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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 1987-15 : Theoretical and practical aspects of the "Functional Absorber" method of arranging sound absorbing panels. E.W. Taylor Measurements of the absorption of sound by functional absorbers (panels of porous material mounted so that both sides are exposed to the sound field) are described, the absorbers being arranged in a number of different configurations. The effect of increasing the surface density of the absorbing panels without significantly changing their...
Topics: absorption, absorbers, absorber, sound, panels, absorbing, reverberation, coefficient, arrangement,...
R&D Report 1960-23 : Analogue computer for aerial radiation patterns H. Page, G.J. Phillips, J.A.S. Fox An analogue computer has been constructed to calculate the horizontal radiation patterns of aerial arrays comprising a number of radiating elements mounted on a central support mast. The radiation pattern of a single element must be known, and from this the pattern for a number of identical elements round the mast may be calculated. The currents in the elements may have any desired...
Topics: radiation, uniselector, circuit, wiper, elements, pattern, output, contacts, stepping, wipers,...
R&D Report 1995-03 : Controlled Image Design: The measurement of Time-Frequency responses. R. Walker This Report describes the measurement of acoustic events in a 3-dimensional measurement domain. An outline of the general theoretical background is followed by a description of the special requirements for the measurement of short-term acoustic responses in rooms. The results of measurements on an experimental synthesis of a single room reflection are also presented. It is shown that the...
Topics: frequency, response, fourier, measurement, transform, impulse, reflection, signal, responses,...
R&D Report 1976-35 : Some considerations on the use of pre-amplifiers at low-power UHF relay stations. J.L. Riley A number of inexpensive, commercially available pre-amplifiers are examined and their performances in respect of gain, noise factor, linearity and impedance match are compared. Some theoretical planning curves are presented for considering low-field conditions and formulae are derived for dealing with high-signal conditions. A re-broadcast link front-end, made up from the most...
Topics: amplifier, input, aerial, output, isolation, amplifiers, signal, noise, receiving, feeder, received...
R&D Report 1955-24 : The Stephens electrostatic microphone Type C-1. D.C. Derham Laboratory tests have been carried out on a single specimen of the Stephens Trusonic Microphone, Type C-1, a pressure-operated electrostatic instrument which functions by amplitude-modulating a radio-frequency carrier. Measurements of frequency response, sensitivity, variation of sensitivity with mains voltage, impedance and susceptibility to interference from magnetic fields have been made; the stray...
Topics: frequency, microphone, stephens, transformer, circuit, demodulator, impedance, electrostatic,...
R&D Report 1962-13 : Determination of the effective modulation depth of monophonic programme transmitted on the Zenith-GE stereophonic system D.E.L. Shorter In the Zenith-G.E. stereophonic broadcasting system, a small proportion of the available modulation capacity is taken up by a pilot signal used in the demodulation process at the receiver. The remainder is divided between the sum of the left- and right-hand stereophonic signals, transmitted in the same way as a monophonic programme, and...
Topics: signal, monophonic, stereophonic, programme, test, transmitter, level, modulation, amplitude,...
R&D Report 1961-07 : Crystal-diode modulators for the frequency range 10-1000 Mc/s. G.J. Phillips, R.G. Manton This report describes the development of low-power balanced diode modulators suitable for amplitude modulation by television or sound signals of a carrier in the frequency range 10-1000 Mc/s. From an original model, built in 1954, two later models have been developed having better performance in regard to the insertion loss at the carrier frequency, and uniformity of modulation...
Topics: modulator, modulation, frequency, insertion, signal, amplitude, impedance, transformer, output,...
R&D Report 1964-47 : Impact of users' needs on the design of data processing systems R.W. Lee, M.E.B. Moffat The conference was held at the Heriot-Watt College Edinburgh from 31st March to 3rd April 1964. The conference papers were divided into four main categories (a) Programming and Operating Systems, (b) Storage technology and organization, (c ) Maintenance, (d) Input, output and Man-Machine Communications.
Topics: computer, data, processing, computers, digital, large, programme, magnetic, author, processer,...
