Highly accurate group delay measurements in long singlemode fibers were achieved over the full 1200-1600 nm spectral range by measuring phase shifts of a modulated lightwave. The high modulation frequency is shifted down to the kilohertz range using a second optical modulation at the fiber output end, so that low-frequency ultrasensitive detection and phase measurement can be performed with hig...

This technical report presents the development of a simple envelope, or group, delay filter whose magnitude response emulates allpass characteristics for relatively broad frequency passbands. Unlike traditional allpass delay networks, the filter presented herewith exploits no inductances and maintains a common ground between its input and output ports. The absence of circuit inductances simplif...

We measure group delay and group velocity dispersion of silica colloidal photonic crystals in the near-infrared with white light interferometry. While group delay and group velocity dispersion increase with sample thickness, scattering on sample imperfections is found to counteract this development, resulting in group delays lower than theoretically expected. For thin photonic crystals, group v...

A new technique for designing digital allpass IIR filters is proposed. The approach is based on the vector space projection method. Constraint sets, and their associated projectors, that capture the properties of the desired group delay are given. Examples that demonstrate the advantages and flexibility of this method as well as comparisons with a wellknown method are furnished

We present a simple electronic circuit which provides negative group delays for band-limited, base-band pulses. It is shown that large time advancement comparable to the pulse width can be achieved with appropriate cascading of negative-delay circuits but eventually the out-of-band gain limits the number of cascading. The relations to superluminality and causality are also discussed.

The temporal response of double-grating monochromators is analyzed considering two effects on the ultrafast pulse given by the configuration. The first effect is the compensation of the pulse-front tilt, i.e., all the rays emitted by the source in different directions at the same wavelength have to travel the same optical path. The second effect is the group delay introduced by the two gratings...

The conventional statistical parametric speech synthesis (SPSS) focus on characteristics of the magnitude spectrum of speech for speech synthesis by ignoring phase characteristics of speech. In this work, the role of phase information to improve the naturalness of synthetic speech is explored. The phase characteristics of excitation signal are estimated from the integrated linear prediction res...

High-resolution F0 analysis using a speech database with simultaneously recorded EGG (Electroglottogram) signals indicated that there are systematic F0 glitches around nasal-vowel transitions. The durations of the glitches are 10 to 20 ms and they introduce 5 to 10 Hz F0 shifts. A detailed series of analyses of these glitches indicated that the major contributing factor of these glitches is sud...

We observed the thirteen extragalactic radio sources of the complete S5 polar cap sample at 15. We present the maps from those two epochs, along with maps obtained from observations of the 2 cm VLBA survey for some of the sources of the sample, making a total of 40 maps. We discuss the apparent morphological changes displayed by the radio sources between the observing epochs. Our VLBA observati...

In this paper, a threshold based approach using an acoustic parameter derived from the modified group delay function is presented for the detection of nasalized vowels from the mixture of oral and nasalized vowels of normal speakers. It is shown through acoustic analysis on the modified group delay spectrum that during the event of nasalization additional formants (resonances) at various freque...