Browsing by Author "Guelke, R"
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- ItemOpen AccessA compact short-wave receiving antenna for use in high-noise areas(1960) Muggleton, Louis Miles; Guelke, R; Besseling, LAn antenna has been developed with a signal-to-noise performance that is better than that of a typical Rhombic antenna during local thunder storms. Although the design is of general application to the reception, in high-noise areas, of long distance transmissions, this work deals in particular with the London-Salisbury circuit, at September noon, 1956, on 21.47 Mc/s. A basis of theoretical comparison between the performances of different antennas has been proposed. It relies on the technique of replacing a thunder storm by an "equivalent radio transmitter" set up on the frequency to which the receiver is tuned and for which the antenna is designed. A V.H.F. scale model has been used to produce an optimum design for the proposed antenna which is an end-fire array of parasitic elements. The polar diagrams and signal-to-noise performance of the proposed design are derived for several different types of earth mat. The method used for these derivations is substantiated by correlation with practical sampling measurements. A specification for the final configuration is given and its applicability is indicated by applying the design to the problem of improving the expected performance on the London-Salisbury transmissions from September to December, 1960.
- ItemOpen AccessA voice pitch indicator for training deaf scholars(1965) Anderson, Fred; Guelke, RThe instrument to be described, is based on experimental work documented by the author in 1960 and was developed specifically as a teaching aid to be used in the speech training of deaf scholars. The only natural means by which a completely deaf child can compare his own speech with that of his teacher, is by observation of lip and facial movements and by feeling the vibrations of the vocal organs. Hence he is using the senses of sight and touch neither of which is capable of passing sufficient information to allow the child to develop good voice intelligibility. Two properties of speech which contribute significantly to intelligibility are pitch and stress, and since these are relatively slowly varying quantities, the sense of sight can readily be trained to receive and process this information if presented to it in suitable form. In this instrument, pitch or amplitude information is displayed as the ordinate of a graph, the abscissa of which is time. A continuous time-base is obtained by rotating a cathode-ray-tube with a long-persistence screen inside a stationary deflecting coil. The patterns thus formed, remain visible for a sufficient length of time for detailed interpretation by the sense of sight. Pitch information is derived from measurements performed on the waveform of the speech signal, a process which unavoidably leads to errors. A system for detecting and eliminating these errors is described. The application of the instrument, which has been used successfully over an extended period of time, is described briefly.