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 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,...
Topics: absorption, absorber, wideband, frequency, acoustic, mineral, bbc, zintec, weldmesh, absorbers,...
R&D Report 1973-06 : Equipment for the transfer of digital video signals to paper tape C.K.P Clarke A digital computer can be used to simulate processing methods for the bit-rate reduction of digital television. To assess such methods, television signals must be converted to a form compatible with computer data-handling systems. This report describes equipment for transferring monochrome pulse-code modulation signals derived from a slide scanner to punched paper tape. One eight-bit word is...
Topics: signals, picture, digital, counter, sampling, samples, punched, bbc, paper, transfer, slide...
Topics: signals, picture, digital, counter, sampling, samples, punched, bbc, paper, transfer, slide...
R&D Report 1992-11 : A modular wideband sound absorber G.D. Plumb The absorption coefficients were measured of various depths of RW2 grade Rockwool laid directly on the floor of the ISO-Standard reverberation room at BBC Research Department. The Rockwool was very effective as a wideband sound absorber. A new absorber was designed and tested, having the dimensions of existing BBC type A modular absorbers and containing RW2 Rockwool. The new absorber has a smoother absorption coefficient...
Topics: absorption, absorber, rockwool, infill, hardboard, plywood, modular, coefficient, absorbers, panel,...
Topics: absorption, absorber, rockwool, infill, hardboard, plywood, modular, coefficient, absorbers, panel,...
BBC Research and Development Reports
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D.E.L. Shorter, H.D. Harwood, R.J. Packer
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R&D Report 1955-08 : The Robbins-Joseph (R-J) loudspeaker enclosure. D.E.L. Shorter, H.D. Harwood, R.J. Packer Tests have been carried out on a small loudspeaker cabinet known as the "R-J enclosure" which has been claimed to give improved bass reproduction. A small increase in efficiency at low frequencies resulting from the particular form of construction adopted is accompanied by some reduction of response in other parts of the frequency range.
Topics: enclosure, response, loudspeaker, frequency, vent, impedance, enclosures, cone, axial, frequencies,...
Topics: enclosure, response, loudspeaker, frequency, vent, impedance, enclosures, cone, axial, frequencies,...
R&D Report 1988-14 : On the design of loudspeakers for broadcast monitoring. C.D. Mathers By designing its own monitoring loudspeakers for about the past forty years, the BBC has achieved a degree of continuity and consensus in a subject where there are almost as many opinions as there are designers. This report describes the approach that has evolved within the Corporation towards design and assessment, and indicates how calculation and objective measurement are supplemented by experience...
Topics: loudspeaker, bbc, design, frequency, damping, coil, acoustic, unit, diaphragm, drive, relative...
Topics: loudspeaker, bbc, design, frequency, damping, coil, acoustic, unit, diaphragm, drive, relative...
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,...
Topics: absorption, absorbers, absorber, sound, panels, absorbing, reverberation, coefficient, arrangement,...
BBC Research and Development Reports
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P. Knight, G.D. Monteath
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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,...
Topics: ooooo, ooo, oooooo, mmmmm, oooo, cfl, iiiii, gain, ooooo ooooo, tfl, moooo ooooo, power radiated,...
R&D Report 1983-10 : The design of the prototype LS5/9 studio monitoring loudspeaker. K.E. Randall, C.D. Mathers The prototype of a new medium-power studio monitor is described which is physically small enough to be accommodated in areas where a large high-power monitor would be inappropriate. The main design and performance features are as follows:- A vented cabinet having a volume of 28 litres (1 cubic foot). Two drive units; a proprietary 34mm soft-domed high-frequency unit and a BBC...
Topics: loudspeaker, unit, frequency, sound, diaphragm, drive, bbc, profile, crossover, prototype, sound...
Topics: loudspeaker, unit, frequency, sound, diaphragm, drive, bbc, profile, crossover, prototype, sound...
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,...
Topics: antenna, multipath, polarized, receiving, wrotham, signal, antennas, polarization, reception,...
R&D Report 1990-15 : The design and application of modular, acoustic diffusing elements. R. Walker The requirements for and the advantages of a modular acoustic diffusing element are described. This module was intended to complement the existing range of acoustic absorbing elements already in widespread use. The theoretical background to the principles is summarised, based on the published work of M.R. Schroeder, and a design for such a module is discussed. The performance of the resulting...
Topics: acoustic, diffusers, bbc, primitive, frequency, modular, diffusing, sequence, module, diffuser,...
Topics: acoustic, diffusers, bbc, primitive, frequency, modular, diffusing, sequence, module, diffuser,...
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,...
Topics: waveform, digital, pulse, synchronising, timing, analogue, pulses, sampling, jitter, waveforms,...
