Recent Patents in Signal Processing (October 2016) – Radar imaging

For our October 2016 issue, we cover recent patents dealing with radar imaging. The section below covers patents granted recently for radar signal visualization, synthetic radar imaging, compressive imaging techniques, object detection and fusion, and radar based navigation.

The disclosure presented in Patent no 9,354,307 provides an ultra-wideband radar imaging system comprising an antenna with at least one receiver and a plurality of transmitters operating in multi-static mode, method of operating thereof and volume visualization unit to be used in conjunction with the multi-static ultra-wideband radar imaging system. The method comprises: receiving by said at least one receiver a plurality of signals, each respectively representing return data in a channel associated with the receiver and one of the transmitters among said plurality of transmitters, thus giving rise to a plurality of spatial data channels; among said plurality of spatial data channels selecting data channels for further processing; and providing volume visualization by processing data corresponding merely to the selected spatial data channels.

In patent no. 9,335,410 a spotlight synthetic aperture radar (SAR) image is generated by directing randomly a beam of transmitted pulses at a set of two or more areas using a steerable array of antennas. Each area is illuminated by an approximately equal number of the transmitted pulses. Then, a reconstruction procedure is applied independently to received signals from each area due to reflecting the transmitted pulses to generate the image corresponding to the set of areas.

In patent no. 9,335,409 a bistatic synthetic aperture radar (SAR) imaging system and method include: combining each radar return pulse from airborne radar platforms with a sinusoid; deskewing each reduced radar return pulse; estimating motion parameters based on a maximum likelihood estimation (MLE); performing MLE motion correction to generate motion-corrected radar return pulses; acquiring position and velocity estimates of the airborne radar platforms and scattering locations; defining bistatic range and velocity vectors; defining new bistatic range and velocity vectors in a new set of orthogonal axes; projecting vector distance differences between the radar scattering locations along the new set of orthogonal axes to generate new range and velocity measurements along the new set of orthogonal axes; converting the new range and velocity measurements to map Doppler frequency into cross-range; and forming a bistatic SAR image in range and cross-range based on cross-range extent derived from the Doppler frequency mapping.

As described in patent no.  9,322,908, a concealed radar imaging system includes a visible light mirror, a radar device positioned behind the visible light mirror, and a processing circuit coupled to the radar device. The visible light mirror includes a reflective layer configured to reflect visible light, and allow a radar signal to pass therethrough. The radar device is configured to transmit the radar signal, receive a reflection of the radar signal, and generate reflection data based on the reflected radar signal. The processing circuit is configured to control operation of the radar device, receive the reflection data from the radar device, and generate imaging data based on the transmitted radar signal and the reflection data.

A method, apparatus and computer-readable medium is provided in patent no. 9,291,711, that can utilize an undersampling method and can produce a radar image of a target. The radar image of the target can be based on a collection of waveform measurements, where the collection can be based on a significantly reduced number of transmitted and received electromagnetic pulse waveforms.

A method of detecting and tracking objects using multiple radar sensors is presented in the invention no. 9,255,988. Objects relative to a host vehicle are detected from radar data generated by a sensing device. The radar data includes Doppler measurement data. Clusters are formed, by a processor, as a function of the radar data. Each cluster represents a respective object. Each respective object is classified, by the processor, as stationary or non-stationary based on the Doppler measurement data of each object and a vehicle speed of the host vehicle. Target tracking is applied, by the processor, on an object using Doppler measurement data over time in response to the object classified as a non-stationary object; otherwise, updating an occupancy grid in response to classifying the object as a stationary object.

In patent no. 9,110,170 a terrain aided navigation using multi-channel monopulse radar imaging is introduced to provide a navigation position update. The monopulse radar transmits a single RF pulse transmission or multiple quick RF pulse train bursts to generate a monopulse radar image that can be correlated with a digital terrain segment to provide navigation updates when requested. The radar has monopulse and off-axis capability that allows for selection of a terrain segment within the radar's search area that will provide a good terrain correlation. The radar measurements are made on a range/Doppler cell-by-cell basis that includes angle information. The cells in the range/Doppler map corresponding to the antenna main beam return are converted into a high resolution (x,y,z) image and correlated to the selected terrain segment in the data base reference frame to provide an updated navigation position estimate.

