Skip to main content
Internet Archive's 25th Anniversary Logo

BBC Research and Development Reports

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



rss RSS

1,337
RESULTS


Show sorted alphabetically

Show sorted alphabetically

SHOW DETAILS
up-solid down-solid
Prior Page
eye
Title
Date Published
Creator
R&D Report 1977-06 : CEEFAX: measurement techniques M.G. Croll New techniques have been developed to measure the characteristics of a CEEFAX waveform and to assess the performance of a CEEFAX installation. Methods are discussed for measuring the normal CEEFAX waveform in terms of its level and other factors which affect the CEEFAX service at a receiving installation. Techniques are also described for assessing the CEEFAX performance of signal paths using special test signals. The techniques...
Topics: ceefax, waveform, data, signal, oscilloscope, measurement, eye, display, horizontal, pulse,...
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 1977-22 : An aerial diversity switch for the Channel Islands television re-broadcast link. G.H. Millard, H.M. Price The report describes an experimental diversity switch which operates during the field blanking period of the television waveform. The switch is solid state and operates very rapidly to minimize the disturbance to the television waveform. The results of an experimental period of operation are given.
Topics: diversity, signal, switch, signals, threshold, attenuator, video, receiver, ratio, aerial, video...
R&D Report 1983-17 : Digital audio: dynamic range control of digital audio signals. G.W. McNally Digital methods for control of the dynamic range of digitally coded audio signals are described. Block diagram representations are given for both the realisation of static and dynamic characteristics of a dynamic range controller. The methods for calculating coefficients representing the controlling parameters are derived and the effect of restricting the accuracy of the processing by the use of...
Topics: digital, dynamic, control, input, drc, range, gain, signal, output, audio, block diagram, audio...
R&D Report 1985-14 : The performance of a satellite link using the BBC Transportable Earth Station with EBU-leased capacity in the European Communication Satellite system. C. Gandy The Report describes a series of tests on a satellite link established between the BBC Transportable Satellite Earth Station and a BTI fixed earth station using an EBU-leased transponder on the ECS 2 satellite. The transmitted power was limited to comply with new regulations imposed by the satellite operator, but...
Topics: tes, satellite, tests, operating, conditions, dbw, ecs, bbc, transponder, earth, fading margin, bbc...
R&D Report 1987-06 : A review of the semiconductor storage of television signals: Part 2 -- Applications 1975 - 1986. J.L. Riley This is the second of two reports. In the first, the emerging semiconductor memory technology over the last two decades and some of the important operational characteristics of each ensuing generation of device are described together with the design philosophy for forming the devices into useful tools for the storage of television signals. This second report...
Topics: store, data, video, memory, storage, delay, devices, picture, control, television, memory devices,...
R&D Report 1988-02 : The assessment of the colorimetric properties of light sources for use in television scene lighting. E.W. Taylor An account is given of the Television Consistency Index method of assessing the colorimetric properties of light sources for use in television scene lighting. Theoretical limits have been determined within which this Index may be used as a general description of lamp performance, bearing in mind the inevitable differences in spectral analysis characteristics...
Topics: consistency, colour, lamp, test, camera, reference, values, television, analysis, spectral,...
R&D Report 1969-49 : A narrow band audio spectrometer K.F.L. Lansdowne This report describes a narrow-band spectrometer primarily intended to investigate speech colourations in small studios; a readily-portable version would be a useful instrument for many other investigations.
Topics: filter, spectrometer, speech, bandwidth, spectrum, outputs, colourations, sampling, frequency,...
R&D Report 1972-13 : The performance of a non-synchronous AM detector designed to remove asymmetric-sideband distortion N.H.C. Gilchrist Asymmetry between the upper side-band and the lower side-band of an amplitude-modulated signal gives rise to distortion of the signal in receivers employing envelope detectors. The use of a synchronous detector removes the problem of asymmetric-sideband distortion. An alternative, non-synchronous, detector has been developed which could replace the...
Topics: detector, carrier, enhancement, modulation, khz, distortion, signal, envelope, sideband, grade,...
R&D Report 1954-25 : Visibility of random noise in a television picture M. Gilbert This report describes an investigation into the relative visibility of narrow bands of noise within a 3 Mc/s video bandwidth. This is an essential preliminary to the assessment of the relative annoyance of different types of noise spectra on the television picture. A set of curves has been deduced and a suitable network has been proposed.
Topics: noise, visibility, attenuation, annoyance, band, frequency, random, threshold, score, bands,...
R&D Report 1954-30 : The measurement of the vertical polar diagram of medium-wave transmitting aerials - summary of two methods. R.A. Rowden, L.F. Tagholm, D.E. Susans, D.N. Cudlip This report describes two methods for the measurement of the vertical polar diagrams of medium-wave aerials. A practical example of the application of both the methods is given as the results of measurements made on the high mast radiator at Bookman's Park on 877 kc/s. One of the methods employs a direct...
Topics: pulse, aerial, output, pulses, frequency, anode, transmitter, polar, consists, cathode, tuned...
BBC Research and Development Reports
texts

