R&D Report 1968-37 : Aspects of frequency-division-multiplex colour systems for television field-store standards converters D.W. Osborne This report describes an investigation into certain aspects of a proposal to use a frequency-division-multiplex system for the transmission of a colour television signal through the 'advanced' Field-Store Standards Converter. The investigation showed that the use of such a system, within the band-width of currently-available ultrasonic delay, would be...
Topics: intermodulation, order, signal, luminance, interference, unit, delay, frequencies, signals,...
R&D Report 1971-25 : Satellite broadcasting: Possible advantages of using digital modulation for television A. Brown This report is concerned with the broadcasting of television from satellites. It compares the carrier-to-noise ratios and co-channel protection ratios required for digitally-coded modulation, with those required for frequency modulation. It is unlikely that a digital system will permit a significantly lower transmitter power than that required for a FM system. However, a...
Topics: digital, pulse, bandwidth, system, amplitude, noise, signal, modulation, error, required, digit...
R&D Report 1974-21 : Satellite broadcasting: channel separation requirements for FM television signals and for a FM sound signal adjacent to a FM television channel N.H.C. Gilchrist This report describes experimental work carried out to determine the frequency separation required between high-deviation FM sound signals, and between FM sound and FM television signals, when they are transmitted on adjacent channels. A frequency separation of 0.8 MHz is recommended for situations where two FM...
Topics: signal, sound, mhz, frequency, ratio, interfering, separation, television, adjacent, signals,...
R&D Report 1987-07 : A digital audio link to the Channel Islands in the UHF television band: protection of television signals from digitally modulated interference. J.H. Stott, P.R. Durrant Proposals have been made to use a digitally modulated signal in a UHF television channel to feed radio programme sound to the Channel Islands. It is clearly necessary to demonstrate that the proposed link will not cause unacceptable interference to existing UHF television services, including those of...
Topics: interference, frequency, offset, protection, signal, ratio, digital, mhz, modulated, digitally,...
R&D Report 1975-01 : The estimation of the service areas of medium- and long-wave broadcasting stations. R.A. Rowden, C.P. Bell The aim of this report is to enable persons having no previous experience of the subject to make reasonably accurate estimates of the service areas of medium- and long-wave broadcasting stations, taking account of the vertical and horizontal directivity of the transmitting installation, its radiation efficiency, and the influence of the ground constants and of...
Topics: strength, field, conductivity, curves, aerial, interfering, transmitter, interference, field...
R&D Report 1991-01 : Interference protection requirements for terrestrial microwave link in the UK private-user frequency bands. P.D. Gill, M.C.D. Maddocks Many broadcast television circuits are carried on microwave links in the private-user frequency bands. At present the television signals are carried in analogue form. High data-capacity links would be required to allow television signals to be carried in digital form. The bandwidth available in the lower frequency private-user bands...
Topics: interference, mhz, offset, spectrum, measured, qpsk, signal, frequency, interfering, calculations,...
R&D Report 1993-04 : Alleviation of co-channel interference at Poole relay station J.H. Moore, A.I.E. Booker The Rowridge UHF television transmitting station, situated on the Isle of Wight, radiates the four principal UK domestic television channels to the south coast of England, and provides an off-air feed to a number of dependent relays. At one relay station (Poole), occasional Co-channel Interference (CCI) is known to occur. It is particularly noticeable during the summer and autumn...
Topics: offset, precision, channel, rowridge, relay, frequency, poole, interference, impairment, cci, total...
R&D Report 1969-34 : Frequency response characteristics of four a.m. receivers K. Hacking, R.J.J. Roach Measurements have been made to determine the amplitude-versus-frequency response characteristics of a selection of four domestic a.m. receivers currently used in the m.f/l.f bands. The electrical and he acoustical characteristics were both investigated, and the results have been combined to produce the overall repsonse. Subjective meausurements of the adjacent-channel protection ratios of...
Topics: frequency, response, receiver, khz, acoustical, loudspeaker, carrier, receivers, characteristics,...
R&D Report 1978-13 : Computer programs for v.h.f. interference prediction using a terrain data bank. J.H. Causebrook, B. Tait A set of computer programs has been written to aid broadcast service planning work in the VHF bands. They are intended for FM sound in Band II as well as new television and other possible services in Bands I and III. The prime object is the prediction of interference levels from other transmitters into a service area. The methods are an extension of those employed...
Topics: interference, transmitter, receiver, iii, protection, data, interfering, programs, bands, band,...