R&D Report 1966-06 : Subjective assessments of the portrayal of motion produced by simulations of field-store standards conversion R.E. Davies, S.J. Lent, M.T.A. Salter It is shown that the process of television standards conversion involving a change of field frequency degrades the portrayal of movement in the scene by introducing a jerky motion to certain types of movement. Experiments are described which show that in order to provide satisfactory portrayal of motion, when converting...
Topics: frames, fields, movement, conversion, standards, portrayal, observers, second, grade, picture,...
R&D Report 1967-35 : Kidderminster UHF relay station: Summary of installation G.H. Millard A brief data sheet detailing frequencies, equipment installed, radiation characteristics etc, including graphs of radiation patterns.
Topics: kidderminster, unwanted, mhz, vertical, ith, transmitter, radiation, iii, stockholm, relay
R&D Report 1968-16 : Llanidloes VHF relay station: Summary of installation R.D.C. Thoday, J.P. Crean Brief data sheet detailing equipment used, frequencies, radiation characteristics etc, together with graphs of horizontal and vertical radiation patterns.
Topics: band, aerial, transmitting, etn, radiation, transmitter, receiving, horizontal, arrangement, relay,...
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 1973-16 : Medium frequency directional aerials L.K. Bradley The principal design considerations for highly directional MF aerial arrays are presented together with a detailed calculation relating to a particular example of an in-line four-element directional array. Techniques for providing phase control and power splitting are also considered.
Topics: directional, phase, aerial, radiators, mast, arrays, impedances, bbc, required, aerials, aerial...
R&D Report 1977-46 : The CSI 1 kW 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 Thorn CSI 1 kW metal-halide discharge lamp when excited from a sinusoidal power source at various frequencies in the range 50 Hz to 1000 Hz. Operating conditions which reduce motion picture film exposure variations to acceptable...
Topics: ripple, lamp, frequency, ratio, luminance, shutter, asymmetry, supply, frame, camera, frame...
R&D Report 1978-27 : The variation of absorption coefficient of absorber modules with ambient conditions. H.D. Harwood, K.E. Randall, K.F.L. Lansdowne The absorption coefficient of a given absorber is shown not to be a unique quantity, but to depend on a number of factors. These include the size of room in which it is located, as well as the proximity of other absorbers and of diffusing obstacles. The magnitude of these effects and the frequency range over which they are significant has...
Topics: absorption, absorbers, iso, modules, room, absorber, reverberation, coefficient, frequency, model,...
R&D Report 1982-03 : Radio-frequency ignition hazards: the power available from non-resonant structures. P. Knight Structures in petrochemical and similar industrial plants can act as inadvertent receiving aerials, leading to a risk of ignition of flammable vapours when strong radio waves are present. The hazard is greatest when the structure is tuned to the transmission frequency. When several transmissions are present, the structure is unlikely to be tuned to more than one transmission at...
Topics: voltage, tuned, frequency, curves, power, crane, structures, structure, transmission, impedance,...
R&D Report 1985-09 : Digital television routing systems: an introduction to integrated optical waveguide techniques and devices. J.P. Willson The development of a digital standard for the coding of component video signals (CCIR Rec. 601) has raised the problem of the appropriate technology to be used for the routing and distribution of such signals within a television studio centre. Optical fibres offer a number of advantages over coaxial cable, such as high bandwidth, low loss, and small...
Topics: optical, switch, coupler, waveguides, waveguide, lithium, directional, integrated, array,...
R&D Report 1988-06 : A flat-plate antenna for DBS reception. M.C.D. Maddocks A flat-plate antenna for the reception of DBS transmissions using low-cost materials has been designed, built and measured. The antenna is essentially a multilayer printed structure consisting of a polarisation converter, an array of elements and a beamforming network. The antenna can be mounted flat on the most suitable wall of an arbitrarily-orientated house and aligned to receive signals from satellite.
Topics: antenna, beam, slew, array, dbs, gain, polariser, lens, angles, required, antenna gain, dbs...
