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BBC Research and Development Reports

A collection of BBC Research and Development reports and white papers, dating from the 1960s through to 1996.



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R&D Report 1975-31 : Pulse code modulation of video signals: Visibility of level quantising effects in processing channels. M. Weston Previous work has shown the number of bits per sample needed to represent gamma-corrected television signals. A theoretical analysis extends these results to non-gamma-corrected and logarithmic signals which occur in signal origination equipment. This analysis shows that level quantisation of non-gamma-corrected signals is most visible in dark areas of the...
Topics: quantisation, visibility, input, signals, output, signal, visible, luminance, quantised, tests,...
R&D Report 1995-02 : Digital Audio Broadcasting: Measuring techniques and coverage performance for a medium power vhf single frequency network M.C.D. Maddocks, I.R. Pullen, J.A. Green The advent of digital formats such as CD has created demand for uniformly high audio quality from radio. In order to provide such high-quality stereo reception, a Digital Audio Broadcasting (DAB) system capable of reliable reception in vehicles and on portables has been developed by the European EUREKA 147...
Topics: dab, signal, coverage, measurements, transmitter, locations, transmitters, audio, strength, system,...
R&D Report 1964-07 : Effect of fabric coverings on the sound absorption of porous materials A.N. Burd Measurements have been carried out by the reverberation room method to determine the effect of fabric coverings on the sound absorption of porous backing materials. It is hoped that it may prove possible in the future to predict the behaviour of materials from measurements on small samples.
Topics: fabrics, absorption, resistance, fabric, backing, materials, measurements, flow, high, stretched,...
R&D Report 1969-03 : Field strength near the ground at VHF and UHF: theoretical dependence on polarisation P. Knight Under ideal conditions, vertically-polarized vhf and uhf transmissions would give much higher field strengths close to the ground than horizontally-polarized transmissions. Although the theoretical difference between the two polarizations could be as much as 30 dB at ground level, it decreases rapidly with height and is less than 3 dB at a height of one wavelength.
Topics: ground, field, dielectric, polarization, ratio, aerial, theoretical, reflection, height, heights,...
R&D Report 1972-07 : The optimum characteristics for a simple luminance notch in a PAL colour television decoder S.J. Lent The various considerations which govern the characteristics of a luminance notch filter in a PAL decoder are discussed and subjective experiments are described which were carried out to find the optimum characteristics of such a filter.
Topics: notch, luminance, chrominance, characteristics, notches, pal, optimum, subcarrier, sidebands,...
R&D Report 1984-04 : Filtering of the colour-difference signals in 4:2:2 YUV digital video coding systems. V.G. Devereux Specifications are proposed for the characteristics of the low-pass filters required at the input and output of the U and V channels of a 4:2:2 YUV digital video coding system. In such a system, the Y (luminance) signal is sampled at 13.5MHz and the U and V (colour-difference) signals are sampled at 6.75MHz as specified in CCIR Rec. 601. It has been concluded on both...
Topics: mhz, filters, digital, filtering, yuv, signals, frequency, filter, sampled, data, digital...
R&D Report 1960-03 : The power gain of multi-tiered VHF transmitters aerials P. Knight, G.D. Monteath Transmitting aerials for vhf broadcasting usually consist of a number of similar groups or tiers of radiating elements, spaced at intervals along a supporting mast. The power gain of such an arrangement depends on the number of tiers, on the spacing between them, and also on the vertical radiation pattern of each individual tier. A method of calculating the gain is described in this report....
Topics: ooooo, ooo, oooooo, mmmmm, oooo, cfl, iiiii, gain, ooooo ooooo, tfl, moooo ooooo, power radiated,...
R&D Report 1963-56 : Performance of certain television receivers designed for the 525/60 standard when operated from a 50 c/s mains supply. G.C. Wilkinson This report describes subjective tests on the performance of three domestic receivers, all designed to operate from either 50 or 60 c/s power supplies while displaying 525-line, 60 field-per-second television pictures; the tests and measurements were based upon techniques described previously. The test results show that, when operating...
Topics: receiver, receivers, picture, wobble, flicker, subjective, supply, mains, displayed, television,...
R&D Report 1969-26 : Pulse-code modulation for high-quality sound-signal distribution: A simulation of instantaenous companding A.H. Jones This report describes a series of subjective tests made to discover whether instantaneous companding could profitably be applied to a pulse-code-modulation system designed for high quality sound signals. It was concluded that the benefits derived from this type of companding would be too small to justify the additional instrumental complexity involved.