BBC Research and Development Reports
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C.D. Mathers (editor)
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R&D Report 1996-14 : WTDM Pilot Installation. A report on the work of RACE Project 2001 C.D. Mathers (editor) The BBC has led two RACE-sponsored projects to develop the technology for a fibre-optic based video signal router. In the first project, R1036, prototype equipment was developed; a demonstration in 1992 showed that optical routeing was not only feasible, but could accommodate different signal formats such as serial digital 625-line and uncompressed EU-95 HDTV. In a second RACE...
Topics: optical, wavelength, wtdm, network, pilot, nrk, installation, routeing, demultiplexer, equipment,...
Topics: optical, wavelength, wtdm, network, pilot, nrk, installation, routeing, demultiplexer, equipment,...
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,...
Topics: mdf, door, insulations, bitumen, damping, measured, bbc, sound, acoustic, lightweight, band centre,...
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...
Topics: mkh, type, sennheiser, akg, impedance, frequency, noise, microphone, microphones, circuit, akg...
R&D Report 1977-03 : Factors in the design of loudspeaker cabinets. H.D. Harwood, R. Matthews The mechanical properties of timber, wood products and other materials potentially suitable for the construction of loudspeaker cabinets have been measured and details of the results are given. Various commercially available damping materials have also been assessed and their relative efficiencies are listed. A new method of test for the cabinets of completed loudspeakers has been devised and a...
Topics: loudspeaker, damping, cabinet, materials, frequency, grain, material, modulus, elastic, resonance,...
Topics: loudspeaker, damping, cabinet, materials, frequency, grain, material, modulus, elastic, resonance,...
BBC Research and Development Reports
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S.R. Ely
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R&D Report 1996-03 : MPEG video coding: A basic tutorial introduction S.R. Ely MPEG has been outstandingly successful in defining standards for video compression coding, serving a wide range of applications, bit-rates, qualities and services on a worldwide basis. The standards are based upon a flexible toolkit of techniques for bit-rate reduction. MPEG video coding uses a combination of motion-compensated interframe prediction (for reducing temporal redundancy) with Discrete Cosine...
Topics: prediction, dct, coding, picture, macroblock, coded, quantisation, mpeg, frame, coder, video...
Topics: prediction, dct, coding, picture, macroblock, coded, quantisation, mpeg, frame, coder, video...
BBC Research and Development Reports
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H.D. Harwood, D.E.L. Shorter
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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,...
Topics: ribbon, microphone, pgs, response, microphones, frequencies, impedance, frequency, transverse,...
BBC Research and Development Reports
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H.D. Harwood, R.J. Packer
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R&D Report 1954-23 : The Neumann microphone Type U47 H.D. Harwood, R.J. Packer A new directional electrostatic microphone, type U 47, produced by the firm of Neumann in Berlin, incorporates the capsule originally designed for the type M 49 microphone but uses a cheaper form of head amplifier. The U 47 microphone is designed to give either cardioid or omnidirectional polar response. Frequency characteristics, sensitivity and noise have been measured on a single specimen for both conditions....
Topics: microphone, omnidirectional, cardioid, characteristics, condition, output, neumann, frequency,...
Topics: microphone, omnidirectional, cardioid, characteristics, condition, output, neumann, frequency,...
BBC Research and Development Reports
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G.I. Ross
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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,...
Topics: pontop, truleigh, strength, pike, temporary, transmitters, transmitter, field, field strength,...
BBC Research and Development Reports
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R.H.Evans
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R&D Report 1996-10 : Radio with Pictures - A new medium R.H.Evans The advent of digital radio broadcasting provides the broadcaster with the opportunity to convey a variety of data types, to considerably enhance a basic audio service. Analogue FM broadcasts already benefit from a variety of features from the Radio Data System (RDS), but while RDS uses an additional carrier to convey this digital data, the emerging all-digital services such as Eureka DAB, Inmarsat IDDS and WorldSpace, have...
Topics: rwp, audio, pictures, programme, news, data, inmarsat, picture, receiver, radio, television news,...
Topics: rwp, audio, pictures, programme, news, data, inmarsat, picture, receiver, radio, television news,...
R&D Report 1976-29 : The design of the miniature monitoring loudspeaker Type LS3/5A. H.D. Harwood, M.E. Whatton, R.W. Mills This report describes the design of a miniature two-unit loudspeaker of adequate sound quality and loudness to serve as a monitor in conditions where larger existing designs would be unusable. Details are given of the construction and performance of the loudspeaker which is shown to be equally suitable for monophonic, stereophonic and quadraphonic purposes.