R&D Report 1996-02 : MPEG-2: Overview of the systems layer P.A. Sarginson The MPEG-2 Systems specification describes how MPEG-compressed video and audio data streams may be multiplexed together with other data to form a single data stream suitable for digital transmission or storage. This Report introduces the principles and terminology of the MPEG-2 Systems layer. The Report covers three main areas: Firstly, the structure of the multiplexes; secondly, the service information that may be...
Topics: elementary, stream, buffer, coder, programme, access, transport, decoder, video, streams,...
R&D Report 1955-06 : The service area of the temporary television transmitter at Redmoss, Aberdeen. L.F. Tagholm, G.I. Ross, R.S.A. Sandell This report shows that the temporary transmitter at Radmoss, near Aberdeen, provides the city of Aberdeen with a reasonable television service using an effective radiated power of 3 watts. It is shown that the service will, in general, be similar to that expected from the final transmitter at Meldrum.
Topics: transmitter, aberdeen, temporary, redmoss, strength, vision, field, watts, field strength,...
R&D Report 1966-64 : Transmitting aerials for the Sky (Skriaig) VHF television and VHF sound station D.W. Osborne, R.D.C. Thoday The Skye (Skriaig) relay station came into operation on the 14th March 1966. It provides a television and sound service to the Isle of Skye (with the exception of Portree), adjacent coastal areas of Invernessshire, Ross and Cromarty, most of the islands of Barra, Benbecula, North and South Uist and some areas in the south east of the Isle of Lewis.
Topics: aerial, transmitting, band, mast, templet, dipole, gain, horizontal, aerials, skye, transmitting...
R&D Report 1968-30 : Propagation over rounded hills K. Hacking Several features of the diffraction of electromagnetic waves by large obstacles are examined both theoretically and by optical experiments using a laser source and idealized models. The underlying purpose of the work was to establish and verify, where possible, working methods for estimating the field strength in the shadows of rounded hills. The emphasis throughout is for the special conditions which arise in UHF broadcasting,...
Topics: diffraction, field, crest, shadow, crests, diffracting, surface, curvature, profile, receiver,...
R&D Report 1971-09 Pulse-code modulation for high-quality sound-signal distribution: Deviation, bandwidth and power for a frequency-modulated link R.V. Harvey
Topics: deviation, noise, carrier, signal, error, optimum, frequency, bandwidth, mhz, modulation,...
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 1977-02 : Quadraphony: developments in Matrix H decoding. P.S. Gaskell, P.A. Ratliff The Matrix H 2-channel quadraphonic encoding system has been designed to transmit the maximum amount of directional information consistent with mono and stereo compatibility. This report discusses methods of decoding such transmission signals for 'surround-sound' reproduction. The basic form of decoder is a complex-coefficient linear matrix, but this has an inherent lack of separation between the...
Topics: matrix, logic, decoder, decoding, modified, separation, linear, signals, quadraphonic, basic, basic...
R&D Report 1979-06 : Digital recording using hologram arrays: laser-beam deflection and modulation. K. Hacking, I. Childs The feasibility of optical methods of recording a digital television signal in real-time depends inter-alia on the successful development of devices for modulating and deflecting laser beams. For recording using the holographic approach, these devices must be able to handle many data channels in parallel and be optically efficient. Various methods have been investigated,...
Topics: crystal, plzt, beam, deflector, polarisation, deflection, modulator, optical, light, hologram,...
R&D Report 1983-07 : Enhanced UK teletext: experimental equipment for high-quality picture coding and other enhancements. J.L. Riley A recent Research Department Report described how it would be possible to enhance the basic teletext service, to include facilities for improving its access time and lead up to the inclusion of high-quality still pictures. The present Report describes the construction of a pair of microcomputer-based units which will serve as a research tool in engineering...
Topics: teletext, data, microcomputer, row, picture, enhanced, store, frame, equipment, software,...
R&D Report 1989-15 : Long-distance propagation measurements at UHF: Comparisons between results using BBC and CCIR prediction methods C.P. Bell This report gathers together available data on measurements over long distance propagation paths in the UHF Broadcast Band made by the BBC and other UK organizations, and uses them to test the accuracy of both BBC and CCIR field strength prediction methods. The former makes use of terrain database, and the latter, as contained in CCIR...
