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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 1963-36 : Varotal V. A 10 to 1 zoom lens for the image orthicon format (No 617566) W.N. Sproson Measurements are reported on the zoom lens Varotal V. These include modulation transfer factor, vignetting, transmission and veiling glare and geometrical distortion. An overall assessment based on sharpness and vignetting is given and comparisons are made with other lenses, both of fixed focal-length and of varifocal length.
Topics: focal, aperture, lens, modulation, lenses, length, zoom, varotal, curves, transfer, geometrical...
R&D Report 1965-21 : The Pumbicon camera tube J. Redmond, D.R. Morse, C.B.B. Wood The purpose of this report is to review the present technical performance of the plumbicon tube and to explore Philips' ability to supply the tubes which the Corporation may require for operation in future colour television cameras. The report discusses the current situation and arrives at the conclusion and recommendations which are set out in the main part of the report.
Topics: plumbicon, tubes, tube, camera, bbc, colour, sensitivity, philips, electronica, target, target...
R&D Report 1972-37 : The contrast handling requirements of a colour television display R.N. Robinson A survey of domestic television viewing conditions is described. These conditions were reproduced in a laboratory in order to determine the contrast range of the eye. The dependence of the contrast range visible to the eye upon ambient illumination and upon the form and brightness of the displayed picture have been investigated; these results are then interpreted in terms of the contrast...
Topics: luminance, tube, ambient, display, subjective, reflectance, flare, viewing, contrast, light,...
R&D Report 1971-28 : 16 mm film: Image steadiness in television presentation. Part 1: The measurement of unsteadiness and prediction of subjective impairment D.T. Wright Measurements of the overall steadiness of television film reproduction have shown that the error distribution is often not Gaussian. Since the frequency spectrum of the image displacement (regarding the latter as a function of time) can vary considerably for different films, account must be taken of the relative subjective...
Topics: unsteadiness, vertical, horizontal, subjective, disturbance, disturbances, weighted, picture,...
R&D Report 1965-36 : Statistical survey of scanning amplitudes and aspect ratio of domestic television receivers R.F. Vigurs Measurements have been made on a number of domestic television receivers, operating under normal home conditions, with regard to their settings of horizontal and vertical scanning amplitudes and aspect ratio. These measurements revealed that the accuracies of the adjustments made on installation, and the standard maintained by the receivers, in these respects, were...
Topics: picture, visible, aspect, receivers, distributions, histograms, statistical, width, ratio, 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 1956-01 : The Philips moving-coil microphone Type EL.6040. W.I. Manson Laboratory tests have been carried out on two specimens of the Philips microphone type EL.6040. Measurements of frequency response, sensitivity, impedance and interference from magnetic fields have been made. The microphone has also been tested in the parabolic reflector PRB/2.
Topics: microphone, frequency, ohms, response, ohm, impedance, specimen, output, parabolic, philips,...
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 1964-13 : Line-store standards conversion: The subjective determination of the necessary number of stores A.H. Jones This report gives an outline of measurements made in order to assist in determining then number of stores required in a line-store standards converter. A series of subjective tests was carried out in order to assess the effect of the sampling a television picture at a constant rate, the sampling being coherent from one line to the next. It was found that the...
Topics: sampling, frequency, signal, output, video, image, components, spectrum, interlace, filters,...
R&D Report 1962-01 : Tests of three systems of bandwidth compression of television signals G.F. Newell, W.K.E. Geddes This report describes an investigation into three similar methods of reducing the bandwidth required for the transmission of television pictures. The three methods all involve the isolation of the essential brightness changes in the picture; these are redistributed to occur at a uniform rate for transmission. A second signal must be transmitted in order to allow correct...
Topics: bandwidth, waveform, brightness, pulses, pictures, amplitude, required, picture, quantized, system,...
R&D Report 1964-65 : Field-store converter using ultrasonic delays as the storage medium W. Wharton, E.R. Rout, R.E. Davies In this report, the conversion of television pictures between standards having different field frequencies is discussed and a method is proposed whereby a standards converter capable of conversion between the British 625-line/50 fields and American 525-line/60 fields standards could be realised by the use of ultrasonic delays. Such a standards converter would have a...