Topics: loudspeaker, sound, impedance, bbc, unit, cabinet, axial, frequency, resonance, design, report...
Topics: loudspeaker, sound, impedance, bbc, unit, cabinet, axial, frequency, resonance, design, report...
R&D Report 1978-21 : Narrow-band FM system for television links: interference between fm and am television signals. N.H.C. Gilchrist, A.G. Lyner The Band-V fm television links used for television outside broadcasts have suffered more and more from interference as the network of uhf television broadcasting transmitters has expanded. There is also thought to be an increasing danger that Band-V links will cause interference to broadcast television reception. Experimental work has been carried...
Topics: mhz, signal, interference, interfering, channel, television, sidebands, signals, frequency, system,...
Topics: mhz, signal, interference, interfering, channel, television, sidebands, signals, frequency, system,...
BBC Research and Development Reports
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J.R. Chew
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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,...
Topics: frequency, ionophone, horn, distortion, output, tuning, loudspeaker, axial, corona, overload,...
R&D Report 1992-10 : The design of a modular sound absorber for very low frequencies. J.A. Fletcher Studios and sound control rooms usually have their walls acoustically treated to control the reverberation time. in the BBC, this treatment often takes the form of modular absorbers of which there are a number of BBC designed types for sound absorption in different frequency bands. This report describes an investigation of the feasibility of a modular absorber for the 50-100 Hz frequency...
Topics: absorption, frequency, absorber, absorbers, bbc, helmholtz, reverberation, modular, measured, wave,...
Topics: absorption, frequency, absorber, absorbers, bbc, helmholtz, reverberation, modular, measured, wave,...
R&D Report 1977-12 : LF and MF propagation: a study of sky-wave field-strength variation. P. Knight LF and MF sky-waves vary in strength during periods which may be as short as a minute or as long as 11 years; this range includes day-to-day, diurnal, seasonal and solar-cycle variations. A detailed study has been made of all that is known about LF and MF sky-wave field-strength variation and this has been supplemented by further analysis of measured data.
Topics: variation, measurements, field, propagation, strengths, strength, seasonal, median, frequency,...
Topics: variation, measurements, field, propagation, strengths, strength, seasonal, median, frequency,...
BBC Research and Development Reports
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D.E.L. Shorter, G.J. Phillips
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R&D Report 1959-15 : A 41.5 Mc/s transistor field strength monitoring receiver. D.E.L. Shorter, G.J. Phillips This report describes a simple field strength recording receiver designed for monitoring television sound transmissions at comparatively short distances from the transmitter. The main characteristics of the receiver are a good gain stability, small size and low power consumption. The receiver has been designed for use at 41.5 Mc/s but receivers of similar design will be built for...
Topics: receiver, gain, amplifier, transistor, input, output, audio, emitter, circuit, stage, gain...
Topics: receiver, gain, amplifier, transistor, input, output, audio, emitter, circuit, stage, gain...
R&D Report 1963-27 : An introduction to the theory of aerials H. Page This report gives an introduction to the theory of aerials with emphasis on broadcasting. The function of an aerial, when transmitting, is to propagate the electro-magnetic waves flowing from the source into space.
Topics: aerial, radiation, impedance, vertical, doublet, field, aerials, current, transmitting, pattern,...
Topics: aerial, radiation, impedance, vertical, doublet, field, aerials, current, transmitting, pattern,...
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...
Topics: field, khz, magnetic, electric, terrain, clutter, transmitter, measurements, bbc, impedance, free...
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,...
Topics: cone, frequency, surround, mould, unit, shape, characteristic, axial, goodmans, loudspeakers,...
BBC Research and Development Reports
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G.D. Monteath, G.H. Millard
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R&D Report 1954-19 : The effect of the ground constants, and of an earth system, on radiation from a vertical aerial. G.D. Monteath, G.H. Millard This report describes a theoretical investigation into earth systems for medium-wave transmitting stations. The change in the groundwave field strength for a given input current, resulting from the installation of an earth system, has been calculated by the compensation-theorem method. Attention is mainly directed to perfectly-conducting circular...
Topics: earth, aerial, groundwave, system, ground, field, vertical, impedance, conducting, radius,...
Topics: earth, aerial, groundwave, system, ground, field, vertical, impedance, conducting, radius,...
R&D Report 1994-04 : Multi-channel sound for HDTV: Subjective tests on sound channel configuration J.A. Fletcher This report describes subjective tests carried out as part of the Eureka 95 project to compare different multi-channel sound systems being considered for use with HDTV. In the tests, the number of sound channels varied from one (mono) to five (three front channels and two surround channels). The improvement in quality obtained by increasing the number of front channels from two...