eye 150

favorite 0

comment 0

R&D Report 1956-19 : Low power television transmitters -- Rosemarkie. C.J. White, D.W. Taplin, R.S. Sandell, J. Hall This report gives the results of tests at the site selected for a television transmitter at Rosemarkie, near Inverness. It is shown that a low power transmitter at Rosemarkie will provide most of the population in the Dornoch and Moray Firth areas with a satisfactory television service. Reception tests show that the Meldrum television transmission should provide a...
Topics: aerial, meldrum, rosemarkie, television, strength, site, field, transmitter, dornoch, median,...
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 1961-12 : AKG electrostatic microphones Types C26 and C28. H.D. Harwood, J.R. Chew, R.L. Deane, R.J. Packer This report describes tests on two electrostatic microphones manufactured by the Akustische und Kino-Gerate Gesellschaft (A.K.G.). The first, type C26, has omnidirectional and the second, type C28, cardioid characteristics. The microphones are of small dimensions and provision is made in each case for introducing an extension piece between the capsule and the head...
Topics: type, microphone, capsule, extension, interference, impedance, characteristics, frequency, noise,...
R&D Report 1964-08 : Stereophony: the effect of difference between the phase-frequency characteristics of left and rights channels H.D. Harwood, W.I. Manson, D.E.L. Shorter In a stereophonic transmission system, differences between the phase-frequency characteristics of the left - and right-hand channels may result in displacement or dispersion of the sound images across the stage, may also impair the volume or quality of the compatible monophonic programme. These effects have been...
Topics: interchannel, phase, frequency, stereophonic, compatible, monophonic, curve, difference, upper,...
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 1964-16 : UHF amplifier and distribution unit D.E. Susans This report describes a simple single-transistor u.h.f. amplifier suitable for use either as a low noise pre-amplifier for a receiver or as a mast-head amplifier remote from the receiver. The amplifier, with a gain of 12 dB, can be made for use at any single Band IV and V television channel. A bridge distribution unit is also described which enables the output of the amplifier or other u.h.f. source to be split into four...
Topics: amplifier, distribution, input, bridge, transistor, unit, output, circuit, outlets, cable,...
R&D Report 1966-43 : Simple application to broadcasting of the results of subjective tests. R.D.A. Maurice The report discusses some different scales of criteria suitable for subjective tests for broadcasting applications and mentions a method of using the statistical results of subjective tests that may make maximum use of them aid management decision making.
Topics: subjective, impairment, grade, assessments, gaussian, statistical, tests, broadcasting, percentage,...
R&D Report 1965-52 : Some applications of birefringent polarizing prisms in flying-spot scanning K. Hacking The properties of Wollaston birefringent polarizing prisms are examined. The device is shown to be useful as a means of obtaining twin scanning-spots in a flying-spot film scanner. Outline suggestions are given for the possible application of twin-spot scanning, in the simulation of standards conversion and vertical aperture correction in pictures.
Topics: prism, scanning, wollaston, aperture, optical, polarizing, prisms, correction, output, field,...
R&D Report 1965-53 : Band III transmitting aerial for the Sandale television station D.W. Osborne A summary of the Band III transmitting aerial for the Sandale Television Station.
Topics: aerial, transmitting, sandale, horizontal, tier, transmitter, height, band, templet, mast,...
R&D Report 1971-16 : A brief investigation into the permissable amplitude modulation of a UHF television sound carrier A. Brown Abstract This report considers the amount of amplitude modulation which can be permitted to occur on the sound carrier of UHF Standard I television transmissions. Some brief subjective tests have been carried out using domestic receivers, and these show that slight impairment of the sound signal may occur with the amount of intermodulation occurring in existing...
Topics: sound, amplitude, modulation, carrier, spurious, impairment, variation, vision, receiver, signal,...
R&D Report 1969-13 : The subjective effect of frequency shift in the transmission of high-quality sound signals W.I. Manson This report describes tests carried out to determine the subjective effect, on the reproduction of high-quality sound signals, of shifting the frequency of each spectral component by the same amount. The results obtained are discussed and suggestions made for a working tolerance.
Topics: frequency, shift, observers, tests, impairment, session, subjective, test, quartet, grading,...
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 1968-56 : An investigation of head clogging on transverse-scan video tape recorders M.E.B. Moffat The investigation involved both work within the BBC and co-operation with interested parties outside the Corporation. Results are given of both qualitative and quantitative surveys of the problem. Poorly manufactured tape was generally blamed for head clogging, but it was found that some other factors were almost as much to blame, notably damaged headwheels and improper environmental...