Topics: signal, quantizing, instantaneous, digits, levels, curves, transition, companding, simulation,...
R&D Report 1989-06 : The first year's work of RACE Project 1036 WTDM broadband customer premises network. A. Oliphant (edited by) This Report describes the first year's work on RACE project 1036. The aim of this project is to develop a Broadband Customer Premises Network (BCPN) suitable for broadband service providers and for a wide range of applications in industry, commerce, education, and public services. The BCPN uses a combination of wavelength-division multiplexing and electrical...
Topics: optical, demultiplexer, wavelength, ibcn, broadband, bcpn, laser, project, race, network, planar...
R&D Report 1957-13 : The construction and design of dichroic mirrors K. Hacking The somewhat stringent optical performance of beam-splitting dichroic mirrors imposed by three-colour television can be satisfactorily achieved with present-day apparatus and techniques for preparing multilayer interference films. A guide to the design and performance of such mirrors is afforded by considering the effects of the several physical parameters in idealized systems of layers. Exact formulae, based on...
Topics: layer, layers, reflection, thickness, dichroic, mirrors, wavelength, transmission, optical,...
R&D Report 1974-37 : Digital video: Some bit-rate reduction methods which preserve information in broadcast-quality digital video signals D.F. Reid PCM digital video-signals require a very high bit rate and for economic reasons particularly in transmission, it is desirable to minimise the required bit rate. Methods for reducing the bit rate fall into two main categories; (a) those methods which remove information to which the human eye is insensitive, and (b) those which exploit the...
Topics: entropy, code, reversible, digital, coding, signal, probability, coder, video, signals, code word,...
R&D Report 1978-10 : Digital aperture correction. M. Weston An experimental digital aperture corrector has been constructed which provides vertical correction together with 'in-band' horizontal and 'out of band' horizontal aperture correction of the luminance component of 8-bit PCM Red, Green and Blue signals from an experimental digital signal processing channel. The vertical and horizontal aperture correctors operate in parallel on a 'luminance' signal matrixed from R, G, B inputs to...
Topics: correction, aperture, corrector, signal, horizontal, corrected, vertical, digital, frequency,...
R&D Report 1982-23 : The design of microcomputer-controlled equipment for the measurement of reverberation time. R. Walker, M.M. Leather The practical methods of measuring reverberation time are discussed briefly. The design of a microprocessor controlled system for measuring reverberation time in a wide range of different types of rooms is described. The system employs analogue signal processing to provide the loudspeaker excitation signal and to receive and process the microphone output...
Topics: reverberation, frequency, amplifier, display, signal, filter, data, microphone, measurement, range,...
R&D Report 1964-20 : Considerations affecting the aperture and beam-tilt of UHF transmitting aerials P. Knight Curves are presented showing how field strength varies with distance for idealised uhf transmitting aerials of various apertures with different amounts of beam-tilt. From these curves conclusions are drawn regarding the maximum permissible aperture and the optimum beam-tilt for aerials erected on tall masts.
Topics: aerial, aerials, strength, transmitting, tilt, distances, aperture, field, apertures, lobe,...
R&D Report 1966-32 : Sennheiser MKH 404 and AKG 628 microphones. H.D. Harwood Two new capacitor microphones, the Sennheiser type MKH 404 and the Akustische und Kino Gerate type 628, have been produced which employ transistor circuits and radio-frequency polarizing of the capsule; both have a cardioid directional characteristic and are of the end-fire type. Measurements of the frequency characteristics have been carried out for sound incident at various angles; the degree of self-generated...
Topics: mkh, type, sennheiser, akg, impedance, frequency, noise, microphone, microphones, circuit, akg...
R&D Report 1957-12 : Band III experimental transmissions from Kirk O' Shotts. B. Davis, D.W. Taplin A field strength survey has been made to determine the area that could be served by a Band III television transmitter of effective radiated power (e.r.p.) 100 kW at Kirk o' Shotts. The results show that most of the highly populated central areas between the Clyde and the Forth would receive a satisfactory service, with the exception of a small area in Edinburgh and Portobello where the field...
Topics: contours, median, kirk, shotts, experimental, iii, field, strength, transmissions, band, median...
R&D Report 1962-08 : A Band V signal-frequency unit for a V.H.F./U.H.F. field-strength recording receiver. G.J. Phillips, P.T.W. Vance The report describes a signal-frequency unit, for use in Band V (610-960 Mc/s), which forms part of a v.h.f./u.h.f. field-strength recording receiver. Details are given of the mechanical and electrical design of the unit and some problems which arose in its development are discussed. The unit includes two coupled coaxial line resonators for signal-frequency...