Topics: delay, input, output, conversion, converter, fields, lines, field, interpolator, duration, output...
R&D Report 1991-15 : Radio-cameras: the development of radio systems for portable cameras used in television production. C. Gandy Mobile and portable television cameras are often used for television outside broadcasts, and for live programmes, a camera is connected to the vision mixer using either a cable or a radio link. The radio option, now known as a 'radio-camera', has become very popular because it affords the producer greater flexibility in the choice of camera shots. In its simplest...
Topics: antenna, ghz, signal, transmitting, frequency, antennas, propagation, multipath, path, bbc,...
R&D Report 1955-04 : Colour television: The effect of picture-tube-characteristic non-linearity on the brightness of a monochrome compatible picture. D. Maurice It is shown that in a colour television system, using the standard N.T.S.C. method of gamma correction, the deterioration in panchromaticity of the monochrome compatible picture can be reduced by the presence of the dot pattern due to the chrominance sub-carrier. A "notch" or sub-carrier elimination filter is thus...
Topics: luminance, signal, chrominance, brightness, monochrome, equation, tan, arc, filter, transition,...
R&D Report 1963-58 : Measured performance of typical German and American Band IV/V indoor aerials. D.J. Whythe This report describes measurements made on three typical German and three typical American domestic indoor receiving aerials designed for television reception in Bands IV and V. The effective gain (relative to a half-wave dipole) and the horizontal radiation pattern of each aerial are given at 522 Mc/s, 666 Mc/s and 778 Mc/s.
Topics: aerial, feeder, aerials, coaxial, balanced, dipole, horizontal, radiation, hilo, model, indoor...
R&D Report 1994-16 : Digital Audio Broadcasting: Comparison of coverage at Band II and Band III. I.R. Pullen, P.J. Doherty, M.C.D. Maddocks A Digital Audio Broadcasting (DAB) system capable of reliable reception in vehicles and portables has been developed by the EUREKA 147 project. This Report describes a set of experiments performed to compare the coverage area when radiating a DAB signal of equal power in Band II and Band III. It is concluded that a slightly lower level of signal...
Topics: band, dab, signal, iii, variation, mhz, transmitter, coverage, map, bbc, transmitting equipment,...
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R&D Report 1955-36 : Sound level distribution in concert halls. M.W. Greenway, T. Somerville, F.L. Ward. This report describes measurements recently carried out in five concert halls to determine the difference in sound level between the seats close to the orchestra and those at the back of the hall. The source of sound was an orchestra in all cases and measurements were made both during rehearsals and public performances.
Topics: level, reverberation, hall, reflector, microphone, halls, reverberant, sound, stalls, direct,...
R&D Report 1974-09 : Subjective study of two large music studios W.N. Sproson Users of two BBC large music studios (Maida Vale 1 and Glasgow 1) were asked to give their opinions on various acoustic characteristics of these studios using a specially devised questionnaire. Three statistical methods of analysing the raw data were used and the results obtained are outlined in this report. One aspect of the work concerns users' views on what would constitute an 'ideal' music studio and these are...
Topics: studio, maida, vale, variables, analysis, tone, coefficient, characteristics, timbre, ensemble,...
R&D Report 1955-01 : Mutual interference between naval radar and VHF FM broadcasting in Band II -- B.B.C. and A.S.R.E. tests R.A. Rowden, D.G. Beadle, G.I. Ross, D.E. Susans, K.H. Green Tests were carried out by the Admiralty Signal and Radar Establishment and the B.B.C. Research Department to investigate the mutual interference likely to arise from the co-channel operation of naval radar sets Type 281 and Type 960 with VHF FM broadcasting stations. Specific measurements and observations on...
Topics: interference, type, radar, wrotham, strength, broadcasting, tests, field, set, naval, radar sets,...
R&D Report 1994-14 : The sound insulations of studio doors: Part 1: Door Blanks G.D. Plumb, R. Clark The sound insulations of a range of different door blanks were measured. The results were compared with the sound insulations of existing BBC door blanks. The new doors were made from medium density fibreboard (MDF) which is more stable than the blockboard used in existing studio doors. Consequently, they should require less maintenance and adjustment and should have a longer lifespan. The...
