US 2026/0110796 A1Published application

Satellite tomography of precipitation and motion via synthetic aperture radar

AssigneeBAE Systems Information and Electronic Systems Integration Inc.

InventorsMartin F. Ryba, Kevin R. Maschhoff

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Abstract

A precipitation scanning aperture RADAR system comprises at least one transmitting satellite (TX) and a plurality of receiving satellites (RXs) flying in a multi-static formation. The TX emits fixed frequency, pseudo-random, non-repeating phase modulated RADAR energy. Range and Doppler information is extracted from reflected signals received by the RXs to form coherent 2D along track/vertical images, which are combined into a 3D reflectivity map using a power-based incoherent modeling algorithm, such as a Gaussian mixture model. Embodiments implement a spotlight mode in which, for each RX, a plurality of the coherent 2D images obtained during successive coherent processing intervals (CPIs) are incoherently combined, and the satellites adjust their orientations between each CPI to compensate for satellite movement. Inter-satellite timing synchronization of 10 ns or better is sufficient for forming the 3D reflectivity map. The range and Doppler information can be extracted by concurrently demodulating at a plurality of reference frequencies.

Claims20

Dependent claims

A system for determining a three-dimensional (3D) reflectivity map of a precipitation field in a region of interest (ROI), the system comprising:

a plurality of platforms configured to fly in a multi-static formation at an altitude that is higher than an altitude of the precipitation field, the plurality of platforms comprising a first transmitting platform, and first and second receiving platforms, the first transmitting platform being configured to participate in a first bi-static pair with the first receiving platform, and to participate in a second bi-static pair with the second receiving platform;
and
a processor group comprising at least one processor;
wherein:
the first transmitting platform is configured, while flying in the multi- static configuration, to transmit a phase-encoded RADAR waveform at a constant transmission frequency toward the ROI, the constant frequency, phase-encoded waveform being reflected by the precipitation field, thereby creating first and second reflected signals;
the first receiving platform is configured to receive the first reflected signal during a first coherent processing interval (CPI), and the second receiving platform is configured to receive the second reflected signal during the first coherent processing interval (CPI);
the processor group is configured to form a first two-dimensional (2D) vertical and along-track scanning aperture radar (SAR) image of the precipitation field according to range and Doppler information extracted from the first reflected signal;
the processor group is configured to form a second 2D vertical and along-track SAR image of the precipitation field according to range and Doppler information extracted from the second reflected signal;
and
the processor group is configured to determine a 3D reflectivity map of the precipitation field according to the first and second 2D vertical and along-track SAR images.

7 more elements

A computer program product including one or more non-transitory machine-readable mediums encoded with instructions that when executed by one or more processors cause a process to be carried out for satellite tomography of a precipitation field via a synthetic aperture radar, the process comprising:

transmitting by a transmitting platform, while flying in a multi-static configuration, a phase-encoded RADAR waveform at a constant transmission frequency toward a region of interest (ROI), the constant frequency, phase-encoded waveform being reflected by the precipitation field, thereby creating first and second reflected signals;
receiving by a first receiving platform during a first coherent processing interval (CPI), while flying in the multi-static configuration, the first reflected signal, and receiving by a second receiving platform during the first coherent processing interval (CPI), while flying in the multi-static configuration, the second reflected signal;
forming a first two-dimensional (2D) vertical and along-track scanning aperture radar (SAR) image of the precipitation field according to range and Doppler information extracted from the first reflected signal;
forming a second two-dimensional (2D) vertical and along-track range/Doppler SAR image of the precipitation field according to range and Doppler information extracted from the second reflected signal;
and
determining a 3D reflectivity map of the precipitation field according to the first and second 2D vertical and along-track SAR images.

3 more elements

Dependencies are inferred from the claim text.