The a system for measuring distance between an RFID reader and tag, including an adaptive linear combiner, which is a tapped delay line with controllable weights on each tap, and outputs that are summed and subtracted from a reference to produce an error signal. After a sufficient number of cycles, the weight distribution indicates the delay of the received signal with respect to the reference, and by extension determines the distance between the tag and receiver.

A radar sensing system includes a transmitter and a receiver. The transmitter is configured to transmit a radio signal. The receiver is configured to receive radio signals that include the transmitted radio signal reflected from objects in the environment. The transmitter and receiver are configured to distribute the signal power over frequency so that it is separated from noise and impairments at DC and low frequencies as may be caused by some radar system components which introduce DC offsets and/or low frequency (e.g. flicker) noise.

A method (e.g., a method for measuring a separation distance to a target object) includes transmitting an electromagnetic first transmitted signal from a transmitting antenna toward a target object that is a separated from the transmitting antenna by a separation distance. The first transmitted signal includes a first transmit pattern representative of a first sequence of digital bits. The method also includes receiving a first echo of the first transmitted signal that is reflected off the target object, converting the first echo into a first digitized echo signal, and comparing a first receive pattern representative of a second sequence of digital bits to the first digitized echo signal to determine a time of flight of the first transmitted signal and the echo.

Automotive radar methods and systems for enhancing resistance to interference using a built-in self-test (BIST) module. In one illustrative embodiment, an automotive radar transceiver includes: a signal generator that generates a transmit signal; a modulator that derives a modulated signal from the transmit signal using at least one of phase and amplitude modulation; at least one receiver that mixes the transmit signal with a receive signal to produce a down-converted signal, the receive signal including the modulated signal during a built-in self-test (BIST) mode of operation; and at least one transmitter that drives a radar antenna with a selectable one of the transmit signal and the modulated signal.

A method of operating a monolithic microwave integrated circuit (MMIC) in a radar transmitter includes: sending a radio frequency (RF) signal to a power amplifier of the radar transmitter, where the power amplifier is controlled by a termination control signal, where when the termination control signal is de-asserted, the power amplifier is configured to pass the RF signal through the power amplifier for transmission by an RF antenna, where when the termination control signal is asserted, the power amplifier is configured to terminate the RF signal in the power amplifier; transmitting the RF signal by de-asserting the termination control signal; and after de-asserting the termination control signal, disabling transmission of the RF signal by: reducing a power of the RF signal; and asserting the termination control signal.

A radar system includes first, second, and third transmitter branches. The first transmitter branch transmits a first frequency-modulated continuous wave (FMCW) signal having a first set of chirps having a first phase setting such that phase values of consecutive chirps differ by a first phase difference. The second transmitter branch transmits a second FMCW signal having a second set of chirps having a second phase setting such that phase values of consecutive chirps differ by a second phase difference. The third transmitter branch transmits a third FMCW signal having a third set of chirps having a third phase setting such that phase values of consecutive chirps differ by a third phase difference. The first phase difference, the second phase difference, and the third phase difference are different phase differences. The first phase difference, the second phase difference, and the third phase difference are asymmetrically distributed relative to each other.

A radar system for a vehicle includes a transmitter and a receiver. The transmitter transmits an amplified and frequency modulated radio signal. Each transmitter comprises a frequency generator, a code generator, a modulator, a constant-envelope power amplifier, and an antenna. The frequency generator generates the radio signal with a desired center frequency. The code generator generates a sequence of chips at a selected chiprate. A modulation interval between successive chips is a reciprocal of the chiprate. The modulator frequency modulates the radio signal using shaped frequency pulses. The shaped frequency pulses correspond to a first signal, the frequency of which deviates from the desired center frequency during each of the modulation intervals according to a selected pulse shape. The selected pulse shape is determined by the generated sequence of chips. The constant-envelope power amplifier amplifies the frequency modulated radio signal at a desired transmit power level. The antenna transmits the radio signal.

A radar sensing system for a vehicle includes a transmitter, a receiver, and an interference mitigation processor. The transmitter transmits radio signals. The receiver receives radio signals. The received radio signals include reflected radio signals that are each transmitted radio signals reflected from objects in the environment. The receiver also down-converts and digitizes the received radio signals to produce a baseband sampled stream. The interference mitigation processor produces a second received radio signal that includes reflected radio signals that are transmitted radio signals reflected from a first object. The interference mitigation processor uses the second received radio signal to remove selected samples from the baseband sampled stream that are attributed to radio signals reflected from the first object to produce a modified baseband sampled stream. The receiver uses the modified baseband sampled stream to detect a second object more distant than the first object.

A shared radar and communication system for a vehicle includes capabilities for radar detection and communication with vehicles equipped with similar systems. The radar system is equipped with pluralities of transmit antennas and pluralities of receive antennas. The radar transmits a signal modulated with spread codes that are information bits. A receiver discriminates the signals sent from own transmitters and multiple reflections to detect objects of interest. In addition, the receiver discriminates signals transmitted from different systems on other vehicles. This requires the receiving system to have knowledge of the codes transmitted by the other vehicle. The receiving system determines the information bits sent by the other vehicle. If multiple radar systems on multiple vehicles use different sets of codes (but known to each other), the multiple systems can create a communication infra-structure in addition to radar detection and imaging.

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 able to receive radio signals. The received radio signals include transmitted radio signals that are reflected from objects in the environment. The received radio signals further include radio signals transmitted by at least one other radar system. The processor samples the received radio signals to produce a sampled stream. The processor is configured to control an adaptive filter. Responsive to the processor, the adaptive filter is configured to filter the sampled stream, such that the radio signals transmitted by the at least one other radar system are removed from the received radio signals.