Topics: frequency, band, oscillator, unit, multiplier, coupling, receiver, circuit, tuning, input, tuned...
R&D Report 1966-31 : Colour film and colour television C.B.B. Wood This report discusses the use of colour film for colour television, with particular reference to the choice of film stocks.
Topics: colour, film, television, mhz, eastman, kodachrome, telerecording, films, ektachrome, contrast,...
R&D Report 1986-03 : Design of a prototype moving-coil high-frequency loudspeaker drive unit. K.E. Randall A high-frequency loudspeaker drive unit (tweeter) suitable for use in a high-quality studio monitoring loudspeaker is described and the necessary manufacturing information provided. Design considerations are outlined and development problems discussed. Performance is assessed and possible improvements are suggested.
Topics: prototype, tweeter, bbc, khz, harmonic, characteristic, diaphragm, unit, current, design, drive...
R&D Report 1956-34 : Investigation of poor reception from Crystal Palace in the Reigate and Horsham areas B. Davis, G.D. Monteath, G.I. Ross An investigation has been made into complaints of poor reception, in the Reigate, Redhill and Crawley and Horsham districts, of the Crystal Palace television transmitter installation, in its temporary conditions. The field strength in these areas is lower than the value predicted from site test measurements and the prevalence of flutter fading due to...
Topics: palace, crystal, strength, field, tower, alexandra, flutter, horsham, measurements, aircraft, site...
R&D Report 1971-30 : An experimental quadrature modulation system for video signals R.N. Robinson An experimental two-channel quadrature modulation system operating at VHF has been developed. This is used to illustrate the performance that may be expected of a practical system for transmission of wide-band signals in the UHF or SHF bands. This method of modulation enables two signals to be transmitted at the same carrier frequency. Two carriers of identical frequency, but displaced in phase...
Topics: phase, signal, frequency, loop, modulation, crosstalk, carrier, oscillator, signals, quadrature,...
R&D Report 1974-07 : Hadamard transformation: A real-time transformer for broadcast standard television R. Walker The requirements and design of a modular Walsh-Hadamard transformer for the real-time transformation of broadcast quality PCM television are discussed. Although the example given is for a transform size of 32 picture elements, the modular approach allows any size of transformer to be constructed, using similar units. This experimental transform system includes the means by which...
Topics: transform, transformer, data, hadamard, input, matrix, storage, output, walsh, inverse, broadcast...
R&D Report 1970-10 : Permissible bass rise in talks studios N.F. Spring, K.E. Randall An investigation has been carried out into the extent to which the low-frequency reverberation-time may be allowed to rise in a talks studio without impairing speech quality. Factors likely to affect the acceptability are taken into account. It is shown that microphone type has a particularly strong influence on the acceptability. Recommendations for allowing a degree of bass rise are made which permit a...
Topics: microphone, bass, condition, permissible, reverberation, room, studios, passages, grade, talks,...
R&D Report 1970-08 : A computer program for calculating sky-wave field strengths at medium frequencies A.D. Olver, A.G. Lyner, P. Knight A computer program has been developed to calculate sky-wave field strengths at medium frequencies, assuming an idealized horizontally stratified ionosphere. Ionospheric data and ground constants at the terminals are specified and the losses are computed using a ray-tracing technique. The program will calculate theoretical losses over single hop or two hop...
Topics: loss, wave, ray, transmitter, ionosphere, refractive, ground, polarization, frequency, ionospheric,...
R&D Report 1973-13 : MF propagation: A wave-hop method for ionospheric field-strength prediction P. Knight A new method for calculating the strength of medium-frequency sky-wave signals at night is described. Estimated losses due to all the ionospheric and terrestrial factors which affect a wave as it propagates from transmitter to receiver are subtracted from the field strength which would arise if losses were absent. This process is carried out for each propagation mode which is likely to...
Topics: ionospheric, loss, field, paths, strength, reflection, polarisation, propagation, ground, magnetic,...
R&D Report 1973-06 : Equipment for the transfer of digital video signals to paper tape C.K.P Clarke A digital computer can be used to simulate processing methods for the bit-rate reduction of digital television. To assess such methods, television signals must be converted to a form compatible with computer data-handling systems. This report describes equipment for transferring monochrome pulse-code modulation signals derived from a slide scanner to punched paper tape. One eight-bit word is...
Topics: signals, picture, digital, counter, sampling, samples, punched, bbc, paper, transfer, slide...