Topics: clogging, tape, headwheel, video, coating, bbc, recorders, head, clogged, headwheels, air...
R&D Report 1969-23 : An automatic method for the measurement of reveration-time M.E.B. Moffat, N.F. Spring The automatic measurement of reverberation-time includes the making of a special recording which is characteristic of the studio or other room tested; equipment subsequently selects the required signals from the recording, converts them to digital form and punches a paper tape describing relevant characteristics of the signals. Reverberation-times may then be calculated using suitable...
Topics: reverberation, decay, signal, adc, amplifier, jump, studio, tape, reset, test, logarithmic...
R&D Report 1969-43 : A camera tube lag meter M.J. Mortimore, I.D. Chisholm The exposure of a camera tube to a brief flash of light and the measurement of the magnitude of the signal current after a known number of television fields can provide an indication of the speed of response of the tube to changing light levels. A meter which permits accurate measurements, in the presence of noise, to within an accuracy of plus or minus 0.1% of white level is described and its performance is...
Topics: tube, lag, illumination, output, source, samples, light, sampling, magnitude, camera, sampling...
R&D Report 1970-01 : Detemination of the current distribution for aerial arrays of collinear elements with any number of sidelobes having equal maxima J.W. Head A 'normalized radiation pattern' is derived initially for a system having only four equally spaced elements. The general nature of a 'normalized radiation pattern' with good sidelobe suppression ratio is then discussed, and the relevance of Chebyshev polynomials is considered. A general formula for the feed currents in each aerial...
Topics: sidelobe, suppression, radiation, chebyshev, ratio, beamwidth, equation, normalized, elements,...
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 1973-18 : The automatic plotting of aerial radiation patterns G.H. Millard, N.F. Spring The presentation of aerial radiation patterns in the form of contour plots is described and a brief account is given of the plotting algorithm.
Topics: radiation, contours, bbc, pattern, aerial, horizontal, plotting, contour, patterns, diagram, beam...
R&D Report 1973-08 : Computer program: MF sky-wave interference J.L. Eaton, A.M. Bunting A short self-contained computer program for calculating sky-wave interference at MF has been written. The program employs a simple empirical law for calculating field-strength and makes a correction for the transmitting aerial vertical radiation pattern, the take-off angle being derived from the great circle distance and the number of 'hops'. Protected field-strengths are calculated for each wanted...
Topics: transmitter, frequency, transmitters, interference, bbc, weighting, program, interfering, ccir,...
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 1980-06 : A study of peak multiplexed signal level in the context of 2 1/2- or 3-channel surround-sound transmissions. E.W. Taylor The effect on peak multiplexed signal level of quadrature modulating the 38kHz subcarrier of a pilot-tone stereophonic system with the third of 'T' signal of a 2.5 or 3-channel System UHJ surround-sound transmission is discussed. Theoretically-derived values are compared with measurements made using test material received during Independent Local...
Topics: signal, peak, multiplexed, level, equation, phase, signals, subcarrier, sin, pilot, phase shift,...
R&D Report 1984-17 : Television animation store: recording pictures on a parallel transfer Magnetic disc. A.J.Durey This Report describes the recording and replaying of digital video signals using a computer-type magnetic disc-drive as part of an electronic rostrum camera animation system developed to enable picture sequences to be generated directly as television signals, instead of using cine film. The characteristics of the disc-drive are described together with data processing, error...
Topics: error, data, code, codes, bits, digital, replayed, rate, mhz, recording, recording code, parity...
R&D Report 1983-02 : Interference to television reception from large wind turbines. J.L.Eaton, R.I. Black, G.H. Taylor The interference to television reception in the future from large wind turbine generators is discussed and methods for estimating the effect from proposed installations are presented. The results of some measurements in the field are given. These show that potential interference to viewers may occur in certain areas if the plans of the Electricity Generating Authorities to...
Topics: wind, grade, images, interference, antenna, burgar, blades, signal, keelylang, field, keelylang...
R&D Report 1990-06 : NICAM 728 -- digital two-channel sound for terrestrial television A.J. Bower This report describes the development and technical specification of the NICAM 728 system for broadcasting digital two-channel sound with terrestrial television transmissions. NICAM 728 conveys two high-quality digitally-coded sound signals along with the picture and monophonic FM sound signals of the existing system I and systems B, G and H terrestrial television transmission standards. The...
Topics: nicam, sound, digital, system, data, television, carrier, signal, parity, signals, digital stereo,...
BBC Research and Development Reports
by J.T. Zubrzycki, R.H. Evans, P. Shelswell, M.A. Gamma, M. Gutierrez
texts

