Digital Data Recording System (DDRS) operating and maintenance manual

The digital data recording system (DDRS) was designed, fabricated, tested, and delivered. This unit is the interface between the synthetic aperture radar (SAR) and the recording system. The SAR data are formatted in the DDRS for data processing on the ground

Implementation of Offset Pulse Position Modulation

Optical fibre systems have played a key role in making possible the extraordinary growth in world-wide communications that has occurred in the last 25 years, and are vital in enabling the proliferating use of the Internet. Its high bandwidth capabilities, low attenuation characteristics, low cost, and immunity from the many disturbances that can afflict electrical wires and wireless communication links make it ideal for gigabit transmission and a major building block in the telecommunication infrastructure. The main concern of this thesis is a full and detailed investigation and implementation of the Offset Pulse Position Modulation (Offset PPM) communication system. Novel work is carried out for applying Offset PPM over an optical communication channel theoretically and experimentally to examine the system performance. An Offset PPM encoder and decoder were implemented to code Pulse Code Modulation (PCM) format into Offset PPM format and to decode back the Offset PPM to PCM. The first paradigm of implementation was implemented using electronic components. A further investigation took place on the Offset PPM associated output. Computer programming and simulation using the VHSIC Hardware Description Language (VHDL) of this PPM code was considered and comparison with previous theoretical results presented. The received Offset PPM signal returned back to its original input PCM form without errors. Successful VHDL and Field Programmable Gate Array (FPGA) implementation using Altera Quartus II of Offset PPM encoder and decoder as a single system has been presented in the study. An FPGA embedded Bit Error Rate (BER) test device has also been implemented for sensitivity measurements purposes and all the designs have been tested successfully with back-to-back testing. Results show that Offset PPM is an advantageous PPM code for optic communication. Furthermore, the system has achieved a very high data rate of 50 Mb/s without an optical communication set. An optical communication system (transmitter/receiver) over POF was developed and the Offset PPM scheme was investigated through this optical channel. Results show that the Offset PPM sequence transferred through the optic system without being altered. In addition, this implementation is optimised PPM coding; the system is working perfectly with up to 10 Mb/s with 10-12 BER based on the limitations of the optical communication set. All the results and analyses indicate that Offset PPM is an ideal alternative to be considered for highly dispersive optical channels, and performance evaluation for higher bandwidths also favourably compares to existing coding schemes

The Deep Space Network

Deep Space Network progress in flight project support, tracking and data acquisition, research and technology, network engineering, hardware and software implementation, and operations is cited. Topics covered include: tracking and ground based navigation; spacecraft/ground communication; station control and operations technology; ground communications; and deep space stations

Channel and Z-sections braced by diaphragms

The behavior of thin-walled cold formed channel and Z-sections, braced on their upper flange by light-gage steel diaphragms under static loading is studied. The objective of the study is to obtain mathematical solutions, to verify these solutions by tests, and to derive design formulations for the bending behavior of channel and Z-section beams with various boundary conditions. This type of structural element is encountered as purlins and girts to support the roof cover and siding of metal buildings. The roof cover is connected to the upper flange of the purlins and gives rise to the case of braced compression flange when the system is under gravity loading. Similarly, for the uplift caused by wind forces, the beam is braced on its tension flange. The bracing capability of the diaphragms is due to their shear rigidity and/or due to the rotational restraints at the beam diaphragm connection. The effect of the shear rigidity as well as of the rotational restraint on the load carrying capacity of the beams have been investigated. Since in some applications, the lower flange of the beam which is not connected to the diaphragm is braced by X-bracings or sag rods, the additional effect of this discrete bracing is also included in this study. The differential equation of the diaphragm braced channel and Z-section beams have been derived and a series solution has been obtained by the Galerkin Method. Based on these studies, a computer program is written for the determination of the yield load of the beam. The program is capable of considering any desired number of terms in the series solution and in many cases, it is sufficient to use but a few terms of the series. The computer program is sufficiently general to include the effect of all geometric parameters. Using a single term solution of the differential equation, design formulas for the yield moment are derived for the beams considered. The designer is thus given the choice of using these simple formulas or the computer program if he desires more accurate analysis. Based on theoretical and experimental results, pertinent conclusions are obtained and recommendations for further studies are included

Pre-phase A: Development of a far-ultraviolet photometric- and spectroscopic-survey small-explorer experiment

We propose to perform a far ultraviolet photometric and spectroscopic survey covering the lambda lambda 1300-2000 band with a sensitivity comparable to that of the Palomar Sky Survey. This survey will proceed in three phases: an all-sky survey in three bands to 18-19.5(sup m), deep surveys of selected targets of interest in the same bands to 21-22(sup m), and a spectroscopic survey of 2 percent of the sky to 18(sup m) with a resolution of 3-20A. This mission, the Joint Ultraviolet Nightsky Observer (JUNO), can be performed by a Small-Explorer-class satellite

On-board B-ISDN fast packet switching architectures. Phase 1: Study

The broadband integrate services digital network (B-ISDN) is an emerging telecommunications technology that will meet most of the telecommunications networking needs in the mid-1990's to early next century. The satellite-based system is well positioned for providing B-ISDN service with its inherent capabilities of point-to-multipoint and broadcast transmission, virtually unlimited connectivity between any two points within a beam coverage, short deployment time of communications facility, flexible and dynamic reallocation of space segment capacity, and distance insensitive cost. On-board processing satellites, particularly in a multiple spot beam environment, will provide enhanced connectivity, better performance, optimized access and transmission link design, and lower user service cost. The following are described: the user and network aspects of broadband services; the current development status in broadband services; various satellite network architectures including system design issues; and various fast packet switch architectures and their detail designs