Characterization of causes of signal phase and frequency instability Final report

Characteristic instabilities in phase and frequency errors of reference oscillator

Frequency Modulation Studies

Contains research objectives

Modulation Theory and Systems

Contains a report on a research project

Multipath Transmission

Contains research objectives

Frequency Modulation

Contains research objectives and reports on one research project

Special studies of AROD system concepts and designs

Signal to noise ratios in airborne range and orbit determination system, and carrier and range loop performance analyse

Education Governance in Sub-Saharan Africa

This paper addresses the issue of education governance in SSA in an attempt to shed light on the status of and developments in this area with a focus on lessons learned from various efforts across the region and recommendations on how to strengthen governance of secondary education. The paper is intended to serve as a background paper on secondary education governance in SSA which will be used to contribute to a more comprehensive publication on secondary education in SSA and the future of work. The paper addresses two key topics under secondary education governance: 1) Accountability as an important aspect of education governance, and 2) the need for enhancing institutional capacity to collect and use educational statistics, and how effective use of data can support education governance. The authors identify several specific actionable recommendations to help policy makers in SSA countries, depending on the local context, implement improvements in the governance of their secondary education systems at central, provincial, and local level

Simulation of the TDRS multipath environment

Design principles and implementation methods are discussed for simulating the propagation path between a tracking and data relay satellite and a mission spacecraft. The emphasis is on multipath and Doppler simulation but additive disturbances are also considered. The recommended form of the simulator is fed separately with the unmodulated carrier, the unmodulated subcarriers (or spread-spectrum components) and the data signals. The perturbations are also introduced separately; then successive modulation operations are performed. The simulator is segmented into elements that perform the various functions of direct and specular multipath, diffuse fading, Doppler shift and delay spread. Delay spreads are realized by discrete delays operating on baseband signals. Doppler simulation and ionospheric or diffuse multipath fading are applied to individual paths before or after modulation of the carrier by delayed baseband signals. Block diagrams are presented on how the different elements are combined to create a complete channel simulator

Multipath Transmission

Contains a report on a research project