Topics: mdf, door, insulations, bitumen, damping, measured, bbc, sound, acoustic, lightweight, band centre,...
R&D Report 1985-16 : Digital coding ranges for use in an all-digital sound studio complex. W.I. Manson This Report considers principally the sound-signal coding-range requirements for different applications in a digital studio complex, excluding the internal requirements of processing equipment, such as control desks, etc. It is suggested that the most demanding requirements should be met by a coding standard of 22 bits/sample for uncontrolled sound signals. With manual control the coding...
Topics: digital, coding, signals, signal, analogue, sound, bbc, range, standard, uncontrolled, controlled...
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 1967-39 : UHF transmitting aerial for the Llanddona television station G.H. Millard A u.h.f. transmitting aerial for the Anglesey and North Wales area has been built as a top-mast on the existing BBC mast at Llanddona. The station started trade tests on 20th May 1967 and full service on 3rd June 1967.
Topics: channel, aerial, vision, transmitter, carrier, feeder, radiation, horizontal, stockholm,...
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,...
C.D. Mathers, K.F.L. Lansdowne Exposure to high sound levels can cause damage to the auditory system, either gradually over a period of time, or, in the case of very intense sounds, instantaneously. Particular care is therefore required in the use of headphones, which are capable of generating much higher effective sound levels than loudspeakers. This report summarises the results of a series of tests which show that headphone wearers tend to listen at significantly higher levels than...
Topics: headphone, hearing, levels, headphones, tests, artificial, ear, sound, loudspeakers, listening,...
R&D Report 1978-07 : Computation of groundwave attenuation over irregular and inhomogeneous ground at low and medium frequencies. G.D. Monteath A computer program based on an integral equation due to Hufford has been written to calculate groundwave field strength at low and medium frequencies. Account is taken of arbitrary variation of the ground constants and the height above sea level along the path of propagation. A variety of tests show the program to be fast and the results accurate....
Topics: attenuation, calculation, factor, equation, spherical, surface, interval, plane, ground, earth,...
R&D Report 1991-12 : The Beverage antenna: a practical way of assessing the radiation pattern using off-air signals. A.G. Lyner This report describes a method for assessing the performance of a Beverage, long wire, receiving antenna using off-air HF broadcast signals. The method was used to assess the improvement in performance which should result from using a lower wire antenna. It indicated a 5 dB improvement in all-round rejection of off-beam interference for the antenna which was...
Topics: antenna, beverage, sensitivity, signals, pattern, induced, polarised, wire, signal, transmission,...
R&D Report 1993-06 : Metal-framed partitions with reduced thicknesses: Part 2 -- Built-in acoustic treatment. G.D. Plumb Laboratory measurements were made of the sound insulations and absorption coefficients of a range of metal-framed partitions having built-in acoustic treatment. The optimum constructions for single and double leaf absorbent partitions had marginally lower sound insulations (approximately 1 dB) than those of comparable single and double metal-framed Camdens. The effective...
Topics: partitions, absorption, partition, sound, insulation, unperforated, perforated, leaf, acoustic,...
R&D Report 1987-19 : Designing variable-length codes with good error-recovery properties. M.J. Knee An algorithm for calculating the expected resynchronisation time of a variable-length code following a transmission error is described. The results of calculations based on examples are used, together with insights gained from a simplification of the algorithm, to determine the effect on the expected resynchronization time certain easily recognizable design features of codes. The report...
Topics: code, error, codes, codewords, resynchronization, probability, algorithm, codeword, sequence,...
R&D Report 1970-18 : Pulse code modulation for high quality sound distribution: Quantizing distortion at very low signal levels M.G. Croll In PCM systems, distortion of very low level signals is known to occur, and in high-quality programme distribution it is the most objectionable signal degradation caused by this kind of system. This report describes a series of subjective tests which show that it is necessary to use 14 bits per sample to code the audio signal in order to make this form...
Topics: distortion, granular, quantizing, noise, system, attenuator, input, signal, level, inaudible,...