Topics: zirkus, knie, preference, surround, acrobats, vilia, tipsy, listeners, sound, eliott, knie peg,...
Topics: zirkus, knie, preference, surround, acrobats, vilia, tipsy, listeners, sound, eliott, knie peg,...
R&D Report 1963-03 : Visit to United States - 30th November to 9th December 1962. H. Page, D.E. Todd The BBC were invited to send representatives to a Conference of the VOA Science Advisory Group which was held at Greenville North Carolina from December 3rd - 5th 1962. This is a report of that visit.
Topics: rca, voa, colour, transmitters, fcc, sideband, bbc, propagation, srl, transmitter, colour camera,...
Topics: rca, voa, colour, transmitters, fcc, sideband, bbc, propagation, srl, transmitter, colour camera,...
R&D Report 1990-01: Antennas for portable VHF-FM receivers. R.D.C. Thoday This report describes a number of compact antennas which have been considered as replacements for the standard whip antenna which is normally fitted to VHF portable receivers. A comparison made of their characteristics shows that, of the antennas considered in the survey, the quarter whip still provides the best sensitivity. However the normal-mode helix is a more convenient and compact antenna and is shown to perform...
Topics: antenna, receiver, helix, whip, sensitivity, tuning, ferrite, antennas, impedance, portable,...
Topics: antenna, receiver, helix, whip, sensitivity, tuning, ferrite, antennas, impedance, portable,...
BBC Research and Development Reports
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W.I. Manson, D.E.L. Shorter, H.D. Harwood, J. Nash, R.J. Packer
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R&D Report 1954-40 : The Telefunken microphones Type Elam 200 and Elam 201. W.I. Manson, D.E.L. Shorter, H.D. Harwood, J. Nash, R.J. Packer Tests have been carried out on specimens of the Telefunken electrostatic microphones type ELAM 200 and ELAM 201. The ELAM 200 microphone is pressure-operated while the ELAM 201 can be switched to give either omnidirectional or cardioid characteristics; identical pre-amplifier arrangements are used for both types. The usual measurements of frequency...
Topics: elam, blam, microphones, sensitivity, microphone, omnidirectional, cardioid, frequency,...
Topics: elam, blam, microphones, sensitivity, microphone, omnidirectional, cardioid, frequency,...
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...
Topics: dipole, dipoles, gain, relative, radiating, tangential, radiated, mutual, doublets, cylinder, free...
BBC Research and Development Reports
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W.I. Manson
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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,...
Topics: microphone, frequency, ohms, response, ohm, impedance, specimen, output, parabolic, philips,...
R&D Report 1987-13 : Band II VHF antenna for home construction. S. Wakeling A wideband Band II Yagi antenna, suitable for home construction, has been designed using computer techniques. The antenna is intended for use as a domestic receiving antenna for VHF/FM sound broadcasting at frequencies in the range 88 to 108 MHz. Scale-model antennas were constructed and measured to verify the performance predicted by the computer. Finally, a full-scale Yagi antenna was constructed and its radiation...
Topics: antenna, yagi, dipole, vhf, antennas, ccir, design, impedance, element, folded, single dipole,...
Topics: antenna, yagi, dipole, vhf, antennas, ccir, design, impedance, element, folded, single dipole,...
R&D Report 1979-22 : Design of the high-level studio monitoring loundspeaker type LS5/8. C.D. Mathers A new studio monitor is described which can provide high-quality sound at sufficiently high levels to fulfil the complete range of monitoring requirements from pop to serious music. The design principles and criteria are outlined, and the performance of the prototypes is assessed both subjectively and objectively.
Topics: frequency, loudspeaker, bbc, cabinet, monitoring, drive, unit, design, filter, baffle, loudspeaker...
Topics: frequency, loudspeaker, bbc, cabinet, monitoring, drive, unit, design, filter, baffle, loudspeaker...
BBC Research and Development Reports
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W.N. Sproson
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R&D Report 1954-34 : A new photo-electric optical bench. W.N. Sproson An outline of the photoelectric method of testing lenses is given, together with some details of the two types of test pattern now in use and the form of aperture correction necessitated by the finite width of the scanning slit. The photoelectric test bench is described and a few preliminary results are quoted.
Topics: lens, modulation, wave, test, bench, microscope, optical, pattern, slit, photoelectric, wave...
Topics: lens, modulation, wave, test, bench, microscope, optical, pattern, slit, photoelectric, wave...
