Monostatic radar with progressive length transmission may be used with half-duplex systems or with full-duplex systems to reduce self-interference. The system transmits a first signal for a first duration and receives a first reflection of the first signal from a first object during a second duration. The system transmits a second signal for a third duration longer than the first duration and receives a second reflection of the second signal from a second object during a fourth duration. The system calculates a position of the first object and the second object based on the first reflection and the second reflection. The first signal, first duration, and second duration are configured to detect reflections from objects within a first distance of the system. The second signal, third duration, and fourth duration are configured to detect reflections from objects between the first distance and a second distance from the system.

This document describes techniques and systems for asymmetrical frequency-division multiplexing (FDM) for radar systems. In some examples, a radar system includes multiple transmitters, multiple receivers, multiple polyphase shifters, and a processor. The transmitters can transmit electromagnetic (EM) signals in an FDM scheme. The receivers can receive EM signals reflected by one or more objects that include multiple channels. The polyphase shifters can introduce at least four potential phase shifts. The processor can control the polyphase shifters to introduce phase shifts asymmetrically spaced in a frequency spectrum. The processor can determine, using residue estimation and subtraction, potential detections of the objects. In this way, the described asymmetrical FDM for radar systems can support many simultaneous MIMO channels, increase the dynamic range of the radar system, resolve Doppler ambiguities, and provide an efficient processing scheme.

A radar transmitter transmits a radar signal through a transmitting array antenna at a predetermined transmission period, and a radar receiver receives a reflected wave signal which is the radar signal reflected by a target through a receiving array antenna. A transmitting array antenna and a receiving array antenna each include multiple subarray elements, the subarray elements in the transmitting array antenna and the receiving array antenna are linearly arranged in a first direction, each subarray element includes multiple antenna elements, the subarray element has a dimension larger than a predetermined antenna element spacing in the first direction, and an absolute value of a difference between a subarray element spacing of the transmitting array antenna and a subarray element spacing of the receiving array antenna is equal to the predetermined antenna element spacing.

A radar return channel is estimated at a radar receiver by processing an existing channel estimate along with a radar return signal for an ideal transmission, to produce an updated estimate. Updating can be carried out based on a determination that the existing estimate has become degraded. Embodiments include using a least squares deconvolution to update polynomials describing a transfer function of the channel estimate.

A radar return channel is estimated at a radar receiver by processing an existing channel estimate along with a radar return signal for an ideal transmission, to produce an updated estimate. Updating can be carried out based on a determination that the existing estimate has become degraded. Embodiments include using a least squares deconvolution to update polynomials describing a transfer function of the channel estimate.

A radar sensor system transmits a radar signal that comprises first pulses in a first frequency band and second pulses in a second frequency band. The radar sensor system receives a return of the radar signal from a target, wherein the return comprises the first pulses and the second pulses. The radar sensor system concatenates the first pulses and the second pulses, and computes an estimated range to a target based upon a Fourier transform of the concatenated first and second pulses. A range resolution of the estimated range is based upon a bandwidth of a third frequency band that includes the first frequency band and the second frequency band.

A stepped frequency radar system is disclosed. The system includes components for performing stepped frequency scanning across a frequency range using frequency steps of a step size, the stepped frequency scanning performed using at least one transmit antenna and a two-dimensional array of receive antennas, changing at least one of the step size and the frequency range, and performing stepped frequency scanning using the at least one transmit antenna and the two-dimensional array of receive antennas and using the changed at least one of the step size and the frequency range.

A stepped frequency radar system is disclosed. The system includes components for performing stepped frequency scanning across a frequency range using frequency steps of a step size, the stepped frequency scanning performed using at least one transmit antenna and a two-dimensional array of receive antennas, changing at least one of the step size and the frequency range, and performing stepped frequency scanning using the at least one transmit antenna and the two-dimensional array of receive antennas and using the changed at least one of the step size and the frequency range.

A patient monitoring device includes a signal transmission device configured to direct a signal transmission toward a target area and to receive reflected signals from the target area, and a signal analysis device having a processing device and at least one non-transitory computer readable data storage device storing instructions, that when executed by the processing device, cause the patient monitoring device to transmit signals, receive reflected signals, and determine a non-contact vital sign measurement based on data from the reflected signals.

The disclosure relates to a radar transceiver having a transmitter comprising a phase shifter. Example embodiments include a radar transceiver (200) having a normal mode of transmitter operation and a self-test mode of operation, the transceiver (200) comprising: a digital controller (116) configured to provide a digital control signal indicative of a phase shift; a digital to analogue converter (122) configured to receive the digital control signal and provide an analogue signal in accordance with the phase shift; a phase shifter (124) configured to receive the analogue signal and provide a phase shifted output signal for transmission; a dummy load (240) connected to receive the analogue signal from the digital to analogue converter (122) and to provide an analogue output; a resistor network (331) connected across an output of the dummy load (240); a testing module (335) configured to measure the analogue output of the dummy load (240); and a controller module (339) configured to control operation of the dummy load (240), testing module (335) and digital controller (116) during the self-test mode of operation by: enabling the dummy load (240); operating the digital controller (116) to provide a range of digital control signals to the digital to analogue converter (122); and operate the testing module (335) to measure the analogue output of the dummy load (240) to determine a measure of linearity of the digital to analogue converter (122).