R&D Report 1977-29 : The HMI 575-watt metal-halide discharge lamp: measurements and predicted effects of intensity ripple using sinusoidal lamp excitation. E.W. Taylor A description is given of measurements of the light intensity ripple characteristics shown by the Wotan HMI 575-watt metal-halide discharge lamp as manufactured by Osram BmbH, Germany, when excited from a sinusoidal power source at various frequencies in the range 50Hz-2KHz. Operating conditions which reduce motion picture...
Topics: ripple, lamp, frequency, supply, shutter, camera, ratio, iii, intensity, dissipated, shutter...
R&D Report 1954-09 : Information on short wave propagation conditions from reception results on fixed frequencies. T.W. Bennington Regular hourly observations made at Panorama, South Africa, on reception of five fixed frequencies from Standard Frequency Station WWV have been analysed to obtain information on propagation conditions and their daily and seasonal variations, for comparison with those given by world charts of predicted MUF. The results indicate that the predications agree well...
Topics: reception, muf, frequencies, gmt, propagation, signal, frequency, predicted, luf, panorama, sinpo...
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R&D Report 1959-10 : Peterborough: Television and V.H.F. sound services; Site tests. D.W. Taplin, C.J. White, R.S. Sandell, J. Hall The results of a site test at Morborne Hill, near Peterborough, are given. A Band I transmitter with a mean effective radiated power (e.r.p.) of 1.1 kW will provide a much improved service over most of the area but the overlap with the adjacent Crystal Palace and Holme Moss transmitters is inadequate in certain areas. A Band II transmitter with a mean e.r.p. of...
Topics: transmitter, peterborough, strength, television, unipoles, exceeded, contours, field, field...
R&D Report 1956-03 : The Ronette crystal microphone cartridge Type MC.65. W.I. Manson, D.E.L. Shorter The report gives tests results on three samples of the Ronette diaphragm-type crystal microphone cartridge MC.65. The performance varies considerably between individual specimens but is on the average superior to that of earlier microphone of this kind.
Topics: microphone, ronette, frequency, crystal, cartridge, specimens, response, specimen, axial, noise,...
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R&D Report 1955-02 : The suppressed frame system of telerecording C.B.B. Wood, E.R. Rout, A.V. Lord, R.F. Vigurs This part summarises the fundamental and practical aspects of a suppressed-frame 35 mm telerecording machine designed and constructed by Research Department in order to provide an additional telerecording channel for use in connection with the Coronation.
Topics: signal, picture, film, recording, characteristic, frame, unit, correction, television, circuit,...
R&D Report 1965-13 : Transmitting aerials for the Granton VHF television and VHF sound station D.W. Osborne, R.D.C. Thoday The Grantown relay station came onto operation on 8th February 1965. It provides a television and v.h.f sound service to Grantown, Nethy Bridge, Boat of Garten, Carrbridge and Duthil; parts of Aviemore are also served.
Topics: aerial, horizontal, dipole, tiers, gain, templet, transmitting, band, tower, radiation, radiation...
R&D Report 1964-01 : Stereophony: the effect of crosstalk between left and right channels H.D. Harwood, D.E.L. Shorter The investigation of the effect of interchannel crosstalk in a stereophonic system, of which the first results were given in Research Report L-049, has been continued. The experiments have covered crosstalk in different regions of the audio-frequency band. The influence of acoustic environment and of the observer's position in relation to the loudspeakers has been...
Topics: crosstalk, frequency, observer, listening, image, perceptible, room, frequencies, position,...
R&D Report 1965-39 : UHF aerials for the Hertford television relay station G.H. Millard A summary of the installtion of the UHF Aerials for the Hertford Television Relay Station.
Topics: aerials, transmitting, feeder, mounted, dipoles, oin, horizontal, aerial, distribution,...
R&D Report 1965-35 : Line-store standards conversion: The design of video transmission lines. A.H. Jones This report discusses requirements affecting the design of transmission-lines suitable for the distribution of video signal within the store assembly of one form of line-store converter. The development of two types of transmission-line which meet requirements defined is described.
Topics: store, capacitance, impedance, input, transmission, signal, lines, output, reflexions, pulses,...
R&D Report 1969-52 : A p.c.m. sound-in-syncs distribution system: combination and separation of sound and video signals C.J. Dalton This report, one of a series of four, gives the basic requirements and simple descriptions of experimental equipment for the combination and separation of sound and video signals as used in the 'sound-in-syncs' system for conveying a sound signal together with a video signal along a video link. Performance figures for the equipment are given and from the...
Topics: sound, pulse, signal, video, separator, detection, pulses, sync, separation, distribution, sound...