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R&D Report 1959-23 : Long distance overland propagation measurements at 180.4 Mc/s. J.W. Stark, K.H. Green, S.J. Ashdown, J.M. Caine, I. Rhodes This report presents the results of field strength measurements of v.h.f. transmissions on 180.4 Mc/s overland paths at distances up to 294 miles (473 km). These measurements extended over a period of approximately 3 1/2 years and have been used in the preparation of field strength/distance curves for various percentages of the overall time. The...
Topics: site, field, strength, pontop, propagation, receiving, coldfield, mursley, trees, sutton, permanent...
R&D Report 1973-20 : An investigation into a proposal for a simplified television field synchronisation signal G.M Le Couteur, P.H.C. Legate This report concerns a proposal which relates to a simplification of the 625/50 television field synchronisation signal; the object of the proposal is to reduce the duration of the synchronisation signal so as to leave more time in the field blanking interval for the transmission of data, test signals etc. The work described in this report was...
Topics: equalising, pulses, pulse, receivers, waveform, field, interference, synchronising, pre, receiver,...
R&D Report 1976-15 : The wave-tilt method of measuring electrical ground constants in the LF and MF bands. J.L. Eaton The theory of the wave-tilt method of determining ground constants (conductivity and permittivity) at lf and mf is outlined and the limitations of the theory in practice is discussed. Typical instrumentation for conducting wave tilt measurements is mentioned and the effect of measurement errors assessed.
Topics: constants, ground, tilt, axial, plane, surface, measurement, method, bbc, ellipse, measurement...
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 1987-09 : A digital audio link to the Channel Islands in the UHF television band: preliminary experimental results M.C.D. Maddocks A digital link at UHF has been proposed as a means of feeding radio programmes over the long sea path to the Channel Islands. An experimental link has been installed to test the viability of such a proposal. Results from the first five months of operation are presented in this Report.
Topics: link, signal, measured, uhf, performance, predicted, field, digital, data, strength, wanted signal,...
R&D Report 1954-01 : The service area of the temporary television transmitters at Truleigh Hill, Pontop Pike and Glencairn. G.I. Ross This report gives the results of a survey of the service areas of the temporary low power transmitters at Trueleigh Hill, Pontop Pike and Glencairn. Tests in the service area of the Glencairn transmitter revealed that echo effects (ghosts) are not serious and are readily eliminated. Reference is made to the deterioration in the service that may expected when...
Topics: pontop, truleigh, strength, pike, temporary, transmitters, transmitter, field, field strength,...
R&D Report 1962-10: V.H.F. sound broadcasting: Mutual interference between transmissions with 100 kc/s channel separation radiating either the same or different programmes. J.G. Spencer Subjective tests have been carried out, using four recent models of domestic a.m./f.m. sound receivers, to determine to permissible ratio of wanted- to unwanted-carrier levels when an interfering f.m. transmission is spaced by 100 kc/s from a wanted f.m. transmission and is broadcasting either the same or a...
Topics: interference, signal, ratio, programme, frequency, transmission, receiver, interfering, modulation,...
R&D Report 1962-45 : 405-line and 625-line television pictures: The relative impairment produced by random noise. W.K.E. Geddes Subjective assessments have been made, for 405-line and 625-line television pictures, of the impairment produced by addition of random noise to the video signal. It has been found that, for equal impairment, the signal-to-noise ratio must be about 2 dB for a 405 line picture for a 625-line picture.
Topics: noise, subjective, bandwidth, impairment, ratio, random, attenuator, triangular, flat, television,...
R&D Report 1965-05 : Surface-wave feeders for U.H.F. site tests D.E. Susans This report describes experimental surface-wave feeders and launching horns for use with balloons for u.h.f. site tests. The general problems associated with design of this type of transmissions system are discussed together with the results on some practical feeders and horns.
Topics: horn, feeder, cable, dielectric, conductor, loss, feeders, balloon, power, conical, launching horn,...
R&D Report 1972-29 : The feasibility of correcting for failure of constant luminance in a colour television system D.T. Wright In a colour television transmission system such as the PAL system a constant-luminance failure is caused because the red, green and blue separation signals used to form the chrominance and luminance signals are not linearly related to the light outputs required from the red, green and blue display picture-tube phosphors. As a result, not all of the displayed picture...