R&D Report 1956-21 : A comparison of CW interference effects on colour and monochrome television transmissions. A.V Lord, G.F. Newell This respect describes measurements of the interference by an unmodulated carrier with both colour and monochrome transmissions. The British 405-line system was used for both colour and monochrome transmissions, the colour system being a modified N.T.S.C. type. The results show that colour transmissions are more susceptible than monochrome transmissions to...
Topics: monochrome, colour, receivers, protection, transmission, ratios, interference, receiver,...
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 1987-08 : A digital audio link to the Channel Islands in the UHF television band: planning considerations M.C.D. Maddocks, A.P. Robinson A digital link at UHF has been proposed as a means of feeding radio programmes over the trans-horizon sea path to the Channel Islands. The theoretical performance of such a link and its compatibility with existing UHF transmissions is investigated. It is predicted that such a link will operate with a reliability in excess of 99.5% time (due to...
Topics: interference, aerial, signal, strength, channel, ratio, link, stockland, field, digital, radiation...
R&D Report 1986-16 : The permissable level of lower sideband radiation from a UHF TV transmitter A.P. Robinson Amplitude-modulated television signals are transmitted with a vestigial lower sideband for reasons of spectrum economy. The question of the degree of suppression of the lower sideband needed to avoid interference to reception of the lower adjacent channel has been re-examined by subjective tests. The currently accepted protection ratio of 3 dB for interference coming from the upper...
Topics: sideband, interference, suppression, lower, transmitter, signal, ratio, vision, mhz, interfering,...
R&D Report 1966-15 : Compatible single-sideband modulation: Experimental investigation of the performance with conventional AM receivers. J.B. Izatt A laboratory investigation is described of the overall performance of a compatible single sideband (c.s.s.b) system when used with current types of domestic receivers. The systems employs an alternative method of amplitude modulation to that normally used in the l.f., m.f. and h.f. broadcasting bands, the sideband on one side of the carrier...
Topics: signal, interference, modulation, receiver, fading, audio, receivers, tuning, measurements,...
R&D Report 1968-47 : The subjective assessment of multiple co-channel television interference A. Brown The increase in protection ratio required by a number of simultaneous constant-level interfering signals, compared with the ratio required for a single interfering signal is considered. The results of some subjective tests are presented, and formulae are deduced to enable the additional protection ratio to be calculated, for related and unrelated types of interference
Topics: interferences, interfering, subjective, addition, signals, unrelated, impairment, interference,...
R&D Report 1993-03 : Coverage aspects of a Single Frequency Network designed for Digital Audio Broadcasting C.P. Bell, W.F. Williams Since the early 1960s, the VHF/FM pilot tone system has been used by broadcasters to supply high quality stereophonic programmes to listeners equipped with fixed receivers and modest gain directional antennas mounted externally at a height of about 10 metres above ground level. More recently, with the advent of improved radio receivers and digital technology...
Topics: frequency, bbc, antenna, required, network, propagation, protection, transmitters, guard,...
R&D Report 1967-34 : The protection ratio required by an asymmetric-sideband, frequency-modulated monochrome television signal against an unwanted CW signal D.W. Osborne This report describes subjective tests which were made to determine the protection ratio required by an asymmetric-sideband, frequency-modulated monochrome television signal in order to reduce interference from an unwanted CW signal to a 'just not perceptible' level.
Topics: signal, interference, frequency, protection, monochrome, mhz, unwanted, ratio, required, ratios,...
R&D Report 1971-19 : Satellite broadcasting: Co-channel protection ratios for FM television A. Brown Abstract Some of the parameters required for an FM system suitable for direct television broadcasting from a geo-stationary satellite are discussed. Using a system with such parameters, the results of subjective tests on co-channel interference are presented, and a simple formula is derived relating protection ratio and picture impairment grade.
Topics: impairment, deviation, sound, modulation, subcarrier, mhz, interference, interfering, protection,...
R&D Report 1964-32 : Local oscillator interference with UHF television reception J.G. Spencer This report discusses the possible effects of local-oscillator interference, from u.h.f. and v.h.f. receivers, with u.h.f. television reception. Measures which can be taken in respect of u.h.f. station planning and receiver design in order to minimize these effects are indicated.
Topics: interference, receiver, receivers, monochrome, iii, radiation, aerial, frequency, aerials, colour,...
R&D Report 1962-19 : Television co-channel interference at very low offsets. E.W. Taylor The subjective appearance of the patterns that are produced when a television transmission suffers co-channel interference at very low offsets is described, and the protection ratio required at these offsets is discussed. In the case of non-offset working, an assessment is made of the improvement of the frequency stability of each of the two vision carriers required to give a worth-while reduction of...