R&D Report 1966-61 : Choice of interpolation apertures for line-store standards converters V.G. Devereux This report is concerned with the manner in which the output signal from a line-store standards converter is influenced by the type of interpolation aperture which is used in deriving this output signal. The optimum shape of the interpolation aperture is deduced theoretically for apertures of various widths and an experiment is described which was carried out to examine the agreement...
Topics: aperture, interpolation, spectrum, input, output, vertical, signal, frequency, converted, scanning,...
R&D Report 1969-07 : Band II FM sound broadcasting: The effects of a change to circular polarization J.G. Spencer Measurements have been made to determine the effects on reception by fixed, portable and car radio receivers of a change from horizontal to circular polarization of the Band II FM transmissions. For reception in the home, a change to circular polarization would be equivalent to a change of transmitter power of between +1 dB and -3 dB, depending on the type of receiving aerial in...
Topics: aerial, field, measurements, transmission, aerials, vertical, reception, polarization, component,...
R&D Report 1970-06 : Automatic registration feasibility study: Fundamental considerations J.R. Sanders This report describes some of the problems involved in the design of automatic systems of registration for three-tube and four-tube cameras. Particular attention is paid to methods of error detection and correction. It is concluded that any fully comprehensive automatic registration system which might be added to existing cameras would require considerable additional equipment and might...
Topics: error, registration, correction, detector, signals, vertical, errors, camera, signal, delay, error...
R&D Report 1967-59 : 3x3 matrices for use with plumbicon colour cameras using three tubes W.N. Sproson This report describes the latest developments in the derivation of the coefficients of [3 x 3] linear matrices for use with the three-plumbicon type of colour television camera. Values are recommended which are equally applicable for both natural daylight and indoor (tungsten) illumination.
Topics: colour, matrix, phosphors, luminance, saturated, desaturated, chromaticity, error, colours, flesh,...
R&D Report 1967-55 : Digital methods in television G.D. Monteath, V.G. Devereux This report indicates some of the advantages to be gained by converting television waveforms to trains of binary digits before signal processing operations such as standards conversion are carried out. These operations could then be effected by digital storage and logic circuits, the main advantages being reliability and freedom from distortion. A brief description is given of possible methods of performing...
Topics: digital, signal, television, signals, binary, store, conversion, converter, analogue, required,...
R&D Report 1970-21 : The design and replacement aerials for Moorside Edge P. Knight The design of a new medium-frequency aerial system for Moorside Edge is described. The effect of the hilly nature of the surrounding area on the performance of the aerials is discussed, and it is concluded that no advantage could be gained by centre-feeding.
Topics: aerial, mast, moorside, wires, radio, radiation, aerials, height, radius, antifading, height...
R&D Report 1975-24 : Prototype equipment to measure co-channel interference on 625-line television signals. M.J. Kallaway This report describes prototype equipment designed to measure the level of co-channel interference (CCI) on a 625-line television signal. The CCI measuring equipment's primary application is at transmitters fed by re-broadcast links (RBL) where it would measure the level of CCI on the incoming television signal and record it on a chart recorder. The CCI measuring...
Topics: offset, frequency, equipment, level, interference, nominal, filter, measuring, interfering, pulses,...
R&D Report 1976-20 : An experimental 4-phase differential-phase-shift-keying system to carry two high-quality digital sound signals. M.J. Kallaway The report describes an experimental 4-phase differential-phase-shift- keying system to carry two high-quality sound signals. The system has possible applications in outside broadcast links and satellite broadcasting. The system offers a good compromise between the requirements of carrier power, signal bandwidth and instrumental simplicity. The...
Topics: signal, carrier, phase, amplitude, modem, spectrum, recovery, digital, symbol, experimental,...
R&D Report 1975-04 : Digital video: Sub-Nyquist sampling of PAL colour signals. V.G. Devereux A simple method of applying sub-Nyquist sampling techniques to digital coding of PAL colour video signals is described. This technique employs a sampling frequency of twice the colour subcarrier frequency, the sampling instants being maintained at a specified phase relative to the reference subcarrier. For System I (625-line, PAL) video signals the resulting sampling frequency is about 8.87 MHz....
Topics: sampling, frequency, signal, components, filter, signals, comb, pal, video, subcarrier, pal video,...
R&D Report 1973-26 : Radio microphones: Operation at low frequencies R.D.C. Thoday This report considers the use of low frequencies for radio microphones and talk back systems in Television Studios. Mutual interference with other apparatus in the studio, particularly with television cameras, rules out the possibility of using these frequencies. The risk of interference from numerous external sources would also exist.
