a pre-shared key. The first and second random identifiers, the pre-shared key, and the transient key derived therefrom are shared between the first and second devices, but are not known to any other devices. The embodiments further include encrypting measurement data exchanged between the two devices using the transient key, and using the encrypted measurement data to calculate and verify a separation distance between the devices.