Publications

The Federal Aviation Administration (FAA), National Weather Service and Air Force Weather Service are currently engaged in a program to develop a next generation of weather radars (NEXRAD) capable of satisfying (to the greatest extent possible) the common weather information needs of these agencies. This report identifies the unique FAA weather radar surveillance requirements and examines the technical issues that arise in attempting to meet these requirements with the NEXRAD strawman radar sensors and siting. Current air traffic control (ATC) weather data usage and statistics of aviation weather hazards and system efficiency are used to prioritize products needed for ATC. The strawman NEXRAD capability is then reviewed in the context of the identified weather products and factors such as: (1) effects of front end noise and weather return statistics (2) resolution and low altitude coverage constraints (3) the clutter environment associated with various siting options, and (4) data quality required for real time automated display of hazardous weather regions to ATC controllers. It is concluded that significant problems will arise in attempting to simultaneously provide terminal and en route weather surveillance by a single radar as envisioned in the NEXRAD strawman. An analytical/experimental research and development program is described to resolve the identified technical uncertainties in the NEXRAD strawman design for FAA applications. The suggested research and development program includes an operationally oriented interactive data gathering program to evaluate weather products at an ARTCC and TRACON using existing pencil beam S-band radars (e.g., similar to that at MIT) to be followed by similar evaluations in other key geographical areas (e.g., the southeast) using a transportable testbed. Both radar systems would incorporate special features to minimize the likelihood of false targets (e.g., due to obscuration and/or clutter) as well as automated display and short term prediction of hazardous weather regions for use by ATC controllers.

During the last few years, the Radar Techniques Group at Lincoln Laboratory has been applying digital processing techniques to the problem of automatic detection of moving vehicles in the presence of ground and weather clutter. An outgrowth of this effort is the development of a real-time radar signal processor, the Parallel Microprogrammable Processor, or PMP. Conceptually the PMP consists of a single control unit and an array of identical processing modules. The control unit sequences through a program stored in its control memory, providing identical instructions to each processing module, so that all modules are performing the same operation in parallel, each on its own set of data. The talk will focus on the motivation for, and advantages of such a parallel architecture, as presently implemented with TTL medium-scale integrated circuits. Some examples of parallel computation will be illustrated as well as more general issues relating to programmability of the PMP. Much of the information in the talk will be based on experience with an operational prototype, which has a control unit and one processor module.