Robert J. Simpson

Comments on "Signal stabilization of hysteresis-type relay systems

An analysis based on the concepts of equivalent non-linearity and describing function is used to derive an expression for the minimum amplitude of dither required to quench limit cycle oscillations in feedback systems containing a hysteresis-type nonlinearity in the forward path. The treatment is related to recent work by Manohar and Sellappan.

Use of high frequency signals in identification of certain non-linear systems

By filtering the output of a non-linear element, whose input consists of the normal low frequency input signal with a high frequency (dither) signal added, the equivalent non-linearity of the element can be obtained. Illustrative examples of equivalent non-linearities for several non-linear elements are given. It is shown that the technique of dither injection permits the identification of certain types of open and closed-loop systems. Practical results are included to show the accuracy of the method.

System identification using almost periodic functions: application to non-linearities with memory

A method for measuring by crosscorrelation the impulse responses of the linear portions of a system containing a zero-memory non-linearity is shown to be applicable to certain typos of non-linear characteristic with memory. Several situations are analysed and some experimental results presented. A computer programme is given for calculating the parameters of the input signal from a given tabulated non-linear characteristic.

Dynamic analysis of an adaptive control system using the concept of equivalent nonlinearity

A dither-adaptive control system recently proposed by Wagner as the solution to a constant fuel-rate problem is analyzed by decomposing the system into two loops via an extension of the concept of the equivalent nonlinearity. The method provides a general framework for the study of such systems.

System input/output

When a microprocessor is used to control a system, it must be capable of accepting input information, responding, and outputting appropriate signals to implement the required control action. The input/output (I/O) signals may have to be subjected to signal conditioning so that their forms and levels are compatible with the input/output interface elements. The chapter highlights this point by considering two contrasting practical examples. A common technique employed in microprocessor interfacing is to establish the I/O interface as a memory-mapped device. The peripheral interface adapter (PIA) has two 8 bit bidirectional data buses (PA0 to PA7, and PB0 to PB7) for interfacing with peripheral equipment and four control lines CA1, CA2, CB1, and CB2. Each bidirectional data line must be initialized to act as either an input or an output. This is achieved by setting a 0 in the corresponding bit in the data direction register (DDR) if the line is to be an input or a 1 if the line is to be an output.

Digital filtering using the NEC mPD7720 signal processor

Abstract The concepts of digital filtering using the NEC μPD7720 single-chip digital signal processor are presented. The architecture and instruction formats of the device are summarised. The design philosophy and practical hardware and software considerations of using the 7720 as a peripheral to a host 8085 microprocessor system are discussed.

The NEC μPD7720 Digital Signal Processor — A Laboratory-Based Case Study

The concepts of single-chip digital signal processing are presented via a student-oriented tutorial/laboratory case study. This involves the design of a highpass digital filter using the first-difference design method and its implementation using the NEC μPD7720 Signal Processor.

Digital Filtering Using the Intel 2920 Signal Processor

The concepts of single-chip digital Filter implementation are presented via a student-oriented tutorial/laboratory case study. This involves the design of lowpass, highpass, bandpass and bandstop digital filters using the bilinear z-transform method. Concurrent implementation of the Filters using the Intel 2920 single-chip signal processor is described.

Stability and subharmonic responses of a nonlinear system with dither injection

The stability properties of a nonlinear system containing a relay with hysteresis, and subjected to high-frequency dither injection, are discussed. Subharmonic responses of the system are reported, including a jump resonance between two sub-harmonics.

Book Review: Signal Processing, Image Processing and Graphics Applications with Motorola's DSP96002 Processor:Signal Processing, Image Processing and Graphics Applications with Motorola's DSP96002 Processor: EL-SHARKAWYM. (Prentice-Hall, 1994, 620 pp., £42.50)

Signal Processing, Image Processing and Graphics Applications with Motorolas DSP96002 Processor: M. EL-SHARKAWY (Prentice-Hall, 1994,620 pp., £42.50) The DSP96002 is a member of the high-performance, single-chip, general-purpose digital signal processor family from Motorola. The device has a 32-bit multiple bus architecture and the processor supports 32-bit signed and unsigned fixed point arithmetic. It also supports IEEE Standard 745 single precision and single extended precision floating point arithmetic. This book describes the operation of the DSP96002 processor and discusses and explains the addressing modes and instructions set. The available application development tools and assembler and simulator software programs are also explained. Separate chapters are devoted to the design and implementation of FIR filters, IIR filters and adaptive FIR filters using the DSP96002. There is also a chapter on implementing the fast Fourier and discrete cosine transforms. Chapter 9 is a useful chapter for educators because it describes digital signal processing student projects. In this chapter details are given of a wideband coding project using the DSP96002 and a real-time two channel analog input to analog output signal processing system controlled by the DSP96002. The book concludes with an extensive appendix section containing Motorola reference material. The book is very suitable for students, engineers and scientists requiring details of the DSP96002 and some practical applications. ROBERT J. SIMPSON, Professor of Electronic Engineering, University of Central Lancashire, Preston