This paper discusses the disadvantages of several existing objective quality evaluation methods for frame interpolation techniques. Samples show that these disadvantages lead the objective quality measurement inconsistent with what humans perceive. Based on these observations, a new metric designed to evaluate the performance of frame interpolation techniques is proposed. This metric combines the severity of interpolation artifacts and several human visual factors into a single quality score. Final implementation shows that the proposed metric out-performs other commonly used metrics.

This paper presents a metric to quantify frame loss according to the impact on perceived temporal quality. This metric particularly aims at measuring the temporal quality degradation caused by both regular and irregular frame loss. Experimental results with subjective viewing demonstrate high performance on prediction of perceptual temporal quality.

Sharpness, one of the most effective factors in video quality assessment, usually dominates the first impression of the representation of the compressed video or image signals. In this paper, a new sharpness metric is presented. Without the original video sequence, this metric evaluates the level of sharpness of a compressed video sequence based on the presence of high frequency signals components. Also, an attention module and several human visual factors are included in order to make the measurement results more correlated to human perception. Finally, psychovisual experiments show high correlation between the metric prediction and subjective ranking of video sharpness

In this paper, a new implementation of the human attention map is introduced. Most conventional approaches share characteristics such as the pooling rule is fixed and prior knowledge of camera aim is discarded. Unlike previous research, the proposed method allows more freedom at the feature integration stage since human eyes have a different sensitivity for each feature under different video aiming scenarios. An intelligent mechanism is designed to identify the importance of each feature for each type of camera motion and skin tone feature, and the feature integration is adaptive to different content. With this framework, more important features are emphasized and less important features are suppressed

In order to mitigate narrow-band interference in spread spectrum communications systems, novel communications receivers incorporating transform domain filtering techniques are designed. In this paper, lapped transforms are used to transform the received data signal to the transform domain wherein adaptive excision is performed. Transform domain detection algorithms, which yield bit decisions based on the remaining signal energy, are analyzed and, together with excision, are employed on a block-by-block basis to suppress single-tone and narrow-band Gaussian interference. System performance is analytically quantified in terms of the overall system bit-error rate (BER). Subsequent results are presented for a variety of channel conditions and compared to those obtained using excision algorithms based on orthonormal block transforms (Medley 1995). These results demonstrate the improved performance and increased robustness with respect to jammer frequency and bandwidth of lapped transform domain excision techniques relative to similar algorithms based on nonweighted block transforms.

A method of applying spread-spectrum techniques to optical communication is presented. The interference-suppression capability of spread-spectrum systems is shown to be enhanced by optical transform domain processing, and a design for spectral coding at optical frequencies is given. The encoding system is based on optical pulse compression and shaping. Several possible implementations of this system are suggested, and applications to fiber optics, laser radar, free-space optical communications, and other systems are discussed.>

An intercept receiver which uses a transform-domain-processing filter is described. This receiver detects direct-sequence binary-phase-shift-keyed (DS-BPSK) spread-spectrum signals in the presence of narrowband interference by employing adaptive narrowband interference rejection techniques. The improvement in the system performance over that of conventional detection techniques is shown by presenting the results of experimental measurements of probability of detection versus false alarm for an enhanced total power detector. Also presented are certain results corresponding to detection of the spectral lines generated at twice the carrier frequency, wherein the goal is often not just signal detection, but also carrier frequency estimation. The receiver uses one of two transform-domain-processing techniques for adaptive narrowband interference rejection. In the first technique, the narrowband interference is detected and excised in the transform domain by using an adaptive notch filter. In the second technique, the interference is suppressed using soft-limiting in the transform domain.>

It is well known that least-mean-squared (LMS) adaptive filtering can be used to suppress narrow-band jammers in a direct sequence spread spectrum receiver. To date, much of the work in this area has concentrated on the use of transversal adaptive filter structures. This paper demonstrates the performance of an adaptive lattice filter in this application. The reflection coefficients of the filter are adjusted using a gradient descent algorithm in an effort to minimize the mean-squared error and, in the process, suppress narrow-band interference. Experimental bit-error-rate performance curves are presented for 7- and 31- chip spreading sequences with a single tone jammer.

This paper describes the structure of a digital implementation of the Widrow-Hoff LMS algorithm which uses a burst processing technique to obtain some hardware simplification. This adaptive system is used to suppress narrow-band interference in a direct-sequence spread-spectrum communication system. Several different narrow-band interferers are considered, and probability of error results are presented for all cases. While, in general, the results show significant improvement in performance when the LMS algorithm is used, certain disadvantages are also present and are discussed in this paper.

In this paper, a technique is described which uses multiple surface acoustic wave (SAW) devices in parallel to reduce the acquisition time of a direct sequence spread-spectrum communication system. Analysis of system performance in both the search and lock modes is presented, and key quantities such as probability of false alarm, probability of correct detection, mean dwell time, and mean time to lose lock are derived.

Analytical results have shown that adaptive filtering can be a powerful tool for the rejection of narrow-band interference in a spreadspectrum receiver. However, the complexity of adaptive filtering hardware has hindered the experimental verification of these results. This paper describes a new adaptive filter architecture for implementing the Widrow-Hoff LMS algorithm while using only two multipliers regardless of filter order. This hardware simplification is achieved through the use of a burst processing technique. A 16-tap version of this adaptive filter constructed using charge-transfer devices (CTD's) is used to suppress a single tone jammer in a direct sequence spread-spectrum receiver. Probability of error measurements demonstrating the effectiveness of the adaptive filter for suppressing the single tone jammer along with simulation results for the optimal Weiner-Hopf filter are presented and discussed.

Employing the technique of transform domain filtering described in Part I of this paper, a system is presented to detect a binary spread-spectrum signal embedded in a wide-band, stationary, colored Gaussian noise process. Using a specific example of a colored noise process, the performance of the system is analyzed. In addition, a specific technique using surface acoustic wave devices is presented which allows the estimation of the spectral density of the interference when such information is initially unknown.

This paper provides a detailed analysis of the performance of systems recently proposed by various authors in which the received signal is Fourier transformed in real time (usually with a surface acoustic wave device) and then filtered by a multiplication of the transformed signal by an appropriate transfer function. We shall refer to this operation as transform domain filtering. General expressions for the output waveforms of the system will be derived, and a specific example illustrating the performance of the system when operating in the presence of a narrow-band interferer plus additive white Gaussian noise will be presented. It will be shown that certain filtering techniques not feasible in conventional systems, such as filtering with ideal bandpass filters, become straightforward using transform domain filtering. Finally, a receiver will be described which will eliminate that intersymbol interference between adjacent data symbols due to filtering at the receiver.

In this paper, various potential implementations of spread spectrum systems using surface acoustic wave (SAW) devices are discussed and experimental results for a phase-shift keyed (PSK) signal embedded in unwanted interference is presented. An overview of acoustic surface wave technology as it applies to signal processing in spread spectrum communication systems is presented. The ability to implement most of the basic elements of such systems using SAW devices is discussed, with emphasis on the space charge coupled convolver and Fourier transformer. SAW implementation of a fairly general block diagram applicable to a variety of signal and interference situations is described, and the relative advantages of SAW technology with respect to other technologies such as charge coupled devices is discussed.