Network Development of Network First measurements made in July 1992; just after start of International GPS Serviceigs). Since then measurements each year and often multiple campaigns per year. -The current network has over 1000 sites, many of them being recovery marks for the main

GPS Groups/Gs There are many international and national groups involved in the deployment of GPS The international organization is the International GPs Service(IGs)

Primary research programs Geophysical research GPS analysis packages GAMIT (GPS at MIT): Uses double differences GYPSY: Jet Propulsion Laboratory (JPL) processing packages: Uses one-way observables and explicitly estimates clocks Bernese: Developed at Astronomical Institute

Basic antenna operation Receiving and transmitting antennas are identical: Time just flows in opposite directions. Antenna problems are solved knowing the current distribution J(x') in the antenna and using a vector potential

Propagation: lonospheric delay Summary -Quick review/introduction to propagating waves -Effects of low density plasma Additional effects -Treatment of ionospheric delay in GPS processing -Examples of some results

Topic 8 16.31 Feedback Control State-Space Systems What are state-space models? Why should we use them? How are they related to the transfer functions used in classical control design and how do we develop a state- space model?

Lecture Outline Air Cargo Industry Types of air cargo and air cargo carriers Largest air cargo carriers Demand for Air Cargo Services Drivers of air cargo growth Constraints on growth Recent Trends in Air cargo

TOTAL CARGO MARKET GIANT MARKET CONSISTING OF TRUCKING RAIL SEABORNE AIR CARGO AS THE WORLD GETS SMALLER THE GROSS VOLUME OF FREIGHT HAS INCREASED DRAMATICALLY

Using architecture Models to Understand Policy Impacts ncreas cost B-TOS Policy increases Swarm of small sats.3 launch probability doing observation Utility for mu of success

Architecture Trade space exploration A process for understanding complex solutions to complex problems Model-based high-level assessment of system capability Ideally, many architectures assessed Avoids optimized point solutions that will not support