Dale F Dubbert

6836240, Dec 28, 2004

May 13, 2003

10/437329

Dale F. Dubbert - Cedar Crest NM
Peter A. Dudley - Albuquerque NM
Armin W. Doerry - Albuquerque NM
Bertice L. Tise - Albuquerque NM

Sandia Corporation - Albuquerque MN

G01S 735

342194, 342 25, 342195

Frequency dependent corrections are provided for Local Oscillator (LO) feed-through. An operational procedure filters LO feed-through effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SARs QDWS signal where it is demodulated in a receiver, unwanted energies, such as LO feed-through energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of LO feed-through can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

6864827, Mar 8, 2005

Oct 15, 2003

10/686379

Bertice L. Tise - Albuquerque NM, US
Dale F. Dubbert - Cedar Crest NM, US

Sandia Corporation - Albuquerque NM

G01S013/90

342 25A, 342 25 D, 342 25 F, 342194, 342195

A digital IF receiver (DRX) module directly compatible with advanced radar systems such as synthetic aperture radar (SAR) systems. The DRX can combine a 1 G-Sample/sec 8-bit ADC with high-speed digital signal processor, such as high gate-count FPGA technology or ASICs to realize a wideband IF receiver. DSP operations implemented in the DRX can include quadrature demodulation and multi-rate, variable-bandwidth IF filtering. Pulse-to-pulse (Doppler domain) filtering can also be implemented in the form of a presummer (accumulator) and an azimuth prefilter. An out of band noise source can be employed to provide a dither signal to the ADC, and later be removed by digital signal processing. Both the range and Doppler domain filtering operations can be implemented using a unique pane architecture which allows on-the-fly selection of the filter decimation factor, and hence, the filter bandwidth. The DRX module can include a standard VME-64 interface for control, status, and programming. An interface can provide phase history data to the real-time image formation processors.

7259716, Aug 21, 2007

Oct 15, 2003

10/686168

Dale F. Dubbert - Cedar Crest NM, US
Peter A. Dudley - Albuquerque NM, US

Sandia Corporation - Albuquerque NM

G01S 7/35
H04H 1/40

342194, 342 25 F, 342131, 342165, 455 76, 455 6711, 4551151

A Quadrature Error Corrected Digital Waveform Synthesizer (QECDWS) employs frequency dependent phase error corrections to, in effect, pre-distort the phase characteristic of the chirp to compensate for the frequency dependent phase nonlinearity of the RF and microwave subsystem. In addition, the QECDWS can employ frequency dependent correction vectors to the quadrature amplitude and phase of the synthesized output. The quadrature corrections cancel the radars' quadrature upconverter (mixer) errors to null the unwanted spectral image. A result is the direct generation of an RF waveform, which has a theoretical chirp bandwidth equal to the QECDWS clock frequency (1 to 1. 2 GHz) with the high Spurious Free Dynamic Range (SFDR) necessary for high dynamic range radar systems such as SAR. To correct for the problematic upconverter local oscillator (LO) leakage, precision DC offsets can be applied over the chirped pulse using a pseudo-random noise dither. The present dither technique can effectively produce a quadrature DC bias which has the precision required to adequately suppress the LO leakage.

8400349, Mar 19, 2013

Jul 27, 2010

12/844576

Dale F. Dubbert - Cedar Crest NM, US
Bertice L. Tise - Albuquerque NM, US

Sandia Corporation - Albuquerque NM

G01S 13/58

342113, 342128, 342129

The spurious-free dynamic range of a wideband radar system is increased by apportioning de-ramp processing across analog and digital processing domains. A chirp rate offset is applied between the received waveform and the reference waveform that is used for downconversion to the intermediate frequency (IF) range. The chirp rate offset results in a residual chirp in the IF signal prior to digitization. After digitization, the residual IF chirp is removed with digital signal processing.

6825800, Nov 30, 2004

May 13, 2003

10/436728

Peter A. Dudley - Albuquerque NM
Armin W. Doerry - Albuquerque NM
Dale F. Dubbert - Cedar Crest NM
Bertice L. Tise - Albuquerque NM

Sandia Corporation - Albuquerque NM

G01S 735

342195, 342 25, 342194

Frequency dependent corrections are provided for quadrature imbalance. An operational procedure filters imbalance effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SARs QDWS signal where it is demodulated in a receiver; unwanted energies, such as imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of quadrature imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.