Research And Application Of Plc-based Logic Control System Of Tv Transmitter

Early television transmitters commonly use analog control system, in which the electric power distribution of traditional relay components is controlled by the logic control system of discrete components. This control mode includes a lot of interlocking contacts and complex wiring, with the improvement of control functions and control parameters, the line has become complicated. Meanwhile, the discrete logic structure greatly reduces the running reliability of the equipment, each level even each point would be a mistake to break off the logical operation step, leading to high fault rate of control system. Due to the complexity of the control circuit, finding out the error point becomes so difficult, so the dealing with abrupt breakdown time can not adjust to safety broadcast work "three minutes" request.CCTV-1 and HNTV-5 programs of Henan Broadcast and TV Transmitting Station cover as many as seven million people in Zhengzhou. Both channel 2 and channel 9 use electron tube TV transmitters, which are produced by Beijing Broadcast Equipment Factory in 1980s. Also the logic control system is made of discrete components. In order to improve the reliability of the transmitter operation, the author, with Professor Huang Yan of PLA Information Engineering University and the associated engineers of Henan Broadcast and TV Transmitting Station, repeatedly discussed the relevant technology. Without changing the transmitter's original logical relation, we designed a PLC-based logic control system, adding detection circuit and external auxiliary circuit, and finally completed the control system technical transformation.PLC-based control technology in television transmitter is a basic application of computer control system in radio and television technology. At present, to achieve the running situation of equipment, daily monitoring in most of the national transmitting stations mainly depends on staff's 24 hours on duty monitoring transmitting signal quality, visiting the transmitting equipment regularly, and recording technical target. Once error happens, it is necessary to quickly respond to the failure phenomenon, through artificial intervention to deal with all kinds of accidents. With the rapid development of computer, network, radio and television technology, to improve the management of transmitting station, automatic monitoring instead of"machine people watched"mode will be a development direction of TV transmitting station. Against current situation and future development direction ,in this paper we give a design of PLC-based, real-time monitoring system of transmitter, and the realized function, hardware structure, data management and software design are described in detail. Finally aimed to the working environment, the anti-jamming measures and manners to ensure reliability are introduced.