We introduce a modified matching pursuit algorithm, called fast ridge pursuit, to approximate -dimensional signals with Gaussian chirps at a computational cost ( ) instead of the expected ( 2 log ). At each iteration of the pursuit, the best Gabor atom is first selected, and then, its scale and chirp rate are locally optimized so as to get a “good” chirp atom, i.e., one for which the correlatio...

This work deals with the analysis of chirp signals by means of time-frequency representation. We propose a chirp adapted time-frequency representation (CA) in which the interferences are significantly reduced. This method is applied to the analysis of acoustic echoes of a sphere target. Comparison of the results to other types of time-frequency distribution of the Cohen’s class shows that the i...

A data-processing technique is proposed for use with conventional frequency-chirped absorption spectroscopy to ensure accurate mapping of spectral features into time-domain signatures with arbitrarily fast readout chirp rates. This technique recovers the spectrum from a signal that is distorted owing to the fast chirp rate and therefore facilitates fast measurement of the spectral features over...

We experimentally demonstrate a superior performance of 2.1-Tb/s·km OFDM signal transmission over 100-km long-reach PONs. While the bandwidth of a 100-km SMF transmission system is limited to 4.3 GHz due to positive chirp, we successfully achieve spectrally-efficient 21-Gb/s signaling by using a cost-effective and low-chirp EAM, and adopting the 128-QAM format and adaptive subcarrier pre-emphasis.

Ten Gb/s low power penalty ( 0 5 dB)error-freetransmission was achieved through 75 km using a high-perfor-mance sampled-grating (SG) distributed Bragg reflector (DBR)laser/EAM transmitter. Large signal chirp measurements shownegative chirp operation across the entire tuning range of the de-vices. An integration-oriented quantum-well-intermixing (QWI)process was emplo...

A novel scheme of optical label encoding by wavelength conversion based on electroabsorption modulators (EAMs) is reported. Based on the experimental observations, the chirp properties of the wavelength-converted signal are discussed and a wide dynamic range of the chirp -parameter is found allowed. Compared with cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA), the EAM ha...

A new variation to the RLS algorithm is presented. In the clipped RLS algorithm (CRLS), proposed in updating the filter weights and computation of the inverse correlation matrix, the input signal is quantized into three levels. The convergence of the CRLS algorithm to the optimumWiener weights is proved. The computational complexity and signal estimation error is lower than that of the RLS algo...

This paper presents a experimental platform that allows comparing objectively any radar waveforms. This is realized by equating radar characteristics, using the same test-bench HYCAM-Research, the same signal processing and also insuring the reproducibility of the experiments. The experimental measurements on linear chirp and multitones are analyzed through distance and velocity imaging. Keywor...

Measurements of small-signal intensity modulation from direct-modulated distributed feedback (DFB) semiconductor lasers after propagation in dispersive fiber have previously been used to extract intrinsic laser chirp parameters such as linewidth enhancement factor and crossover frequency. Here, we demonstrate that the simple rate equations do not satisfactorily account for the frequency respons...

The biomechanical properties of soft tissues vary with pathological phenomenon. Ultrasound elasticity imaging is a noninvasive method used to analyze the local biomechanical properties of soft tissues in clinical diagnosis. However, the echo signal-to-noise ratio (eSNR) is diminished because of the attenuation of ultrasonic energy by soft tissues. Therefore, to improve the quality of elastograp...