Alan D Siggia

US Patent:

7589666, Sep 15, 2009

Filed:

Dec 30, 2005

Appl. No.:

11/322524

Inventors:

Alan D. Siggia - Acton MA, US

Assignee:

Vaisala, Inc. - Westford MA

International Classification:

G01S 7/486
G01S 7/493
G01S 13/95
G01S 13/00

US Classification:

342196, 342 26 R, 342 89, 342159, 342175, 342192, 342194, 342195

Abstract:

Systems and methods that adapt to the weather and clutter in a weather radar signal and apply a frequency domain approach that uses a Gaussian clutter model to remove ground clutter over a variable number of spectral components that is dependent on the assumed clutter width, signal power, Nyquist interval and number of samples. A Gaussian weather model is used to iteratively interpolate over the components that have been removed, if any, thus restoring any overlapped weather spectrum with minimal bias caused by the clutter filter. The system uses a DFT approach. In one embodiment, the process is first performed with a Hamming window and then, based on the outcome, the Hamming results are kept or a portion of the process is repeated with a different window. Thus, proper windows are utilized to minimize the negative impact of more aggressive windows.

US Patent:

7605744, Oct 20, 2009

Filed:

Jun 3, 2008

Appl. No.:

12/132366

Inventors:

Pentti Karhunen - Vantaa, FI
Sebastian Torres - Norman OK, US
Alan Siggia - Westford MA, US
Richard Passarelli - Westford MA, US

Assignee:

Vaisala OYJ - Helsinki

International Classification:

G01S 13/00
G01S 13/58
G01S 13/08

US Classification:

342 26R, 342 26 A, 342 26 B, 342 26 C, 342 26 D, 342112, 342159, 342127, 342128, 342129, 342137

Abstract:

A method for extension of unambiguous range and velocity of a weather radar. To avoid pulse overlaying, the pulse repetition time of a single pulse can be extended such that any return echo will arrive at the radar before the next pulse is transmitted. When pulse repetition time is increased, the maximum unambiguous range increases while the maximum unambiguous velocity decreases. The pulse overlaying can be avoided if consecutive pulses are sent on different frequencies that are far enough from each other to allow separation of pulses arriving simultaneously at the radar. When different frequencies are used an unknown phase difference is generated by distributed atmospheric targets to the return signals. This normally prevents use of the shorter pulse repetition time for velocity calculation.

US Patent:

20070046526, Mar 1, 2007

Filed:

Aug 25, 2006

Appl. No.:

11/510060

Inventors:

Fritz O' Hora - Pepperell MA, US
Richard Passarelli - Groton MA, US
Alan Siggia - Acton MA, US

Assignee:

Vaisala Oyj - Helsinki

International Classification:

G01S 13/95

US Classification:

34202600R, 342195000, 342159000

Abstract:

A system and method for processing data related to weather phenomena in a meteorological radar system. The method includes receiving an echo signal generated by transmitting a long pulse and employing a mismatched windowed filter on the echo signal such that the echo signal is compressed in time to achieve fine range resolution without substantially degrading sensitivity and while achieving low range time side lobes for Doppler velocities expected to be measured by the meteorological radar system.

US Patent:

20070229348, Oct 4, 2007

Filed:

Dec 20, 2006

Appl. No.:

11/643416

Inventors:

Fritz O'Hora - Pepperell MA, US
Alan Siggia - Acton MA, US

Assignee:

Vaisala, Inc. - Westford MA

International Classification:

G01S 13/00

US Classification:

34202600R, 342132000

Abstract:

A system and method for detecting meteorological phenomena by transmitting a sequence of pulses, each pulse having a long range section and a short range section. Echoes based on the sequence of pulses are received. A filter is applied to the echoes to create an ambiguity signal that allows simultaneous detection of targets for a range from range zero up to and including a maximum unambiguous range.