BBC Research and Development Reports
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G.H. Millard, R.H. Minns, G.D. Monteath
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R&D Report 1956-22 : Power measurement in the frequency range 30-1000 Mc/s. G.H. Millard, R.H. Minns, G.D. Monteath Laboratory equipment has been developed for measuring power over a wide range of levels in the frequency range 30-1000 Mc/s. A milliwatt meter using thermistors measures powers between 1 and 20 mW directly, and its use is extended to higher powers by means of dissipative attenuators and directional couplers. Each item of the equipment is fitted with connectors, suitable for...
Topics: power, directional, impedance, thermistors, measurement, attenuators, coupler, thermistor, voltage,...
Topics: power, directional, impedance, thermistors, measurement, attenuators, coupler, thermistor, voltage,...
BBC Research and Development Reports
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P. Shelswell
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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...
Topics: symbol, cofdm, signal, frequency, bbc, modulation, carriers, digital, dab, fourier, modulation...
R&D Report 1987-14 : Improvements to a UHF rebroadcast television link suffering tidal fading: Countisbury UHF relay station. J.H. Moore The Countisbury UHF relay station serves the localities of Lynmouth and Lynton in Devon. For some time, the problems of co-channel interference and tidal fading have on occasion been evident. The report gives results obtained utilizing a new Rebroadcast Link (RBL) antenna array, which has improved very considerably the quality of signals received at this...
Topics: channel, array, antenna, countisbury, strength, relay, bbc, picture, phased, grade, video cassette,...
Topics: channel, array, antenna, countisbury, strength, relay, bbc, picture, phased, grade, video cassette,...
R&D Report 1964-23 : Low noise amplifiers for UHF reception R.V. Harvey, J.B. Izatt, P.C.J. Hill Noise in broadcast receivers generally increase as the frequency increases, whereas noise from external sources decreases. In receivers designed for u.h.f. using conventional valve or transistor circuits, the noise is about 10 dB greater than the aerial noise. There is therefore an obvious economic advantage to be gained by reducing receiver noise at u.h.f., particularly for special purposes...
Topics: amplifier, frequency, noise, diode, idler, circuit, parametric, signal, pump, gain, negative...
Topics: amplifier, frequency, noise, diode, idler, circuit, parametric, signal, pump, gain, negative...
BBC Research and Development Reports
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M.P.Shovelton
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R&D Report 1996-13 : PlanTx: The universal tool for digital and analogue transmitter planning M.P.Shovelton Terrestrial radio-frequency planning is undergoing a revolution. With the movement of broadcasters towards digital transmission, the RF planning book is being re-written. The design of digital transmitter networks demands new techniques and innovative new prediction tools in order to allow these networks to be accommodated within the already tightly-packed broadcast spectrum (that is,...
Topics: transmitter, matrix, interference, digital, transmitters, plantx, analogue, terrain, bbc,...
Topics: transmitter, matrix, interference, digital, transmitters, plantx, analogue, terrain, bbc,...
R&D Report 1994-15 : The sound insulations of studio doors: Part 2: Door seals G.D. Plumb, R. Clark The acoustic performances of a range of proprietary acoustic door seals were measured in the Transmission Suite. The seals were fitted to a standard BBC lead-cored door hung in a purpose-built blockwork wall. As a result of the work, suitable plant-on magnetic perimeter seals and drop-down threshold seals are recommended. The use of these seals will simplify the existing door frame design and...
Topics: seals, threshold, perimeter, fitted, raven, insulations, magnetic, door, compression, bbc, octave...
Topics: seals, threshold, perimeter, fitted, raven, insulations, magnetic, door, compression, bbc, octave...
R&D Report 1954-20 : AKG microphone Type DYN 60K. W.I.Manson Laboratory tests have been carried out on a single specimen of the AKG microphone type 60K. Measurements of frequency response, sensitivity, impedance and susceptibility to interference from magnetic fields have been made and are described.
Topics: microphone, frequency, dyn, response, magnetic, oooooo, akg, impedance, characteristics, output,...
Topics: microphone, frequency, dyn, response, magnetic, oooooo, akg, impedance, characteristics, output,...
BBC Research and Development Reports
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W.K.E. Geddes, M.W. Greenway, A.L. Newman and F.L. Ward
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R&D Report 1954-38 : Sound insulation and acoustics in the Belfast studio centre W.K.E. Geddes, M.W. Greenway, A.L. Newman and F.L. Ward. During the years 1952/3, all the studios in Broadcasting House, Belfast, except Studios Nos. 1 and 4, were given permanent acoustic treatment. This report summarises the results of acoustic measurement in all the studios, describes certain modifications which were made during the building work, and discusses conclusions of a general nature which resulted...
Topics: studio, studios, reverberation, cubicle, frequency, continuity, acoustic, insulation, measurements,...
Topics: studio, studios, reverberation, cubicle, frequency, continuity, acoustic, insulation, measurements,...
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,...