eye 152

favorite 0

comment 0

R&D Report 1996-05 : Experimental satellite broadcast of Eureka 147 DAB from Solidaridad 2 J.T. Zubrzycki, R.H. Evans, P. Shelswell, M.A. Gamma, M. Gutierrez BBC Research and Development Department, in collaboration with Telecomunicaciones de Mexico and the Instituto Mexicano de Comunicaciones, has carried out highly successful test transmissions of the Eureka 147 Digital Audio Broadcasting (DAB) system in Mexico from the Solidaridad 2 satellite from 17 to 21 July 1995. This included tests...
Topics: satellite, dab, solidaridad, antenna, transponder, mobile, eureka, signal, power, broadcasting,...
R&D Report 1963-10 : The Design of aerials for long-distance VHF television reception. D.J. Whythe Whilst tropospheric conditions enable v.h.f. radio communication to continue well beyond the horizon, the occurrence of fading sets a limit to the useful range for a reliable broadcasting service. Although satisfactory television reception is not generally possible for the average viewer at distances greater than about 50 miles (80 km) from the transmitter, some BBC stations rely, for their...
Topics: aerial, interference, reception, fading, propagation, receiving, signal, aerials, diversity,...
R&D Report 1964-64 :Philips three-tube Plumbicon colour camera. C.B.B. Wood, F.G. Parker, A.R. Stanley, R. Larry A visit to Paris in September 1964 to assess the Phillips Three-Tube Plumbicon Colour Camera.
Topics: camera, colour, plumbicon, registration, luminance, secam, picture, philips, monitor,...
R&D Report 1964-25 : Aerial distribution systems for the monitoring services. J.B. Izatt The factors affecting the design of distribution systems for monitoring services in the low-, medium- and high-frequency bands are considered and a number of experimental amplifiers is described. The intermodulation products generated in amplifier are at a very low level, and the methods of achieving the linearity required are discussed.
Topics: amplifier, octave, amplifiers, circuit, distribution, filters, feedback, output, aerial, valves,...
R&D Report 1964-70 : UHF field trials 1962/63: laboratory tests carried out on prototype 625-line u.h.f. colour and monochrome receivers E.W. Taylor The characteristics of nine prototype 625-line colour receivers and fourteen 625-line monochrome receivers were evaluated in connection with the 'home-viewing' tests that formed part of the U.H.F. Field Trials which took place during 1962/63. This investigation was undertaken jointly by the BBC Designs and Research Departments. In this report,...
Topics: frequency, receiver, channel, carrier, signal, receivers, tuning, vision, ratio, measurements,...
R&D Report 1966-03 :Transmitting aerials for the Churchdown VHF television and VHF sound station D.W. Osborne, R.D.C. Thoday, J.P. Crean A brief summary of the installation of Churchdown Relay Station.
Topics: transmitting, horizontal, templet, aerial, band, spaced, aerials, yagis, radiation, churchdown,...
R&D Report 1966-28 : The design of a low-frequency unit for monitoring loudspeakers. H.D. Harwood The present state in the design of low-frequency loudspeaker units is reviewed and the areas where improvement is desired are indicated. Experimental details are given leading to the design of 12 in. (305 mm) unit incorporating a vacuum-formed cone of toughened polystyrene with a p.v.c. (poly-vinyl chloride) surround and it is shown by objective and by listening tests that this design is...
Topics: cone, frequency, surround, mould, unit, shape, characteristic, axial, goodmans, loudspeakers,...
R&D Report 1966-29 : Consideration of aircraft noise and studio roof insulation A.N. Burd The increase of noise arising from the widespread use of jet aircraft has led to interference with programme in some broadcasting studios. The actual levels and spectra of noise from aircraft and the distribution of noise levels around a major airport are considered in order to reach a specification for the sound insulation of roofs to exclude such noise.
