DOI:10.1049/ree.1966.0091

出版商:IERE    

年代:1966

数据来源: IET

摘要:

This paper describes a multiple filter spectrograph for recording the spectrum of a radio signal in the v.l.f. band. The primary use of the equipment is in recording the Doppler shift of v.l.f. signals received via the whistler mode. There are other uses in narrow-band filtering applications.

DOI:10.1049/ree.1966.0092

出版商:IERE    

年代:1966

数据来源: IET

摘要:

The equations which represent the effect of the upper sideband in a conventional parametric amplifier are derived in detail. It is then shown that the effect of the upper sideband is to present a positive conductance to the signal circuit and partly to nullify the negative resistance associated with the idler circuit. The noise figure expression is derived and shows that noise is introduced into the amplifier at the upper sideband and is converted to signal circuit, degrading the noise figure of the amplifier.

DOI:10.1049/ree.1966.0093

出版商:IERE    

年代:1966

数据来源: IET

摘要:

This paper studies the limitation on the angular resolving power of linear aerial arrays. It is shown that there are some fundamental differences between the resolving powers of arrays, depending upon whether they are mechanically rotated or undergo electronic beamscanning and this leads to a new approach to superdirectivity for arrays employing continuous mechanical rotation. It is shown that a superdirective array can be used with electronic scanning but this process requires discontinuous changes in the array excitation. The ultimate resolving power of a fixed linear array in the absence of noise is studied in terms of its ability to determine separately the angular location of a number of point sources. It is shown that the maximum number of such sources that can be independently located by ann-element array is given by (n—1). It is further shown that the use of multiplicative signal processing or any other form of non-linear processing on the output of the array can produce no improvement over this limit. The change in the resolving power of arrays from the noise-free case to the noise-limited case is also discussed.

DOI:10.1049/ree.1966.0094

出版商:IERE    

年代:1966

数据来源: IET

摘要:

The accuracy and simplicity of measurement of the four main parameters of the received I.L.S. signal, i.e. centring accuracy, off-course sensitivity, mean modulation depth and relative tone phase, has been greatly improved by the introduction of a new technique based on phaselocked detection of the 90 and 150 Hz tones using a 120 Hz reference frequency. The paper states the principles of the phase-locked system with the aid of vector diagrams. Basic block diagrams are shown for the various practical systems according to the measurement application, e.g. test equipment calibration,course line monitoring, field use, etc. The particular requirements for measurements in the presence of noise and large unwanted signals are also considered. The performance requirements for the main circuit blocks show that the a.f. circuitry is basically simple and non-critical and is adaptable to micro-miniature techniques. Finally a comparison is made between phase-locked detection and previous filter methods. In particular a centring accuracy of 01 /xA, equivalent to 0.05% difference in tone amplitudes, is easily obtained, and this represents an order of magnitude improvement over filter methods taken to the limit of present-day techniques.

DOI:10.1049/ree.1966.0095

出版商:IERE    

年代:1966

数据来源: IET

摘要:

An experimental system for monitoring on the round the I.L.S. localizer signals reflected from a landing aircraft is described. Special features of the equipment developed for the monitor, and a selection of the trials' results which give an indication of the correlation obtained between airborne and ground recordings, are included.

DOI:10.1049/ree.1966.0096

出版商:IERE    

年代:1966

数据来源: IET

摘要:

The approximate analogy between the angular spectrum of radiation reflected from a one-dimensional rough surface and the frequency spectrum of a burst of carrier, phase modulated by an appropriate waveform which is directly related to the surface profile, is described. In each case, and subject to certain approximations, the relationship is a Fourier transform. A simple analogue computer is described and used to justify the principle and demonstrate a convenient means of studying reflection problems approximately for both regular and random rough surfaces. Use of the analogue method allows changes in the surface parameters to be introduced easily so that their effects on the angular spectrum may be observed. The technique is applicable to normal or oblique incidence.

DOI:10.1049/ree.1966.0097

出版商:IERE    

年代:1966

数据来源: IET

摘要:

A portable lightweight instrument developed to investigate the effect of total wind flow on plant growth is described. The sensing device is a directly-heated thermistor bead. From the cooling effect of the wind on the bead the electronic circuits produce a voltage that varies linearly with respect to speed over the range of 1–30 miles/hour. This voltage is integrated by a d.c. motor with an attached revolution counter to give the wind flow over a time determined by the operator. The reading is sufficiently independent of direction to be useful in the intended application.

DOI:10.1049/ree.1966.0098

出版商:IERE    

年代:1966

数据来源: IET

摘要:

The paper describes the performance of an S-band parametric amplifier pumped at J-band using a balanced idler technique where two varactor diodes are incorporated in one encapsulation. It is shown that this technique produces a simple amplifier where the idler and signal circuits can be considered to be completely separate.Effects produced by operating the amplifier at frequencies where the circuits are not at resonance are also discussed.

DOI:10.1049/ree.1966.0099

出版商:IERE    

年代:1966

数据来源: IET

摘要:

A system for programmed setting of electronic temperature or humidity controllers, which can commandany of sixteen available settings, is described. The main application is to a set of controlled climate rooms which have different levels of temperature and humidity by day and by night. A defined change from one level to another is required.Wheatstone bridges, set to give the required day and night conditions, are adjusted by transistor switches operated in binary sequence from the states of a counter. These give sixteen steps between and including the day and night settings. The selection of these steps in time is done by a train ofpulses whose rate defines a period for the change between day and night levels. By operation of two switches, the counter is commanded to ‘increase’, ‘decrease’, or ‘stop’. The system can be used for programs more complex than a defined change.

DOI:10.1049/ree.1966.0100

出版商:IERE    

年代:1966

数据来源: IET