Topics: bbc, ccir, path, prediction, predictions, measurements, method, paths, clutter, receiving, field...
R&D Report 1964-10 : Visit to NV Philips Gloeilampenfabrieken, Eindhoven 15 to 17 January 1964. D.R. Morse, C.B.B. Wood Members of the department visited Philips in Eindhoven in january 1964 to discuss the technical performance of the Plumbicon Camera Tube. This report is an account of this visit.
Topics: plumbicon, philips, tube, bbc, production, peto, tubes, camera, monochrome, colour, colour...
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 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 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,...
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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 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 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 1964-48 : Transmitting aerial for the Dundee VHF television station D.W. Osborne A brief summary of the installation of Dundee Relay Station.
Topics: aerial, transmitting, dundee, aerials, technological, templet, height, tower, consists, vertical,...
R&D Report 1964-27 : Visit to Telefis Eireann, 5th and 6th March 1964 E.R. Rout Members of BBC Research visited Telefis Eireann in March 1964, the following report is an account of that visit.
Topics: telefis, eireann, converter, receivers, studio, eire, bbc, transmissions, vidicon, transmitters,...
R&D Report 1965-08 : Specification of the impedance of transmitting aerials for monochrome and colour television signals D.J. Whythe Any departure of the impedance of a television transmitting aerial from the characteristic impedance of its feeder results in the transmission of delayed signals. This report specifies the maximum departures of impedance that are permissible without visible distortion for 405-line and 625-line monochrome and colour television signals. The specifications for...
Topics: delayed, signal, aerial, impedance, feeder, signals, reflexions, monochrome, transmitter,...
R&D Report 1968-53 : Bedford VHF relay station: Summary of installation R.D.C. Thoday, J.P. Crean Brief data sheet detailing equipment used, frequencies, radiation characteristics etc, together with a graph of horizontal radiation.
Topics: transmitting, aerial, band, bedford, transmitter, bbc, installation, horizontal, receiving, tower,...
R&D Report 1969-41 : Signal injector for l.f. and m.f. receivers with ferrite-rod aerials C.R.G. Reed A transportable unit was built for the testing of l.f. and m.f. receivers. It provides more than 60 dB of screening from the effects of external fields and includes a simple signal-injection system that produces a sensibly uniform field within a volume 600 x 300 mm.
Topics: box, field, signal, injector, receiver, screened, receivers, screening, connexions, transmission,...
R&D Report 1970-09 : UHF television: the interference caused by a receiver operating on channel n to an adjacent receiver tuned to n+4 J.G. Spencer The interference that a television receiver tuned to a UHF channel n can cause to a neighbouring receiver tuned to channel n + 4 was considered in the early stages of development of the UHF plan. It then appeared that this type of interference could constitute a serious impairment of the quality of a colour television service at UHF. Since that...
Topics: receiver, interference, aerial, mhz, receivers, channel, coupling, frequency, strength, tuned,...
R&D Report 1971-32 : A feasability study of an adaptive system for UHF television D.E. Susans, J.G. Spencer This report describes the results of an investigation into the feasibility of producing an adaptive receiving system for UHF television suitable for rebroadcast links in situations where, with standard techniques, there would be unacceptable interference. The system is designed to adjust continuously the directivity pattern of a receiving aerial array so as to steer minima onto the...
Topics: interference, signal, adaptive, system, test, synchronising, waveform, aerial, pulse, aerials,...
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 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 1974-03 : LF and MF propagation: Sky-wave field-strength prediction P. Knight During the night, medium-frequency sky-waves propagate to great distances via the ionosphere. The report describes the various factors which affect the waves as they travel from transmitter to receiver. Several methods which can be used for estimating the strength of sky-wave signals are compared.
Topics: curves, propagation, loss, ionospheric, wave, magnetic, coupling, polarisation, ccir, variation,...