Topics: luminance, signal, correction, colour, saturated, corrected, displayed, signals, frequencies,...
R&D Report 1970-28 : A PCM sound-in-syncs system for outside broadcasts C.J. Dalton The standard Sound-in-Syncs system that has been developed for use on distribution networks has shortcomings when used on temporary links of poor quality. A ruggedised version is described which, in exchange for a reduction in audio bandwidth and signal-to-noise ratio, provides sound and vision circuits over links which have been degraded to an extent where they would normally be regarded as unusable. Field...
Topics: sound, pulse, signal, sync, input, syncs, pulses, video, ruggedised, separator, restored video,...
R&D Report 1991-02 : Digital Audio Broadcasting: the first UK trial. P. Shelswell, C.P. Bell, J.H. Stott, S.Wakeling, M.C.D. Maddocks, J.H.Moore, P.R.Durant, R.F.Rudd In February and March of 1990, the BBC was offered equipment for transmission and reception of Digital Audio Broadcasting signals using COFDM (Coded Orthogonal Frequency Division Multiplex) and MASCAM (Masking-pattern Adapted Sub-band Coding and Multiplexing). This report gives details of the trials that were carried out in...
Topics: frequency, signal, cofdm, system, kenley, digital, crystal, reception, signals, receiver, active...
R&D Report 1985-03 : Further developments of CCD line-array telecine. I. Childs In recent years there have been several advances in technology relevant to the use of solid-state line-array sensors in telecine applications. This Report will examine the improvements in performance of recent generations of line-array sensors, together with the further benefits obtainable by using improved signal processing. The use of digital storage as a necessary part of a line-array telecine also opens up...
Topics: film, dirt, sensor, concealment, telecine, scan, output, signal, sensors, ccd, double sampling,...
R&D Report 1954-13 : The Klein-Plessey Ionophone loudspeaker. J.R. Chew A novel type of loudspeaker, known as an "Ionophone", has been tested. In this loudspeaker the conventional vibrating diaphragm is dispensed with and the sound is produced by a modulated r.f. corona discharge. The device is used in conjunction with a horn radiator and its main field of application is therefore in the high-frequency range; smooth response can be obtained up to at least 20 kc/s. In its present...
Topics: frequency, ionophone, horn, distortion, output, tuning, loudspeaker, axial, corona, overload,...
R&D Report 1965-37 : Class-AB amplifiers employing a complementary pair of transistors: Improved method for negative feedback J.B. Izatt This note describes a method of applying current negative feedback to transformerless audio class-AB transistor stages. The output impedance of the circuit is very high but the circuit may also be conveniently adapted to provide a matched output resistance, for example, for a 600-ohm line.
Topics: output, feedback, circuit, current, transistors, transistor, impedance, amplifier, distortion,...
R&D Report 1972-32 : A note on dichroic gratings for colour encoding K. Hacking The information-encoding action of a pair of dichroic gratings (sometimes known as striped filters) is analysed in general terms, using the effect on the spatial frequency spectrum of the image of a scene to reveal their intrinsic properties. Two colour-television camera systems based on a single pick-up tube are discussed, and an attempt is made to assess the physical tolerances required in the construction of...
Topics: gratings, grating, spatial, frequency, encoding, outputs, spectral, dichroic, filtering,...
R&D Report 1973-21 : Digital transmission codes: Preliminary investigation of HDB3 and related ternary codes for broadcast signal distribution. T.A. Moore An investigation has been carried out to assess the implications for broadcast signal distribution of the use of HDB3 as the proposed customer interface code in the Post Office digital communication network. HDB3 is a three-level transmission code with no DC component and with a bound on the maximum number of successive equi-level...
Topics: transmission, binary, signal, bipolar, errors, code, codes, error, digital, ternary, digital...
R&D Report 1986-08 : The measurement of large values of airborne sound insulation. R.Walker The requirements for and the measurement of airborne sound insulation between areas in a broadcasting centre are discussed. In particular, the high values of insulation required in some cases and the difficulties of measurement are described. One method which has been used for such measurements, using explosive charges, has been investigated in detail. Some of the results obtained in the past using...
Topics: sound, measurement, insulation, signal, level, noise, frequency, pressure, overload, acoustic, peak...
