Shuttle/TDRSS modelling and link simulation study

A Shuttle/TDRSS S-band and Ku-band link simulation package called LinCsim was developed for the evaluation of link performance for specific Shuttle signal designs. The link models were described in detail and the transmitter distortion parameters or user constraints were carefully defined. The overall link degradation (excluding hardware degradations) relative to an ideal BPSK channel were given for various sets of user constraint values. The performance sensitivity to each individual user constraint was then illustrated. The effect of excessive Spacelab clock jitter on the return link BER performance was also investigated as was the problem of subcarrier recovery for the K-band Shuttle return link signal

Shuttle Ku-band signal design study

Carrier synchronization and data demodulation of Unbalanced Quadriphase Shift Keyed (UQPSK) Shuttle communications' signals by optimum and suboptimum methods are discussed. The problem of analyzing carrier reconstruction techniques for unbalanced QPSK signal formats is addressed. An evaluation of the demodulation approach of the Ku-Band Shuttle return link for UQPSK when the I-Q channel power ratio is large is carried out. The effects that Shuttle rocket motor plumes have on the RF communications are determined also. The effect of data asymmetry on bit error probability is discussed

Engineering evaluations and studies. Volume 3: Exhibit C

High rate multiplexes asymmetry and jitter, data-dependent amplitude variations, and transition density are discussed

Quaternary pulse position modulation electronics for free-space laser communications

The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (QPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented

RAPID CLOCK RECOVERY ALGORITHMS FOR DIGITAL MAGNETIC RECORDING AND DATA COMMUNICATIONS

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN024293 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

High-speed optical fibre transmission using advanced modulation formats

The rapid growth in interactive bandwidth-hungry services demands ever higher capacity at various stages of the optical network, leading to a potential capacity exhaust, termed the capacity crunch. The main aim of the research work described in this thesis was to help solve the potential capacity crunch by exploring techniques to increase the data rate, spectral efficiency and reach of optical fibre systems. The focus was on the use of advanced signal modulation formats, including optical time-division multiplexing (OTDM), quadrature phase shift keying (QPSK), and 16-state quadrature amplitude modulation (QAM16). QPSK and QAM16 modulations formats were studied in combination with coherent detection and digital signal processing (DSP) for the compensation of transmission impairments. In addition, return-to-zero (RZ) pulses were explored to increase the tolerance towards nonlinearity for coherently detected signals, and nonlinearity compensation (NLC) through the DSP. Initially, to maximise the bit-rate, research was focused on the study of OTDM transmission at 80Gbit/s with the aim to optimise the phase difference between the adjacent OTDM channels. A new technique to achieve bit-wise phase control using a phase-stabilised fibre interferometer was proposed. Faced with a limited fibre capacity, the need to maximise the spectral efficiency became paramount, and thus the need to use phase, amplitude and polarisation domains for signal transmission. In combination with coherent detection the research focused on the performance of optical fibre systems using QPSK and QAM16 modulation formats, including their generation, transmission and detection in single-channel and WDM regimes. This included the study of the impact of pulse shapes, and the mitigation of linear and nonlinear transmission impairments with receiver-based DSP at bit-rates ranging from 42.7 to 224Gbit/s. The technique demonstrated for bit-wise phase control for OTDM was successfully used to demonstrate a new method for QAM16 signal generation. Longest transmission distances (up to 10160km in 112Gbit/s QPSK, 4240km in 112Gbit/s QAM16, and 2000km in 224Gbit/s QAM16) have been achieved with the use of NLC and RZ pulses. The efficiency of these two techniques is explored through a comprehensive set of experiments in both single-channel and WDM transmission experiments. The results can be used in the design of future optical transmission systems

A study of the minimum shift keying modulation scheme

This thesis concerns itself with the study of the Minimum Shift Keying (MSK) modulation scheme. The aspects considered are its operation under non-linear conditions as well as an investigation into the hardware implementation of both coherent and non-coherent MSK modems. The literature on digital data transmission and MSK in particular is surveyed, and a comprehensive theoretical description of MSK is given. In addition, papers on the operation of MSK under non-linear conditions were studied, and their major findings are presented. Due to the lack of theory on the effects of incorrect modulation index on the error performance of MSK, an investigation into this avenue was performed. The design of a correction mechanism for maintaining the modulation index at its correct value is described, and aspects of its implementation are considered. Using the available literature, various modules of which a coherent MSK modem is comprised were developed, and their design is discussed. The design of a non-coherent MSK demodulator is also described