DOI:10.1049/ree.1972.0026

出版商:IERE    

年代:1972

数据来源: IET

摘要:

On 8th April 1970 the Selective Chopper Radiometer (S.C.R.) was launched into a polar orbit on theNimbus4 meteorological spacecraft. Since that date the instrument has produced nearly four million temperature profiles of the Earth's atmosphere, from the ground up to 50 km, in most cases to an accuracy of 1 or 2K. This has therefore made it possible for the first time to study the temperature parameters of the atmosphere daily on a global basis. Results from the S.C.R. and future experiments will therefore have a marked effect on meteorology, which in the past has had to rely on rather sparsely distributed radio and rocket sondes.The principle of operation of the experiment is the measurement of infra-red energy in the 15 μm band originating from atmospheric carbon dioxide, but within the band, precise wavelength selection is obtained by combination of interference filters and selective chopping by carbon dioxide cells. This enables the six channels to be tuned to regions of different absorption coefficient in the 15 μm wavelength band, and hence to receive radiation from different heights within the atmosphere.

DOI:10.1049/ree.1972.0027

出版商:IERE    

年代:1972

数据来源: IET

摘要:

The general engineering problem of pulse signal recovery from a reactive (i.e. energy-storing) transducer is considered. It is shown that by using active filters (i.e. filters which are not subject to the constraints imposed upon passive systems by the second law of thermodynamics), pulses of energy less than kθ/2 (where θ is the absolute temperature) are detectable.The arguments are then extended to apply to the situation involving a resonant detector — this is relevant to the gravitational wave detectors which are currently being engineered. In the resonant case the appropriate system function is centred on the resonance frequency ω0/2π rather than on zero frequency.Expressions for the signal/noise ratio and the minimum detectable energy are obtained for a detector in terms of the Q values of the bar and the transducer, and β, a parameter representing the degree of electro-mechanical coupling. Under optimum operating conditions the split bar is found to be more sensitive than the single bar by a factor of about 10; if, however, a time resolution of a few milliseconds is required for coincidence measurements the single bar shows a penalty of nearly 3000 compared with the split bar.

DOI:10.1049/ree.1972.0028

出版商:IERE    

年代:1972

数据来源: IET

摘要:

The inherent limitations of existing lumped parameter networks and electro-mechanical systems for simulating a continuously variable transport delay are shown. Electronic sampled-data storage schemes overcome these difficulties and result in a much higher performance transport delay unit. Cost effectiveness is shown to be markedly enhanced by linear interpolation and m.o.s. shift-register storage of the sampled data.

DOI:10.1049/ree.1972.0029

出版商:IERE    

年代:1972

数据来源: IET

摘要:

This transport delay simualtor was designed to extend the facilities of an analogue computer when used, in particular, for plant simulation purposes. An abridged performance specification is given in the Appendix which shows that this delay simulator has compatible performance with a wide range of modern analogue simulator equipment.Its principle of operation, chosen after consideration of several alternatives, is based on sampling and digital storage. The store comprises m.o.s. integrated-circuit shift registers. Linear interpolation is used to minimize the sampling rate and storage capacity required to achieve the specified accuracy.An alternative mode of operation is as a function generator, the ordinates of the given function being initially written into the store from punched paper tape or an analogue signal source.

DOI:10.1049/ree.1972.0030

出版商:IERE    

年代:1972

数据来源: IET

摘要:

This paper reviews work in the field of design and fault investigation of special integrated circuits intended for use in military radio equipment. The circuits considered were designed, developed and master layouts prepared by the author and his colleagues. Fabrication was carried out by industry. The fault investigation was mainly centred around the spread of design parameters and the faults associated with device fabrication. Initial investigation was by means of ‘black box’ measurements; more detailed measurements were carried out within the circuit chip using optical and electron microscope and mechanical probes.

DOI:10.1049/ree.1972.0031

出版商:IERE    

年代:1972

数据来源: IET

摘要:

To assist in meeting the explosive growth expected in telecommunications in the next twenty years the Post Office and the Science Research Council have begun what is probably the largest microwave-propagation study yet to be mounted anywhere. This project could have a major influence in opening up the 10–100 GHz range of the radio spectrum (wavelength down to 3 mm) to new microwave telecommunication system use. As frequencies rise about 10 GHz, transmissions are increasingly affected by the weather and the object of the study is to find out just how radio transmissions at these millimetric wavelengths are affected and what can be done to avoid disruption of service. This article describes the broad details of project.

DOI:10.1049/ree.1972.0032

出版商:IERE    

年代:1972

数据来源: IET