Wave Tube for TV Transmitter
Development of Powerful High Efficiency Broadband Travelling Wave Tube for ТV Transmitter of New Generation in Band IV-V
Tech Area / Field
- INF-SIG/Sensors and Signal Processing/Information and Communications
3 Approved without Funding
NPO Toriy, Russia, Moscow
- Rohde&Schwarz GmbH & Co., Germany, Munich
Project summaryAt present in Russia and other countries of СIS to broadcast more television programs is the urgent problem. It was shown by analysing in common with Scientific and research institution of radio, that this problem can be solved by a manufacturing of a large number of ТV transmitters in band IV-V with 1-5 kW sync peak power for small, average and large cities under the traditional approach to this problem.
The tendency to increase a number of ТV channels will be remained for a long time. ТV transmitters that are manufacturing in Russia in band IV-V ("ILMEN") have essential defects: significant instability of the characteristics, low reliability, small efficiency and low ТV signal quality.
Therefore at the enterprises FSUE RPC “Toriy” and Scientific and Research Institute of Long-distance Radio Communication, included now in Concern "Radiotechnic and informational Systems", Inc., which developed earlier THE systems of anti-missiles defence, the possibility to create the multi-channel ТV transmitter of a new generation in band IV-V on the basis of their technological potential and earlier fulfilled developments was considered. As a result the project of TV transmitter of a new generation in band IV-V has been developed which for the first time will provide the multi-channel mode of operation in all frequency range 470-860 МHz improved quality of ТV signal and reduced energy consumption due to the output stage on the basis of powerful (up to 50-60 kW in saturation) broadband (bandwidth about 60%) TWT with a multi-stage depressed collector (technical efficiency not less than 40%). That ТV transmitter will ensure advantages on the basic characteristics not only before "Ilmen" transmitter, produced in Russia, but also before Rohde & Schwarz ТV transmitter of the type NT 354 A1, as well as the operational expenses will be decreased essentially by reducing of quantity of the attendants in multi-channel TV transmitter.
The development of the powerful broadband TWT with a multi-stage depressed collector should be the main step of the creation TV transmitter of a new generation, to which the proposed Project is intended.
On the first stage of the project it was planned to obtain sufficiently full information about possible market promotion of the designed TWT. It was supposed for that objective to determine the place of multi-channel TV transmitters in the system of Russia and CIS countries broadcasting, to find the multi-channel transmitter market capability, to carry out the search of potential customers, to reveal their demands to multi-channel transmitter use (as our collaborator has suggested) and to define more precisely the requirements to TWT output parameters.
The first stage works were carried out under the Project Development Grant # 922-99.
During the work under GDP 922-99 the draft technical project on the development of high-power automatic multi-channel TV radio transmitter for broadcasting of the colour TV signals in IV-V frequency bands (470-860 MHz) in any of three modes of operation was prepared in common with Scentific and Research Institute of Long-distance Radio Communication and Scientific and Research Institute of Radio:
– digital multi-channel terrestrial television broadcasting (DVB-T) according to the requirements of the standard EH 300.744 (ETS);
– analogue mutli-channel terrestrial television broadcasting (DK) according to the requirements of the national standards of countries, where MTVT will be delivered;
– simultaneous broadcasting of digital and analogue multi-channel TV signals.
In accordance with the project to use of two semi-complects (active reserve) with designed powerful broadband TWT in output cascade of every semi-complect is planned in the multi-channel transmitter structure scheme. The main features of TWT input signal forming and its parameters, the characteristics of TWT input and output cable feeder networks, the parameters of high voltage sources and TWT cooling system, the requirements to TWT output signal according to the abovementioned standards for digital and analogue TV broadcasting were determined. Besides the possibility of TWT operation not only in stationary conditions but in TV transmitter of container performance is necessary to take into consideration.
It was shown, that the best expedient variant for such the station will be overlapping only the part of IV-V frequency band (one third, for example) for the satisfaction of some technical problems. So all the TV range 470-860 MHz can be pided into the three subbands. It will permit to decrease the requirements to the bandwidth of the separate transmitter units and to increase their reliability. As a result the requirements to the TWT bandwidth can be decreased to 130-200 MHz for operation in two or three subbands of IV-V UHF range. In this case the technological base of FSUE RPC”Toriy”, created for the manufacture of YB-308 for anti-missile defence, will be used in the best way for new TWT design.
Before TWT design the following necessary works were carried out:
– the correction of software for 2-dimensions computer programs for interaction region simulation, multi-stage depressed collector design and the computation of the multi-signal mode of TWT operation;
– the analysis of various variants of electron gun, electro-optical system, multi-stage collector and TWT as a whole.
The opinion estimation of 20 large Russian TV Centres, carried out under the marketing investigations together with Russian State Television and Radiobroadcasting Company for the revelation of potential consumers of the multi-channel transmitters, was shown that almost all the TV Centres have the interest in use of such the transmitters. The results of this opinion estimation permit to make in common with Russian State Television and Radiobroadcasting Company the following conclusions:
– expansion of television network in Russia will mainly be carried out in a range of ultra high frequencies (470-860 MHz);
– the basic prospect of technical development of TV network in Russia is the digital TV of high and superhigh definition on the basis of the broadband TV transmitters;
– design and introduction of multi-channel TV transmitters on the basis of powerful broadband TWT will permit to transit gradually to digital TV broadcasting in Russia and CIS countries due to possibility of simultaneous broadcasting of several channels in analogue and digital formats, to modernize in the best way transmitting technical means of Regional TV Transmitting Centres and to use in the best way the informational field including “Internet”;
– possibility of the operation in broad frequency band by one transmitter simplifies broadcasting control, decreases the running costs due to reduce of serving staff, provides the extremely high quality of TV signal and simplifies the multi-channel operation by the single antenna due to addition of channel powers on the TWT input, but not the output;
– it is expedient to make in short time the model of multi-channel transmitter and test it in one of Regional TV Centres with assistance of Russia State Television Radiobroadcasting Company;
– all above-mentioned features of Russian TV market make it the best prepared to use multi-channel TV transmitters (the total volume of 5 kW TV transmitters in UHF band in Russia is not less than 400 units).
In spite of the Western Europe tendency to some lowering of the terrestrial broadcasting volume, carried out opinion estimation shows that in Russia and CIS countries opposite tendency takes place – striving to increase channel quantity of the terrestrial broadcasting.
The main conclusion of the results obtained under the Grant # 922-99 is the extremely high importance of proposed multi-channel transmitter for Russian market.
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