R&D Report 1976-33 : UHF field strength measurement of the ATS-6 satellite J. Middleton Space technology can now provide a geosynchronous satellite capable of radiating over 100 kW EIRP within the UHF band. Therefore the question of interference to existing or planned television services sharing this band merits investigation whenever the opportunity arises. The report describes a series of measurements undertaken to establish whether the ATS-6 UHF aerial used for transmitting an...
Topics: bbc, strength, mhz, field, signal, receiver, aerial, satellite, broadcasting, measurement, field...
R&D Report 1963-05 : Photographic film grain: A study with the aid of an optical correlator. K. Hacking The autocorrelation and power-spectrum approach to the problem of describing near-random functions of time in electrical communications systems is applied to the objective description of the underlying granular structure of photographic images. The analogy between random electrical noise and emulsion granularity seems even more direct when considering television applications of film,...
Topics: emulsion, grain, wiener, transmission, function, spectrum, granularity, autocorrelation, emulsions,...
R&D Report 1962-06 : The Visibility of small brightness differences in television displays. G.F. Newell, W.K.E. Geddes This report describes measurements of the smallest brightness difference which can be reliably identified in television displays. The amplitude of the brightness difference is plotted as a function of the brightness level at which it can be just recognized. An estimate is made of the number of discrete levels into which a television picture should be quantized in order to...
Topics: brightness, numerals, waveform, picture, amplitude, superimposed, visibility, levels, monitor,...
R&D Report 1972-17 : A UHF aerial for elliptical polarisation G.H. Millard, J.H. Moore, N.F. Spring A special aerial was made for tests of a proposal to reduce tidal fading to be carried out from the Rosneath site. It consists of a vertically-polarised printed panel aerial modified by the addition of a single horizontal dipole, fed with current of appropriate amplitude and phase.
Topics: aerial, polarised, component, polarisation, aerials, height, bbc, horizontal, batwing, elliptical,...
R&D Report 1972-18 : Pulse-code modulation for high-quality sound-signal distribution: Protection against digit errors J.R. Chew, M.E.B. Moffat Techniques for protecting a high-quality sound-signal pulse-code modulation (PCM) distribution system against bit-errors are compared. The criteria for choosing a technique suitable for a particular PCM transmission system are discussed. The optimum choice for binary PCM transmission of the sound signals via SHF radio links is shown to comprise a...
Topics: error, errors, signal, concealment, subjective, analogue, extrapolation, muting, digital,...
R&D Report 1980-11 : Colour operation of a solid state sensor telecine. I. Childs An experimental colour film scanner has been constructed using solid state CCD image sensors. Such a scanner should give improved reliability and ease of maintenance together with good picture quality. Various technical aspects of performance are discussed and the picture quality is shown to be in most respects at least as good as that of a flying spot scanner. One possible exception is the noise level, which...
Topics: sensor, sensors, ccd, noise, colour, signal, frequency, sensitivity, spatial, response, light...
R&D Report 1966-04 : Acoustic tests on the Walker Memorial Hall, Birmingham. C.L.S. Gilford, T.J.B. Smith Acoustic tests carried out before and after modifications to the Walker Memorial Hall, Birmingham are described. Floor resonances which caused unacceptable musical quality satisfactorily removed.
Topics: reverberation, measurements, floor, studio, decay, accelerometer, cubicle, acoustic, resonances,...
R&D Report 1966-05 : Colorimetric analysis of interference in colour television. K Hacking The report commences with a study of the effects of perturbing one or more of the primary stimuli in three-primary additive colour systems, and develops formulae for computing the magnitude of these effects. The interpretation of some fundamental relationships in terms of the geometrical configuration of the chromaticity co-ordinates of the primary stimuli on a colour diagram is shown to be useful....
Topics: luminance, primaries, chromaticity, noise, transmission, ntsc, chromatic, colour, component,...
R&D Report 1972-04 : Interference characteristics of dual-standard monochrome television receivers operating in the UHF bands C.R.G. Reed This report gives the results of a series of measurements made in 1970 on the interference-rejection characteristics of six British monochrome dual-standard (Systems A and I) receivers operated in the UHF bands (Bands IV and V) using System I.