Topics: offset, protection, ratio, frequency, required, nominal, interference, offsets, television, scan,...
R&D Report 1990-07 : Satellite broadcasting: a common-frequency approach to wideband HDTV with a hand-made example 'plan' J.H. Stott The generation and analysis of a "hand-made" plan for satellite broadcasting are described. The plan is intended as an example of what could be achieved within any band which may be allocated for wide-band HDTV at a forthcoming World Administrative Radio Conference. It is shown that the whole of such a band could be used by every country...
Topics: ghz, orbit, hdtv, countries, frequency, interference, band, antenna, satellite, modulation,...
R&D Report 1966-07 : C.W. Interference with monachrome UHF television reception R V Harvey The protection ratios for a monochrome a television transmission against an interfering c.w. signal, as given in CCIR Recommendation 418, 1963, in the case of Standard 1 (the current U.K. standard on u.h.f.), were confined to frequency offsets between -2 Mc/s and +5 Mc/s from the vision carrier frequency. The work described in this report extends this data to offsets of up to 6.5 Mc/s, including the...
Topics: impairment, interference, sound, carrier, vision, signal, ratios, offsets, ccir, monochrome,...
R&D Report 1974-33 : UHF television: requirements for long-term and short-period carrier drive frequency stability R.V. Harvey The frequency stability required for the carrier drives of a group of co-channel television transmitters is examined theoretically. An upper limit is suggested for the permissible levels of long-term frequency drift and of frequency modulation uncorrelated with the video waveform. This takes into account both protection against co-channel interference and impairment...
Topics: frequency, modulation, phase, stability, precision, khz, deviation, carrier, interference,...
R&D Report 1972-04 : Interference characteristics of dual-standard monochrome television receivers operating in the UHF bands C.R.G. Reed This report gives the results of a series of measurements made in 1970 on the interference-rejection characteristics of six British monochrome dual-standard (Systems A and I) receivers operated in the UHF bands (Bands IV and V) using System I.
Topics: receiver, interference, signal, channel, mhz, amplitude, receivers, frequency, signals, carrier,...
R&D Report 1973-11 : MF network planning: The coverage under daytime conditions from a network of transmitters arranged in a uniform lattice R.A. Rowden The report collates definitions of the various types of network where transmitters are arranged geographically over an area and a given number of frequency channels is available for use. The method of calculation of the coverage is described and useful formulae stated. An exemplary tabulation, for limited ranges of power, frequency, ground...
Topics: kms, transmitters, coverage, network, khz, equilateral, transmitter, frequency, service range,...
R&D Report 1971-10 : Reduction of adjacent-channel interference in the LF and MF broadcast bands by reduction of the modulation bandwidth C.R.G. Reed Abstract Transmitter carrier frequencies in the LF and MF broadcast bands assigned under the Copenhagen Plan of 1946 are, for the most part, separated by 9 kHz. Transmitters and receivers operating in these bands are usually designed for a modulation bandwidth greater than 4.5 kHz although the receiver response may be appreciably attenuated at...
Topics: khz, interference, modulation, signal, filter, frequency, bandwidth, receiver, tests, interfering,...
R&D Report 1967-62 : Television co-channel interference: PAL transmissions A. Brown Subjective tests of the impairment produced by co-channel interference are described, with particular reference to PAL colour transmissions and the use of precision control of the vision carrier frequencies, and suitable protection ratios for planning purposes are recommended.
Topics: interfering, signal, offset, colour, tests, chrominance, khz, monochrome, protection, impairment,...
R&D Report 1971-35 : Protection ratios for 625-line System I television transmissions, impaired by interfering frequency-modulated television signals A. Brown Subjective tests have been carried out to find the protection ratio required by a 625-line system I television transmission, when the interfering signal is FM television. The effects of deviation, pre-emphasis, and energy-dispersal of the interfering signal are considered, as well as the addition of random white noise.
Topics: impairment, interfering, interference, protection, mhz, modulation, frequency, deviation, ratio,...
R&D Report 1983-18 : Satellite broadcasting: protection ratio requirements for enhanced transmissions using Extended PAL vision and digital sound signals. P. Shelswell The BBC has conducted experiments with signals for satellite broadcasting to demonstrate the possibilities of enhancement to both vision and sound. The resultant signal has a different spectrum from that of a conventionally coded signal. Thus it is necessary to examine interference protection ratios for the enhanced signal...
Topics: pal, warc, extended, mhz, protection, interference, signal, unwanted, enhanced, impairment, test...