R&D Report 1976-06 : Diversity reception at high-frequencies using the single-sideband mode. D.E. Susans When using long-distance HF and SSB re-broadcast links it is customary to use dual-diversity reception. This method of reception has considerable advantages over a single-channel under conditions of 'flat' fading but it has been reported that any improvement is only marginal when the fading is predominantly frequency-selective. The reasons for this are discussed and a new correlation...
Topics: fading, audio, combiner, signals, phase, output, signal, diversity, receiver, correlation, fading...
R&D Report 1982-12 : High quality decoding for PAL inputs to digital YUV studios. C.K.P. Clarke With the planned conversion of studio equipment to digital component signal operation, there will be a requirement for high quality PAL decoders at the interface with current equipment. The addition of movement detection circuits to picture delay comb filters was expected to produce a decoder with good overall performance. However, movement detection methods have so far been unable to produce a...
Topics: chrominance, luminance, decoding, yuv, frequency, digital, signals, pal, movement, comb, yuv...
R&D Report 1986-17 : Review and analysis of VHF/UHF field strength measurements: measurements at VHF over path lengths greater than 100 km R.S. Sandell, C.P. Bell, D.W. Taplin In 1983 CCIR IWP 5/5 put forward a number of proposals for improvements to the field strength prediction methods of CCIR recommendations 370 and associated report 239, as used for international planning negotiations in the VHF and UHF Broadcast Bands. This report describes the results of studies carried out by the...
Topics: bbc, curves, jun, paths, correction, propagation, dec, vhf, nov, band, vhf band, pontop pike,...
R&D Report 1954-08 : A determination of subjective white under four conditions of adaptation. W.N. Sproson Subjective white has been determined for twelve colour-normal observers under four conditions of adaptation. Two methods were used and a comparison is made between the results. Further comparisons are made between the results of the present investigation and those of other workers. The report concludes with a recommendation for subjective white for television viewing with a tungsten...
Topics: observers, method, adaptation, colour, tungsten, observer, chromaticity, white, daylight, adapting,...
R&D Report 1955-19 : The application of correlation methods and phase-coherent detection to room acoustics. M.W. Greenway, C.L.S. Gilford. In an attempt to produce an improved method of displaying the acoustic behaviour of a room, an investigation has been made into some phase-sensitive and correlation methods. In particular, a phase-coherent modification of the pulsed glide type of display has been developed, in which the microphone output is modulated by the original frequency of...
Topics: coherent, glide, pulsed, display, logarithmic, output, correlation, frequency, studio, tone,...
R&D Report 1962-35 : The E702A display storage tube. W.K.E. Geddes Tests have been carried out on a E702A display storage tube in order to assess its potentialities for the display of single television pictures.
Topics: storage, tube, brightness, writing, surface, erasure, potential, display, electrode, electrons,...
R&D Report 1964-33 : Transmitting aerial for the Ventnor VHF television station D.W. Osborne A brief summary of the installation of Ventnor Television Relay Station.
Topics: aerial, ventnor, horizontal, tower, carrier, templet, channel, transmitting, dipoles, dipole,...
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 1971-17 : Active aerial arrays: Reciprocity J.L. Eaton Abstract It is shown that the usual Reciprocity Theorem does not hold in general for active aerial arrays. A new formulation of reciprocity is presented which can be applied to active aerials.
Topics: reciprocity, amplifier, amplifiers, aerial, output, transmitting, array, active, linear,...
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 1994-03 : Measurements of wideband multipath propagation at 531MHz and 1.265GHz C.P. Bell, P.J. Brightwell, P.J. Brightwell, R.F. Rudd, W.F. Williams Multipath propagation measurements and their analyses are described. The work was carried out by the BBC over the period 1988 - 1990 as a contribution to the Eureka 147 Project, with the aim of providing statistical data required in the configuration of a Digital Audio Broadcast system. Two different areas were chosen for the tests,...
Topics: mhz, delay, bbc, measurements, croydon, urban, ghz, multipath, frequency, propagation, correlation...
R&D Report 1956-17 : The design of the PGD and PGS Ribbon microphones final report H.D. Harwood, D.E.L. Shorter This report completes the account begun in Report M-015, of the design and performance of the new ribbon type pressure-gradient microphones. Additional information on performance, including measurements of wind noise and non-linearity, is given.