Topics: type, microphone, capsule, extension, interference, impedance, characteristics, frequency, noise,...
R&D Report 1984-12 : The susceptibility of aeronautical navigational aids to interference from adjacent-band broadcast transmissions. G.H. Millard Measurements to determine the susceptibility of some airborne navigation receivers to interference from v.h.f/f.m sound transmissions are described. The measurements were designed to investigate both the response to interference radiated in-band and to intermodulation in the receivers . The results of the measurements were submitted to an ITU...
Topics: receiver, ils, interference, intermodulation, frequency, signal, mhz, broadcast, transmissions,...
Topics: receiver, ils, interference, intermodulation, frequency, signal, mhz, broadcast, transmissions,...
R&D Report 1963-63 : Some investigations into the performance of the CPS Emitron television camera tube. S.J. Lent, A.H. Jones This report describes a series of experiments carried out in order to determine the behaviour of a C.P.S. Emitron television camera tube in the operating conditions encountered in image-transfer standards converters. Some previously undetected aspects of the storage characteristics are described, and beam pulling has been considered in some detail. Finally, the...
Topics: beam, camera, scanning, illumination, target, exposure, output, signal, tube, storage, beam...
Topics: beam, camera, scanning, illumination, target, exposure, output, signal, tube, storage, beam...
BBC Research and Development Reports
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L.F. Tagholm, G.I. Ross, R.S.A. Sandell
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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,...
Topics: transmitter, aberdeen, temporary, redmoss, strength, vision, field, watts, field strength,...
BBC Research and Development Reports
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J.T. Zubrzycki
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R&D Report 1996-12 : Mobile Broadband System. A report on the work of RACE Project 2067. J.T. Zubrzycki Mobile Broadband System (MBS) is a wireless cellular radio network capable of carrying digital signals at bit rates sufficient for digital video, including compressed HDTV. The technological feasibility has been studied in RACE* Project 2067 MBS, which had the aim to extend the Broadband Integrated Services Digital Network (B-ISDN) to mobile users, providing much higher capacity to users...
Topics: mbs, mobile, ghz, base, broadband, demonstrator, antennas, antenna, project, diversity, diversity...
Topics: mbs, mobile, ghz, base, broadband, demonstrator, antennas, antenna, project, diversity, diversity...
BBC Research and Development Reports
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P.A. Sarginson
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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,...
Topics: elementary, stream, buffer, coder, programme, access, transport, decoder, video, streams,...
R&D Report 1976-28 : Hadamard transformation: Assessment of bit-rate reduction methods. C.K.P. Clarke This report is concerned with the bit-rate reduction of signals produced by Walsh-Hadamard transformation of PCM television signals. The main characteristics of the transform signals are outlined and the methods of linear and non-linear coding used to reduce their bit rate are described. It was found that, with linear coding, a slightly higher bit rate is required to describe the transform...
Topics: transform, bits, coefficients, signal, coding, hadamard, errors, signals, impairment, sampling,...
Topics: transform, bits, coefficients, signal, coding, hadamard, errors, signals, impairment, sampling,...
R&D Report 1995-13 : Evaluations of high quality, multichannel audio codecs carried out on behalf of SO/IEC MPEG. D.J. Meares BBC R&D has been conducting audio tests for and on behalf of ISO/IEC MPEG since 1973. This report summarises the more important of those tests and the methods used for the assessments. Systems tested include MPEG-2 Layers II and III, as well as the more recent Non-Backwards Compatible codecs. It is reported that the optimisation is still in progress.
Topics: mpeg, coding, layer, audio, codecs, tests, iii, codec, nbc, test, moving pictures, harp mane, layer...
Topics: mpeg, coding, layer, audio, codecs, tests, iii, codec, nbc, test, moving pictures, harp mane, layer...
R&D Report 1977-30 : A wideband microstrip UHF hybrid. J.L. Riley The use of discrete power-splitting hybrids in uhf circuit design can cause unnecessary mismatches and losses at connector junctions. A printed hybrid, with similar electrical characteristics, overcomes these problems and offers further savings of space and cost. Tight coupling, however, is difficult to achieve in conventional microstrip construction. Also with tight coupling the velocity dispersion of coupled lines is more...
Topics: coupler, coupling, microstrip, impedance, lines, design, coupled, interdigitated, hybrid,...
Topics: coupler, coupling, microstrip, impedance, lines, design, coupled, interdigitated, hybrid,...
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...
Topics: frequency, signal, cofdm, system, kenley, digital, crystal, reception, signals, receiver, active...