Topics: loop, interference, studio, magnetic, field, transmitting, radio, frequencies, measurements,...
R&D Report 1982-04 : Relationships between normal-incidence and statistical absorption coefficients. E.W. Taylor The theory underlying the absorption of sound at normal incidence is summarised and its extension to include absorption at random incidence is discussed. A chart of the relationships between the normal-incidence and random-incidence or 'statistical' absorption coefficients is given, and a method of using this chart to obtain values of the statistical absorption coefficient from...
Topics: impedance, sound, absorption, equation, surface, pressure, coefficient, acoustic, velocity,...
R&D Report 1979-24 : A statistical analyser for digital field strength data. A.P. Robinson This report describes digital equipment using a microprocessor which carries out a statistical analysis of field strength data as measurements are made. The results are obtained immediately and are printed. The analyser is intended primarily for use with a measuring receiver in a vehicle but the report also discusses the scope for other applications. The equipment obtains results which used to be...
Topics: analyser, marker, event, samples, data, markers, field, strength, median, block, digital field,...
R&D Report 1977-11 : A Band II ferrite aerial unit for portable receivers. R.D.C. Thoday The whip aerial needed for good reception at VHF is a drawback to the use of portable sound receivers. A small VHF aerial unit has been built using a recently developed ferrite rod which is commercially available at low cost. The unit has been incorporated inside the cabinet of a simple VHF domestic portable receiver. It provides adequate signal pick-up and has the advantage of being less disturbed by...
Topics: ferrite, aerial, receiver, rod, portable, signal, circuit, unit, tuned, tuning, maximum signal,...
R&D Report 1982-05 : Carfax': the effects of co-channel interference. M.E. Bailey The Report describes subjective tests performed to ascertain the level of co-channel interference that would be tolerable during the reception of a "CARFAX" announcement, due to other distant "CARFAX" transmissions occurring simultaneously.
Topics: interfering, interference, signals, message, coded, carrier, tests, signal, transmitters,...
R&D Report 1981-04 : VHF radio-data: experimental BBC transmissions. S.R. Ely This report describes in detail a new system for transmitting data signals from vhf radio-broadcast transmitters along with the normal sound-programme signal. These data signals are primarily intended to aid radio listeners in tuning their receivers to a desired station or programme. These data signals are primarily intended to aid radio listeners in tuning their receivers to a desired station or programme. They...
Topics: block, data, synchronisation, code, crc, khz, transmitted, subcarrier, bbc, decoder, biphase...
R&D Report 1981-07 A digital field strength measuring receiver for l.f. and m.f. A.P. Robinson, J.H. Causebrook
Topics: receiver, aerial, field, calibration, tuning, digital, bbc, frequency, oscillator, khz, department...
R&D Report 1988-13 : Investigation of mutual interference between digitally modulated signals. J.D. Newland This report considers the effects of co-channel and adjacent-channel interference on a QPSK modulation system. From previous theoretical studies it identifies an upper and lower error bound. It examines practically how useful these bounds are at predicting the performance of QPSK at various levels of noise and interference. The two error bounds gave a good indication of the error...
Topics: digital, interference, interferer, error, sinusoidal, noise, frequency, qpsk, ratio, constellation,...
R&D Report 1986-04 : Review of VHF Band I field strength prediction. R.S. Sandell, J. Malcolm-Coe The report describes the results of a review of VHF Band I field strength measurements and prediction methods. Most of the measurements were made by the BBC, and many were used in the early Nineteen-sixties to prepare CCIR propagation curves. Modern computational methods have permitted a fuller analysis of the data than has been possible previously. This has led to conclusions about the...
Topics: ccir, prediction, terrain, bbc, antenna, propagation, field, measurements, strength, height,...
R&D Report 1994-11 : High frequency room responses : Acoustic design and the control of stereophonic image quality R. Walker Aspects of mid and high frequency acoustic design are described, mainly in the context of relatively small rooms. The factors affecting the design and some of the difficulties which may be encountered are also discussed. The primary means of evaluating the quality of reproduced sound is the studio control room (and its associated equipment). This Report is written...
Topics: acoustic, sound, absorption, frequency, surfaces, reflections, design, reverberation, diffuse, bbc,...
R&D Report 1955-35 : A television check receiver for band I, Channel I R.E. Jones., C.G. Mayo A television receiver suitable for picture-quality checking is described; it is designed for the reception of double-sideband signals on Channel 1, vision carrier 45 Mc/s. The receiver gives negligible phase and amplitude distortion of modulation frequencies up to 3 Mc/s, and provides 35 dB suppression of the sound carrier on 41.5 Mc/s. The output contains full synchronising pulses and the d.c....
