Abstract:
A radar sensing function is performed in a mobile communication device that operates in a Time Division Duplex (TDD) wireless communication system having an air interface that comprises a plurality of uplink symbol times associated with symbols transmitted in an uplink direction and a plurality of downlink symbol times associated with symbols transmitted in a downlink direction, and in which each transmitted symbol from a plurality of transmitted symbols has a corresponding cyclic prefix that is transmitted immediately before the corresponding transmitted symbol, and that is a repetition of an end part of the corresponding transmitted symbol. Information about a path delay between the mobile communication device and a receiver is used as one of one or more bases to determine a timing of a radar operation window having a duration that is shorter than a duration of a cyclic reception window of the receiver and comprising a radar signal transmission time and a radar backscatter reception period. The determined timing of the radar operation window is configured to cause the radar signal, when transmitted from the mobile communication device at the determined radar signal transmission time, to arrive at the receiver during a portion of the cyclic prefix reception window of the receiver. The radar signal is transmitted at the determined time.
Abstract:
Certain aspects of the present disclosure provide techniques for joint communication and radar sensing. A method is provided for wireless communications by a network entity. The method generally includes communicating one or more radar signals in a first set of slots. Each of the first set of slots comprises an extended cyclic prefix have a first length. The method generally includes communicating one or more signals in a second set of slots, each of the second set of slots comprising a normal cyclic prefix having a second length that is shorter than the first length.
Abstract:
A method of measuring the phase of a response signal relative to a periodic excitation signal, comprises the steps of producing for each cycle of the response signal two transitions synchronized to a clock and framing a reference point of the cycle; swapping the two transitions to confront them in turns to the cycles of the response signal; measuring the offsets of the confronted transitions relative to the respective reference points of the cycles; performing a delta-sigma modulation of the swapping rate of the two transitions based on the successive offsets; and producing a phase measurement based on the duty cycle of the swapping rate.
Abstract:
A radar apparatus is provided. The radar apparatus includes a transmission and reception unit configured to transmit a close distance pulse signal, a medium distance pulse signal, and a far distance pulse signal in an order of the close distance pulse signal, the far distance pulse signal, the medium distance pulse signal, and then the far distance pulse signal, and receive reflection waves of the transmitted pulse signals, the far distance pulse signal having a wider pulse width than the close distance pulse signal, the medium distance pulse signal having a pulse width wider than the close distance pulse signal and narrower than the far distance pulse signal, and a signal processor configured to generate a radar image by using a first detection result and a second detection result.
Abstract:
Narrow virtual transmit pulses are synthesized by differencing long-duration, staggered pulse repetition interval (PRI) transmit pulses. PRI is staggered at an intermediate frequency IF. Echoes from virtual pulses form IF-modulated interference patterns with a reference wave. Samples of interference patterns are IF-filtered to produce high spatial resolution holographic data. PRI stagger can be very small, e.g., 1-ns, to produce a 1-ns virtual pulse from very long, staggered transmit pulses. Occupied Bandwidth (OBW) can be less than 10 MHz due to long RF pulses needed for holography, while spatial resolution can be very high, corresponding to ultra-wideband (UWB) operation, due to short virtual pulses. X-Y antenna scanning can produce range-gated surface holograms from quadrature data. Multiple range gates can produce stacked-in-range holograms. Motion and vibration can be detected by changes in interference patterns within a range-gated zone.
Abstract:
This invention relates to radar signal processing. In particular, this invention concerns Doppler processing and clutter filtering on irregular Pulse Repetition Time (PRT) sampled signal. This invention solves the above-mentioned drawbacks, in particular solving the velocity ambiguity and filtering any type of clutter, providing a deconvolution method which filter any kind of clutter even varying clutter like sea clutter, rain clutter . . . The deconvolution method of irregular pulse repetition time sampled signal x(tm), comprises the following steps: [S1] conversion of the irregular samples x(tm) to regular samples r(iT&egr;); [S2] computation of the spectrum dft(r) of these regular samples; [S3] isolation of the clutter spectra in dft(r) by assuming clutter spreads over more than a few range gates; [S4] estimation of the clutter spectral lines from the mean and the width of the isolated clutter spectra; [S5] subtraction of the estimated clutter spectra from the total spectrum dft(r); [S6] deconvolution of the remaining spectra.
Abstract:
A method, apparatus, and processing system for radar detection and tracking of a target using monopulse ratio processing comprising the following steps. First, receiving a signal comprised of a plurality of sum azimuth beams and difference azimuth beams. Then staggering the received signal. Next, filtering and localizing a clutter signal which is a portion of the received sum and azimuth beams. Then adaptively forming a sub-array sum azimuth beam and a sub-array difference azimuth beam from the filtered output to cancel the clutter. The adaptive beam forming including the determination of a sum and difference beam weight where the adaptive weight be equated to a product of the weight and the respective covariance matrices of the sum and difference beams, the product having no constraint points. Finally, forming a final sum azimuth beam and final difference beam where the first sub array is related to the sum and azimuth beams of a plurality of other sub-array sum and difference beams, an overall final sum beam is formed and is used for target detection. In addition, an overall final difference beam is formed and the ratio of the overall final difference beam to the overall final sum beam is used for angle location determination.
Abstract:
A moving target detector (MTD) in a radar system uses corrected weighting coefficients to compensate for pulse stagger effect on transmitted pulses. Transmitted pulses are sampled when the radar is switched to a test mode for determining a correction factor which is used to calculate the corrected weighting coefficients. The radar return signals are processed in the MTD by a finite impulse response (FIR) filter using the stored corrected weighting coefficients calculated for each sequence of transmitted pulses including block stagger and pulse stagger sequences.
Abstract:
A VARIABLE INTERPULSE PERIOD SEQUENCE IS USED IN A DIGITAL MTI RADAR SYSTEM WHICH FOLLOWS AN EXPONENTIALLY INCREASING AND/OR DECREASING PATTERN TO REDUCE THE NUMBER OF SETS OF WEIGHTS WHICH MUST BE STORED WITHIN THE
SYSTEM TO ACHIEVE AN OPTIMUM VELOCITY RESPONSE CHARACTERISTIC.