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- R. Neil Braithwaite
- IEEE Transactions on Microwave Theory and…
- 2015

This paper shows that digital predistortion (DPD) used to linearize an RF power amplifier (PA) can achieve wide bandwidth distortion cancellation using measurements obtained from a narrow bandwidth observation path. The DPD module creates a correction signal using a set of nonlinear basis waveforms, weighted by adjustable coefficients. The coefficients are… (More)

- R. Neil Braithwaite
- IEEE Journal on Selected Areas in Communications
- 2000

This paper investigates the effects of Walsh code selection and baseband filtering on the statistical moments of the bandlimited forward-link CDMA signal. A normalized moment, the “power variance”, is proposed as a measure of the signal’s sensitivity to nonlinear amplification. The estimation of the power variance for the case of a bandlimited… (More)

- R. Neil Braithwaite
- 2017 IEEE Topical Conference on RF/Microwave…
- 2017

Strategies for reducing the number of basis waveforms used in a Volterra series model for digital predistortion (DPD) of RF power amplifiers (PAs) are proposed. Simple DPD models are generalized so that elemental terms within the Volterra series are grouped together or pruned. It is shown that grouping and pruning produce similar ACLR results when the… (More)

- R. Neil Braithwaite, Bir Bhanu
- CVPR
- 1994

This paper presents a new representation called “hierarchical G a b o r f i l ters” and associated novel local measures which are used t o detect potent ial objects of interest in images. The “first stage” of the approach uses a wavelet set of wide-bandwidth separable Gabor f i l ters t o extract local measures f r o m an image. The “second stage makes… (More)

- R. Neil Braithwaite, Scott Carichner
- IEEE Transactions on Microwave Theory and…
- 2009

This paper describes algorithms used to improve linearity, efficiency, and peak power of a Doherty amplifier whose auxiliary transistor gate voltage is adjusted digitally as a function of the signal envelope. Two predistortion stages are used to compensate for high-order memoryless nonlinearities and low-order memory effects. The digital gate voltage… (More)

- R. Neil Braithwaite
- IEEE Transactions on Microwave Theory and…
- 2013

A combined approach to digital predistortion (DPD) and crest factor reduction (CFR) is proposed. The new CFR is structured similar to DPD and is implemented by introducing a steady-state offset into the DPD coefficients. The DPD and CFR coefficients are estimated using separate adaptive processes but applied to the transmission path in a common module. The… (More)

- R. Neil Braithwaite, Michael P. Beddoes
- IEEE Trans. Image Processing
- 1992

J.G. Daugman's (1988) neural network solution to the Gabor expansion of an image is reformulated as a steepest descent implementation. Nonlinear optimization theory is then applied to select an appropriate convergence factor. Two quasi-Newton-based nonlinear optimization techniques are applied to improve the convergence for certain types of lattice.

This paper presents an algorithm for camera-based navigation of a conventionally steered vehicle. The destination bearing, obtained by actively panning the camera to fixate on the destination, is the primary measurement. A steering sequence designed to direct a moving vehicle towards a visible destination is generated using an extension of predictive… (More)

- R. Neil Braithwaite, Bir Bhanu
- ICIP
- 1995

This paper describes how the phase, obtained by Gabor filtering an image, can be used to aggregate related Gabor elements (simple features identified by peaks in the Gabor magnitude). This phase-based feature grouping simplifies the perennial problem of target/background segmentation because we need to only determine if the aggregate feature is target or… (More)

- R. Neil Braithwaite
- IEEE Journal on Selected Areas in Communications
- 2001