A radio frequency (RF) circuit includes a signal path coupled between two RF inputs and at least one baseband output terminal. The signal path includes a 90° hybrid coupler including a first port that receives a first RF signal and a second port that receives a second RF signal. The 90° hybrid coupler generates a first coupler output signal based on the first RF signal and the second RF signal and generates a second coupler output signal based on the first RF signal and the second RF signal. The signal path includes a quadrature down-converter configured to down-convert the first coupler output signal into a first baseband signal and down-convert the second coupler output signal into a second baseband signal. The RF circuit includes a baseband combiner circuit configured to combine the first baseband signal and the second baseband signal to generate at least one of output signal.

A method for operating a radar system of a motor vehicle includes receiving a reception signal, deriving the reception signal from time, ascertaining parameters of an interference signal from the derived reception signal, reconstructing the interference signal from the parameters, and eliminating the interference signal from the reception signal.

A sensor device includes a radio wave sensor and a signal processor. The signal processor includes an identifier and a noise remover configured to remove, from a second sensor signal, at least one frequency component determined as a noise component by the identifier. The identifier compares a signal intensity of each of the frequency components with one or more signal intensities of other frequency components. When a signal intensity of a first frequency component is greater than signal intensities of one or more second frequency components located in the vicinity of the first frequency component by an extent exceeding a threshold range, the identifier determines the first frequency component as the noise component.

To track an object with radar, and achieve greater than range resolution precision, the phase of a difference signal can be utilized and adjusted as the tracked object crosses between resolution ranges. Changes in the object's distance can be detected with greater than range resolution precision by utilizing the phase. Such changes can iteratively inform the determined distance across multiple phase cycles within a single distance range. As the movement of the object approaches, and then crosses, between resolution ranges, the phase as determined within an origin resolution range can be compared with a coincident phase within the destination resolution range and the difference can then be utilized to adjust the phase as the object then remains within the destination resolution range. Such phase adjustments can be applied across multiple resolution ranges, allowing for the tracking of an object, utilizing radar, while achieving greater than range resolution precision.

An object detection apparatus 1 includes: an emitting unit 101 for emitting an RF transmission signal; a receiving unit 201 for receiving, if the RF transmission signal is reflected off an object, the reflected RF transmission signal as an RF reception signal; an IF signal generating unit 202 for generating, in every period, a complex IF signal based on a signal obtained by mixing the RF transmission signal with the RF reception signal; a position detecting unit 203 for detecting the position of the object based on an evaluation function generated based on the complex IF signal generated in every period; and a displacement detecting unit 204 for detecting a displacement of the object based on the position of the object and the phase of complex reflectance of the object calculated based on the complex IF signal.

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 patient immersion sensor includes a radio detection and ranging (RADAR) apparatus to determine a time of flight (TOF) of a RADAR pulse and a reflected signal that is reflected by a patient or by a portion of a patient support surface supporting the patient. The TOF is indicative of an immersion depth or a distance toward bottoming out of a patient supported on the patient support surface, such as a mattress or a pad. The RADAR apparatus emits pulses of very short duration so as to be able to detect objects, such as a patient or a portion of a mattress or pad, at very close distances. The RADAR apparatus may use time-of-flight (TOF) between transmission of the pulse and receipt of a reflected signal to determine a distance toward bottoming out by the patient, thereby to determine if the patient is properly immersed into the patient support surface. Adjustments to inflation or deflation of one or more bladders are made to achieve a desired immersion amount within a tolerance range between upper and lower TOF thresholds.

A digital FMCW radar is described that simultaneously transmits and receives digitally frequency modulated signals using multiple transmitters and multiple receivers and associated antennas. Several sources of nearby spillover from transmitters to receivers that would otherwise degrade receiver performance are subtracted by a cancellation system in the analog radio frequency domain that adaptively synthesizes an analog subtraction signal based on residual spillover measured by a correlator operating in the receivers' digital signal processing domains and based on knowledge of the transmitted waveforms. The first adaptive cancellation system achieves a sufficient reduction of transmit-receive spillover to avoid receiver saturation or other non-linear effects, but is then added back in to the signal path in the digital domain after analog-to-digital conversion so that spillover cancellation can also operate in the digital signal processing domain to remove deleterious spillover components.

Devices and methods are provided for determining frequency spectra, as well as the polarity of frequency, of energy in quadrature signals. In Doppler detection systems, found in sonar, radar, lidar, optical velocimeters using interferometers, and ultrasonics applications, for example, this information can be used to determine target speed and direction. Embodiments obtain a quadrature signal and determine a sine transform of a cross correlation between the I and Q components of the quadrature signal, and can provide an output comprising a signed frequency spectrum. A sign of a sample of the signed frequency spectrum can correspond to a polarity of frequency. The signed frequency spectrum can be rapidly determined over a unipolar frequency span that may be only approximately half the baseband sampling frequency. The signed frequency spectrum may be impervious to imaging under severe conditions of uncorrected quadrature amplitude imbalance.

A FMCW radar receiver includes a LO providing a chirped LO signal, an in-phase (I) channel for outputting I-data and a quadrature (Q) channel for outputting Q-data. A dynamic correction parameter generator generates IQ phase correction values (P[n]s) and IQ gain correction values (G[n]s) based on a frequency slope rate of the chirped LO signal for generating during intervals of chirps including a first sequence of P[n]s and G[n]s during a first chirp and a second sequence of P[n]s and G[n]s during a second chirp. An IQ mismatch (IQMM) correction circuit has a first IQMM input coupled to receive the I-data and a second IQMM input receiving the Q-data, and the P[n]s and G[n]s. During the first chirp the IQMM correction circuit provides first Q′-data and first I′-data and during the second chirp the IQMM correction circuit provides at least second Q′-data and second I′-data.