Digital Signal Processing Research Program

Contains table of contents for Section 2, an introduction, reports on twenty-two research projects and a list of publications.Sanders, a Lockheed-Martin Corporation Contract BZ4962U.S. Army Research Laboratory Contract DAAL01-96-2-0001U.S. Navy - Office of Naval Research Grant N00014-93-1-0686National Science Foundation Grant MIP 95-02885U.S. Navy - Office of Naval Research Grant N00014-96-1-0930National Defense Science and Engineering FellowshipU.S. Air Force - Office of Scientific Research Grant F49620-96-1-0072U.S. Navy - Office of Naval Research Grant N00014-95-1-0362National Science Foundation Graduate Research FellowshipAT&T Bell Laboratories Graduate Research FellowshipU.S. Army Research Laboratory Contract DAAL01-96-2-0002National Science Foundation Graduate FellowshipU.S. Army Research Laboratory/Advanced Sensors Federated Lab Program Contract DAAL01-96-2-000

A neuromorphic silicon photonics nonlinear equalizer for optical communications with intensity modulation and direct detection

We present the design and numerical study of a nonlinear equalizer for optical communications based on silicon photonics and reservoir computing. The proposed equalizer leverages the optical information processing capabilities of integrated photonic reservoirs to combat distortions both in metro links of a few hundred kilometers and in high-speed short-reach intensity-modulation-direct-detection links. We show nonlinear compensation in unrepeated metro links of up to 200 km that outperform electrical feedforward equalizers based equalizers, and ultimately any linear compensation device. For a high-speed short-reach 40Gb/s link based on a distributed feedback laser and an electroabsorptive modulator, and considering a hard decision forward error correction limit of 0.2 x 10(-2), we can increase the reach by almost 10 km. Our equalizer is compact (only 16 nodes) and operates in the optical domain without the need for complex electronic DSP, meaning its performance is not bandwidth constrained. The approach is, therefore, a viable candidate even for equalization techniques far beyond 100G optical communication links

A combined digital linearization and channel estimation approach for IM/DD fast-OFDM systems

A combined digital linearization and channel estimation scheme is proposed and experimentally demonstrated for short-reach intensity-modulation and direct-detection (IM/DD) optical Fast-OFDM systems. Known 2PAM-Fast-OFDM sequences are used for training a memoryless polynomial based adaptive post-distorter and for FFT-based channel estimation in IM/DD 4PAM-Fast-OFDM systems. The 2PAM signals are transmitted only over the odd SCs of the training sequences. With the combined compensation scheme, significant BER improvements are achieved for 10- and 22-km length 12.5 Gbit/s SMF links. Compared with a conventional IM/DD Fast-OFDM, the receiver sensitivity of the proposed IM/DD Fast-OFDM system is improved by about 3 dB at a bit error ratio (BER) of 10–3, after 22-km SMF transmission. In addition, the experimental results for different bias voltages and under strong filtering effects show that the proposed compensation approach can deal with some degree of MZM bias drift and can be applied for realistic wideband optical Fast-OFDM systems

An enhanced pulse position modulation (PPM) in ultra-wideband (UWB) systems

Simplicity, transmission rate, and bit error rate (BER) performance are three major concerns for ultra-wideband (UWB) systems. The main advantage of existing pulse-position modulation (PPM) schemes is simplicity, but their BER performance is poorer than that of an on-off-keying (OOK) modulation scheme, and their transmission rate is lower than that of an OOK scheme. In this research project, I will explore a novel PPM scheme, which can maintain the simplicity of the PPM schemes as well as achieve a BER performance and a transmission rate similar to the OOK scheme. During the research, I will thoroughly investigate the relationship between pulse position allocation and the BER performance and the transmission rate of UWB systems through computer simulations and theoretical analysis, and develop a whole set of design rules for the novel PPM scheme

Finding Music in Chaos: Designing and Composing with Virtual Instruments Inspired by Chaotic Equations

Using chaos theory to design novel audio synthesis engines has been explored little in computer music. This could be because of the difficulty of obtaining harmonic tones or the likelihood of chaos-based synthesis engines to explode, which then requires re-instantiating of the engine to proceed with sound production. This process is not desirable when composing because of the time wasted fixing the synthesis engine instead of the composer being able to focus completely on the creative aspects of composition. One way to remedy these issues is to connect chaotic equations to individual parts of the synthesis engine instead of relying on the chaos as the primary source of all sound-producing procedures. To do this, one can create a physically-based synthesis model and connect chaotic equations to individual parts of the model. The goal of this project is to design a physically-inspired virtual instrument based on a conceptual percussion instrument model that utilizes chaos theory in the synthesis engine to explore novel sounds in a reliable and repeatable way for other composers and performers to use. This project presents a two-movement composition utilizing these concepts and a modular set of virtual instruments that can be used by anyone, which can be interacted with by a new electronic music controller called the Hexapad controller and standard MIDI controllers. The physically-inspired instrument created for the Hexapad controller is called the Ambi-Drum and standard MIDI controllers are used to control synthesis parameters and other virtual instruments

Digital Signal Processing Research Program

Contains table of contents for Section 2, an introduction, reports on twenty research projects and a list of publications.Lockheed Sanders, Inc. Contract BZ4962U.S. Army Research Laboratory Grant QK-8819U.S. Navy - Office of Naval Research Grant N00014-93-1-0686National Science Foundation Grant MIP 95-02885U.S. Navy - Office of Naval Research Grant N00014-95-1-0834U.S. Navy - Office of Naval Research Grant N00014-96-1-0930U.S. Navy - Office of Naval Research Grant N00014-95-1-0362National Defense Science and Engineering FellowshipU.S. Air Force - Office of Scientific Research Grant F49620-96-1-0072National Science Foundation Graduate Research Fellowship Grant MIP 95-02885Lockheed Sanders, Inc. Grant N00014-93-1-0686National Science Foundation Graduate FellowshipU.S. Army Research Laboratory/ARL Advanced Sensors Federated Lab Program Contract DAAL01-96-2-000