Topics: filter, circuit, amplifier, impedance, receiver, rejection, aerial, frequency, anode, attenuator,...
R&D Report 1964-69 : Production of sinusoidal resolution bar patterns for inclusion in the television Test Cards 'D' and 'E'. T.N.J. Archard, D.H Rumsey, R. Sims The methods previously used for the production of sinusoidal bar patterns are first discussed and their limitations given. A modified form of one of these systems using rotating Polaroid filters and a travelling slit is fully described together with the methods used in determining the various parameters and details of processing of...
Topics: slit, density, polaroid, sinusoidal, rotating, enlarger, bar, patterns, bars, test, sinusoidal...
R&D Report 1969-30 : The contrast law of shadow mask display tubes J.R. Sanders, G.D. Judd Contrast law (gamma) measurements on typical 19 inch (49 cm) tubes are discussed. The value of gamma obtained depends on factors such as first-anode potential, and whether cathode or grid drive is used. In addition, any failure of regulation of tube supplies, video non-linearity or clamp failure, can affect the overall gamma of pictures from different types of monitor or receiver using a particular...
Topics: contrast, law, gamma, patch, drive, potentials, grid, measurements, tube, output, department...
R&D Report 1968-04 : A theoretical study of the application of electronic masking to television A.H. Jones Electronic masking enables a film scanner to be used to recover, from the film, information relating to its original exposure to the scene. This report considers how this may best be done, having regard to requirements for calorimetric accuracy and good noise performance. The suitability of the original exposure to the television display is then examined, and proposals for film...
Topics: masking, analysis, matrix, colour, scanner, signals, dye, film, noise, curves, film analysis,...
R&D Report 1967-32 : A review of vertical aperture correctors W. Wharton, S.M. Edwardson A vertical aperture corrector for television can be constructed in two basic forms. The first of these uses two delays, each of one television line period, whilst the second uses only one such delay and the signal re-circulates, passing more than once through the delay path. The report compares the two basic forms and discusses their relative advantages and disadvantages in the light of practical...
Topics: vertical, aperture, corrector, correction, blanking, correctors, delay, signal, output, picture,...
R&D Report 1967-21 : Guildford UHF relay station: Summary of installation G.H. Millard A brief data sheet detailing frequencies, equipment installed, radiation characteristics etc, including graphs of horizontal and vertical radiation patterns.
Topics: guildford, transmitter, relay, ohm, vertical, installation, technological, horizontal, aerial,...
R&D Report 1972-27 : The measurement of phosphor grain and electrical noise components in the signals from a flying-spot telecine F.A. Griffiths Measurements are frequently made of the signal-to-noise ratios of signals from flying-spot telecines. The results do not indicate whether the measured noise is predominantly photomultiplier noise or due to the static pattern of the phosphor grain of the scanning tube. The methods described attempt to distinguish between noise and grain in order...
Topics: noise, grain, phosphor, telecine, error, tube, ratio, signal, component, measured, noise component,...
R&D Report 1972-01 : A medium-wave field-strength measuring review D.E. Susans, R.D.C. Thoday, M.J. Buckley This report describes a field-strength measuring system for the frequency range 510-1610 kHz. It incorporates a commercially available receiver, with some modifications. The loop aerial used with this receiver is mounted on the roof of a Commer 2000 metal-bodied vehicle. The calibration arrangement, using a specially constructed unit with an oscillator, permits the receiver to give...
Topics: calibration, loop, receiver, tuning, attenuator, output, amplifier, oscillator, aerial, vehicle,...
R&D Report 1970-27 : Satellite broadcasting: An aerial design for domestic reception in the 12 GHz band G.H. Millard A design of aerial suitable for use in Television Band VI (11.7 GHz - 12.7 GHz) is described. The aerial should be capable of mass-production at low cost to meet a possible domestic requirement.
Topics: aerial, ghz, gain, isotropic, satellite, log, broadcasting, aperture, ccir, relative, effective...
R&D Report 1971-23 : Colour film telerecording using a shadow-mask display tube J.D. Lunn The development of shadow-mask tubes with increased luminance has justified an investigation into the feasibility of using such a display in colour-film telerecording equipment. This would represent a considerable simplification over an earlier colour telerecording proposal in which a system of dichroic mirrors superimposed the displays from three separate cathode ray tubes, each carrying a single...
