摘要:

In a two-interval forced-choice (2 IFC) audiometric test the observer has to decide which of the two intervals contains an auditory stimulus. The paper discusses the basic design philosophy and principle of operation of a hard-wired experimental facility for automatically locating specific points on the psychometric function for this type of test. Variable intervals and stimuli frequencies and means of recording and analysing the responses are provided.

DOI:10.1049/ree.1978.0015

出版商:IERE    

年代:1978

数据来源: IET

摘要:

Linear segment approximation to a sine wave is almost exclusively used in the modern function generator signal source. This paper offers an in-depth treatment of the question of breakpoint selection. Computer-aided analysis is used to obtain required data for design purposes according to two criteria of minimizing either the number of harmonics or the total harmonic distortion by appropriate positioning of breakpoints. The results obtained indicate that values for total harmonic distortion of less than 0.1% lead to undue amounts of hardware and this value represents a practical limit for this technique.

DOI:10.1049/ree.1978.0016

出版商:IERE    

年代:1978

数据来源: IET

摘要:

The advent of microprocessors has produced an unprecedented need for greater software productivity and reliability. The paper describes a microcomputer application development environment, based on a central minicomputer, which has been designed to aid the production and testing of microprocessor software. The main objectives of the design have been : to minimize microprocessor dependence; to centralize expensive peripherals; to reduce investment in any supported microcomputer; and create disciplined environments for writing and testing programs.

DOI:10.1049/ree.1978.0017

出版商:IERE    

年代:1978

数据来源: IET

摘要:

It is shown that the output from a rate multiplier can control the long-term stability of a voltage-controlled oscillator, without any adverse effects on its spectral purity. This is mainly achieved by using a special digital frequency-detector with a dead band. It is now possible to convert a simple local oscillator for an r.f. receiver to afrequency synthesizer by adding a few integrated circuits.

DOI:10.1049/ree.1978.0018

出版商:IERE    

年代:1978

数据来源: IET

摘要:

A new mode of diversity transmission is described which largely overcomes problems of multipath fading for the outgoing path in land mobile radio. The technique can be applied in many forms, depending on the type of modulation used. Trials with data transmissions have shown two orders of magnitude reduction in error rates as compared with conventional transmission. The system is compatible with quasi-synchronous working.

DOI:10.1049/ree.1978.0019

出版商:IERE    

年代:1978

数据来源: IET