BBC Research and Development Reports
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R.G. Manton
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R&D Report 1959-08 : Low-signal amplifying valves for use at U.H.F. R.G. Manton The object of this report is to review some of the types of valve that are suitable for use in u.h.f. amplifying stages in receivers, and to describe units which have been constructed to test the performance of two of these valves at a frequency of about 655 Mc/s.
Topics: amplifier, valve, output, input, amplifiers, anode, bandwidth, grid, gain, impedance, electrical...
Topics: amplifier, valve, output, input, amplifiers, anode, bandwidth, grid, gain, impedance, electrical...
R&D Report 1991-11 : Field strength prediction for VHF/UHF terrestrial broadcasting and mobile radio services R.S. Sandell, R.W. Lee, C.P. Bell The propagation curves used internationally for the planning of services in the VHF and UHF Broadcast Bands are those of CCIR Recommendation 370 and associated Report 239. Derivations from these are also used for Mobile Radio planning in this frequency range. These curves, first produced some 30 years ago, have subsequently been the subject of...
Topics: terrain, ccir, prediction, curves, propagation, antenna, height, measurements, receiving, bbc,...
Topics: terrain, ccir, prediction, curves, propagation, antenna, height, measurements, receiving, bbc,...
R&D Report 1974-30 : Arrays of UHF log-periodic aerials: a vertically-polarised receiving aerial for re-broadcast links G.H. Millard, J.L. Riley The aerial array described comprises four UHF ruggedised log-periodic aerials and is suitable for vertically-polarised reception at some RBL sites. The UHF bands IV and V are covered by two versions, differing in dimensions only. The impedance match to 50 ohms and the horizontal radiation pattern sidelobe level meet the specification. The average...
Topics: aerial, aerials, array, bbc, radiation, ruggedised, mhz, band, horizontal, gain, department report,...
Topics: aerial, aerials, array, bbc, radiation, ruggedised, mhz, band, horizontal, gain, department report,...
R&D Report 1972-24 : The calculation of electronic masking for use in telecine F.A. Griffiths Electronic masking provides a means whereby some of the defects in the reproduction of a scene by colour motion-picture photography may be compensated electronically when the film is scanned by television. Prior to the use of electronic masking, television film scanners could do no more than attempt to give a reproduction of the scene similar to that produced by optical projections, and the results...
Topics: film, telecine, dye, density, dyes, analysis, masking, matrix, signals, spectral, colour film, band...
Topics: film, telecine, dye, density, dyes, analysis, masking, matrix, signals, spectral, colour film, band...
R&D Report 1971-15 : Low-frequency sound absorbers A.N. Burd Abstract Membrane low-frequency absorbers have been used for many years in the BBC for the absorption of low-frequency sound. A variant of this type of absorber using a compound panel had some success, but careful choice of the size and shape was necessary to obtain the optimum performance. Simplifications in the construction of perforated absorbers have led to a cheaper and more easily reproducible prefabricated form.
Topics: absorbers, absorber, impedance, measurements, studio, membrane, reverberation, absorption, studios,...
Topics: absorbers, absorber, impedance, measurements, studio, membrane, reverberation, absorption, studios,...
R&D Report 1992-09 : Low-frequency room responses: Part 2 -- Calculation methods and experimental results. R. Walker The development of a relatively simple method for predicting low- frequency responses for near-rectangular rooms based on the summation of modal responses and their coupling coefficients for the source and receiver positions is outlined. Comparisons between calculated and measured responses show that many of the response features can be reproduced. The question of optimum...
Topics: room, frequency, loudspeaker, frequencies, loudspeakers, octave, measured, mode, modes, response,...
Topics: room, frequency, loudspeaker, frequencies, loudspeakers, octave, measured, mode, modes, response,...
BBC Research and Development Reports
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C.J. White, D.W. Taplin, R.S. Sandell, J. Hall
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R&D Report 1956-09 : Low power television transmitters -- Site tests in Londonderry. C.J. White, D.W. Taplin, R.S. Sandell, J. Hall Two sites, Sheriffs Mountain and Lisdillon, have been tested. Of these the Sheriffs Mountain site will provide the better service and, in conjunction with the Divis transmitter, coverage over most of Northern Ireland will be achieved with the exception of the Enniskillen area. Reception tests indicate that the field strength of Divis at Sheriffs Mountain should...
Topics: sheriffs, divis, mountain, site, lisdillon, contour, tests, londonderry, aerial, field, principal...
Topics: sheriffs, divis, mountain, site, lisdillon, contour, tests, londonderry, aerial, field, principal...