R&D Report 1968-21 : Television co-channel interference: Protection ratio for five-thirds line frequency precision offset of carriers with moving pictures. A. Brown This report gives the results of subjective tests which were carried out to assess the protection ratio required when the vision carriers are offset by nearly the optimum frequency in the region of five-thirds line-scan frequency, and the modulation is a moving picture. The results obtained from different classes of observer are...
Topics: offset, ratio, protection, impairment, frequency, interference, carriers, observers, pictures,...
R&D Report 1963-09 : An appraisal of the Zenith- G.E. stereophonic system H. Page, G.J. Phillips, J.G. Spencer This report appraises performance of the Zenith-G.E. system of stereophonic broadcasting from the results of laboratory tests and of field trials with the Wrotham Third Programme transmitter. It also assesses the grade of service areas of five of the high-power v.h.f. sound transmitters, if this system were adopted. Provided that those listeners in unfavourable receiving locations...
Topics: stereophonic, interference, monophonic, field, ignition, frequency, receiver, degradation, field...
R&D Report 1971-18 : Selectivity of MF transistor portable receivers M.J. Buckley, J.G. Spencer Abstract Subjective measurements have been made in the laboratory on ten transistor portable receivers of current and recent type to determine their selectivity on the MF band, and the extent to which they might suffer overloading by strong local signals. The investigation covered frequency spacings between the wanted and interfering transmissions of from 9 kHz to approximately 250 kHz. The...
Topics: signal, frequency, receivers, selectivity, wanted, interference, interfering, khz, protection,...
R&D Report 1974-20 : Satellite broadcasting: channel separation requirements for FM television signals N.H.C. Gilchrist A practical investigation has been conducted in order to determine the frequency separation required between FM television signals, both with and without a sound subcarrier, so that mutual interference is avoided. The investigation was concerned primarily with interference between PAL colour television signals, but brief tests were conducted to determine the requirements...
Topics: mhz, signal, filter, receiver, frequency, channel, signals, sound, interfering, tests, sound...
BBC Monographs Collection
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A.E. Gallon, R.G. Kelly, J.L. Eaton, Mrs A.M. Bunting, R.A. Rowden, P. Knight, J.L. Eaton
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BBC Engineering 99, August, 1974. A.E. Gallon, R.G. Kelly, J.L. Eaton, Mrs A.M. Bunting, R.A. Rowden, P. Knight, J.L. Eaton. * Editorial: The Computer in Broadcasting * Principal Articles:Wenvoe - the BBC's Largest Television Station * The BBC General Election Computer System * A Computer Program for Calculating M F Sky-wave Interference * M F Network Planning: The Coverage under Daytime Conditions from a Network of Transmitters (arranged in a uniform lattice) * LF and MF Sky-wave...
Topics: bbc, transmitter, transmitters, conductivity, band, coverage, network, frequency, propagation,...
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J. Redmond, G.G. Johnstone, P.A. Tingey, R.V. Harvey
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BBC Engineering 103, June, 1976. J. Redmond, G.G. Johnstone, P.A. Tingey, R.V. Harvey. * Editorial: The future of broadcasting * Principal Articles:The Future of Broadcasting * A Portable Comprehensive UHF Test Set * A Crystal-controlled Monitoring Receiver for Medium and Low Frequencies * UHF Television: Requirements for Long-term and Short-period Carrier Drive Frequency Stability.
Topics: frequency, signal, bbc, output, television, carrier, modulation, broadcasting, oscillator,...
R&D Report 1970-38 : Satellite broadcasting: Spectrum efficiency of television services in the 12 GHz band G.J. Phillips The report is confined to a study of the use of geostationary satellites transmitting in the 12 GHz band to provide multiple television broadcast services within a wide area. The theoretical possibilities are first examined with reference to an ideal lattice of just-overlapping circular service areas. By proper assignment of satellite positions in the equatorial orbit and...
Topics: satellite, aerial, protection, receiving, lattice, satellites, transmitting, channel, service...
R&D Report 1974-06 : Computer programs for UHF co-channel interference prediction using a terrain data bank R.W. King, J.H. Causebrook A set of computer programs has been written to predict the interference caused by co-channel stations to the service of a television transmitter. These programs use geographical and transmitter information stored permanently on a magnetic drum. In this report an outline is given of the methods employed by the programs. Details are given of the required input...
Topics: data, transmitter, terrain, path, paths, calculation, receiver, profile, iii, field, path profile,...