Topics: noise, levels, aircraft, roof, studio, octave, sound, insulation, spectra, pndb, pressure levels,...
R&D Report 1966-37 : 2.5 ms delay unit suitable for use in a television field delay D. Howorth, J.G. Ingleton This report describes the design and construction of a 2.5. ms delay unit which has been developed as part of a field delay for television applications. A brief description of the ultrasonic delay-line used is given, together with a detailed description of the input and output amplifiers and the ancillary circuits necessary to achieve an overall gain of unity and a delay stability...
Topics: delay, amplifier, ultrasonic, input, characteristic, network, output, equalizing, unit, circuit,...
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 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 1968-58 : Ray tracing for ionospheric and tropospheric propagation studies K. Hacking Adapted for a digital computer, conventional ray tracing becomes a potentially useful technique for studying several aspects of long-range wave propagation through stratified media. The development of a ray tracing program and its application to both medium-frequency sky-wave propagation through the ionosphere and ultra-high-frequency (UHF) propagation in the troposphere are described in this...
Topics: ray, propagation, height, trajectory, equation, ionospheric, absorption, refractive, range, angle,...
R&D Report 1969-04 : The use of sharp cut-off vestigial sideband filters at television transmitting stations A. Brown An amplitude and group-delay characteristic of the special vestigial sideband filters that may be required at UHF stations working in a channel adjacent to a radio astronomy band is considered, and the effect on transient response assessed. The group-delay errors of the filter, which is assumed to be at the transmitter output terminal, can be satisfactorily corrected by...
Topics: correction, delay, amplitude, sideband, overshoot, receiver, filter, characteristic, vestigial,...
R&D Report 1971-29 : 16 mm film: Image steadiness in television presentation. Part 2: Causes of unsteadiness J.R. Sanders The steadiness of pictures derived from film and presented by television is very often unsatisfactory. The causes of this unsteadiness have been determined so that the contributions from each part of the system are known. Suggestions are made as to ways in which the present performance could be improved.
Topics: unsteadiness, telecine, steadiness, camera, weighted, perforation, vertical, film, negative,...
R&D Report 1971-04 : Colorimetric errors due to a non-linear transfer characteristic and inaccurate gamma tracking G. Brown Abstract Gamma-correction of video signals is carried out to counteract the non-linearity in the television display tube. It is well known that the display tube characteristic follows a true power law closely, and if the laws of the camera gamma-correctors are not the true inverse of the tube characteristic, colour errors are to be expected. At present the...
Topics: errors, gamma, chromaticity, transfer, camera, luminance, characteristic, colorimetric, colour,...
R&D Report 1974-06 : Computer programs for UHF co-channel interference prediction using a terrain data bank R.W. King, J.H. Causebrook A set of computer programs has been written to predict the interference caused by co-channel stations to the service of a television transmitter. These programs use geographical and transmitter information stored permanently on a magnetic drum. In this report an outline is given of the methods employed by the programs. Details are given of the required input...
Topics: data, transmitter, terrain, path, paths, calculation, receiver, profile, iii, field, path profile,...