Topics: phosphor, display, luminance, telerecording, matrix, spectral, phosphors, film, colour, luminances,...
R&D Report 1980-02 : Carfax': an example of an f.m. signal generated using digital techniques. P. Shelswell This report describes a method of generating frequency-modulated signals using digital techniques. The digital process introduces little distortion and provides a stable centre frequency. The drive for a "CARFAX" transmitter is described as an example of its application.
Topics: frequency, signal, sampling, carrier, quantizing, noise, modulation, digital, accuracy, analogue,...
R&D Report 1977-21 : Digital video: multiple sub-Nyquist coding. J.H. Stott, G.J. Phillips This Report considers the effect of multiple digital coding of signals, with particular emphasis on sub-Nyquist sampling. Theory is developed which shows that conditions exist whereby no extra degradation due to re-sampling occurs. Experimental work confirming these results is described, and the theory is extended to the use of mixed analogue and digital transmissions, including allowance for...
Topics: filter, sampling, comb, analogue, frequency, coding, digital, response, filters, signal, video...
R&D Report 1985-10 : Digital audio editing G.W. McNally, P.S. Gaskell, A.J. Stirling New techniques are needed for reliable, fast and accurate editing of digital audio. The objective is to provide the facilities to which audio editors have grown accustomed while maintaining high operational speed and precise control, even when a tape is cut. Three levels of performance are discussed. The first and simplest is to cut the tape and use error concealment and electronic crossfading to smooth the...
Topics: audio, data, editing, disc, rio, auxiliary, digital, edit, control, edits, audio editing, edit...
R&D Report 1994-01 : Implementation of amplitude modulation companding using a digital signal processor. C.R.Nokes BBC Amplitude Modulation (AM) radio transmissions have for some time been using amplitude modulation companding (AMC) - a method of companding whose purpose is to reduce the costs of transmission whilst maintaining, as far as possible, the audibility of the radio service. AMC is one form of compression of AM transmissions more generally called dynamic carrier control (DCC). The...
Topics: signal, compression, modulation, amplitude, amc, bbc, carrier, dsp, enhancement, transmitter,...
R&D Report 1992-14 : Building penetration loss measurements for DAB signals at 211 MHz. J.A. Green Digital Audio Broadcasting is being considered as a future method of transmitting radio programmes to the public. Some of the advantages of DAB over conventional Frequency Modulation (FM) include its resistance to multipath and its ruggedness in the presence of interference. Because of these qualities it is ideally suited for reception by mobile and portable receivers. It is proposed that a...
Topics: field, strength, measurements, dab, location, ground, penetration, floor, measured, noise, minimum...
R&D Report 1968-40 : A set of phosphors for use in a colour telerecording display E.W. Taylor, G.D. Judd The spectral and actinic characteristics of three phosphors (red, green and blue) for use in a colour-telerecording display are described. Absorption-type filters are specified for shaping their emission spectra.
Topics: phosphors, phosphor, spectral, actinic, exposure, display, telerecording, cathode, filters,...
R&D Report 1981-03 : Satellite broadcasting: an experimental transmission of television with digital stereophonic sound. J.L.Eaton, R.V. Harvey Satellite Broadcasting tests carried of television with two sound channels digitally modulated onto a subcarrier were carried out through the European Orbital Test Satellite (OTS). The parameters of the sound system (subcarrier amplitude and frequency) were varied during the experiments and error rates were measured in the sound channels. The tests...
Topics: mhz, subcarrier, sound, frequency, carrier, error, bbc, satellite, ots, channel, theoretical error,...
R&D Report 1957-05 : Colour television: The adaptation of the NTSC system to UK standards Part 3: A triple video channel for use with a colour slide or film scanner. A.V. Lord, S.J. Lent A triple video channel has been developed for use with colour slide or film scanning apparatus. This channel includes al the signal correction and modifications necessary to provide standard colour separation signals suitable for coding. An outline is given of the considerations influencing the design; the...
Topics: corrector, signal, afterglow, gamma, output, aperture, correction, characteristic, pulses, pulse,...
R&D Report 1966-11 : Acoustic tests in Dubbing Suite 1, East Block, Television Centre. D.K. Jones The installation of a new Dubbing Theatre and its associated Mixer and Recording Rooms has recently been completed in the East Block at Television Centre. Reverberation times and noise levels were measured in the three rooms and the sound insulation between the rooms taken in pairs was obtained. The results are given in Section 2, and their implications are discussed in Section 3.
Topics: reverberation, mixer, insulation, recording, noise, rooms, theatre, dubbing, sound, room,...