摘要:

A series of measurements in urban, suburban and city-centre areas has been conducted at frequencies in the range 40 MHz to 900 MHz. Analysis of the detected envelope of man-made noise in this frequency range has shown that notwithstanding the different experimental conditions, there is a general decrease in the level of noise as the monitoring frequency increases. At lower frequencies external noise is dominant but this is not the case at u.h.f. There is no evidence of a change in the fundamental character of manmade noise as frequency changes.

DOI:10.1049/ree.1983.0022

出版商:IERE    

年代:1983

数据来源: IET

摘要:

Recordings of the detected envelope of v.h.f. man-made noise measured at various urban and suburban locations have been analysed to produce amplitude and time statistics. These are presented as graphs of amplitude probability distribution, average level crossing rate, pulse duration distribution and pulse interval distribution. Corresponding graphs at different locations have the same general form but the detailed shape varies with the density and pattern of traffic flow. There is evidence that occasional noise bursts exist with pulses too closely spaced in time to be adequately resolved by a narrow-band receiver.

DOI:10.1049/ree.1983.0023

出版商:IERE    

年代:1983

数据来源: IET

摘要:

The basis for processing synthetic aperture radar signals is derived and the limitations imposed by unwanted platform motion discussed. The hardware realization of both unfocused and focused SAR processing is briefly described in terms of a block diagram and of the required complex multiplication time and storage capacity. Some additional processes are also briefly outlined.It is not possible to describe in great detail the full processing required to produce SAR images. Each application has its own priorities and problems. Instead an attempt has been made to present an overview of the requirements and the likely limitations affecting the processed image.

DOI:10.1049/ree.1983.0024

出版商:IERE    

年代:1983

数据来源: IET

摘要:

This paper first reviews the first seven years history and evolution of digital video recording. Secondly it examines some of the technical issues currently under review by experts within the industry. Consideration is given to the limitations of magnetic recording and the influence these have on the choice of tape format for digital video recording. Finally a review is presented of the experience gained from both theoretical and experimental studies, as a basis for further progression towards a practical digital video recorder.

DOI:10.1049/ree.1983.0025

出版商:IERE    

年代:1983

数据来源: IET

摘要:

A sensor is described which allows the detection of rotation with respect to an inertial frame. The sensor is based on the Sagnac effect, which is measured with a fibre-optic ring interferometer. The fibre gyro is characterized by the following features: a phase modulation scheme to obtain a high sensitivity; a single-mode filter to achieve low drift; depolarized light in order to get a constant scale factor; light with short coherence length to avoid noise due to backscattering.

DOI:10.1049/ree.1983.0026

出版商:IERE    

年代:1983

数据来源: IET

摘要:

The carrier-domain magnetometer generates an electrical output having a frequency proportional to an applied magnetic field, arising from the rotation of the current distribution in a circular bipolar transistor structure with its axis parallel to the field. An improved version of this silicon transducer has been designed and investigated, which has a sensitivity of about 100 kHz/T. The sensitivity depends on temperature and electrical bias conditions, and compensation techniques are described. If a magnetic field is applied parallel to the plane of the circle, its angular position can be monitored since the domain follows it.

DOI:10.1049/ree.1983.0027

出版商:IERE    

年代:1983

数据来源: IET