Topics: ribbon, microphone, pgs, response, microphones, frequencies, impedance, frequency, transverse,...
R&D Report 1955-34 : The effect of an interleaved Band III aerial on the performance of a Band II slot aerial G.D. Monteath, D.J. Whythe Two tiers of four Band III batwings could be mounted on each tier of the Band II aerial at Sutton Coldfield without impairing its performance. The horizontal radiation pattern remains very uniform, though less so than formerly. The bandwidth is not degraded, although re-adjustment of the matching controls would be necessary.
Topics: band, iii, admittance, slot, tiers, batwings, batwing, aerial, susceptance, elements, admittance...
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 1964-76 : Photometric lens-aperture measuring equipment H.A.S. Philippart A photometric lens-aperture measuring set is described by means of which lenses can be calibrated in terms of the 'T' number. The apparatus can deal with lenses whose focal lengths lie within the range 1 in. to 40 in. (2.54 cm to 1.02 m). The system used is similar to that used by M.G. Townsley and consists of a comparison method in which two beams of light are used, one to provide light for the lens under...
Topics: lens, aperture, focal, calibration, beam, calibrated, lenses, wedge, photometric, light,...
R&D Report 1963-40 : Long distance tropospheric propagation measurements over the North Sea at 560 Mc/s D.W. Taplin This report presents the results of field strength measurements on horizontally polarised uhf transmissions at 560 Mc/s over the North Sea at distances from 123 miles (198 km) up to 591 miles (950 km). These measurements extended over a period of two years and have been used in the preparation of field strength/distance curves for various percentages of the overall time....
Topics: field, happisburgh, strength, site, curves, measurements, receiving, strengths, band, propagation,...
R&D Report 1964-52 : Logarithmic amplifier using non-linear silicon diodes K.F.L. Lansdowne The principle of the construction of a logarithmic amplifier using semi-conductor Germanium diodes as logarithmic elements was described in Report B-056, Serial No. 1953/14. This report describes an amplifier using currently available silicon junction diodes.
Topics: logarithmic, amplifier, diodes, silicon, diode, output, circuit, impedance, oscilloscope, voltage,...
R&D Report 1966-39 : Mutual resistance between radiating elements mounted on cylinders: application to vhf aerial gain calculation P. Knight, R.E. Davies A method for calculating the gain of a v.h.f. aerial from the mutual resistances between the radiating elements is described. The computation of mutual resistances between dipoles and unipoles mounted on a support mast is discussed. A set of tables of mutual resistances is included, together with notes on their use.
Topics: dipole, dipoles, gain, relative, radiating, tangential, radiated, mutual, doublets, cylinder, free...
R&D Report 1967-23 : Transmitting aerials for the Northampton VHF television and VHF sound station D.W. Osborne, R.D.C. Thoday, J.P. Crean The Northampton relay station came into operation on 26th September 1966. It provides a television and v.h.f. sound service to the town of Northampton and the villages of Weston Favell, Duston and Hardingstone.
Topics: aerial, transmitting, tiers, band, yagis, pid, aerials, etn, templet, tower, horizontal radiation,...
R&D Report 1968-35 : Airborne sound insulation requirements in studio centres T.J.B. Smith, C.L.S. Gilford This report assembles data on the sound power levels of various sources of interference, including studios and other technical areas, and on the permissible levels of noise in all parts of a studio centre. From these data, curves showing the required attenuation between sound sources and all types of broadcasting area are derived. As the shapes of the curves thus obtained do not in...
Topics: sound, studio, curve, studios, partition, levels, noise, reduction, criterion, insulation, required...
R&D Report 1968-42 : The reflection of sound from television scenery flats A.N. Burd Measurements of the sound-pressure reflection coefficients of typical scenery-flat materials have been made. Substantial agreement has been found between two methods of measurement with regard to the order in which they rank the reflective properties of typical materials. The report ends with some comments relating to the sound insulation and acoustics of sets with open sides and tops, which are relevant to...