Topics: receiver, interference, signal, channel, mhz, amplitude, receivers, frequency, signals, carrier,...
R&D Report 1970-29 : LF/MF receivers with synchronous demodulation for double- or single-sideband transmissions K. Hacking, D.E. Susans The theoretical and practical requirements for introducing synchronous demodulation into domestic receivers for MF/LF broadcasting are discussed. The difficulties encountered in the construction and operation of experimental receivers with an optional synchronous mode of demodulation are outlined. Subjective tests were carried out with these receivers, both...
Topics: synchronous, carrier, demodulation, demodulator, fading, modulation, frequency, receiver,...
R&D Report 1976-27 : A UHF programmable digital field strength measuring receiver. M.W. Harman A description is given of a field strength measuring receiver suitable for measuring broadcast television signals between 470 and 854 MHz. It represents a re-design of an earlier model with digital readout. It gives facilities for automatic operation which permits surveys to be carried out more effectively.
Topics: receiver, frequency, counter, digital, oscillator, output, mhz, signal, display, detector, strength...
R&D Report 1979-19 : Ground-wave propagation in a realistic terrain. J.H. Causebrook, B. Tait LF and MF ground-wave propagation over a realistic terrain has been found to be very different to that over an assumed smooth earth. This report describes the basic nature of these differences, which include a non-simple relationship for field variation with distance and a non-free-space relationship between magnetic and electric fields. The theory of why these effects occur is summarized, and the...
Topics: field, khz, magnetic, electric, terrain, clutter, transmitter, measurements, bbc, impedance, free...
R&D Report 1984-18 : Acoustic scaling: a re-evaluation of the acoustic model of Manchester Studio 7. R. Walker The reasons for the reconstruction and re-evaluation of the acoustic scale model of a large music studio are discussed. The design and construction of the model using mechanical and structural considerations rather than purely acoustic absorption criteria is described and the results obtained are given. The results confirm that structural elements within the studio gave rise to...
Topics: acoustic, model, absorption, reverberation, scale, ventilation, frequency, studio, bbc, modelling,...
R&D Report 1994-12 : A wideband absorber for television studios. M.D.M. Baird The acoustic treatment in BBC television studios has taken various forms to date, all of which have been relatively expensive, some of which provide inadequate absorption. An investigation has been conducted into the possibilities of producing a new type of wideband absorber which, would be more economic, also taking installation time into account, than earlier designs. This Report describes the absorption...
Topics: absorption, absorber, wideband, frequency, acoustic, mineral, bbc, zintec, weldmesh, absorbers,...
R&D Report 1964-19 : Measured performance of Plumbicon camera tubes November 1963 C.B.B. Wood The performance of ten sample Plumbicon television camera tubes has been measured and the results are discussed. To determine the practical importance of known defects of the tube in its present form, further operational trials are desirable.
Topics: plumbicon, tube, tubes, resolution, signal, response, measured, camera, plumbicons, image, peak...
R&D Report 1995-10 : A method for the calculation of tolerances for display primary chromaticity coordinates. A. Roberts The manufacturers of displays for television and other visual display systems are rarely given sufficient information to ensure that their products perform satisfactorily. Typically, parameters such as the peak brightness and primary chromaticities, transfer characteristic and illumination uniformity are supplied, but this information is usually generic, it does not refer...
Topics: ebu, error, tolerances, primaries, zones, vertex, primary, tolerance, extrinsic, colour, primary...
R&D Report 1964-57 : UHF field trials 1962/63: measurements of vision, chrominance and sound field strengths made in channels 34 and 44 in the London area W. Wharton, E. W. Taylor Statistical information is given concerning the ratios of the vision, sound and chrominance field strengths of colour television signals radiated in Channels 34 and 44. This information is based on measurements made by mobile laboratories in the London area during the 1962/63 U.H.F. Field Trials.
Topics: field, chrominance, channels, strength, ratio, measurements, strengths, channel, trials, luminance,...