R&D Report 1973-25 : Frequency-dependent limiters for FM sound transmitters W.I. Manson Sound signals applied to FM transmitters are normally subjected to high-frequency pre-emphasis. If no form of overload protection is included in the system the transmitters can be overmodulated by high-level, high-frequency audio components, even with programme signals correctly controlled at the studio. In practice, conventional limiters have long been included in the chain to restrict pre-emphasis...
Topics: limiter, components, programme, frequency, experimental, signals, bbc, limiters, control, level,...
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 1972-39 : Television System I: A proposed specification for group delay at high video frequencies R.W. King, A. Brown The specification described is based on the results of subjective tests in which particularly critical still pictures were subjected to group delay variations at frequencies above the colour subcarrier. Large variations can be tolerated towards the top of the band: there is little impairment when the delay rises from nearly zero at 4.4 MHz to 1.1 microseconds at...
Topics: delay, impairment, pulse, distortion, chrominance, grade, subcarrier, specification, subjective,...
R&D Report 1977-09 : An experimental digital picture store. R. Walker, G.W. McNally This Report outlines the design of a 3.6 Mbit digital store suitable for television signals sampled at frequencies of up to approximately 3 x colour sub-carrier frequency. The design had to be flexible in order to meet a wide-range of requirements involving this type of storage. The final machine met its target specification and incorporated a comprehensive store control system which greatly assists the user...
Topics: store, data, storage, clock, logic, buffer, input, address, power supplies, output, input buffer,...
R&D Report 1976-19 : Subjective effects of band-limiting the colour-difference signals in PAL television System I. R.A. Belcher, P.S. Gaskell This report describes an initial study of the subjective effects of band-limiting colour-difference signals in PAL television System I. It provides a basis for possible future work on minimising the sampling frequency required in the digital encoding of colour-difference signals. It was estimated from results that the optimum U', V' transmission...
Topics: pal, filters, filter, transmission, impairment, mhz, subjective, codec, frequency, chrominance, pal...
R&D Report 1975-19 : Stereophonic reception using the pilot-tone system: compatibility of current receivers when quadrature subcarrier modulation is added D.J. Whythe This Report describes the results of measurements made on ten current stereo receivers to determine the effect on stereo reception when a pair of sidebands are added in quadrature to those of the existing difference signal, centred on 38 kHz. The measurements were mainly objective but the results of a brief listening test are...
Topics: quadrature, sidebands, modulation, receiver, stereo, harmonic, khz, subcarrier, sin, regenerated,...
R&D Report 1979-29 : Surface-acoustic-waves: experimental device fabrication. A. Roberts, K. Hacking An experimental Surface-Acoustic-Wave (SAW) device production technique has been developed, using a stepping camera and safe chemical processes. Devices can be made, operating in the frequency range from 15 to 100 MHz on a variety of piezo-electric substrates. Delays, frequency filters and resonators are the most common types of device, but convolers, dispersive filters and many other types...
Topics: resist, width, device, exposure, fabrication, coating, devices, transducer, slide, mask, metal...
R&D Report 1984-10 : 'Teletrak' -- a special effect. R. Storey This report describes the theory of operation of a television special effects processor called Teletrack, which is broadly similar to a system developed by CBS. The factors involved in the design of a Teletrack processor are outlined and the operation of two preferred forms is described in detail along with the special considerations required for operation on composite PAL signals. Teletrack was the forerunner of a whole family...