R&D Report 1978-33 : M.F. andL.F. reception: susceptibility of domestic receivers to interference. R.V. Harvey Self-generated interference in domestic lf and mf broadcast receivers has been investigated theoretically and the susceptibility of five typical receivers has been measured. A systematic analysis of the results has been attempted and a procedure established for assisting planning exercises by assessing the likelihood of interference from particular combinations of frequencies.
Topics: khz, frequency, interference, frequencies, receivers, interfering, mechanism, signal, coefficients,...
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 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,...
R&D Report 1977-10 : UHF scatter propagation across the English Channel. G.H. Millard The incidence of scatter propagation in a trans-horizon path across the English Channel has been studied in order to assess the effect it has on the performance of a uhf television re-broadcast link to the Channel Islands. For small angles of scatter the degree of scattering observed was consistent with simple theory. The effect will result in a relatively minor degradation of link performance.
Topics: aerial, signal, scattering, interference, surface, kippure, aerials, directivity, scattered,...
R&D Report 1962-26 : Pattern visibility in television co-channel interference. E.W. Taylor The dependence of the subjective visibility of the primary interference pattern upon offset and protection ratio is discussed. On the assumption that the inclination of the interference stripes does not affect the visibility of the pattern, it is suggested that offsets may be gathered into a number of groups, each group containing offsets giving rise to patterns of equal visibility. The relationship...
Topics: offset, pattern, offsets, interference, ratio, visibility, frequency, stripes, curve, curves, wide...
R&D Report 1966-40 : Pulse sound: Protection ratios for 625-line colour transmissions in a 5 MHz channel: Specification of transmitter and receiver response/frequency characteristics. S.M. Edwardson, R.V. Harvey, D.W. Osborne In this report the response/frequency characteristics of transmitters and receivers of a 625-line NTSC colour television system with pulse sound occupying a 5 MHz channel are discussed and protection ratios for co-channel and adjacent-channel interference are deduced.
Topics: colour, mhz, transmissions, channel, subcarrier, ratios, protection, interference, adjacent, sound,...
R&D Report 1996-06 : The Crystal Palace FM filler experiment R.H. Evans, A.J. Bower In some areas of London, listeners to BBC Radio National FM services had suffered from poor reception for some time. The problem was particularly severe immediately south of the River Thames where around one million people suffered with unsatisfactory reception on portable and car receivers. This was due to path blocking of the direct signal from the BBCâs Wrotham transmitter, located several miles south...
Topics: wrotham, crystal, filler, palace, mhz, transmitter, frequency, khz, transmitters, offset, khz...
R&D Report 1968-46 : Calculation of the field strength required for a television service, in the presence of co-channel interfering signals. Part 3: The computer program R.W. Lee Parts 1 and 2, which have been issued separately, give the theory underlying the calculation processes which have been actually used in the BBC Research Department. Part 3 describes the original computer program used for carrying them out.
Topics: transmitter, field, terrain, location, test, interfering, calculation, strength, path, calculate,...
R&D Report 1975-09 : A traffic information service employing time division multiplex transmissions. R.S. Sandell, M.W. Harman The use of broadcasting to provide traffic and road information to motorists continues to be developed, but there remain several problems. It would seem that a real improvement could be realised if it were possible to provide the driver with a service dedicated to his needs, but which would not overwhelm him with irrelevant data. The shortage of frequencies and other...
Topics: traffic, field, receiver, strength, frequency, stations, mute, announcements, tdm, bbc, local...
R&D Report 1962-14 : Co-channel interference between television signals of the same or different standards. G.F. Newell, E.W. Taylor This report describes measurements of the ratios of the amplitudes of wanted and interfering signals which produce a particular subjective grade of interference. The measurements were made in order to ascertain the required protection ratios for mutual interference between two stations each operating on any of the three television standards at present in use...
Topics: interference, offset, signal, protection, frequency, ratios, offsets, interfering, required,...
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A.J. Pilgrim, K. Hacking, D.E. Susans, C.R.G. Reed, S.W. Amos
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BBC Engineering 89, January, 1972. A.J. Pilgrim, K. Hacking, D.E. Susans, C.R.G. Reed, S.W. Amos. * Editorial: Prospects for the Improvement of Reception in the M.F. and L.F. Bands * Principal Articles:The Move into Broadcasting Centre, Birmingham * Synchronous Demodulation in L.F./M/F/ Receivers * Reduction of Interference by Reduction of Modulation Bandwidth * An Active Deflector for U.H.F. Television Broadcasting.
Topics: receiver, modulation, signal, frequency, filter, bbc, khz, interference, bandwidth, carrier, wanted...