BBC Research and Development Reports
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P. Knight, G.J. Phillips
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R&D Report 1954-07 : Modifications to the Brookmans Park Home-service mast-radiator. P. Knight, G.J. Phillips The report describes modifications to the London Home-Service mast-radiator completed in September 1952. Provision has been made for driving the mast simultaneously at the base and across the break previously used for series loading. New components have been installed in the A.T.H., both for base-funding (standby circuit) and for double-feeding (main circuit). The distribution of...
Topics: mast, current, base, minimum, transmission, impedance, aerial, radiation, circuit, power, field...
Topics: mast, current, base, minimum, transmission, impedance, aerial, radiation, circuit, power, field...
BBC Research and Development Reports
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R.A. Rowden, L.F. Tagholm, D.E. Susans, D.N. Cudlip
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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...
Topics: pulse, aerial, output, pulses, frequency, anode, transmitter, polar, consists, cathode, tuned...
BBC Research and Development Reports
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A.E. Axon, C. Henocq
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R&D Report 1955-05 : The artificial reverberation test set. A.E. Axon, C. Henocq. This report looks at the Artificial Reverberation Test Set which contiunes previous work done by the department.
Topics: reverberation, test, decay, set, machine, logarithmic, cathode, artificial, tone, calibration, jack...
Topics: reverberation, test, decay, set, machine, logarithmic, cathode, artificial, tone, calibration, jack...
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,...
Topics: telefis, eireann, converter, receivers, studio, eire, bbc, transmissions, vidicon, transmitters,...
R&D Report 1992-08 : Low-frequency room responses: Part 1 -- Background and qualitative considerations R. Walker The problems inherent in the reproduction of high-quality sound in relatively small rooms are discussed. Methods of predicting the inevitably uneven low-frequency response from source to listener or microphone are also discussed. It is concluded that, even with perfect prediction methods. there would still be some compromises which could only be resolved by making subjective...
Topics: frequency, frequencies, room, modes, acoustic, mode, response, sound, rooms, modal, low frequency,...
Topics: frequency, frequencies, room, modes, acoustic, mode, response, sound, rooms, modal, low frequency,...
BBC Research and Development Reports
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W.I. Manson, D.E.L. Shorter
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R&D Report 1956-03 : The Ronette crystal microphone cartridge Type MC.65. W.I. Manson, D.E.L. Shorter The report gives tests results on three samples of the Ronette diaphragm-type crystal microphone cartridge MC.65. The performance varies considerably between individual specimens but is on the average superior to that of earlier microphone of this kind.
Topics: microphone, ronette, frequency, crystal, cartridge, specimens, response, specimen, axial, noise,...
Topics: microphone, ronette, frequency, crystal, cartridge, specimens, response, specimen, axial, noise,...
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,...
Topics: partitions, absorption, partition, sound, insulation, unperforated, perforated, leaf, acoustic,...
R&D Report 1970-31 : VHF receiving aerials: The use of active elements D.J. Whythe An array of half-wavelength dipoles forms the most convenient type of aerial for VHF television re-broadcast reception. The principles are well-known by which such an array can be designed to have any specified directivity but re-radiation from the dipole makes it difficult to implement those principles in practice. This report shows that the difficulty can be overcome by incorporating an amplifier directly...
Topics: dipole, array, dipoles, directivity, input, active, impedance, amplifier, rth, terminals, mutual...
Topics: dipole, array, dipoles, directivity, input, active, impedance, amplifier, rth, terminals, mutual...
R&D Report 1970-16 : Field-store standards conversion: Servo-control of the field delay R.E. Davies A servo-control system is described which maintains the duration of a field delay equal to the field duration of the applied television signal. Errors in delay are corrected by binary-related lengths of coaxial cable which are switched into or out of circuit, as required. Since the range of control is insufficient using practical lengths of cable, several quartz delays are also included to...
Topics: delay, synchronising, switched, signals, quartz, pulses, delays, field, signal, duration, quartz...
Topics: delay, synchronising, switched, signals, quartz, pulses, delays, field, signal, duration, quartz...
BBC Research and Development Reports
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R.D. Pittilo, S.J. Ashdown, J. Hall
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R&D Report 1954-18 : Channel Islands television site test. R.D. Pittilo, S.J. Ashdown, J. Hall Tests have been made from a site at Les Platons on the north coast of Jersey. It was found that a transmitter sited here would serve both Jersey and Guernsey adequately.
Topics: strength, guernsey, field, transmitter, contours, islands, jersey, channel, les, site, islands...
Topics: strength, guernsey, field, transmitter, contours, islands, jersey, channel, les, site, islands...
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,...
Topics: antenna, ghz, signal, transmitting, frequency, antennas, propagation, multipath, path, bbc,...
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A collection of BBC Research and Development reports and white papers, dating from the 1960s through to 1996.
Created on
November 2
2011
2011
Jason Scott
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