Topics: signal, teletrack, store, reference, field, images, flag, image, movement, frozen, flag store, flag...
R&D Report 1981-11 : An Extended PAL system for high-quality television. A. Oliphant An Extended PAL system is described which virtually eliminates cross-colour and gives improved luminance resolution for high quality receivers while retaining compatibility with conventional PAL decoders. The system uses the extra bandwidth available in a satellite or cable transmission channel to transmit the high frequency part of the luminance signal outside the normal video band. Tests are described...
Topics: pal, luminance, signal, extended, coder, decoder, mhz, frequency, subcarrier, filter, notch filter,...
R&D Report 1982-10 : Rank order difference analysis applied to tests of the Television Consistency Index. E.W. Taylor An outline of statistical theory concerned with rank order analysis is given, and the Television Consistency Index method of assessing lamps for colour television scene lighting is described. An assessment, in terms of rank order, is made which shows that to a large extent the Consistency Index is representative of lamp performance, while being independent of particular...
Topics: rank, lamp, camera, order, values, oooo, analysis, consistency, difference, lamps, order...
R&D Report 1986-13 : VHF-FM radio broadcasting: tests to compare horizontal, vertical and mixed polarisations. G.H. Taylor, D.S. Cox The BBC is re-engineering its VHF-FM radio networks from horizontal to mixed polarization. This Report describes tests carried out to monitor this change and which confirm the advantages of mixed polarization. Tests from the BBC transmitting station at Wenvoe to compare vertical and horizontal polarization are described. It is concluded that mixed polarization...
Topics: antenna, multipath, polarized, receiving, wrotham, signal, antennas, polarization, reception,...
R&D Report 1987-01 : A survey of achieved levels of airborne sound insulation in broadcasting studio centres. D.J. Meares A survey has been carried out on results from field measurements over the past fifteen years of the sound insulation of partitions in the technical areas of studio centres. The conduct of that survey is outlined and some examples of the acoustic performance of paritions are given.
Topics: sound, insulation, partition, bbc, average, acoustic, studio, partitions, triple, brick, triple...
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 1995-14 : Digital HDTV bit-rate reduction in the studio T. Vlachos, M.G. Croll Two novel source coding algorithms are presented which are suitable for the recording of digital High Definition Television signals. One of the bit-rate reduction schemes is based on the Wavelet Transform and the other on the Lapped Orthogonal Transform (LOT). According to the first scheme, a multi-layered, hierarchical description of the source signal is obtained by means of a quad-tree, half-band...
Topics: coding, wavelet, transform, quantiser, block, quantisation, digital, frequency, compression,...
R&D Report 1994-06 : Acoustic noise criteria for listening rooms and control rooms R. Walker This report is based on a submission document to both EBU G1(LIST) and ITU-R TG 10/3 drafting committees. It describes background noise criteria for high-quality listening environments from a number of different organisations and the derivation of a compromise criterion for the continuous background noise levels. The outcome of the work, and the proposal submitted to those technical groups, was the...
Topics: noise, octave, curves, bbc, iso, oirt, rating, criteria, noise rating, curve, listening rooms, band...
R&D Report 1954-03 : Subjective judgments on brightness. G.I. Ross Experiments have been conducted in the field of acoustics in order to determine whether it is possible for people to judge with any accuracy that one sound is twice as loud as another standard sound, or half as loud as the standard sound. It was found that people can be persuaded to make judgements of "twice as loud" and their results appear to be consistent within reasonable limits. It was concluded that one sound...
