This report summarizes the design of a digital frequency synthesizer for airborne distance measuring equipment. It is the purpose of the frequency synthesizer to provide a stable frequency source for the local oscillator of the airborne receiver and for the power amplifiers in the transmitter chain. The synthesizer is required to furnish a frequency ranging from 260.250 mHz to 287.50 mHz in channel steps of 250 kHz at a power level of +7.0 dBm. the stability of the frequency must be greater than .005% over the temperature range of from minus 45 degrees centigrade to plus 55 degrees centigrade, requiring a crystal controlled source. Digital techniques are employed using two crystal controlled oscillators to synthesize all required channel frequencies. Linear circuits using standard configurations are employed for the oscillators, buffers, and mixers. Primary attention is paid to optimizing the transient characteristics of the synthesizer which employ programmable digital counters to change the division ratio in a phase locked loop. Decoding is provided to interface the modulus of the counters with the aircraft cockpit controls.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 113-117). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 113-117). Also available on the Internet.

Due to the prevalence of pulse encoders for system state information, an all-digital proportional-integral-derivative (ADPID) is proposed as an alternative to traditional analog and digital PID controllers. The basic concept of an ADPID stems from the use of pulse-width-modulation (PWM) control signals for continuous-time dynamical systems, in that the controllers proportional, integral and derivative actions are converted into pulses by means of standard up-down digital counters and other digital logic devices. An ADPID eliminates the need for analog-digital and digital-analog conversion, which can be costly and may introduce error and delay into the system. In the proposed ADPID, the unaltered output from a pulse encoder attached to the systems output can be interpreted directly. After defining a pulse train to represent the desired output of the encoder, an error signal is formed then processed by the ADPID. The resulting ADPID output or control signal is in PWM format, and can be fed directly into the target system without digital-to-analog conversion. In addition to proposing an architecture for the ADPID, rules are presented to enable control engineers to design ADPIDs for a variety of applications.

Thesis (Ocean E)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1979. / Supervised by Ole Secher Madsen and William D. Grant. Includes bibliographical references (leaves 142-144).

Information on transit ridership and operations is a necessary condition as far as efficient management is considered. Transit managements on the acquisition of such a data base can confirm predictions about scheduling, receive warnings about potential dangers and plan future operations on a much broader and precise base. Data from passenger counts provide essential information to marketing and scheduling personnel by identifying peak load-points and the such. Using manual collection methods for such data is expensive and prone to human errors. Automatic Passenger Counting (APC) systems are viewed as an improved and economical technique for data collection. Such systems monitor the progress of a particular vehicle — its position, number of passengers getting on and off, times and distances between stops — and make this data available for processing. These are state of the art systems, mostly microprocessor based and often embracing a modular structure. The Red Pine system is such a system with different dedicated modules for each bank of tasks. Multitasking software is seen to be an powerful tool for such systems and simplify the architecture of the system hardware. A CHMOS hardware design, suited for multitasking softwares is provided. Interfacing software for the Red Pine system has been developed and is explained. Debugging testing and simulation of the Red Pine hardware is detailed. Modifications have been recorded and improvements suggested. / Master of Science