Patent no. 8,963,767 presents a method for detecting the motion of object by ultra-wideband radar imaging and system thereof to be used to present the motion of object in a reference gray-level image by using the delay time to analyze the distance between the detected position of object and the detecting position to compare the time-varying distance variation between the reference distance and the detecting distance. The system includes a transmitter module, a receiver module and a signal processing module. The transmitter module is used to transmit a first ultra-wideband signal from a detecting position to the object. The receiver module is used to receive a second ultra-wideband signal reflected from the object in the detecting position. The signal processing module is used to analyze the signal delay time of the second ultra-wideband signal received in the detecting position to analyze the detecting distance between the second ultra-wideband signal and the detecting position.

If you have an interesting patent to share when we next feature patents related to radar imaging, or if you are especially interested in a signal processing research field that you would want to be highlighted in this section, please send email to Csaba Benedek (benedek.csaba AT sztaki DOT mta DOT hu).

References

Number: 9,354,307
Title:  System and method for volume visualization in ultra-wideband radar imaging system
Inventors: Beeri; Amir (Kfar Neter, IL), Daisy; Ron (Raanana, IL)
Issued: May 31, 2016
Assignee: Camero-Tech LTD. (Kfar Neter, IL)

Number: 9,335,410
Title: System and method for multiple spotlight synthetic radar imaging using random beam steering
Inventors: Liu; Dehong (Lexington, MA), Boufounos; Petros (Boston, MA)
Issued: May 10, 2016
Assignee: Mitsubishi Electric Research Laboratories, INC. (Cambridge, MA)

Number: 9,335,409
Title:  Bistatic inverse synthetic aperture radar imaging
Inventors:  Abatzoglou; Theagenis J. (Huntington Beach, CA), Gonzalez; Johan E. (Carson, CA)
Issued: May 10, 2016
Assignee: Raytheon Company (Waltham, MA)

Number: 9,322,908
Title:  Systems and methods for concealed radar imaging
Inventors: Driscoll; Tom (San Diego, CA), Hyde; Roderick A. (Redmond, WA), Kare; Jordin T. (Seattle, WA), Smith; David R. (Durham, NC), Tegreene; Clarence T. (Mercer Island, WA), Wood, Jr.; Lowell L. (Bellevue, WA)
Issued: April 26, 2016
Assignee: Elwha LLC (Bellevue, WA)

Number: 9,291,711
Title: Compressive radar imaging technology
Inventors: Healy, Jr.; Dennis M. (Hyattsville, MD), Patel; Vishal M. (Laurel, MD), Easley; Glenn R. (Fairfax, VA), Chellappa; Ramalingam (Potomac, MD)
Issued: March 22, 2016
Assignee: University of Maryland, College Park (College Park, MD)

Number: 9,255,988
Title:  Object fusion system of multiple radar imaging sensors
Inventors: Zeng; Shuqing (Sterling Heights, MI), Salinger; Jeremy A. (Southfield, MI), Litkouhi; Bakhtiar B. (Washington, MI), O'Dea; Kevin A. (Ann Arbor, MI), Pazhayampallil; Joel (Bellerose, NY), Murad; Mohannad (Troy, MI), Nickolaou; James N. (Clarkston, MI)
Issued: February 9, 2016
Assignee: GM Global Technology Operations LLC (Detroit, MI)

Number: 9,110,170
Title:  Terrain aided navigation using multi-channel monopulse radar imaging
Inventors:  Woollard; Bruce R. (Tucson, AZ), Owens; Mark A. (Tucson, AZ)
Issued: August 18, 2015
Assignee: Raytheon Company (Waltham, MA)

Number: 8,963,767
Title:  Method for detecting the motion of object by ultra-wideband radar imaging and system thereof
Inventors:  Li; Pai-Chi (Taipei, TW), Chen; Tsung-Chuan (Taipei, TW)
Issued: February 24, 2015
Assignee: National Taiwan University (Taipei, TW)