Topics: brightness, tho, standard, field, judgments, deviations, ratios, readings, subjects, deviation,...
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 1956-33 : A visit to the United States of America, June 10th - July 14th, 1956. P.E. Axon This report describes some of the information obtained and observations made during a visit to the United States occupying a period from the 10th June - 14th July, 1956.
Topics: magnetic, recording, tape, ampex, head, reproducing, system, colour, lenticular, film, picture...
R&D Report 1956-12 : Visit to Vienna, Hamburg and Cologne - November 1955. D.E.L. Shorter For the purpose of studying technical and operational problems connected with microphones, loudspeakers and related equipment used in broadcasting, a visit has been made to Vienna, Hamburg and Cologne. In addition to studio centres in the three cities, the visit included the factory of the Akustische und Kinogerate Gesellschaft in Vienna and the Central Technical Establishment of the Nordwestdeutscher...
Topics: microphones, microphone, loudspeaker, frequency, hamburg, diaphragm, electrostatic, type,...
R&D Report 1956-18 : Measurements on loaded building-board panel sound absorbers. A.N. Burd. Measurements have been made of the absorption coefficient of resonant absorbers consisting of soft building-board panels loaded with steel weights. The results do not substantiate the claims made by Continental workers because the mode of action appears to be completely different from that postulated in a recent paper. A possible explanation of the experimental results is suggested and some measure...
Topics: panel, absorption, frequency, absorbers, reverberation, stiffness, measurements, resonance, peak,...
R&D Report 1956-37 : Temporal variation of the ground-wave field strength of medium frequency broadcasting transmitters. M. Deakin, E. Sofaer, R.A. Rowden This report surveys the results of measurements made by the BBC Research Department and comments on earlier work by others. It is concluded that the effect, which is due apparently to a variety of factors not yet fully investigated, is no longer of significant importance in broadcasting.
Topics: strength, variation, field, variations, temporal, wave, conductivity, transmitters, signal,...
R&D Report 1959-04 : The effects of humidity on reverberation room measurements of absorption coefficient at high frequencies. N.C.H. Druce. An investigation has been carried out to find the reasons for the variability in the results of absorption coefficient measurements at high frequencies in the reverberation room. After elimination of random experimental errors, it appeared that the variations could be due to inaccurate corrections for changes with humidity of the absorption by the air,...
Topics: absorption, humidity, reverberation, errors, air, frequencies, coefficient, measurements, bazley,...
R&D Report 1959-05 : Reception of Crystal Palace 51.5 Mc/s and 45.0 Mc/s channels in South Africa during the increasing phase of the sunspot cycle. T.W. Bennington Reception reports have been received from the Panorama, Johannesburg receiving station of the. South African Broadcasting Corporation in respect of the reception there during the period 1000-1800 GMT of the Crystal Palace 41'5 Mc/s and 45'0 Mc/s frequencies and the data are here presented. The reports have been analysed for 28...
Topics: reception, muf, gmt, variations, monthly, values, percentage, sunspot, mup, frequency, sunspot...
R&D Report 1964-45 : Transmitting aerials for the Okehampton VHF television and VHF sound station D.W. Osborne A brief summary of the installation of Okehampton Relay Station.
Topics: aerials, transmitting, okehampton, vertical, aerial, templet, gain, horizontal, band, carrier,...