R&D Report 1966-19 : The Sennheiser Type MKH 805 microphone. H.D. Harwood This report describes tests carried out on a capacitor type end-fire line microphone made by the German firm of Sennheiser. The head amplifier has transistor circuits and radio frequency biassing of the capsule. Measurements have been made of the frequency characteristics on the axis and at a number of angles to it; the degree of interference from wind and from magnetic fields has also been determined. The quality of...
Topics: frequency, sennheiser, microphone, noise, directional, impedance, mkh, type, measurements,...
R&D Report 1975-33 : A field strength measuring receiver for Band II D.G. Beadle, J.A. Fox This Report describes a receiver designed for the investigation of reception conditions for both monophonic and stereophonic broadcasts using the pilot tone stereo system in the band 87-108 MHz. The design is intended to replace two earlier receivers and, in addition, provides commercial quality stereo reception for assessment of the stereo service provided in any area. These requirements are somewhat...
Topics: receiver, khz, multipath, calibration, mhz, output, oscillator, frequency, display, strength,...
R&D Report 1991-13 : Developments in multichannel sound for HDTV D.J. Meares New sound systems are being developed to accompany HDTV which will generate better listening experiences for the audience. This Report outlines some of the intended improvements and, by way of an example, illustrates some of the production problems that will have to be overcome before the proposals can be implemented. It also discusses the domestic impact of the systems.
Topics: sound, surround, hdtv, bbc, channel, multichannel, channels, loudspeakers, loudspeaker, frontal,...
R&D Report 1989-03 : Some properties of antivibration mounts used in building isolation. C.D. Mathers, R. Walker The isolation of studios from groundborne vibration in order to achieve a quiet acoustic has been a major concern within the BBC for many years. About four years ago, a project was undertaken in which the significant factors in building isolation were investigated; one of these factors was found to be the non-ideal behaviour of antivibration mountings (some more than others)....
Topics: isolation, avm, helical, springs, behaviour, rubber, steel, vibration, spring, antivibration, total...
R&D Report 1970-33 : Multiple wall weathershields for UHF aerials C.D. Mathers Calculations have been made of the effective reflection coefficient, as a function of frequency, of cylindrical weathershields comprising one, two or three dielectric walls. The effect of a dielectric infill between the walls is also considered.
Topics: dielectric, spacings, wall, spacing, mhz, walls, cylinder, band, bandwidth, constant, air spacings,...
R&D Report 1978-29 : 'CARFAX' traffic information service: a general description of the ring system. S.M. Edwardson This report is one of a series concerned with the proposed BBC "CARFAX" traffic information system. It discusses a problem encountered with an earlier proposal and describes the ring system as a possible solution to this problem. The report also looks in general terms at the features and options of the ring system.
Topics: receiver, transmitter, transmitters, signals, bbc, activation, signal, ring, radiated,...
R&D Report 1996-08 : The COFDM Modulation system: The heart of Digital Audio Broadcasting. P. Shelswell Digital audio broadcasting offers the potential to give every radio in Europe the sound quality of a compact disc. To accomplish this, it requires a rugged method of transmission. The coded orthogonal frequency division multiplexing (COFDM) modulation system was developed to meet this need. This Report describes the reasons why a new modulation process was needed, and explains how the...
Topics: symbol, cofdm, signal, frequency, bbc, modulation, carriers, digital, dab, fourier, modulation...
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 1962-38 : The Fernseh standards converter: Visit to Rome and Darmstadt 16th - 19th July 1962. P. Ranger, E.R. Rout The report gives an overview of the visit to Rome and Darmstadt in July 1962 by members of the department to discuss, The Fernesh Standards Converter.
Topics: converter, flicker, vidicon, conversion, display, lag, standards, fernseh, portrayal, camera, scale...
R&D Report 1962-46 : The Service area of the Les Platons VHF sound transmitters (1962). M.J. Buckley, J.H. Stewart This report gives the results of a field strength survey of the v.h.f. sound transmissions radiated from Les Platons in Jersey and Guernsey. Most of Jersey gets a satisfactory service, but about one fifth of the island of Guernsey is not served. An Engineering Information Department (E.I.D.) survey showed that the v.h.f. service in Sark from Les Platons is satisfactory but...
Topics: les, platons, strength, transmitters, ville, aerial, guernsey, field, les platons, receiving, field...
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...