A critique of angle-of-arrival measurements by the phase difference method

In making instantaneous angle-of-arrival measurements with a two-element interferometer, the phase difference of the two received voltages is often used to infer the arrival angle. It is found that this procedure yields an estimate of the beamwidth of the average angle-of-arrival spectrum which is too narrow by approximately1/sqrt{3}.     

Part II--Digital signal processing architecture

A number of the basic considerations involved in the selection of an overall digital signal processor architecture are reviewed.     

The step motor--The next advance in control systems

This paper seeks to consolidate in one place several diverse articles and contributions, with the objective of emphasizing the coming importance of step motors in the field of control engineering. Main topics include the theory of operation of the synchronous inductor motor, its performance characteristics, an improvement in the derivation of the transfer function for a generalized step motor, and a review of the current status of step motors.     

An Experimental Study of Roundoff Effects in a Tenth-Order Recursive Digital Filter

This paper reports experimental measurements of limitcycle amplitude and period in digital recursive filters. The results that were obtained on two cascaded forms of a tenth-order filter show good agreement with existing theoretical bounds. (The bounds only apply to single second-order sections because analysis of cascaded sections is difficult.) Roundoff noise of the filter was measured and it agreed both in spectral shape and total power with that predicted by computer simulation. Some preliminary observations on relative magnitude of limit cycle and roundoff noise were made. In addition, the gradual buildup of a signal through a limit cycle was observed and 1 bit of noise in the least significant bit (LSB) in the filter was seen to break up limit cycles.     

Programmed Strategies for Program Verification

Plover is an automated property-verifier for Haskell programs that has been under development for the past three years as a component of the Programatica project. In Programatica, predicate definitions and property assertions written in P-logic, a programming logic for Haskell, can be embedded in the text of a Haskell program module. Properties refine the type system of Haskell but cannot be verified by type-checking alone; a more powerful logical verifier is needed.Plover codes the proof rules of P-logic, and additionally, embeds strategies and decision procedures for their application and discharge. It integrates a reduction system that implements a rewriting semantics for Haskell terms with a congruence-closure algorithm that supports reasoning with equality. It employs strategies such as structure splitting and case analysis to explore alternative valuations of expressions of type Bool or other finite data types, but these strategies can lead to exponential growth of terms and must be employed cautiously.Plover itself is written in Stratego, which has proven to be a powerful language tool for implementating a verifier. We discuss the design and implementation of some strategies that enable Plover to comprehend Haskell and verify many valid property assertions.