Abstract
Higher-order statistics (HOS) are a powerful analysis tool in digital signal processing. The most difficult task to use it effectively is the estimation of higher-order moments of sampled data, taken from real systems. For applications that require real-time processing, the performance achieved by common microprocessors or digital signal processors is not good enough to carry out the large number of calculations needed for their estimation. This paper presents ProHos-1, an experimental vector processor for the estimation of the higher-order moments up to the fourth-order. The processor's architecture exploits the structure of the algorithm, to process in parallel four vectors of the input data in a pipe-lined fashion, executing the equivalent to 11 operations in each clock cycle. The design of dedicated control circuits led to high clock rate and small hardware complexity, thus suitable for implementation as an ASIC (Application Specific integrated Circuit).

Abstract
Higher-order statistics extend the analysis methods of non-linear systems and non-gaussian signals based on the autocorrelation and power spectrum. The main drawback of their use in real time applications is the high complexity of their estimation due to the large number of arithmetic operations. This paper presents an experimental vector architecture for the estimation of the higher-order moments. The processor's core is a pipelined multiply-accumulate unit that receives four data vectors and computes in parallel the moment taps up to the fourth-order. The design of custom cache memory organization and address generation circuits has led to more than 11 operations per clock cycle. The architecture was modeled and simulated in Verilog and is presently being implemented in XILINX field-programmable gate arrays (FPGAs) and one custom integrated circuit for the multiply-accumulate unit.

Abstract
A new technique is described for the extraction of the intrinsic semiconductor laser parameters from intermodulation measurements of composite second-order (CSO) and composite third-order (CTB) distortion products. The effect of the parasitics elements are eliminated, by taking the distortion measurements at constant optical modulation depth, which enables one to obtain the laser parameters on packaged laser diodes. An optimization algorithm is then described that extracts the relevant laser parameters from the distortion data. This method was applied to a commercially available packaged laser diode and very good agreement was obtained between the measured and theoretical results.

Abstract
This paper addresses source clock recovery in ATM networks for real-time services which require a timing relation between source and destination. A detailed jitter analysis is performed for the synchronous methods, from which a simple design approach is suggested for the clock recovery system. A new timing information transport protocol is proposed for constant bit rate and variable bit rate real-time services, leading to a unified ATM Adaptation Layer for both types of services. The method presented is called Generic Synchronous Technique (GST) and exhibits the following properties: (a) good control on its parameters to satisfy jitter objectives;(b) decoupling between timing and service information; (c) efficient coding leading to reduced overhead; (d) good transmission error immunity and (e) simple implementation. As a case study, it is shown that GST provides adequate clock recovery for MPEG video signals, in the most stringent case when the reconstructed system clock is used to derive a chrominance sub-carrier for use in composite video.

Abstract
Today's available solutions for the production of digitally compressed TV programmes require successive decoding and re-coding operations due both to the multiplicity of digital formats currently in use for signal acquisition and to technology limitations. This has the consequence of increasing the production costs and of reducing the overall signal quality. The ability of using compression also at the production stage will contribute to improve the overall signal quality and to reduce storage requirements and associated costs. The ATLANTIC project (ACTS 078) is developing a digital studio for the production of TV programmes using the MPEG2 format throughout the entire process, from the input of the studio to final programme distribution. EXPO'98, the next international exposition to be held in Lisbon, has been identified as an ideal showcase for audio-visual services developed by ACTS projects. The ATLANTIC project will provide basic infrastructures and technology for compressed-based TV programme production and distribution of audio-visual information and entertainment services for the entire EXPO site. This paper describes the studio reference model of the ATLANTIC project and the role ATLANTIC will be playing within the planned demonstrations of ACTS projects at EXPO'98.

Abstract
An efficient algorithm for dynamically multiplexing MPEG2 encoded video sources is presented. Sources are grouped into classes regarding different combined levels of spatial detail and amount of movement. Simulations were performed using different associations of sources belonging to distinct classes, different bit rates and GOP structures. The implications associated to a real implementation are analysed and a modular architecture is proposed. Simulation results are presented and discussed, showing that sequences with higher spatial detail and motion are those which exhibit the higher quality improvements.