Topics: measurements, reflection, plywood, materials, surface, loudspeaker, coefficient, acoustic,...
R&D Report 1968-43 : Calculation of the field strength required for a television service, in the presence of co-channel interfering signals. Part 2: Effect of multiple interfering sources E. Sofaer With the great expansion in television services in Europe and elsewhere, several transmitting stations will be operating in the same frequency channel. To any one service all transmitters sharing the channel are sources of interference, and it is therefore necessary that some method of estimating...
Topics: probability, deviation, location, signal, standard, field, interference, protection, strength,...
R&D Report 1970-03 : Satellite broadcasing service areas J.W. Head The coverage area provided by a transmitter on a geostationary satellite emitting a right-circular conical beam is mainly considered. For sufficiently small beam-width, the service area is nearly an ellipse in the tangent plane to the Earth at the target point, and the axial lengths and directions are calculated. In general, the service-area boundary is best specified by plotting latitude against longitude, and formulae for...
Topics: satellite, beamwidth, plane, boundary, spi, axial, coordinates, beam, service area, latitude, axial...
R&D Report 1974-17 : The generation of video synchronising pulses and test waveforms by digital synthesis: Timing errors caused by quantising distortion P.A. Ratcliff Digital waveform-synthesis produces interval timing errors, or wave-shape distortion, when generation of transitions is required at intervals which are not integer multiples of the sampling clock period. A rule has been evolved to determine the timing accuracy with which a digital system, with quantisation limitations, is...
Topics: waveform, digital, pulse, synchronising, timing, analogue, pulses, sampling, jitter, waveforms,...
R&D Report 1977-34 : A 2.5 GHz circularly polarized aerial. R.D.C. Thoday A circularly polarized aerial for operation in the 2.5 GHz frequency band is described in this report. The aerial can be used in linear horizontal and vertical polarization modes as well as in left or right hand circular polarization modes. It has been specially developed for experimental outside broadcast propagation tests at these frequencies.
Topics: aerial, polarization, ghz, polarized, circular, circularly, dipole, radiation, feeder, radiating,...
R&D Report 1978-18 : CEEFAX: microprocessor-based clock J.P. Chambers, J.R. Chew When CEEFAX became a public service it was necessary to provide a dependable source of clock-time for transmission as part of the signal. This report describes the principles used in the design of the master clock coupled to the CEEFAX computer.
Topics: clock, khz, mhz, ceefax, msf, signal, output, microprocessor, utc, time, time code, correctly...
R&D Report 1982-07 : Colour separation overlay and its relation to digital video sampling. A. Oliphant Current techniques for Colour Separation Overlay (CSO) are briefly described. The influence of CSO techniques on the formulation of standards for digital video sampling parameters is discussed and experiments are described which investigated the effects on CSO pictures of filtering and sampling the foreground picture signals. The conclusions are that a chrominance bandwidth of at least 3...
Topics: cso, sampling, chrominance, digital, aliasing, luminance, frequency, foreground, signal, mhz,...
R&D Report 1984-19 : L.F. radio-data: specification of BBC phase-modulated transmissions on long-wave. D.T. Wright The BBC long-wave AM transmitter network carries a low bit-rate data signal, in addition to the normal programme signal modulation. The data signal is conveyed by phase-modulation of the carrier, the signal parameters being chosen so that there is no disturbance to reception on existing domestic receivers. This Report describes the data signal and includes details of both the...
Topics: data, block, code, transmitted, cyclic, bits, crc, blocks, prefix, biphase, biphase symbol, binary...
R&D Report 1955-11 : Television service for West Wales site tests at Pant Gwyn, Blaen-Plwy and Mynydd Bach. R.D. Pittilo, C.J. White, J. Hall, S.J. Ashdown, C.S. Dobson This report shows that of the three sites tested, one at Blaen-plwy 4 miles (6.5 km) south of Aberystwyth will give the best television coverage in West Wales. It is not possible to receive a reliable signal from Wenvoe at this site for direct relay and an intermediate link will be required.
Topics: aerial, site, mynydd, pant, height, bach, wenvoe, strength, mast, field, west wales, wales site,...